src/renderer/js/app.js

// ══════════════════════════════════════════════════════════════════════════════
// Chahua Markdown Video Studio - Main Application Controller
// Markdown-First Workflow - v2.0 Timeline Engine
// ══════════════════════════════════════════════════════════════════════════════
// Company: Chahua Development Co., Ltd.
// Version: 2.0.0

import { MarkdownParser } from '../../shared/markdown-parser.js';
import { buildLayoutTreeForSlide, LayoutNodeKind } from '../../shared/layout-schema.js';
import { VideoRenderer, blobToBase64 } from './video-renderer.js';
import { applyTemplate, getAllTemplates } from './templates.js';
import {
    getAllPresets,
    loadPreset,
    getCurrentConfig,
    updateConfigPart,
    initPresentationUI,
    reloadUI,
    loadConfigFromFrontmatter,
    resetConfig,
    computeSafeZoneMargins,
    SAFE_ZONE_CONFIG,
    getSmartLayoutFillRatio,
    getSmartLayoutStageFallback,
    SMART_LAYOUT_CONFIG,
    loadSavedConfig,
    exportConfigToFile,
    importConfigFromFile,
    setDisplayMode,
    getDisplayMode,
    getSafeZoneConfig
} from './presentation-config.js';
import { SlideEditor } from './slide-editor.js';
import { ConfigStorage } from './config-storage.js';
import { 
    switchToIntroMode, 
    switchToPresentationMode, 
    switchToEditorMode,
    getModeManager 
} from './mode-manager.js';

// ==============================================================================
// INTRO SCENE CONSTANTS - DO NOT MODIFY
// ==============================================================================
// WARNING: These constants are used exclusively by the intro scene system
// The intro scene is working perfectly - modifications are not needed
// Do not link these constants to presentation mode or any other logic
// ==============================================================================
// SMART LAYOUT CONSTANTS - Smart content layout optimization
// ==============================================================================
// DEPRECATED: Use SMART_LAYOUT_CONFIG from presentation-config.js instead
// Kept for backward compatibility only
const SMART_LAYOUT_FILL_RATIO = 0.92;
const SMART_LAYOUT_STAGE_FALLBACK = { width: 1280, height: 720 };

// DEPRECATED: Use SAFE_ZONE_CONFIG from presentation-config.js instead
// Kept for backward compatibility only
const SMART_SAFE_ZONE = {
    horizontalRatio: 0.06,
    verticalRatio: 0.08,
    maxHorizontalRatio: 0.12,
    maxVerticalRatio: 0.15,
    minHorizontal: 40,
    minVertical: 40
};

// ==============================================================================
// INTRO SCENE HELPER FUNCTIONS - DO NOT MODIFY
// ==============================================================================
// WARNING: These functions are used exclusively by the intro scene system
// Do not link these to presentation mode - create separate functions if needed
// ==============================================================================

/**
 * LOCKED - Intro scene utility function
 * Do not modify or reuse for other purposes
 */
function clamp(value, min, max) {
    return Math.min(Math.max(value, min), max);
}

/**
 * LOCKED - Intro scene safe zone calculation
 * Do not use for presentation mode - create separate function if needed
 * 
 * DEPRECATED: Use computeSafeZoneMargins from presentation-config.js instead
 */
function computeSafeZoneInsets(stageRect = {}) {
    // Redirect to new centralized function
    return computeSafeZoneMargins(stageRect);
}

/**
 * LOCKED - Intro scene padding formatter
 * Do not modify or reuse for other purposes
 */
function formatSafeZonePadding(insets) {
    return `${Math.round(insets.top)}px ${Math.round(insets.right)}px ${Math.round(insets.bottom)}px ${Math.round(insets.left)}px`;
}

/**
 * LOCKED - Intro scene padding applicator
 * Do not use for presentation mode - create separate function if needed
 */
function applySafeZonePadding(target, insets) {
    if (!target || !insets) return;

    const paddingValue = formatSafeZonePadding(insets);
    target.style.boxSizing = 'border-box';
    target.style.padding = paddingValue;
    target.style.setProperty('--smart-safe-padding', paddingValue);

    target.dataset.safeTop = String(Math.round(insets.top));
    target.dataset.safeBottom = String(Math.round(insets.bottom));
    target.dataset.safeLeft = String(Math.round(insets.left));
    target.dataset.safeRight = String(Math.round(insets.right));
}

const state = {
    markdown: '',
    frontmatter: {},
    slides: [],
    totalDuration: 0,
    template: 'modern',
    videoConfig: {
        resolution: '1920x1080',
        fps: 60,
        quality: 0.95
    },
    themeConfig: {
        accent: '#60a5fa'
    },
    isPlaying: false,
    isPaused: false,
    isPresentationMode: false,
    currentSlideIndex: 0,
    pauseResolve: null,
    errors: [],
    warnings: [],
    screenSensor: {
        width: window.innerWidth,
        height: window.innerHeight,
        pixelRatio: window.devicePixelRatio || 1,
        isLargeScreen: false,
        screenType: 'normal',
        isFullscreen: false,
        availableSpace: window.innerWidth * window.innerHeight,
        lastUpdate: Date.now()
    }
};

const dom = {
    stage: document.getElementById('stage'),
    stageFrame: document.getElementById('stageFrame'),
    pauseOverlay: document.getElementById('pauseOverlay'),
    navControls: document.getElementById('navControls'),
    prevSlideBtn: document.getElementById('prevSlideBtn'),
    nextSlideBtn: document.getElementById('nextSlideBtn'),
    slideCounter: document.getElementById('slideCounter'),
    fullscreenBtn: document.getElementById('fullscreenBtn'),
    sceneElements: null,
    statusPill: document.getElementById('statusPill'),
    statusLog: document.getElementById('statusLog'),
    progressContainer: document.getElementById('progressContainer'),
    progressBar: document.getElementById('progressBar'),
    progressText: document.getElementById('progressText'),
    markdownEditor: document.getElementById('markdownEditor'),
    markdownDiagnostics: document.getElementById('markdownDiagnostics'),
    markdownSummary: document.getElementById('markdownSummary'),
    timelineTotal: document.getElementById('timelineTotal'),
    timelineSceneList: document.getElementById('timelineSceneList'),
    assetChecklist: document.getElementById('assetChecklist'),
    templatesContainer: document.getElementById('templatesContainer'),
    templateActiveLabel: document.getElementById('templateActiveLabel'),
    // Presentation Settings Controls
    presetSelector: document.getElementById('presetSelector'),
    fontHeading: document.getElementById('fontHeading'),
    fontBody: document.getElementById('fontBody'),
    fontCode: document.getElementById('fontCode'),
    colorPrimary: document.getElementById('colorPrimary'),
    colorAccent: document.getElementById('colorAccent'),
    colorBackground: document.getElementById('colorBackground'),
    colorText: document.getElementById('colorText'),
    animationTransition: document.getElementById('animationTransition'),
    animationDuration: document.getElementById('animationDuration'),
    // Font Sizes
    fontSizeH1Min: document.getElementById('fontSizeH1Min'),
    fontSizeH1Base: document.getElementById('fontSizeH1Base'),
    fontSizeH1Max: document.getElementById('fontSizeH1Max'),
    fontSizeH2Min: document.getElementById('fontSizeH2Min'),
    fontSizeH2Base: document.getElementById('fontSizeH2Base'),
    fontSizeH2Max: document.getElementById('fontSizeH2Max'),
    fontSizeTextMin: document.getElementById('fontSizeTextMin'),
    fontSizeTextBase: document.getElementById('fontSizeTextBase'),
    fontSizeTextMax: document.getElementById('fontSizeTextMax'),
    lineHeightHeading: document.getElementById('lineHeightHeading'),
    lineHeightBody: document.getElementById('lineHeightBody'),
    // UI & Visual Effects
    previewOpacity: document.getElementById('previewOpacity'),
    overlayBlur: document.getElementById('overlayBlur'),
    navBorderWidth: document.getElementById('navBorderWidth'),
    backdropSpread: document.getElementById('backdropSpread'),
    backdropBlur: document.getElementById('backdropBlur'),
    // Border Widths
    headingBorderWidth: document.getElementById('headingBorderWidth'),
    blockquoteBorderWidth: document.getElementById('blockquoteBorderWidth'),
    imageBorderWidth: document.getElementById('imageBorderWidth'),
    linkUnderlineWidth: document.getElementById('linkUnderlineWidth'),
    tableBorderWidth: document.getElementById('tableBorderWidth'),
    hrBorderWidth: document.getElementById('hrBorderWidth'),
    // Typography Controls
    paragraphBefore: document.getElementById('paragraphBefore'),
    paragraphAfter: document.getElementById('paragraphAfter'),
    headingBefore: document.getElementById('headingBefore'),
    headingAfter: document.getElementById('headingAfter'),
    indentFirst: document.getElementById('indentFirst'),
    indentBlockquote: document.getElementById('indentBlockquote'),
    listIndent: document.getElementById('listIndent'),
    textAlign: document.getElementById('textAlign'),
    // Page Indicator
    pageIndicatorTop: document.getElementById('pageIndicatorTop'),
    pageIndicatorRight: document.getElementById('pageIndicatorRight'),
    pageIndicatorFontSize: document.getElementById('pageIndicatorFontSize'),
    pageIndicatorOpacity: document.getElementById('pageIndicatorOpacity'),
    pageIndicatorPaddingX: document.getElementById('pageIndicatorPaddingX'),
    pageIndicatorPaddingY: document.getElementById('pageIndicatorPaddingY'),
    pageIndicatorBgColor: document.getElementById('pageIndicatorBgColor'),
    pageIndicatorTextColor: document.getElementById('pageIndicatorTextColor'),
    // Smart List Column Settings
    smartListTwoColumn: document.getElementById('smartListTwoColumn'),
    smartListThreeColumn: document.getElementById('smartListThreeColumn'),
    // Content Layout & Positioning
    contentPaddingSmall: document.getElementById('contentPaddingSmall'),
    contentPaddingLarge: document.getElementById('contentPaddingLarge'),
    contentPaddingUltra: document.getElementById('contentPaddingUltra'),
    contentAlignHorizontal: document.getElementById('contentAlignHorizontal'),
    contentAlignVertical: document.getElementById('contentAlignVertical'),
    // Action Buttons
    saveSettingsBtn: document.getElementById('saveSettingsBtn'),
    resetSettingsBtn: document.getElementById('resetSettingsBtn'),
    // Other Controls
    syncMarkdownBtn: document.getElementById('syncMarkdownBtn'),
    loadMarkdownSample: document.getElementById('loadMarkdownSample'),
    importMarkdownBtn: document.getElementById('importMarkdownBtn'),
    openWorkspaceBtn: document.getElementById('openWorkspaceBtn'),
    presentationModeBtn: document.getElementById('presentationModeBtn'),
    exitPresentationBtn: document.getElementById('exitPresentationBtn'),
    stopPreviewBtn: document.getElementById('stopPreviewBtn'),
    stopExportBtn: document.getElementById('stopExportBtn'),
    previewBtn: document.getElementById('previewBtn'),
    recordWebMBtn: document.getElementById('recordWebMBtn'),
    resetBtn: document.getElementById('resetBtn'),
    securityBtn: document.getElementById('securityBtn'),
    measurementStage: null,
    measurementScene: null,
    measurementRoot: null
};

function flattenLayoutTree(layout) {
    if (!layout || !Array.isArray(layout.sections)) {
        return [];
    }

    const items = [];

    layout.sections.forEach(section => {
        const sectionId = section.id;
        section.blocks.forEach(block => {
            const baseMeta = {
                layoutBlockId: block.id,
                layoutBlockKind: block.kind,
                sectionId
            };

            switch (block.kind) {
                case LayoutNodeKind.HEADING: {
                    const level = Math.min(Math.max(block.level || 1, 1), 6);
                    items.push({
                        ...baseMeta,
                        type: `h${level}`,
                        content: block.text || '',
                        html: block.html || null
                    });
                    break;
                }
                case LayoutNodeKind.TEXT: {
                    items.push({
                        ...baseMeta,
                        type: 'text',
                        content: block.text || '',
                        html: block.html || null
                    });
                    break;
                }
                case LayoutNodeKind.LIST: {
                    const listType = block.listType;
                    block.items.forEach((listItem, index) => {
                        let type = 'list-item';
                        if (listType === 'ordered') type = 'numbered-item';
                        if (listType === 'task') type = 'task-list';

