/**
 * Persistent Storage Manager
 * 
 * จัดการการบันทึกและโหลดการตั้งค่าทั้งหมด (positions, edits, layouts)
 * รองรับ localStorage และ Export/Import JSON
 * Auto-save ทุก 2-3 วินาที
 * 
 * @author Chahua Development Co., Ltd.
 * @version 2.1.0
 */

export class PersistentStorage {
    constructor() {
        this.currentFilePath = null;
        this.autoSaveInterval = null;
        this.autoSaveDelay = 2000; // 2 วินาที
        this.hasUnsavedChanges = false;
        
        // Storage keys
        this.STORAGE_PREFIX = 'chahua-md-presenter';
        this.POSITIONS_KEY = 'positions';
        this.EDITS_KEY = 'edits';
        this.LAYOUTS_KEY = 'layouts';
        this.SETTINGS_KEY = 'settings';
        
        this.init();
    }

    init() {
        // Listen for changes
        this.setupEventListeners();
        
        // Auto-save on window close
        window.addEventListener('beforeunload', () => {
            if (this.hasUnsavedChanges) {
                this.save();
            }
        });
    }

    /**
     * Setup event listeners สำหรับ auto-save
     */
    setupEventListeners() {
        // Listen for position changes
        document.addEventListener('positionChanged', () => {
            this.hasUnsavedChanges = true;
            this.scheduleAutoSave();
        });

        // Listen for content changes
        document.addEventListener('contentChanged', () => {
            this.hasUnsavedChanges = true;
            this.scheduleAutoSave();
        });

        // Listen for layout changes
        document.addEventListener('layoutChanged', () => {
            this.hasUnsavedChanges = true;
            this.scheduleAutoSave();
        });
    }

    /**
     * กำหนดไฟล์ปัจจุบัน
     * 
     * @param {string} filePath 
     */
    setCurrentFile(filePath) {
        this.currentFilePath = filePath;
    }

    /**
     * สร้าง storage key จาก file path และ slide index
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @param {string} dataType - 'positions', 'edits', 'layouts', 'settings'
     * @returns {string}
     */
    getStorageKey(filePath, slideIndex = null, dataType = 'positions') {
        const cleanPath = this.sanitizeFilePath(filePath);
        const slideKey = slideIndex !== null ? `:slide-${slideIndex}` : '';
        return `${this.STORAGE_PREFIX}:${cleanPath}${slideKey}:${dataType}`;
    }

    /**
     * Sanitize file path สำหรับใช้เป็น key
     * 
     * @param {string} filePath 
     * @returns {string}
     */
    sanitizeFilePath(filePath) {
        if (!filePath) return 'untitled';
        
        // แปลง path เป็น hash เพื่อให้สั้นลง
        return this.simpleHash(filePath);
    }

    /**
     * Simple hash function
     * 
     * @param {string} str 
     * @returns {string}
     */
    simpleHash(str) {
        let hash = 0;
        for (let i = 0; i < str.length; i++) {
            const char = str.charCodeAt(i);
            hash = ((hash << 5) - hash) + char;
            hash = hash & hash;
        }
        return Math.abs(hash).toString(36);
    }

    /**
     * บันทึก positions สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @param {Object} positions 
     */
    savePositions(filePath, slideIndex, positions) {
        const key = this.getStorageKey(filePath, slideIndex, this.POSITIONS_KEY);
        const data = {
            timestamp: Date.now(),
            filePath,
            slideIndex,
            positions
        };
        
        try {
            localStorage.setItem(key, JSON.stringify(data));
            return true;
        } catch (error) {
            console.error('Failed to save positions:', error);
            return false;
        }
    }

    /**
     * โหลด positions สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @returns {Object|null}
     */
    loadPositions(filePath, slideIndex) {
        const key = this.getStorageKey(filePath, slideIndex, this.POSITIONS_KEY);
        
        try {
            const data = localStorage.getItem(key);
            if (!data) return null;
            
            const parsed = JSON.parse(data);
            return parsed.positions;
        } catch (error) {
            console.error('Failed to load positions:', error);
            return null;
        }
    }

    /**
     * บันทึก content edits สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @param {Object} edits 
     */
    saveEdits(filePath, slideIndex, edits) {
        const key = this.getStorageKey(filePath, slideIndex, this.EDITS_KEY);
        const data = {
            timestamp: Date.now(),
            filePath,
            slideIndex,
            edits
        };
        
        try {
            localStorage.setItem(key, JSON.stringify(data));
            return true;
        } catch (error) {
            console.error('Failed to save edits:', error);
            return false;
        }
    }

