/**
 * app.js — Robust Frontend logic for Dual Model Image Captioning Web App
 */

// Helper to get DOM elements safely
const getElem = (id) => document.getElementById(id);

let currentFile = null;

// ============================================================
// CHECK MODEL STATUS
// ============================================================
async function checkModelStatus() {
    const modelBadge = getElem('model-badge');
    if (!modelBadge) return;

    try {
        const res = await fetch('/api/status');
        const data = await res.json();
        modelBadge.classList.remove('hidden');
        if (data.status === 'ready') {
            const hasFt = data.has_finetuned ? 'Fine-Tuned & Pretrained Available' : 'Pretrained Available';
            modelBadge.textContent = `⚡ Status: Ready (${hasFt}) | Device: ${data.device}`;
            modelBadge.className = 'model-badge ready';
        } else {
            modelBadge.textContent = '⏳ Models loading...';
            modelBadge.className = 'model-badge loading';
        }
    } catch (e) {
        console.error('Status check failed:', e);
    }
}

// Get selected model mode
function getSelectedModelChoice() {
    const radio = document.querySelector('input[name="model_choice"]:checked');
    return radio ? radio.value : 'both';
}

// Get selected language choice
function getSelectedLangChoice() {
    const radio = document.querySelector('input[name="lang_choice"]:checked');
    return radio ? radio.value : 'both';
}

// ============================================================
// UI VISIBILITY HELPERS
// ============================================================
function showResultArea() {
    const dropZone = getElem('drop-zone');
    const resultArea = getElem('result-area');
    const resultsGrid = getElem('results-grid');
    const loadingSpinner = getElem('loading-spinner');

    if (dropZone) dropZone.classList.add('hidden');
    if (resultArea) resultArea.classList.remove('hidden');
    if (resultsGrid) resultsGrid.innerHTML = '';
    if (loadingSpinner) loadingSpinner.classList.add('active');
}

function showDropZone() {
    const dropZone = getElem('drop-zone');
    const resultArea = getElem('result-area');
    const fileInput = getElem('file-input');

    if (resultArea) resultArea.classList.add('hidden');
    if (dropZone) dropZone.classList.remove('hidden');
    if (fileInput) fileInput.value = '';
    currentFile = null;
    hideError();
}

function showError(message) {
    const errorMsg = getElem('error-msg');
    if (errorMsg) {
        errorMsg.textContent = message;
        errorMsg.classList.remove('hidden');
    }
}

function hideError() {
    const errorMsg = getElem('error-msg');
    if (errorMsg) errorMsg.classList.add('hidden');
}

// ============================================================
// HANDLE FILE
// ============================================================
function handleFile(file) {
    if (!file.type.startsWith('image/')) {
        showError('Please upload an image file (JPEG, PNG, GIF, WebP).');
        return;
    }

    currentFile = file;
    hideError();

    const previewImg = getElem('preview-img');

    const reader = new FileReader();
    reader.onload = (e) => {
        if (previewImg) previewImg.src = e.target.result;
        showResultArea();
        generateCaption(file);
    };
    reader.readAsDataURL(file);
}

// ============================================================
// GENERATE CAPTION (API CALL)
// ============================================================
async function generateCaption(file) {
    const loadingSpinner = getElem('loading-spinner');
    const resultsGrid = getElem('results-grid');

    const modelChoice = getSelectedModelChoice();
    const langChoice = getSelectedLangChoice();
    const formData = new FormData();
    formData.append('file', file);
    formData.append('model_choice', modelChoice);
    formData.append('language', langChoice);

    if (loadingSpinner) loadingSpinner.classList.add('active');
    if (resultsGrid) resultsGrid.innerHTML = '';

    try {
        const res = await fetch('/api/predict', {
            method: 'POST',
            body: formData,
        });

        const data = await res.json();

        if (!res.ok) {
            throw new Error(data.detail || 'Inference failed');
        }

        if (loadingSpinner) loadingSpinner.classList.remove('active');
        renderResults(data.results, langChoice);

    } catch (err) {
        if (loadingSpinner) loadingSpinner.classList.remove('active');
        showError(err.message);
        console.error('Prediction error:', err);
    }
}

// ============================================================
// RENDER RESULTS GRID
// ============================================================
function renderResults(results, langChoice = 'both') {
    let resultsGrid = getElem('results-grid');