                        items.push({
                            ...baseMeta,
                            type,
                            content: listItem.text || '',
                            marker: listItem.marker || '•',
                            number: listItem.number || index + 1,
                            checked: !!listItem.checked,
                            listId: block.id,
                            listItemId: listItem.id,
                            html: listItem.html || null
                        });
                    });
                    break;
                }
                case LayoutNodeKind.CODE: {
                    items.push({
                        ...baseMeta,
                        type: 'code',
                        content: block.content || '',
                        language: block.language || 'text'
                    });
                    break;
                }
                case LayoutNodeKind.TABLE: {
                    items.push({
                        ...baseMeta,
                        type: 'table',
                        rows: block.rows || []
                    });
                    break;
                }
                case LayoutNodeKind.CALLOUT: {
                    items.push({
                        ...baseMeta,
                        type: 'blockquote',
                        content: block.text || '',
                        html: block.html || null
                    });
                    break;
                }
                case LayoutNodeKind.IMAGE: {
                    items.push({
                        ...baseMeta,
                        type: 'image',
                        src: block.src,
                        alt: block.alt || '',
                        title: block.title || ''
                    });
                    break;
                }
                case LayoutNodeKind.DIVIDER: {
                    items.push({
                        ...baseMeta,
                        type: 'hr'
                    });
                    break;
                }
                case LayoutNodeKind.HTML: {
                    items.push({
                        ...baseMeta,
                        type: 'html',
                        content: block.html || '',
                        html: block.html || null
                    });
                    break;
                }
                case LayoutNodeKind.LINK: {
                    items.push({
                        ...baseMeta,
                        type: 'link',
                        text: block.text || block.href || '',
                        url: block.href || '',
                        title: block.title || '',
                        html: block.html || null
                    });
                    break;
                }
                default: {
                    items.push({
                        ...baseMeta,
                        type: 'text',
                        content: block.text || block.content || '',
                        html: block.html || null
                    });
                }
            }
        });
    });

    return items;
}

function enrichSlidesWithLayout(slides) {
    return slides.map(slide => {
        const layout = buildLayoutTreeForSlide(slide);
        const renderItems = flattenLayoutTree(layout);
        const visualLines = slide.visualLines != null ? slide.visualLines : layout?.metrics?.estimatedLines;

        return {
            ...slide,
            layout,
            renderItems,
            visualLines
        };
    });
}

// ==============================================================================
// INTRO SCENE MEASUREMENT STAGE - DO NOT MODIFY
// ==============================================================================
// WARNING: This function creates measurement stage for intro scene only
// Do not link to presentation mode logic
// ==============================================================================

/**
 * LOCKED - Intro scene measurement stage setup
 * Do not modify - intro scene depends on this exact implementation
 */
function ensureMeasurementStage() {
    if (!dom.measurementStage) {
        const measurementStage = document.createElement('div');
        measurementStage.id = 'smartMeasurementStage';
        measurementStage.style.position = 'fixed';
        measurementStage.style.top = '-10000px';
        measurementStage.style.left = '-10000px';
        measurementStage.style.visibility = 'hidden';
        measurementStage.style.pointerEvents = 'none';
        measurementStage.style.zIndex = '-1';

        const measurementScene = document.createElement('div');
        measurementScene.className = 'scene active';
        measurementScene.dataset.scene = 'body';

        const measurementRoot = document.createElement('div');
        measurementRoot.className = 'smart-layout-root relative z-10 space-y-4';

        measurementScene.appendChild(measurementRoot);
        measurementStage.appendChild(measurementScene);

        document.body.appendChild(measurementStage);
        dom.measurementStage = measurementStage;
        dom.measurementScene = measurementScene;
        dom.measurementRoot = measurementRoot;
    }

    updateMeasurementStageSize();

    if (dom.measurementRoot) {
        dom.measurementRoot.innerHTML = '';
    }

    return dom.measurementRoot;
}

// ==============================================================================
// INTRO SCENE SIZE UPDATE - DO NOT MODIFY
// ==============================================================================
// WARNING: This function syncs measurement stage size for intro scene only
// Do not use for presentation mode - create separate function if needed
// ==============================================================================

/**
 * LOCKED - Intro scene measurement stage size synchronization
 * Do not modify - intro scene depends on this exact implementation
 */
function updateMeasurementStageSize() {
    if (!dom.measurementStage) return;

    dom.measurementRoot.innerHTML = '';

    const stageRect = dom.stage
        ? dom.stage.getBoundingClientRect()
        : dom.stageFrame
            ? dom.stageFrame.getBoundingClientRect()
            : getSmartLayoutStageFallback();

    dom.measurementStage.style.width = `${stageRect.width}px`;
    dom.measurementStage.style.height = `${stageRect.height}px`;

    const screenType = state.screenSensor?.screenType || 'normal';
    dom.measurementStage.classList.remove('screen-normal', 'screen-large', 'screen-ultra');
    dom.measurementStage.classList.add(`screen-${screenType}`);

    if (dom.measurementScene) {
        // Get padding values from CSS variables (set by presentation config)
        const root = document.documentElement;
        const paddingSmall = parseInt(root.style.getPropertyValue('--content-padding-small')) || 40;
        const paddingLarge = parseInt(root.style.getPropertyValue('--content-padding-large')) || 48;
        const paddingUltra = parseInt(root.style.getPropertyValue('--content-padding-ultra')) || 64;
        const alignHorizontal = root.style.getPropertyValue('--content-align-horizontal') || 'center';
        const alignVertical = root.style.getPropertyValue('--content-align-vertical') || 'center';

        let paddingTop = paddingSmall;
        let paddingSides = paddingSmall;

        if (screenType === 'large') {
            paddingTop = paddingLarge;
            paddingSides = paddingLarge;
        } else if (screenType === 'ultra') {
            paddingTop = paddingUltra;
            paddingSides = paddingUltra;
        }

        // Apply alignment from config
        dom.measurementScene.style.justifyContent = alignHorizontal;
        dom.measurementScene.style.alignItems = alignVertical;

        dom.measurementScene.style.paddingTop = `${paddingTop}px`;
        dom.measurementScene.style.paddingBottom = `${paddingTop}px`;
        dom.measurementScene.style.paddingLeft = `${paddingSides}px`;
        dom.measurementScene.style.paddingRight = `${paddingSides}px`;
    }

    if (dom.measurementRoot) {
        dom.measurementRoot.style.width = '100%';
        dom.measurementRoot.style.maxWidth = '100%';
    }
}

function setupTabs() {
    const tabButtons = document.querySelectorAll('.tab-button');
    const tabContents = document.querySelectorAll('.tab-content');

    tabButtons.forEach(button => {
        button.addEventListener('click', () => {
            const tabName = button.dataset.tab;

            tabButtons.forEach(btn => btn.classList.remove('active'));
            tabContents.forEach(content => content.classList.remove('active'));

            button.classList.add('active');
            const target = document.querySelector(`[data-tab-content="${tabName}"]`);
            if (target) {
                target.classList.add('active');
            }
        });
    });
}

function getTemplateEmoji(templateId) {
    const icons = {
        modern: '◆',
        classic: '■',
        minimal: '○',
        mono: '●',
        rounded: '◉',
        space: '▲',
        code: '◈',
        tech: '◐',
        display: '▼',
        corporate: '□'
    };
    return icons[templateId] || '◇';
}

// ══════════════════════════════════════════════════════════════════════════════
// Presentation Settings (replaces fixed templates)
// ══════════════════════════════════════════════════════════════════════════════

function setupPresentationSettings() {
    // Initialize UI with callbacks
    initPresentationUI(dom, {
        onUpdate: updateStagePreview,
        onSave: savePresentationSettings,
        setStatus: setStatus
    });
}

function savePresentationSettings(config, presetName) {
    // ⚠️ DEPRECATED: Frontmatter config saving has been removed
    // All settings are now automatically saved to localStorage
    // Use Export Config button to create JSON backup files
    
    console.log('[App] ℹ️ Config auto-saved to localStorage');
    console.log('[App] Current preset:', presetName || 'custom');
    
    // Note: Auto-save is handled by setConfig() and updateConfigPart() in presentation-config.js
    // No manual frontmatter saving needed anymore
}

function setupTemplates() {
    if (!dom.templatesContainer) return;

    dom.templatesContainer.innerHTML = '';
    const templates = getAllTemplates();

    templates.forEach(template => {
        const card = document.createElement('div');
        card.className = `template-card ${template.id === state.template ? 'active' : ''}`;
        card.innerHTML = `
            <div class="text-2xl mb-2">${getTemplateEmoji(template.id)}</div>
            <div class="font-semibold text-sm mb-1">${template.name}</div>
            <div class="text-xs text-slate-400">${template.description}</div>
        `;

        card.addEventListener('click', () => selectTemplate(template.id));
        dom.templatesContainer.appendChild(card);
    });
}

function selectTemplate(templateId) {
    state.template = templateId;

    const cards = dom.templatesContainer ? dom.templatesContainer.querySelectorAll('.template-card') : [];
    cards.forEach(card => card.classList.remove('active'));
    const templates = getAllTemplates();
    const index = templates.findIndex(t => t.id === templateId);
    if (cards[index]) {
        cards[index].classList.add('active');
    }

    applyTemplate(templateId);
    updateTemplateUI();
    upsertFrontmatterValue('template', templateId);

    if (state.slides.length > 0) {
        syncMarkdown();
    }

    setStatus(`Template: ${templateId}`, 'online');
}

function updateTemplateUI() {
    if (!dom.templateActiveLabel) return;
    dom.templateActiveLabel.textContent = state.template;
}