    /**
     * โหลด content edits สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @returns {Object|null}
     */
    loadEdits(filePath, slideIndex) {
        const key = this.getStorageKey(filePath, slideIndex, this.EDITS_KEY);
        
        try {
            const data = localStorage.getItem(key);
            if (!data) return null;
            
            const parsed = JSON.parse(data);
            return parsed.edits;
        } catch (error) {
            console.error('Failed to load edits:', error);
            return null;
        }
    }

    /**
     * บันทึก layout settings สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @param {Object} layout 
     */
    saveLayout(filePath, slideIndex, layout) {
        const key = this.getStorageKey(filePath, slideIndex, this.LAYOUTS_KEY);
        const data = {
            timestamp: Date.now(),
            filePath,
            slideIndex,
            layout
        };
        
        try {
            localStorage.setItem(key, JSON.stringify(data));
            return true;
        } catch (error) {
            console.error('Failed to save layout:', error);
            return false;
        }
    }

    /**
     * โหลด layout settings สำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     * @returns {Object|null}
     */
    loadLayout(filePath, slideIndex) {
        const key = this.getStorageKey(filePath, slideIndex, this.LAYOUTS_KEY);
        
        try {
            const data = localStorage.getItem(key);
            if (!data) return null;
            
            const parsed = JSON.parse(data);
            return parsed.layout;
        } catch (error) {
            console.error('Failed to load layout:', error);
            return null;
        }
    }

    /**
     * บันทึกทุกอย่างสำหรับไฟล์ปัจจุบัน
     * 
     * @param {Array} allData - Array of {slideIndex, positions, edits, layout}
     */
    saveAll(filePath, allData) {
        let savedCount = 0;
        
        allData.forEach(slideData => {
            const { slideIndex, positions, edits, layout } = slideData;
            
            if (positions) {
                this.savePositions(filePath, slideIndex, positions);
                savedCount++;
            }
            
            if (edits) {
                this.saveEdits(filePath, slideIndex, edits);
                savedCount++;
            }
            
            if (layout) {
                this.saveLayout(filePath, slideIndex, layout);
                savedCount++;
            }
        });
        
        this.hasUnsavedChanges = false;
        return savedCount;
    }

    /**
     * โหลดทุกอย่างสำหรับไฟล์ปัจจุบัน
     * 
     * @param {string} filePath 
     * @param {number} totalSlides 
     * @returns {Array}
     */
    loadAll(filePath, totalSlides) {
        const allData = [];
        
        for (let i = 0; i < totalSlides; i++) {
            const positions = this.loadPositions(filePath, i);
            const edits = this.loadEdits(filePath, i);
            const layout = this.loadLayout(filePath, i);
            
            if (positions || edits || layout) {
                allData.push({
                    slideIndex: i,
                    positions,
                    edits,
                    layout
                });
            }
        }
        
        return allData;
    }

    /**
     * Export ทุกอย่างเป็น JSON file
     * 
     * @param {string} filePath 
     * @param {number} totalSlides 
     * @returns {string} - JSON string
     */
    exportToJSON(filePath, totalSlides) {
        const allData = this.loadAll(filePath, totalSlides);
        
        const exportData = {
            version: '2.1.0',
            exportedAt: new Date().toISOString(),
            filePath,
            totalSlides,
            slides: allData
        };
        
        return JSON.stringify(exportData, null, 2);
    }

    /**
     * Import จาก JSON file
     * 
     * @param {string} jsonString 
     * @returns {boolean}
     */
    importFromJSON(jsonString) {
        try {
            const data = JSON.parse(jsonString);
            
            if (!data.version || !data.slides) {
                throw new Error('Invalid JSON format');
            }
            
            const { filePath, slides } = data;
            
            slides.forEach(slideData => {
                const { slideIndex, positions, edits, layout } = slideData;
                
                if (positions) {
                    this.savePositions(filePath, slideIndex, positions);
                }
                
                if (edits) {
                    this.saveEdits(filePath, slideIndex, edits);
                }
                
                if (layout) {
                    this.saveLayout(filePath, slideIndex, layout);
                }
            });
            
            return true;
        } catch (error) {
            console.error('Failed to import JSON:', error);
            return false;
        }
    }