    // Fallback: if results-grid is missing, create it dynamically inside result-area
    if (!resultsGrid) {
        const resultArea = getElem('result-area');
        if (resultArea) {
            resultsGrid = document.createElement('div');
            resultsGrid.id = 'results-grid';
            resultsGrid.className = 'results-grid';
            const clearBtn = getElem('clear-btn');
            if (clearBtn) {
                resultArea.insertBefore(resultsGrid, clearBtn);
            } else {
                resultArea.appendChild(resultsGrid);
            }
        }
    }

    if (!resultsGrid) return;

    resultsGrid.innerHTML = '';

    if (!results) return;

    const keys = Object.keys(results);
    const isGrid = keys.length > 1;

    if (isGrid) {
        resultsGrid.classList.add('dual-grid');
    } else {
        resultsGrid.classList.remove('dual-grid');
    }

    keys.forEach(key => {
        const item = results[key];
        const isFineTuned = key === 'fine-tuned';

        const card = document.createElement('div');
        card.className = `caption-card ${isFineTuned ? 'fine-tuned-card' : 'pretrained-card'}`;

        const captions = item.captions || [];
        const captionsTh = item.captions_th || [];

        const captionsHtml = captions
            .map((c, i) => {
                const thText = captionsTh[i] || '';
                let contentHtml = '';

                if (langChoice === 'en') {
                    contentHtml = `<span class="text text-en">${c}</span>`;
                } else if (langChoice === 'th') {
                    contentHtml = `<span class="text text-th">${thText || c}</span>`;
                } else {
                    // Both
                    contentHtml = `
                        <div class="text-group">
                            <span class="text text-en">${c}</span>
                            ${thText ? `<span class="text text-th">🇹🇭 ${thText}</span>` : ''}
                        </div>
                    `;
                }

                return `
                    <li class="caption-item">
                        <span class="num">${i + 1}</span>
                        ${contentHtml}
                    </li>
                `;
            })
            .join('');

        card.innerHTML = `
            <div class="caption-header">
                <span class="model-title">${item.label}</span>
                <span class="tag ${isFineTuned ? 'tag-ft' : 'tag-pre'}">${isFineTuned ? '🎯 Fine-Tuned' : '🌐 Pretrained'}</span>
            </div>
            <ol class="captions-list">
                ${captionsHtml}
            </ol>
        `;

        resultsGrid.appendChild(card);
    });
}

// ============================================================
// INITIALIZATION ON DOM READY
// ============================================================
document.addEventListener('DOMContentLoaded', () => {
    checkModelStatus();

    const dropZone = getElem('drop-zone');
    const fileInput = getElem('file-input');
    const clearBtn = getElem('clear-btn');

    if (dropZone) {
        dropZone.addEventListener('dragover', (e) => {
            e.preventDefault();
            dropZone.classList.add('dragover');
        });

        dropZone.addEventListener('dragleave', () => {
            dropZone.classList.remove('dragover');
        });

        dropZone.addEventListener('drop', (e) => {
            e.preventDefault();
            dropZone.classList.remove('dragover');
            const files = e.dataTransfer.files;
            if (files.length > 0) {
                handleFile(files[0]);
            }
        });

        dropZone.addEventListener('click', () => {
            if (fileInput) fileInput.click();
        });
    }

    if (fileInput) {
        fileInput.addEventListener('change', (e) => {
            if (e.target.files.length > 0) {
                handleFile(e.target.files[0]);
            }
        });
    }

    if (clearBtn) {
        clearBtn.addEventListener('click', showDropZone);
    }

    // Re-trigger generation if user switches model choice or language radio buttons while viewing results
    const retrigger = () => {
        const resultArea = getElem('result-area');
        if (currentFile && resultArea && !resultArea.classList.contains('hidden')) {
            generateCaption(currentFile);
        }
    };

    document.querySelectorAll('input[name="model_choice"]').forEach(radio => {
        radio.addEventListener('change', retrigger);
    });

    document.querySelectorAll('input[name="lang_choice"]').forEach(radio => {
        radio.addEventListener('change', retrigger);
    });
});

// Global drag behaviors
document.addEventListener('dragover', (e) => e.preventDefault());
document.addEventListener('drop', (e) => e.preventDefault());