// ══════════════════════════════════════════════════════════════════════════════
// Markdown Controls & Parsing
// ══════════════════════════════════════════════════════════════════════════════

function setupMarkdownControls() {
    dom.syncMarkdownBtn.addEventListener('click', syncMarkdown);
    dom.loadMarkdownSample.addEventListener('click', loadSampleDeck);
    dom.importMarkdownBtn.addEventListener('click', importMarkdownFile);
    dom.openWorkspaceBtn.addEventListener('click', openWorkspaceFolder);
    
    let markdownTimeout;
    dom.markdownEditor.addEventListener('input', () => {
        clearTimeout(markdownTimeout);
        markdownTimeout = setTimeout(() => {
            dom.syncMarkdownBtn.classList.add('pulse');
        }, 1000);
    });
    
    // Setup Drag & Drop for markdown editor
    setupMarkdownDropZone();
}

/**
 * Setup Drag & Drop zone for markdown files
 */
function setupMarkdownDropZone() {
    const dropZone = document.getElementById('markdownDropZone');
    const textarea = dom.markdownEditor;
    const overlay = dropZone?.querySelector('.drop-overlay');
    
    if (!dropZone || !textarea || !overlay) return;
    
    // Prevent default drag behaviors on the document
    ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
        dropZone.addEventListener(eventName, preventDefaults, false);
        document.body.addEventListener(eventName, preventDefaults, false);
    });
    
    function preventDefaults(e) {
        e.preventDefault();
        e.stopPropagation();
    }
    
    // Highlight drop zone when dragging over
    ['dragenter', 'dragover'].forEach(eventName => {
        dropZone.addEventListener(eventName, () => {
            dropZone.classList.add('drag-over');
            overlay.classList.remove('hidden');
        }, false);
    });
    
    ['dragleave', 'drop'].forEach(eventName => {
        dropZone.addEventListener(eventName, () => {
            dropZone.classList.remove('drag-over');
            overlay.classList.add('hidden');
        }, false);
    });
    
    // Handle dropped files
    dropZone.addEventListener('drop', handleDrop, false);
    
    async function handleDrop(e) {
        const dt = e.dataTransfer;
        const files = dt.files;
        
        if (files.length === 0) return;
        
        const file = files[0];
        const fileName = file.name.toLowerCase();
        
        // Check if it's a text-based file
        if (!fileName.endsWith('.md') && 
            !fileName.endsWith('.markdown') && 
            !fileName.endsWith('.txt')) {
            setStatus('Please drop a markdown file (.md, .markdown, .txt)', 'online');
            return;
        }
        
        try {
            const text = await file.text();
            textarea.value = text;
            setStatus(`Loaded: ${file.name} (${formatFileSize(file.size)})`, 'online');
            dom.syncMarkdownBtn.classList.add('pulse');
            
            // Auto-sync if markdown is valid
            if (text.trim().length > 0) {
                setTimeout(() => {
                    syncMarkdown();
                }, 500);
            }
        } catch (error) {
            console.error('[App] Drop error:', error);
            setStatus('Failed to read file', 'online');
        }
    }
}

/**
 * Format file size for display
 */
function formatFileSize(bytes) {
    if (bytes < 1024) return bytes + ' B';
    if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' KB';
    return (bytes / 1024 / 1024).toFixed(1) + ' MB';
}

async function syncMarkdown() {
    try {
        dom.syncMarkdownBtn.classList.remove('pulse');
        dom.syncMarkdownBtn.textContent = 'Sync Markdown';
        setStatus('Parsing markdown...', 'online');
        
        state.markdown = dom.markdownEditor.value;
        
        parseFrontmatter();
        
        // Determine slide break mode from frontmatter or use default
        const slideBreakMode = state.frontmatter.slideBreak || 'auto';
        let parserOptions = {
            h1AsSlide: true,
            h2AsSlide: true,
            slideBreak: '---'
        };

        switch (slideBreakMode) {
            case 'h1':
                parserOptions.h1AsSlide = true;
                parserOptions.h2AsSlide = false;
                break;
            case 'h2':
                parserOptions.h1AsSlide = false;
                parserOptions.h2AsSlide = true;
                break;
            case 'delimiter':
            case 'manual':
                parserOptions.h1AsSlide = false;
                parserOptions.h2AsSlide = false;
                break;
            case 'auto':
            default:
                parserOptions.h1AsSlide = true;
                parserOptions.h2AsSlide = true;
        }
        
    const parser = new MarkdownParser(parserOptions);
    const parsedSlides = parser.parse(state.markdown);
    state.slides = enrichSlidesWithLayout(parsedSlides);
    state.totalDuration = state.slides.reduce((sum, slide) => sum + slide.duration, 0);
        
        validateMarkdown();
        updateMarkdownSummary();
        updateTimelineUI();
        updateStagePreview();
        applyConfigFromFrontmatter();
        
        if (state.errors.length === 0) {
            dom.markdownDiagnostics.classList.add('hidden');
            setStatus(`Synced: ${state.slides.length} slides, ${formatDuration(state.totalDuration)}`, 'online');
        } else {
            showDiagnostics();
        }
        
    } catch (error) {
        console.error('[App] Sync error:', error);
        state.errors.push(`Parse error: ${error.message}`);
        showDiagnostics();
        setStatus('Sync failed - see diagnostics', 'online');
    }
}

function parseFrontmatter() {
    state.frontmatter = {};
    const lines = state.markdown.split('\n');
    let inFrontmatter = false;
    let frontmatterLines = [];
    let foundClosing = false;
    
    // Frontmatter must start at line 0 or 1 (after empty line)
    const startLine = lines[0].trim() === '' ? 1 : 0;
    
    for (let i = startLine; i < lines.length; i++) {
        const line = lines[i].trim();
        
        // First delimiter
        if (line === '---' && !inFrontmatter && i === startLine) {
            inFrontmatter = true;
            continue;
        }
        
        // Closing delimiter
        if (line === '---' && inFrontmatter) {
            foundClosing = true;
            break;
        }
        
        // Collect frontmatter lines
        if (inFrontmatter) {
            // Stop if we hit 50 lines without closing (prevent runaway)
            if (i - startLine > 50) {
                console.warn('[App] Frontmatter not closed within 50 lines, ignoring');
                state.frontmatter = {};
                return;
            }
            frontmatterLines.push(line);
        }
    }
    
    // If no valid frontmatter block found, return empty
    if (!foundClosing) {
        state.frontmatter = {};
        return;
    }
    
    // Parse YAML-like frontmatter
    frontmatterLines.forEach(line => {
        const match = line.match(/^([^:]+):\s*(.+)$/);
        if (match) {
            const key = match[1].trim();
            let value = match[2].trim().replace(/^["']|["']$/g, '');
            state.frontmatter[key] = value;
        }
    });
}

function upsertFrontmatterValue(key, value) {
    state.frontmatter[key] = value;
    const lines = dom.markdownEditor.value.split('\n');
    let inFrontmatter = false;
    let frontmatterStartIndex = -1;
    let frontmatterEndIndex = -1;
    let keyFound = false;
    
    // Find frontmatter block
    for (let i = 0; i < lines.length; i++) {
        const line = lines[i].trim();
        if (line === '---') {
            if (!inFrontmatter) {
                inFrontmatter = true;
                frontmatterStartIndex = i;
                continue;
            } else {
                frontmatterEndIndex = i;
                break;
            }
        }
    }

    // If no frontmatter block exists, create one
    if (frontmatterStartIndex === -1) {
        lines.unshift('---', `${key}: ${value}`, '---', '');
        dom.markdownEditor.value = lines.join('\n');
        return;
    }

    // Check if key already exists and update it
    for (let i = frontmatterStartIndex + 1; i < frontmatterEndIndex; i++) {
        const line = lines[i].trim();
        if (line.startsWith(`${key}:`)) {
            lines[i] = `${key}: ${value}`;
            keyFound = true;
            break;
        }
    }
    
    // If key not found, insert before closing delimiter
    if (!keyFound && frontmatterEndIndex > 0) {
        lines.splice(frontmatterEndIndex, 0, `${key}: ${value}`);
    }
    
    dom.markdownEditor.value = lines.join('\n');
}

function applyConfigFromFrontmatter() {
    // ⚠️ CHANGED: Only load config from frontmatter if user has NO saved config
    // This prevents overwriting user's saved settings when loading different markdown files
    
    const hasSavedConfig = ConfigStorage.hasSavedConfig();
    
    if (!hasSavedConfig) {
        // No saved config - load from frontmatter as fallback
        console.log('[App] No saved config found, loading from markdown frontmatter');
        loadConfigFromFrontmatter(state.frontmatter, dom);
    } else {
        console.log('[App] Using saved config, ignoring markdown frontmatter');
    }

    // Legacy template support (fallback for old markdown files)
    if (state.frontmatter.template) {
        state.template = state.frontmatter.template;
        applyTemplate(state.template);
        updateTemplateUI();
    }
    
    // Video config
    if (state.frontmatter['video.resolution']) {
        state.videoConfig.resolution = state.frontmatter['video.resolution'];
        const resSelect = document.querySelector('[data-config="video.resolution"]');
        if (resSelect) resSelect.value = state.videoConfig.resolution;
    }
    
    if (state.frontmatter['video.fps']) {
        state.videoConfig.fps = parseInt(state.frontmatter['video.fps']);
        const fpsSelect = document.querySelector('[data-config="video.fps"]');
        if (fpsSelect) fpsSelect.value = state.videoConfig.fps;
    }
    
    if (state.frontmatter['video.quality']) {
        state.videoConfig.quality = parseFloat(state.frontmatter['video.quality']);
        const qualitySlider = document.querySelector('[data-config="video.quality"]');
        if (qualitySlider) {
            qualitySlider.value = state.videoConfig.quality;
            document.getElementById('qualityValue').textContent = Math.round(state.videoConfig.quality * 100) + '%';
        }
    }
    
    // Theme config
    if (state.frontmatter['theme.accent']) {
        state.themeConfig.accent = state.frontmatter['theme.accent'];
        const accentInput = document.querySelector('[data-config="theme.accent"]');
        if (accentInput) accentInput.value = state.themeConfig.accent;
        document.documentElement.style.setProperty('--accent-color', state.themeConfig.accent);
    }
}

function validateMarkdown() {
    state.errors = [];
    state.warnings = [];
    
    if (!state.markdown.trim()) {
        state.errors.push('Markdown is empty');
        return;
    }
    
    // Check frontmatter validity
    const lines = state.markdown.split('\n');
    if (lines[0].trim() === '---') {
        let foundClosing = false;
        for (let i = 1; i < Math.min(lines.length, 50); i++) {
            if (lines[i].trim() === '---') {
                foundClosing = true;
                break;
            }
        }
        if (!foundClosing) {
            state.errors.push('Missing closing frontmatter delimiter (---). Add --- after your frontmatter block.');
        }
    }
    
    if (state.slides.length === 0) {
        const slideBreak = state.frontmatter.slideBreak || 'auto';
        if (slideBreak === 'h1') {
            state.errors.push('No slides found - add # headings to create slides (slideBreak: h1 mode)');
        } else if (slideBreak === 'h2') {
            state.errors.push('No slides found - add ## headings to create slides (slideBreak: h2 mode)');
        } else {
            state.errors.push('No slides found - add --- separators or # headings');
        }
        return;
    }
    