    /**
     * Download JSON file
     * 
     * @param {string} filePath 
     * @param {number} totalSlides 
     */
    downloadJSON(filePath, totalSlides) {
        const json = this.exportToJSON(filePath, totalSlides);
        const blob = new Blob([json], { type: 'application/json' });
        const url = URL.createObjectURL(blob);
        
        const a = document.createElement('a');
        a.href = url;
        a.download = `presentation-settings-${Date.now()}.json`;
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        URL.revokeObjectURL(url);
    }

    /**
     * Schedule auto-save
     */
    scheduleAutoSave() {
        if (this.autoSaveInterval) {
            clearTimeout(this.autoSaveInterval);
        }
        
        this.autoSaveInterval = setTimeout(() => {
            this.save();
        }, this.autoSaveDelay);
    }

    /**
     * บันทึกทันที (manual save)
     */
    save() {
        if (!this.hasUnsavedChanges) return;
        
        // Trigger save event
        const event = new CustomEvent('persistentStorageSave', {
            detail: {
                filePath: this.currentFilePath,
                timestamp: Date.now()
            }
        });
        document.dispatchEvent(event);
        
        this.hasUnsavedChanges = false;
    }

    /**
     * ลบข้อมูลสำหรับ slide หนึ่ง
     * 
     * @param {string} filePath 
     * @param {number} slideIndex 
     */
    clearSlide(filePath, slideIndex) {
        const posKey = this.getStorageKey(filePath, slideIndex, this.POSITIONS_KEY);
        const editKey = this.getStorageKey(filePath, slideIndex, this.EDITS_KEY);
        const layoutKey = this.getStorageKey(filePath, slideIndex, this.LAYOUTS_KEY);
        
        localStorage.removeItem(posKey);
        localStorage.removeItem(editKey);
        localStorage.removeItem(layoutKey);
    }

    /**
     * ลบข้อมูลทั้งหมดสำหรับไฟล์หนึ่ง
     * 
     * @param {string} filePath 
     */
    clearFile(filePath) {
        const prefix = `${this.STORAGE_PREFIX}:${this.sanitizeFilePath(filePath)}`;
        
        // หา keys ทั้งหมดที่ตรงกับ prefix
        const keysToRemove = [];
        for (let i = 0; i < localStorage.length; i++) {
            const key = localStorage.key(i);
            if (key.startsWith(prefix)) {
                keysToRemove.push(key);
            }
        }
        
        // ลบทั้งหมด
        keysToRemove.forEach(key => localStorage.removeItem(key));
    }

    /**
     * ลบข้อมูลทั้งหมด
     */
    clearAll() {
        const keysToRemove = [];
        for (let i = 0; i < localStorage.length; i++) {
            const key = localStorage.key(i);
            if (key.startsWith(this.STORAGE_PREFIX)) {
                keysToRemove.push(key);
            }
        }
        
        keysToRemove.forEach(key => localStorage.removeItem(key));
    }

    /**
     * Get storage usage info
     * 
     * @returns {Object}
     */
    getStorageInfo() {
        let totalSize = 0;
        let itemCount = 0;
        
        for (let i = 0; i < localStorage.length; i++) {
            const key = localStorage.key(i);
            if (key.startsWith(this.STORAGE_PREFIX)) {
                const value = localStorage.getItem(key);
                totalSize += key.length + value.length;
                itemCount++;
            }
        }
        
        return {
            itemCount,
            totalSize,
            totalSizeKB: (totalSize / 1024).toFixed(2),
            maxSize: 5120, // 5MB typical localStorage limit
            usagePercent: ((totalSize / (5 * 1024 * 1024)) * 100).toFixed(2)
        };
    }

    /**
     * Cleanup old data (optional)
     * ลบข้อมูลที่เก่ากว่า X วัน
     * 
     * @param {number} daysOld 
     */
    cleanupOldData(daysOld = 30) {
        const cutoffTime = Date.now() - (daysOld * 24 * 60 * 60 * 1000);
        const keysToRemove = [];
        
        for (let i = 0; i < localStorage.length; i++) {
            const key = localStorage.key(i);
            if (!key.startsWith(this.STORAGE_PREFIX)) continue;
            
            try {
                const data = JSON.parse(localStorage.getItem(key));
                if (data.timestamp && data.timestamp < cutoffTime) {
                    keysToRemove.push(key);
                }
            } catch (error) {
                // Invalid JSON, skip
            }
        }
        
        keysToRemove.forEach(key => localStorage.removeItem(key));
        return keysToRemove.length;
    }
}

export default PersistentStorage;