    // Warn about short slides
    state.slides.forEach((slide, i) => {
        const slideName = (slide.title || '').trim() || `Slide ${i + 1}`;

        if (slide.duration < 2) {
            state.warnings.push(`${slideName} is very short (${slide.duration}s) - consider adding more content`);
        }
        if (slide.duration > 60) {
            state.warnings.push(`${slideName} is very long (${slide.duration}s) - consider splitting`);
        }
        if (slide.content.length === 0) {
            state.warnings.push(`${slideName} has no content`);
        }
    });
    
    // Warn about total duration
    if (state.totalDuration > 600) {
        state.warnings.push(`Total duration is ${formatDuration(state.totalDuration)} (over 10 minutes) - consider shorter presentation`);
    }
}

function showDiagnostics() {
    if (state.errors.length === 0 && state.warnings.length === 0) {
        dom.markdownDiagnostics.classList.add('hidden');
        return;
    }
    
    const messages = [
        ...state.errors.map(e => `[ERROR] ${e}`),
        ...state.warnings.map(w => `[WARN] ${w}`)
    ];
    
    dom.markdownDiagnostics.innerHTML = messages.join('<br>');
    dom.markdownDiagnostics.classList.remove('hidden');
}

function updateMarkdownSummary() {
    dom.markdownSummary.innerHTML = `
        <strong>Slides:</strong> ${state.slides.length} | 
        <strong>Duration:</strong> ${formatDuration(state.totalDuration)} | 
        <strong>Template:</strong> ${state.template}
    `;
}

// ══════════════════════════════════════════════════════════════════════════════
// Timeline UI Updates
// ══════════════════════════════════════════════════════════════════════════════

function updateTimelineUI() {
    dom.timelineTotal.textContent = formatDuration(state.totalDuration);
    
    let currentTime = 0;
    const sceneHTML = state.slides.map((slide, i) => {
        const startTime = currentTime;
        const endTime = currentTime + slide.duration;
        currentTime = endTime;
        
        // Pagination indicator
        const pageInfo = slide.totalPages > 1 
            ? `<span class="timeline-page-indicator">Page ${slide.pageNumber}/${slide.totalPages}</span>`
            : '';
        
        // Visual lines indicator
        const linesInfo = slide.visualLines 
            ? `<span class="text-xs opacity-60">${Math.round(slide.visualLines)} lines</span>`
            : '';
        
        const titleText = (slide.title || '').trim();
        const slideLabel = titleText
            ? `Slide ${i + 1} - ${escapeHtml(titleText)}`
            : `Slide ${i + 1}`;

        return `
            <div class="py-3 flex flex-col gap-1">
                <div class="flex items-center justify-between text-sm text-slate-200">
                    <div class="flex items-center gap-2">
                        <span>${slideLabel}</span>
                        ${pageInfo}
                    </div>
                    <span>${slide.duration}s</span>
                </div>
                <div class="flex items-center justify-between">
                    <p class="text-xs text-slate-500">
                        ${formatTimecode(startTime)} to ${formatTimecode(endTime)}
                    </p>
                    ${linesInfo}
                </div>
            </div>
        `;
    }).join('<div class="border-t border-slate-800"></div>');
    
    dom.timelineSceneList.innerHTML = sceneHTML || '<p class="text-slate-500 text-sm">No slides yet</p>';
    updateAssetChecklist();
}

function updateAssetChecklist() {
    const assets = [];
    state.slides.forEach(slide => {
        const items = slide.renderItems || slide.content || [];
        items.forEach(item => {
            if (item.type === 'image') {
                assets.push({ path: item.src, status: 'pending' });
            }
        });
    });
    
    if (assets.length === 0) {
        dom.assetChecklist.innerHTML = '<li class="text-slate-500">No assets referenced</li>';
        return;
    }
    
    const assetHTML = assets.map(asset => `
        <li class="flex items-center justify-between">
            <span>${escapeHtml(asset.path)}</span>
            <span class="status-pill ${asset.status}">${asset.status}</span>
        </li>
    `).join('');
    dom.assetChecklist.innerHTML = assetHTML;
}

// ==============================================================================
// INTRO SCENE - STAGE PREVIEW SYSTEM - DO NOT MODIFY
// ==============================================================================
// WARNING: These functions are used exclusively by the intro scene
// The intro scene is working perfectly with UI sidebar and small preview
// Any modifications may break the intro scene display
// Do not link these to presentation mode - use separate functions
// ==============================================================================

/**
 * LOCKED - Intro scene preview data extraction
 * Do not modify - intro scene working perfectly
 */
function getStagePreviewData(slides, totalDuration) {
    if (!slides || slides.length === 0) {
        return null;
    }

    const firstSlide = slides[0];
    const lastSlide = slides[slides.length - 1];

    let currentTime = 0;
    const timelineItems = slides.slice(0, 3).map((slide, index) => {
        const slideTitle = slide.title || 'Untitled Slide';
        const startTime = currentTime;
        const endTime = currentTime + slide.duration;
        currentTime = endTime;

        return {
            label: `Slide ${index + 1} - ${slideTitle}`,
            startTime,
            endTime
        };
    });

    return {
        intro: {
            title: firstSlide.title || 'Untitled Slide',
            subtitle: firstSlide.subtitle || 'Markdown Video Studio'
        },
        outro: {
            title: lastSlide.title || 'Thank You',
            tagline: `${slides.length} slides - ${formatDuration(totalDuration)}`
        },
        timelineItems
    };
}

/**
 * LOCKED - Intro scene preview renderer
 * Do not modify - intro scene working perfectly
 */
function renderStagePreview(previewData) {
    if (!previewData) return;

    const introTitle = document.querySelector('[data-bind="intro.title"]');
    const introSubtitle = document.querySelector('[data-bind="intro.subtitle"]');
    if (introTitle) introTitle.textContent = previewData.intro.title;
    if (introSubtitle) introSubtitle.textContent = previewData.intro.subtitle;

    const outroTitle = document.querySelector('[data-bind="outro.title"]');
    const outroTagline = document.querySelector('[data-bind="outro.tagline"]');
    if (outroTitle) outroTitle.textContent = previewData.outro.title;
    if (outroTagline) outroTagline.textContent = previewData.outro.tagline;

    const timelinePreview = document.getElementById('timelinePreview');
    if (!timelinePreview) return;

    const previewHTML = previewData.timelineItems.map(item => (
        `
            <li class="flex items-start justify-between gap-3">
                <span class="font-semibold">${escapeHtml(item.label)}</span>
                <span class="opacity-70">${formatTimecode(item.startTime)} to ${formatTimecode(item.endTime)}</span>
            </li>
        `
    )).join('');

    timelinePreview.innerHTML = previewHTML;
}

function updateStagePreview() {
    if (state.slides.length === 0) return;

    const previewData = getStagePreviewData(state.slides, state.totalDuration);
    renderStagePreview(previewData);
}

// ══════════════════════════════════════════════════════════════════════════════
// Config Inputs
// ══════════════════════════════════════════════════════════════════════════════

function setupConfigInputs() {
    const resSelect = document.querySelector('[data-config="video.resolution"]');
    if (resSelect) {
        resSelect.addEventListener('change', (e) => {
            state.videoConfig.resolution = e.target.value;
            upsertFrontmatterValue('video.resolution', e.target.value);
        });
    }
    
    const fpsSelect = document.querySelector('[data-config="video.fps"]');
    if (fpsSelect) {
        fpsSelect.addEventListener('change', (e) => {
            state.videoConfig.fps = parseInt(e.target.value);
            upsertFrontmatterValue('video.fps', e.target.value);
        });
    }
    
    const qualitySlider = document.querySelector('[data-config="video.quality"]');
    const qualityValue = document.getElementById('qualityValue');
    if (qualitySlider) {
        qualitySlider.addEventListener('input', (e) => {
            const value = parseFloat(e.target.value);
            state.videoConfig.quality = value;
            if (qualityValue) qualityValue.textContent = Math.round(value * 100) + '%';
            upsertFrontmatterValue('video.quality', value.toFixed(2));
        });
    }
    
    const accentInput = document.querySelector('[data-config="theme.accent"]');
    if (accentInput) {
        accentInput.addEventListener('input', (e) => {
            state.themeConfig.accent = e.target.value;
            document.documentElement.style.setProperty('--accent-color', e.target.value);
            upsertFrontmatterValue('theme.accent', e.target.value);
        });
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Export Controls
// ══════════════════════════════════════════════════════════════════════════════

function setupExportControls() {
    dom.previewBtn.addEventListener('click', previewTimeline);
    dom.recordWebMBtn.addEventListener('click', exportVideo);
    dom.resetBtn.addEventListener('click', resetApplication);
    dom.securityBtn.addEventListener('click', showSecurityStats);
    
    // Stop buttons
    if (dom.stopPreviewBtn) {
        dom.stopPreviewBtn.addEventListener('click', () => {
            stopPreview();
        });
    }
    
    if (dom.stopExportBtn) {
        dom.stopExportBtn.addEventListener('click', () => {
            // Stop export will be handled by the export function
            state.isExporting = false;
            if (dom.stopExportBtn) dom.stopExportBtn.classList.add('hidden');
        });
    }
    
    const rendererBackend = document.getElementById('rendererBackend');
    if (rendererBackend) {
        rendererBackend.textContent = 'MediaRecorder (WebM)';
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Configuration Management (Import/Export/Reset)
// ══════════════════════════════════════════════════════════════════════════════

function setupConfigManagement() {
    // Export Config Button
    const exportConfigBtn = document.getElementById('exportConfigBtn');
    if (exportConfigBtn) {
        exportConfigBtn.addEventListener('click', async () => {
            try {
                await exportConfigToFile();
                setStatus('Config exported successfully', 'online');
            } catch (error) {
                console.error('[App] Failed to export config:', error);
                setStatus('Failed to export config', 'error');
            }
        });
    }

    // Import Config Button
    const importConfigBtn = document.getElementById('importConfigBtn');
    if (importConfigBtn) {
        importConfigBtn.addEventListener('click', async () => {
            try {
                const result = await importConfigFromFile();
                if (result) {
                    setStatus('Config imported and applied successfully', 'online');
                    // Reload UI to reflect new config
                    reloadUI();
                }
            } catch (error) {
                console.error('[App] Failed to import config:', error);
                setStatus('Failed to import config', 'error');
            }
        });
    }

    // Reset Config Button (with confirmation)
    const resetConfigBtn = document.getElementById('resetConfigBtn');
    if (resetConfigBtn) {
        resetConfigBtn.addEventListener('click', () => {
            if (confirm('Reset all settings to default? This will clear your saved configuration.')) {
                resetConfig(true);
                reloadUI();
                setStatus('Configuration reset to defaults', 'online');
            }
        });
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Presentation Mode (Manual Navigation)
// ══════════════════════════════════════════════════════════════════════════════

function setupPresentationMode() {
    // Presentation Mode Button
    if (dom.presentationModeBtn) {
        dom.presentationModeBtn.addEventListener('click', startPresentationMode);
    }
    
    // Exit Presentation Mode Button
    if (dom.exitPresentationBtn) {
        dom.exitPresentationBtn.addEventListener('click', () => {
            exitPresentationMode();
        });
    }
    
    // Navigation Buttons
    if (dom.prevSlideBtn) {
        dom.prevSlideBtn.addEventListener('click', gotoPreviousSlide);
    }
    
    if (dom.nextSlideBtn) {
        dom.nextSlideBtn.addEventListener('click', gotoNextSlide);
    }
    
    // Keyboard navigation (Arrow keys)
    document.addEventListener('keydown', (e) => {
        if (!state.isPresentationMode) return;
        
        // Don't trigger navigation if in edit or drag mode (except ESC)
        if ((slideEditor.isEditMode || slideEditor.isDragMode) && e.code !== 'Escape') {
            return;
        }
        
        if (e.code === 'ArrowLeft') {
            e.preventDefault();
            gotoPreviousSlide();
        } else if (e.code === 'ArrowRight' || e.code === 'Space') {
            e.preventDefault();
            gotoNextSlide();
        } else if (e.code === 'Escape') {
            e.preventDefault();
            exitPresentationMode();
        } else if (e.code === 'Home') {
            e.preventDefault();
            gotoSlide(0);
        } else if (e.code === 'End') {
            e.preventDefault();
            gotoSlide(state.slides.length - 1);
        } else if (e.code === 'KeyE') {
            // Toggle edit mode with E key
            e.preventDefault();
            slideEditor.toggleEditMode();
        } else if (e.code === 'KeyD') {
            // Toggle drag mode with D key
            e.preventDefault();
            slideEditor.toggleDragMode();
        }
    });
}

async function startPresentationMode() {
    if (state.slides.length === 0) {
        setStatus('No slides - sync markdown first', 'online');
        return;
    }
    
    // ตั้งค่าโหมดเป็น presentation และปิดโหมดอื่นทั้งหมด
    // Mode Manager จะจัดการ UI ให้ทั้งหมด (navControls, exitBtn, fullscreenBtn, editBtn)
    switchToPresentationMode();
    
    state.isPresentationMode = true;
    state.currentSlideIndex = 0;
    
    //  ไม่ต้อง show/hide UI elements ด้วยตัวเอง - Mode Manager จัดการแล้ว
    
    // Set current slide for editor (but don't show button - Mode Manager handles it)
    slideEditor.setCurrentSlide(0);
    
    // Disable other controls
    setControlsDisabled(true);
    
    // Detect screen and render first slide with smart layout
    detectScreenSize();
    gotoSlideWithSmartLayout(0);
    
    setStatus('Presentation Mode - Use arrow keys to navigate, ESC to exit', 'online');
}

function exitPresentationMode() {
    state.isPresentationMode = false;
    state.currentSlideIndex = 0;
    
    // กลับไปโหมด intro และปิดโหมดอื่นทั้งหมด
    // Mode Manager จะจัดการ UI ให้ทั้งหมด
    switchToIntroMode();
    
    //  ไม่ต้อง hide UI elements ด้วยตัวเอง - Mode Manager จัดการแล้ว
    
    // Reset slide editor (Mode Manager handles UI hiding)
    slideEditor.reset();
    
    // Exit fullscreen if active
    if (document.fullscreenElement || document.webkitFullscreenElement) {
        exitFullscreen();
    }
    
    // Re-enable controls
    setControlsDisabled(false);
    
    // Reset to intro scene
    showScene('intro');
    
    setStatus('Exited presentation mode', 'online');
}

function gotoSlide(index) {
    if (index < 0 || index >= state.slides.length) return;
    
    state.currentSlideIndex = index;
    
    // Update slide editor
    slideEditor.setCurrentSlide(index);
    
    if (state.isPresentationMode) {
        gotoSlideWithSmartLayout(index);
        return;
    }
    
    const slide = state.slides[index];
    
    renderSlideToStage(slide);
    showScene('body');
    
    updateSlideCounter();
    updateNavigationButtons();
}

function gotoPreviousSlide() {
    if (state.currentSlideIndex > 0) {
        gotoSlide(state.currentSlideIndex - 1);
    }
}

function gotoNextSlide() {
    if (state.currentSlideIndex < state.slides.length - 1) {
        gotoSlide(state.currentSlideIndex + 1);
    }
}

function updateSlideCounter() {
    if (dom.slideCounter) {
        dom.slideCounter.textContent = `${state.currentSlideIndex + 1} / ${state.slides.length}`;
    }
}

function updateNavigationButtons() {
    // Disable prev button on first slide
    if (dom.prevSlideBtn) {
        dom.prevSlideBtn.disabled = state.currentSlideIndex === 0;
    }
    
    // Disable next button on last slide
    if (dom.nextSlideBtn) {
        dom.nextSlideBtn.disabled = state.currentSlideIndex === state.slides.length - 1;
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Fullscreen Control
// ══════════════════════════════════════════════════════════════════════════════

function setupFullscreenControl() {
    if (dom.fullscreenBtn) {
        dom.fullscreenBtn.addEventListener('click', toggleFullscreen);
    }
    
    // Listen for fullscreen changes
    document.addEventListener('fullscreenchange', onFullscreenChange);
    document.addEventListener('webkitfullscreenchange', onFullscreenChange);
    document.addEventListener('mozfullscreenchange', onFullscreenChange);
    document.addEventListener('MSFullscreenChange', onFullscreenChange);
    
    // Keyboard shortcut: F key
    document.addEventListener('keydown', (e) => {
        if (e.code === 'KeyF' && state.isPresentationMode) {
            e.preventDefault();
            toggleFullscreen();
        }
    });
}

function toggleFullscreen() {
    if (!document.fullscreenElement && !document.webkitFullscreenElement) {
        enterFullscreen();
    } else {
        exitFullscreen();
    }
}

function enterFullscreen() {
    const element = dom.stageFrame;
    
    if (element.requestFullscreen) {
        element.requestFullscreen();
    } else if (element.webkitRequestFullscreen) {
        element.webkitRequestFullscreen();
    } else if (element.mozRequestFullScreen) {
        element.mozRequestFullScreen();
    } else if (element.msRequestFullscreen) {
        element.msRequestFullscreen();
    }
}

function exitFullscreen() {
    if (document.exitFullscreen) {
        document.exitFullscreen();
    } else if (document.webkitExitFullscreen) {
        document.webkitExitFullscreen();
    } else if (document.mozCancelFullScreen) {
        document.mozCancelFullScreen();
    } else if (document.msExitFullscreen) {
        document.msExitFullscreen();
    }
}

function onFullscreenChange() {
    const isFullscreen = !!(document.fullscreenElement || document.webkitFullscreenElement);
    
    // Update fullscreen button icon
    if (dom.fullscreenBtn) {
        const icon = dom.fullscreenBtn.querySelector('.fullscreen-icon');
        if (icon) {
            icon.textContent = isFullscreen ? '⛶' : '⛶';
        }
    }

    if (state.isPresentationMode) {
        detectScreenSize();
        gotoSlideWithSmartLayout(state.currentSlideIndex);
        
        // อัปเดต Safe Zone เมื่อเข้า/ออก fullscreen
        if (slideEditor.isDragMode) {
            slideEditor.dragDropManager.updateSafeZoneBorders();
        }
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Smart Content Layout Engine - Intelligent Fullscreen Presentation Mode
// ══════════════════════════════════════════════════════════════════════════════

function setupScreenSensor() {
    ensureMeasurementStage();
    detectScreenSize();

    window.addEventListener('resize', debounce(() => {
        ensureMeasurementStage();
        detectScreenSize();
        if (state.isPresentationMode) {
            gotoSlideWithSmartLayout(state.currentSlideIndex);
        }
    }, 200));

    if (window.screen && window.screen.orientation && typeof window.screen.orientation.addEventListener === 'function') {
        window.screen.orientation.addEventListener('change', () => {
            ensureMeasurementStage();
            detectScreenSize();
            if (state.isPresentationMode) {
                gotoSlideWithSmartLayout(state.currentSlideIndex);
            }
        });
    }
}

function detectScreenSize() {
    const width = window.innerWidth;
    const height = window.innerHeight;
    const pixelRatio = window.devicePixelRatio || 1;
    const isFullscreen = !!(document.fullscreenElement || document.webkitFullscreenElement);
    const availableSpace = width * height;

    let screenType = 'normal';
    let isLargeScreen = false;

    if (availableSpace >= 3840000 || width >= 2560 || isFullscreen) {
        screenType = 'ultra';
        isLargeScreen = true;
    } else if (availableSpace >= 2073600 || width >= 1920) {
        screenType = 'large';
        isLargeScreen = true;
    }

    const previousType = state.screenSensor.screenType;
    state.screenSensor = {
        width,
        height,
        pixelRatio,
        isLargeScreen,
        screenType,
        isFullscreen,
        availableSpace,
        lastUpdate: Date.now()
    };

    const stage = dom.stage || document.getElementById('stage');
    if (stage) {
        stage.classList.remove('screen-normal', 'screen-large', 'screen-ultra');
        stage.classList.add(`screen-${screenType}`);
        updateMeasurementStageSize();
    }

    if (previousType !== screenType) {
        console.log(`[SmartLayout] Screen changed: ${previousType} -> ${screenType} (${width}x${height})`);
    }

    return state.screenSensor;
}

function buildSlideItemHtml(item, { isPreview = false } = {}) {
    const previewClass = isPreview ? 'preview-block' : '';
    const previewAttr = isPreview ? ' data-preview="true"' : '';
    const blockAttr = item.layoutBlockId ? ` data-block-id="${item.layoutBlockId}"` : '';
    const sectionAttr = item.sectionId ? ` data-section-id="${item.sectionId}"` : '';
    const listAttr = item.listId ? ` data-list-id="${item.listId}"` : '';
    const dataAttrs = `${previewAttr}${blockAttr}${sectionAttr}${listAttr}`;
    const language = item.language || '';

    switch (item.type) {
        case 'h1':
            return `<h1 class="slide-heading slide-h1 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h1>`;
        case 'h2':
            return `<h2 class="slide-heading slide-h2 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h2>`;
        case 'h3':
            return `<h3 class="slide-heading slide-h3 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h3>`;
        case 'h4':
            return `<h4 class="slide-heading slide-h4 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h4>`;
        case 'h5':
            return `<h5 class="slide-heading slide-h5 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h5>`;
        case 'h6':
            return `<h6 class="slide-heading slide-h6 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</h6>`;
        case 'list-item': {
            const marker = item.marker || '•';
            return `<li class="slide-list-item ${previewClass}"${dataAttrs}>${escapeHtml(marker)} ${item.html ?? escapeHtml(item.content)}</li>`;
        }
        case 'numbered-item': {
            const numberLabel = item.number != null ? `${item.number}.` : '';
            const prefix = numberLabel ? `${escapeHtml(numberLabel)} ` : '';
            return `<li class="slide-list-item ${previewClass}"${dataAttrs}>${prefix}${item.html ?? escapeHtml(item.content)}</li>`;
        }
        case 'task-list': {
            const checkbox = item.checked ? '☑' : '☐';
            return `<li class="slide-list-item ${previewClass}"${dataAttrs}>${escapeHtml(checkbox)} ${item.html ?? escapeHtml(item.content)}</li>`;
        }
        case 'text': {
            const textClass = isPreview ? 'slide-text slide-text-preview' : 'slide-text';
            return `<p class="${textClass} ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content)}</p>`;
        }
        case 'code':
            return `<div class="relative slide-code ${previewClass}"${dataAttrs}><pre class="code-block"><code class="language-${language}">${escapeHtml(item.content)}</code></pre></div>`;
        case 'blockquote':
            return `<blockquote class="slide-blockquote ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content || '')}</blockquote>`;
        case 'image': {
            const title = item.title ? `title="${escapeHtml(item.title)}"` : '';
            return `<img src="${escapeHtml(item.src)}" alt="${escapeHtml(item.alt)}" ${title} class="slide-image ${previewClass}"${dataAttrs} />`;
        }
        case 'link': {
            const linkTitle = item.title ? `title="${escapeHtml(item.title)}"` : '';
            return `<a href="${escapeHtml(item.url)}" ${linkTitle} class="slide-link ${previewClass}"${dataAttrs}>${escapeHtml(item.text)}</a>`;
        }
        case 'table': {
            let html = `<div class="relative ${previewClass}"${dataAttrs}>`;
            html += '<table class="slide-table">';
            if (item.rows && item.rows.length > 0) {
                html += '<thead><tr>';
                item.rows[0].forEach(cell => {
                    html += `<th>${escapeHtml(cell)}</th>`;
                });
                html += '</tr></thead>';

                if (item.rows.length > 2) {
                    html += '<tbody>';
                    for (let i = 2; i < item.rows.length; i++) {
                        html += '<tr>';
                        item.rows[i].forEach(cell => {
                            html += `<td>${escapeHtml(cell)}</td>`;
                        });
                        html += '</tr>';
                    }
                    html += '</tbody>';
                }
            }
            html += '</table>';
            html += '</div>';
            return html;
        }
        case 'hr':
            return `<hr class="slide-hr ${previewClass}"${dataAttrs} />`;
        case 'html':
            return `<div class="html-content ${previewClass}"${dataAttrs}>${item.html ?? item.content ?? ''}</div>`;
        default:
            return `<p class="text-2xl mb-2 ${previewClass}"${dataAttrs}>${item.html ?? escapeHtml(item.content || '')}</p>`;
    }
}

function htmlToNode(html) {
    const template = document.createElement('template');
    template.innerHTML = html.trim();
    return template.content.firstElementChild;
}

function getSmartSlideBlocks(slides, startIndex, screenType) {
    if (!Array.isArray(slides) || startIndex < 0 || startIndex >= slides.length) {
        return [];
    }

    const candidates = [];
    const maxSlidesToConsider = screenType === 'ultra'
        ? 4
        : screenType === 'large'
            ? 3
            : 2;

    const upperBound = Math.min(slides.length, startIndex + maxSlidesToConsider);

    for (let slideIndex = startIndex; slideIndex < upperBound; slideIndex += 1) {
        const slide = slides[slideIndex];
        if (!slide) continue;

        const isPreviewSlide = slideIndex !== startIndex;
        const sourceItems = slide.renderItems || slide.content || [];

        sourceItems.forEach((originalItem, itemIndex) => {
            if (isPreviewSlide && /^h[1-6]$/.test(originalItem.type || '')) {
                return;
            }

            const block = { ...originalItem };

            if (isPreviewSlide) {
                block.isPreview = true;
                block.fromNextSlide = true;
                block.previewSourceIndex = slideIndex;
                block.previewItemIndex = itemIndex;
            }

            candidates.push(block);
        });
    }

    return candidates;
}

// ==============================================================================
// INTRO SCENE CONTENT PREPARATION - DO NOT MODIFY
// ==============================================================================
// WARNING: This function uses intro scene measurement stage
// Do not link to presentation mode - create separate function if needed
// ==============================================================================

/**
 * LOCKED - Intro scene smart content preparation
 * Do not modify - intro scene depends on this exact implementation
 */
function prepareSmartSlideContent(slides, startIndex, screenType) {
    const measurementRoot = ensureMeasurementStage();
    if (!measurementRoot || !Array.isArray(slides) || startIndex < 0 || startIndex >= slides.length) {
        const fallbackSlide = slides?.[startIndex];
        return fallbackSlide?.renderItems || fallbackSlide?.content || [];
    }

    const stageRect = dom.stage
        ? dom.stage.getBoundingClientRect()
        : dom.stageFrame
            ? dom.stageFrame.getBoundingClientRect()
            : getSmartLayoutStageFallback();

    const safeZoneInsets = computeSafeZoneInsets(stageRect);
    applySafeZonePadding(dom.measurementRoot, safeZoneInsets);

    const usableHeight = Math.max(stageRect.height - safeZoneInsets.top - safeZoneInsets.bottom, 0);
    const heightBudget = usableHeight > 0 ? usableHeight : stageRect.height;
    const maxHeight = heightBudget * getSmartLayoutFillRatio();

    const candidates = getSmartSlideBlocks(slides, startIndex, screenType);
    if (!candidates.length) {
        const fallbackSlide = slides[startIndex];
        return fallbackSlide?.renderItems || fallbackSlide?.content || [];
    }

    const selectedItems = [];

    for (let index = 0; index < candidates.length; index += 1) {
        const originalBlock = candidates[index];
        const block = { ...originalBlock };
        const itemHtml = buildSlideItemHtml(block, { isPreview: !!block.isPreview });
        const node = htmlToNode(itemHtml);

        if (!node) {
            continue;
        }

        measurementRoot.appendChild(node);
        const measuredHeight = dom.measurementRoot.getBoundingClientRect().height;
        const contentHeight = Math.max(measuredHeight - safeZoneInsets.top - safeZoneInsets.bottom, 0);
        const canFit = contentHeight <= maxHeight;
        const forceInclude = selectedItems.length === 0;

        if (canFit || forceInclude) {
            selectedItems.push(block);
        } else {
            measurementRoot.removeChild(node);
            break;
        }
    }

    measurementRoot.innerHTML = '';

    if (selectedItems.length === 0) {
        const fallbackSlide = slides[startIndex];
        return [...(fallbackSlide?.renderItems || fallbackSlide?.content || [])];
    }

    return selectedItems;
}

function gotoSlideWithSmartLayout(index) {
    if (index < 0 || index >= state.slides.length) return;

    const { screenType } = state.screenSensor;
    const baseSlide = state.slides[index];

    let itemsToRender = baseSlide.renderItems || baseSlide.content || [];
    if (screenType === 'large' || screenType === 'ultra') {
        itemsToRender = prepareSmartSlideContent(state.slides, index, screenType);
    }

    renderSlideToStage(baseSlide, itemsToRender);
    
    // Apply slide editor overrides if any
    const activeScene = dom.stage.querySelector('.scene.active');
    if (activeScene) {
        const hasOverrides = slideEditor.applyOverrides(index, activeScene);
        if (hasOverrides) {
            console.log(`[App] Applied slide edits for slide ${index}`);
        }
        
        // Apply position overrides if any
        const hasPositions = slideEditor.applyPositions(index, activeScene);
        if (hasPositions) {
            console.log(`[App] Applied position overrides for slide ${index}`);
        }
    }
    
    showScene('body');

    updateSlideCounter();
    updateNavigationButtons();

    const scheduleBoundsCheck = () => ensureContentWithinBounds();
    if (typeof requestAnimationFrame === 'function') {
        requestAnimationFrame(scheduleBoundsCheck);
    } else {
        setTimeout(scheduleBoundsCheck, 0);
    }
}

let smartLayoutResizeObserver = null;
let smartLayoutMutationObserver = null;
let smartLayoutResizeFrame = null;

function ensureContentWithinBounds() {
    //  ตรวจสอบว่า Smart Layout ควรทำงานหรือไม่ตาม Mode Manager
    const modeManager = getModeManager();
    if (modeManager && !modeManager.isSystemActive('smartLayout')) {
        // ปิดอยู่ ห้ามทำงาน
        return;
    }

    const stage = dom.stage;
    if (!stage) return;

    const root = stage.querySelector('.smart-layout-root');
    if (!root) return;

    root.style.transform = '';
    root.style.transformOrigin = '';
    root.style.width = '';

    const stageRect = stage.getBoundingClientRect();
    const contentRect = root.getBoundingClientRect();

    if (!stageRect.height || !contentRect.height) return;

    // อ่านค่า Safe Zone จาก presentation-config.js แทน dataset
    const safeZoneMargins = computeSafeZoneMargins(stageRect);
    const safeTop = safeZoneMargins.top || 0;
    const safeBottom = safeZoneMargins.bottom || 0;
    const safeLeft = safeZoneMargins.left || 0;
    const safeRight = safeZoneMargins.right || 0;

    const usableHeight = Math.max(stageRect.height - safeTop - safeBottom, 0);
    const usableWidth = Math.max(stageRect.width - safeLeft - safeRight, 0);

    if (usableHeight > 0 && contentRect.height <= usableHeight * 0.97) {
        return;
    }

    const heightTarget = usableHeight > 0 ? usableHeight : stageRect.height;
    if (!heightTarget) {
        return;
    }

    const scale = (heightTarget * 0.94) / contentRect.height;
    if (scale >= 1) {
        return;
    }

    root.style.transform = `scale(${scale})`;
    root.style.transformOrigin = 'top left';

    const widthTarget = usableWidth > 0 ? usableWidth : stageRect.width || stage.offsetWidth;
    if (widthTarget) {
        root.style.width = `${widthTarget / scale}px`;
    }
}

function attachSmartLayoutObservers(layoutRoot) {
    if (smartLayoutResizeObserver) {
        smartLayoutResizeObserver.disconnect();
        smartLayoutResizeObserver = null;
    }
    if (smartLayoutMutationObserver) {
        smartLayoutMutationObserver.disconnect();
        smartLayoutMutationObserver = null;
    }
    if (smartLayoutResizeFrame) {
        cancelAnimationFrame(smartLayoutResizeFrame);
        smartLayoutResizeFrame = null;
    }

    if (!layoutRoot) {
        return;
    }

    const scheduleBoundsCheck = () => {
        if (smartLayoutResizeFrame) {
            cancelAnimationFrame(smartLayoutResizeFrame);
        }
        smartLayoutResizeFrame = requestAnimationFrame(() => {
            smartLayoutResizeFrame = null;
            ensureContentWithinBounds();
        });
    };

    if (typeof ResizeObserver === 'function') {
        smartLayoutResizeObserver = new ResizeObserver(() => scheduleBoundsCheck());
        smartLayoutResizeObserver.observe(layoutRoot);
        if (dom.stage) {
            smartLayoutResizeObserver.observe(dom.stage);
        }
    }

    if (typeof MutationObserver === 'function') {
        smartLayoutMutationObserver = new MutationObserver(() => scheduleBoundsCheck());
        smartLayoutMutationObserver.observe(layoutRoot, {
            childList: true,
            subtree: true,
            characterData: true
        });
    }

    scheduleBoundsCheck();
}

/**
 * ปิด Smart Layout observers (เรียกใช้ตอนเข้าโหมดแก้ไข)
 */
function detachSmartLayoutObservers() {
    if (smartLayoutResizeObserver) {
        smartLayoutResizeObserver.disconnect();
        smartLayoutResizeObserver = null;
    }
    if (smartLayoutMutationObserver) {
        smartLayoutMutationObserver.disconnect();
        smartLayoutMutationObserver = null;
    }
    if (smartLayoutResizeFrame) {
        cancelAnimationFrame(smartLayoutResizeFrame);
        smartLayoutResizeFrame = null;
    }
    console.log('[SmartLayout] Observers detached');
}

/**
 * เปิด Smart Layout observers อีกครั้ง
 */
function reattachSmartLayoutObservers() {
    const activeScene = dom.stage?.querySelector('.scene.active');
    const layoutRoot = activeScene?.querySelector('.smart-layout-root');
    if (layoutRoot) {
        attachSmartLayoutObservers(layoutRoot);
        console.log('[SmartLayout] Observers reattached');
    }
}

// Export functions สำหรับเข้าถึงจากภายนอก
window.smartLayoutControl = {
    detach: detachSmartLayoutObservers,
    reattach: reattachSmartLayoutObservers
};

function debounce(func, wait) {
    let timeoutId;
    return function debounced(...args) {
        clearTimeout(timeoutId);
        timeoutId = setTimeout(() => func.apply(this, args), wait);
    };
}

/**
 * Setup stage click handler for pause/resume during preview
 */
function setupStageClickHandler() {
    if (!dom.stage) return;
    
    // Click to pause/resume (only in preview mode, not presentation mode)
    dom.stage.addEventListener('click', (e) => {
        // Only handle clicks during preview playback (not presentation mode)
        if (!state.isPlaying || state.isPresentationMode) return;
        togglePause();
    });
    
    // Keyboard shortcut: Space or P to pause/resume (only in preview mode)
    document.addEventListener('keydown', (e) => {
        // Don't handle if in presentation mode
        if (state.isPresentationMode) return;
        
        if (!state.isPlaying) return;
        
        if (e.code === 'Space' || e.code === 'KeyP') {
            e.preventDefault();
            togglePause();
        }
        
        // ESC to stop preview
        if (e.code === 'Escape') {
            e.preventDefault();
            stopPreview();
        }
    });
    
    // Also add visual feedback
    dom.stage.style.cursor = 'pointer';
    dom.stage.title = 'Click to pause/resume preview (or press Space/P)';
}

/**
 * Toggle pause/resume state
 */
function togglePause() {
    if (state.isPaused) {
        // Resume playback
        console.log('[App] Resuming preview...');
        state.isPaused = false;
        setStatus('Playing preview... (Click or Space to pause)', 'online');
        
        // Hide pause overlay
        if (dom.pauseOverlay) {
            dom.pauseOverlay.classList.add('hidden');
        }
        
        // Resolve the pause promise to continue
        if (state.pauseResolve) {
            state.pauseResolve();
        }
    } else {
        // Pause playback
        console.log('[App] Paused preview');
        state.isPaused = true;
        setStatus('Preview PAUSED - Click or Space to resume', 'warning');
        
        // Show pause overlay
        if (dom.pauseOverlay) {
            dom.pauseOverlay.classList.remove('hidden');
        }
    }
}

/**
 * Stop preview playback
 */
function stopPreview() {
    console.log('[App] Stopping preview...');
    state.isPlaying = false;
    state.isPaused = false;
    
    // Resume if paused (to unblock waitWithPause)
    if (state.pauseResolve) {
        state.pauseResolve();
        state.pauseResolve = null;
    }
    
    setStatus('Preview stopped', 'online');
}

async function previewTimeline() {
    if (state.isPlaying) return;
    if (state.slides.length === 0) {
        setStatus('No slides - sync markdown first', 'online');
        return;
    }
    
    state.isPlaying = true;
    state.isPaused = false;
    setControlsDisabled(true);
    
    // Show stop preview button
    if (dom.stopPreviewBtn) dom.stopPreviewBtn.classList.remove('hidden');
    
    setStatus('Playing preview... (Click stage to pause)', 'online');
    
    // Hide pause overlay at start
    if (dom.pauseOverlay) {
        dom.pauseOverlay.classList.add('hidden');
    }
    
    try {
        for (let i = 0; i < state.slides.length; i++) {
            state.currentSlideIndex = i;
            await playSlide(state.slides[i]);
            
            // Check if stopped during playback
            if (!state.isPlaying) break;
        }
        setStatus('Preview completed', 'online');
    } catch (error) {
        console.error('[App] Preview error:', error);
        setStatus('Preview error: ' + error.message, 'online');
    } finally {
        state.isPlaying = false;
        state.isPaused = false;
        state.pauseResolve = null;
        state.currentSlideIndex = 0;
        setControlsDisabled(false);
        showScene('intro');
        
        // Hide stop preview button
        if (dom.stopPreviewBtn) dom.stopPreviewBtn.classList.add('hidden');
        
        // Hide pause overlay when done
        if (dom.pauseOverlay) {
            dom.pauseOverlay.classList.add('hidden');
        }
    }
}

async function playSlide(slide) {
    console.log('[App] Playing:', slide.title, slide.duration + 's');
    renderSlideToStage(slide);
    showScene('body');
    await waitWithPause(slide.duration * 1000);
}

/**
 * Wait function that supports pause/resume
 */
async function waitWithPause(duration) {
    const startTime = Date.now();
    let elapsed = 0;
    
    while (elapsed < duration) {
        // Check if paused
        if (state.isPaused) {
            // Wait for resume
            await new Promise(resolve => {
                state.pauseResolve = resolve;
            });
            // Reset pause state after resume
            state.isPaused = false;
            state.pauseResolve = null;
        }
        
        // Wait in small increments (100ms) to allow pause checking
        const remainingTime = duration - elapsed;
        const waitTime = Math.min(100, remainingTime);
        
        await new Promise(resolve => setTimeout(resolve, waitTime));
        
        elapsed = Date.now() - startTime;
    }
}

// ==============================================================================
// INTRO SCENE RENDER FUNCTION - DO NOT MODIFY
// ==============================================================================
// WARNING: This function uses intro scene safe zone calculation
// Do not link to presentation mode - create separate function if needed
// ==============================================================================

/**
 * LOCKED - Intro scene slide rendering
 * Do not modify - intro scene depends on this exact implementation
 */
function renderSlideToStage(slide, itemsOverride = null) {
    const bodyScene = document.querySelector('[data-scene="body"]');
    if (!bodyScene) return;

    const stageRect = dom.stage
        ? dom.stage.getBoundingClientRect()
        : dom.stageFrame
            ? dom.stageFrame.getBoundingClientRect()
            : getSmartLayoutStageFallback();

    const safeZoneInsets = computeSafeZoneInsets(stageRect);

    const htmlParts = ['<div class="smart-layout-root relative z-10 space-y-4">'];

    if (slide.totalPages > 1) {
        htmlParts.push(`<div class="slide-page-indicator">
            <span>
                ${slide.pageNumber} / ${slide.totalPages}
            </span>
        </div>`);
    }

    const isListType = (type) => type === 'list-item' || type === 'numbered-item' || type === 'task-list';
    let listBuffer = null;

    const flushListBuffer = () => {
        if (!listBuffer || listBuffer.items.length === 0) {
            listBuffer = null;
            return;
        }

        const classes = ['smart-list'];
        if (listBuffer.hasPreview) {
            classes.push('has-preview');
        }

        htmlParts.push(`<${listBuffer.tag} class="${classes.join(' ')}">`);
        listBuffer.items.forEach(itemHtml => htmlParts.push(itemHtml));
        htmlParts.push(`</${listBuffer.tag}>`);
        listBuffer = null;
    };

    const items = itemsOverride || slide.renderItems || slide.content || [];

    items.forEach(item => {
        const isPreview = !!(item.isPreview || item.fromNextSlide);
        const itemHtml = buildSlideItemHtml(item, { isPreview });

        if (isListType(item.type)) {
            const tag = item.type === 'numbered-item' ? 'ol' : 'ul';

            if (!listBuffer || listBuffer.tag !== tag) {
                flushListBuffer();
                listBuffer = { tag, items: [], hasPreview: false };
            }

            listBuffer.items.push(itemHtml);
            listBuffer.hasPreview = listBuffer.hasPreview || isPreview;
        } else {
            flushListBuffer();
            htmlParts.push(itemHtml);
        }
    });

    flushListBuffer();

    htmlParts.push('</div>');
    htmlParts.push('<div class="gradient-backdrop"></div>');

    bodyScene.innerHTML = htmlParts.join('');
    applySmartLayoutTransforms(bodyScene);
    const layoutRoot = bodyScene.querySelector('.smart-layout-root');
    applySafeZonePadding(layoutRoot, safeZoneInsets);
    attachSmartLayoutObservers(layoutRoot);
}

function applySmartLayoutTransforms(container) {
    const layoutRoot = container.querySelector('.smart-layout-root');
    if (!layoutRoot) return;

    enhanceSmartLists(layoutRoot);
}

function enhanceSmartLists(layoutRoot) {
    const lists = layoutRoot.querySelectorAll('.smart-list');
    if (!lists.length) return;

    const isLargeScreen = !!state.screenSensor?.isLargeScreen;

    lists.forEach(list => {
        list.classList.remove('smart-balanced', 'smart-balanced-three');

        if (!isLargeScreen) {
            return;
        }

        const items = Array.from(list.querySelectorAll('li'));
        const previewCount = items.filter(li => li.dataset.preview === 'true').length;
        const visibleCount = items.length - previewCount;

        // Get thresholds from config (use default values as fallback)
        const config = getCurrentConfig();
        const twoColumnThreshold = config?.smartList?.twoColumnThreshold || 6;
        const threeColumnThreshold = config?.smartList?.threeColumnThreshold || 12;

        if (visibleCount >= threeColumnThreshold) {
            list.classList.add('smart-balanced-three');
        } else if (visibleCount >= twoColumnThreshold) {
            list.classList.add('smart-balanced');
        }
    });
}

async function exportVideo() {
    if (state.slides.length === 0) {
        setStatus('No slides - sync markdown first', 'online');
        return;
    }
    
    const [width, height] = state.videoConfig.resolution.split('x').map(Number);
    const renderer = new VideoRenderer({
        width,
        height,
        fps: state.videoConfig.fps,
        quality: state.videoConfig.quality,
        format: 'webm'
    });
    
    setControlsDisabled(true);
    dom.progressContainer.classList.remove('hidden');
    setStatus('Recording video...', 'recording');
    
    try {
        await renderer.startRecording(dom.stage);
        
        for (let i = 0; i < state.slides.length; i++) {
            updateProgress(i, state.slides.length);
            await playSlide(state.slides[i]);
        }
        
        const result = await renderer.stopRecording();
        const base64 = await blobToBase64(result.blob);
        const filename = 'chahua-video-' + Date.now() + '.webm';
        
        const saveResult = await window.chahuaVideo.saveVideo({
            blob: base64,
            format: 'webm',
            filename
        });
        
        if (saveResult.success && !saveResult.canceled) {
            setStatus('Video saved: ' + saveResult.filePath + ' (' + formatBytes(saveResult.size) + ')', 'online');
        } else if (!saveResult.canceled) {
            setStatus('Save failed: ' + saveResult.error, 'online');
        } else {
            setStatus('Export canceled', 'online');
        }
    } catch (error) {
        console.error('[App] Export error:', error);
        setStatus('Export error: ' + error.message, 'online');
    } finally {
        setControlsDisabled(false);
        dom.progressContainer.classList.add('hidden');
    }
}

function updateProgress(current, total) {
    const percent = Math.round((current / total) * 100);
    dom.progressBar.style.width = percent + '%';
    dom.progressText.textContent = 'Recording slide ' + (current + 1) + ' of ' + total + '...';
}

// ══════════════════════════════════════════════════════════════════════════════
// File Operations
// ══════════════════════════════════════════════════════════════════════════════

async function loadSampleDeck() {
    const sampleMarkdown = `---
template: modern
video:
  resolution: 1920x1080
  fps: 60
  quality: 0.95
theme:
  accent: #60a5fa
---

# Introduction
subtitle: Markdown Video Studio
duration: 4

Welcome to the new Markdown-first workflow.

---

# Feature Highlights
duration: 6

- Native WebM encoding
- Real-time preview
- Frontmatter config sync
- Offline-first architecture

---

# Conclusion
subtitle: Built with Electron + MediaRecorder
duration: 5

Thank you for watching!
`;
    dom.markdownEditor.value = sampleMarkdown;
    syncMarkdown();
    setStatus('Sample deck loaded', 'online');
}

async function importMarkdownFile() {
    try {
        const result = await window.chahuaVideo.openMarkdownFile();
        if (result.success && !result.canceled) {
            dom.markdownEditor.value = result.content;
            syncMarkdown();
            setStatus('Loaded: ' + result.filePath, 'online');
        }
    } catch (error) {
        console.error('[App] Import error:', error);
        setStatus('Import failed: ' + error.message, 'online');
    }
}

async function openWorkspaceFolder() {
    try {
        const result = await window.chahuaVideo.openWorkspaceFolder();
        if (result.success) {
            setStatus('Opened workspace folder', 'online');
        }
    } catch (error) {
        console.error('[App] Workspace error:', error);
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Application Reset
// ══════════════════════════════════════════════════════════════════════════════

async function resetApplication() {
    // Confirm before reset
    const confirmed = confirm(
        'Reset Application?\n\n' +
        'This will:\n' +
        '• Clear all markdown content\n' +
        '• Reset all slides and timeline\n' +
        '• Reset to default template and settings\n' +
        '• Return to initial state\n\n' +
        'This action cannot be undone.'
    );
    
    if (!confirmed) return;
    
    console.log('[App] Resetting application to initial state...');
    
    // Stop any active playback or presentation
    if (state.isPlaying) {
        state.isPlaying = false;
        if (state.pauseResolve) {
            state.pauseResolve();
        }
    }
    
    if (state.isPresentationMode) {
        exitPresentationMode();
    }
    
    // Reset state to initial values
    state.markdown = '';
    state.frontmatter = {};
    state.slides = [];
    state.totalDuration = 0;
    state.template = 'modern';
    state.videoConfig = {
        resolution: '1920x1080',
        fps: 60,
        quality: 0.95
    };
    state.themeConfig = {
        accent: '#60a5fa'
    };
    state.isPlaying = false;
    state.isPaused = false;
    state.isPresentationMode = false;
    state.currentSlideIndex = 0;
    state.pauseResolve = null;
    state.errors = [];
    state.warnings = [];
    
    // Clear markdown editor
    dom.markdownEditor.value = '';
    
    // Hide diagnostics
    dom.markdownDiagnostics.classList.add('hidden');
    
    // Reset markdown summary
    dom.markdownSummary.innerHTML = 'Awaiting markdown sync.';
    
    // Reset timeline UI
    dom.timelineTotal.textContent = '00:00';
    dom.timelineSceneList.innerHTML = '<p class="text-slate-500 text-sm">No slides yet</p>';
    
    // Reset asset checklist
    dom.assetChecklist.innerHTML = '<li class="text-slate-500">No assets referenced</li>';
    
    // Reset stage to intro scene
    showScene('intro');
    
    // Reset intro content to default
    const introTitle = document.querySelector('[data-bind="intro.title"]');
    const introSubtitle = document.querySelector('[data-bind="intro.subtitle"]');
    if (introTitle) introTitle.textContent = 'Markdown Video Studio';
    if (introSubtitle) introSubtitle.textContent = 'Define every slide, timing, and asset straight from your markdown deck.';
    
    // Reset outro content
    const outroTitle = document.querySelector('[data-bind="outro.title"]');
    const outroTagline = document.querySelector('[data-bind="outro.tagline"]');
    if (outroTitle) outroTitle.textContent = 'Render from Markdown';
    if (outroTagline) outroTagline.textContent = 'Export consistent videos without ever leaving your markdown workflow.';
    
    // Reset timeline preview
    const timelinePreview = document.getElementById('timelinePreview');
    if (timelinePreview) {
        timelinePreview.innerHTML = `
            <li class="flex items-start justify-between gap-3">
                <span class="font-semibold">Slide 1 · Intro</span>
                <span class="opacity-70">00:00 → 00:05</span>
            </li>
            <li class="flex items-start justify-between gap-3">
                <span class="font-semibold">Slide 2 · Agenda</span>
                <span class="opacity-70">00:05 → 00:15</span>
            </li>
            <li class="flex items-start justify-between gap-3">
                <span class="font-semibold">Slide 3 · Demo</span>
                <span class="opacity-70">00:15 → 00:35</span>
            </li>
        `;
    }
    
    // Reset to default template
    applyTemplate('modern');
    updateTemplateUI();
    
    // Reset presentation configuration to default
    resetConfig();
    reloadUI(dom);
    
    // Reset all template cards
    document.querySelectorAll('.template-card').forEach((card, index) => {
        card.classList.toggle('active', index === 0); // First template is 'modern'
    });
    
    // Reset config inputs to defaults
    const resSelect = document.querySelector('[data-config="video.resolution"]');
    if (resSelect) resSelect.value = '1920x1080';
    
    const fpsSelect = document.querySelector('[data-config="video.fps"]');
    if (fpsSelect) fpsSelect.value = '60';
    
    const qualitySlider = document.querySelector('[data-config="video.quality"]');
    const qualityValue = document.getElementById('qualityValue');
    if (qualitySlider) {
        qualitySlider.value = 0.95;
        if (qualityValue) qualityValue.textContent = '95%';
    }
    
    // Hide progress container
    dom.progressContainer.classList.add('hidden');
    
    // Hide pause overlay
    if (dom.pauseOverlay) {
        dom.pauseOverlay.classList.add('hidden');
    }
    
    //  ไม่ต้อง hide UI elements - Mode Manager จัดการแล้ว
    
    // Re-enable controls
    setControlsDisabled(false);
    
    // Reset status
    setStatus('Application reset - Ready to start', 'online');
    
    console.log('[App] Reset complete');
}

// ══════════════════════════════════════════════════════════════════════════════
// Security
// ══════════════════════════════════════════════════════════════════════════════

async function showSecurityStats() {
    try {
        const result = await window.chahuaVideo.getSecurityStats();
        if (result.success) {
            const stats = result.stats;
            alert(`Security Statistics:\n\n` +
                  `Total Operations: ${stats.totalOperations}\n` +
                  `Uptime: ${Math.round(stats.uptime / 1000)}s\n` +
                  `Rate Limit Entries: ${stats.rateLimitEntries}\n` +
                  `Cached Hashes: ${stats.cachedHashes}`);
        }
    } catch (error) {
        console.error('Security stats error:', error);
    }
}

// ══════════════════════════════════════════════════════════════════════════════
// Helper Functions
// ══════════════════════════════════════════════════════════════════════════════

function showScene(sceneId) {
    dom.sceneElements.forEach(scene => {
        scene.classList.toggle('active', scene.dataset.scene === sceneId);
    });
}

function setStatus(message, state = 'online') {
    dom.statusLog.innerHTML = `<strong>${state === 'recording' ? 'Recording:' : 'Status:'}</strong> ${message}`;
    dom.statusPill.textContent = state === 'recording' ? 'Recording' : 'Ready';
    dom.statusPill.className = `status-pill ${state}`;
}

function setControlsDisabled(disabled) {
    dom.previewBtn.disabled = disabled;
    dom.recordWebMBtn.disabled = disabled;
    dom.securityBtn.disabled = disabled;
}

function wait(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

function formatDuration(seconds) {
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return mins > 0 ? `${mins}:${secs.toString().padStart(2, '0')}` : `${secs}s`;
}

function formatTimecode(seconds) {
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return `${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
}

function formatBytes(bytes) {
    if (bytes === 0) return '0 Bytes';
    const k = 1024;
    const sizes = ['Bytes', 'KB', 'MB', 'GB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return Math.round(bytes / Math.pow(k, i) * 100) / 100 + ' ' + sizes[i];
}

function escapeHtml(text) {
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
}

// ══════════════════════════════════════════════════════════════════════════════
// Start Application
// ══════════════════════════════════════════════════════════════════════════════

// Initialize Slide Editor
const slideEditor = new SlideEditor();

function init() {
    console.log('[App] Initializing Markdown Presenter');

    // ตั้งค่าโหมดเริ่มต้นเป็น intro และปิดโหมดอื่นทั้งหมด
    switchToIntroMode();

    // Load saved config FIRST before any UI setup
    const savedConfig = loadSavedConfig();
    if (savedConfig) {
        console.log('[App]  Loaded saved configuration from localStorage');
    }

    dom.sceneElements = Array.from(document.querySelectorAll('[data-scene]'));

    if (dom.markdownEditor) {
        state.markdown = dom.markdownEditor.value;
    }

    document.documentElement.style.setProperty('--accent-color', state.themeConfig.accent);

    setupTabs();
    setupPresentationSettings();  // NEW: Setup presentation config controls
    setupTemplates();              // Keep legacy template support
    updateTemplateUI();
    setupMarkdownControls();
    setupConfigInputs();
    setupExportControls();
    setupPresentationMode();
    setupFullscreenControl();
    setupStageClickHandler();
    setupScreenSensor();
    setupConfigManagement();      // NEW: Setup Import/Export buttons

    if (dom.slideCounter) {
        dom.slideCounter.textContent = state.slides.length > 0
            ? `${state.currentSlideIndex + 1} / ${state.slides.length}`
            : '0 / 0';
    }

    if (dom.prevSlideBtn) dom.prevSlideBtn.disabled = true;
    if (dom.nextSlideBtn) dom.nextSlideBtn.disabled = true;

    //  ไม่ต้อง hide UI elements - Mode Manager จัดการแล้วตอน switchToIntroMode()

    if (dom.progressContainer) dom.progressContainer.classList.add('hidden');
    if (dom.pauseOverlay) dom.pauseOverlay.classList.add('hidden');

    showScene('intro');
    setStatus('Ready - Sync markdown to begin', 'online');
}

init();