// Debug helpers
function debug(message) {
    console.log(`[Debug] ${message}`);
}

document.addEventListener('DOMContentLoaded', function() {
    // Debug print
    debug("UI initialized");
    
    // Get DOM elements
    const urlForm = document.getElementById('url-form');
    const pdfForm = document.getElementById('pdf-form');
    const tabButtons = document.querySelectorAll('.tab-btn');
    const tabPanes = document.querySelectorAll('.tab-pane');
    const fileInput = document.getElementById('pdf-file');
    const fileNameDisplay = document.querySelector('.file-name');
    const resultsContainer = document.getElementById('results');
    const resultsGrid = document.querySelector('.results-grid');
    const progressContainer = document.querySelector('.progress-container');
    const progressText = document.querySelector('.progress-text');
    const progressFill = document.querySelector('.progress-fill');
    const tryNowBtn = document.getElementById('try-now-btn');
    
    // Handle Try Now button click
    if (tryNowBtn) {
        tryNowBtn.addEventListener('click', function() {
            const translatorSection = document.getElementById('translator');
            translatorSection.scrollIntoView({ behavior: 'smooth' });
        });
    }
    
    // Handle tab switching
    tabButtons.forEach(button => {
        button.addEventListener('click', function() {
            // Get the target tab
            const tabId = this.getAttribute('data-tab');
            
            // Remove active class from all tabs and panes
            tabButtons.forEach(btn => btn.classList.remove('active'));
            tabPanes.forEach(pane => pane.classList.remove('active'));
            
            // Add active class to current tab and pane
            this.classList.add('active');
            document.getElementById(tabId).classList.add('active');
            
            debug(`Switched to tab: ${tabId}`);
        });
    });
    
    // Handle file input change
    if (fileInput) {
        fileInput.addEventListener('change', function() {
            if (this.files.length > 0) {
                const fileName = this.files[0].name;
                fileNameDisplay.textContent = fileName;
                debug(`Selected file: ${fileName}`);
            } else {
                fileNameDisplay.textContent = 'No file chosen';
            }
        });
    }
    
    // Handle URL form submission
    if (urlForm) {
        urlForm.addEventListener('submit', async function(e) {
            e.preventDefault();
            
            // Get form data
            const url = document.getElementById('manga-url').value;
            const srcLang = document.getElementById('url-src-lang').value;
            const tgtLang = document.getElementById('url-tgt-lang').value;
            
            debug(`Submitting URL form with url=${url}, srcLang=${srcLang}, tgtLang=${tgtLang}`);
            
            // Show progress bar
            resultsGrid.innerHTML = '';
            progressFill.style.width = '0%';
            progressText.textContent = 'Preparing translation...';
            progressContainer.style.display = 'block';
            
            // Submit form data to API
            try {
                // Create the request body
                const requestBody = {
                    url: url,
                    src_lang: srcLang,
                    tgt_lang: tgtLang,
                    translator: 'google'
                };
                
                // Call the API with streaming response
                await handleTranslation('/translate/url', requestBody);
                
            } catch (error) {
                debug(`Error during URL translation: ${error}`);
                showError("An error occurred during translation. Please try again.");
            }
        });
    }
    
    // Handle PDF form submission
    if (pdfForm) {
        pdfForm.addEventListener('submit', async function(e) {
            e.preventDefault();
            
            // Check if a file is selected
            if (!fileInput.files[0]) {
                showError("Please select a PDF file first.");
                return;
            }
            
            // Get form data
            const file = fileInput.files[0];
            const srcLang = document.getElementById('pdf-src-lang').value;
            const tgtLang = document.getElementById('pdf-tgt-lang').value;
            
            debug(`Submitting PDF form with file=${file.name}, srcLang=${srcLang}, tgtLang=${tgtLang}`);
            
            // Show progress bar
            resultsGrid.innerHTML = '';
            progressFill.style.width = '0%';
            progressText.textContent = 'Preparing PDF translation...';
            progressContainer.style.display = 'block';
            
            // Create FormData
            const formData = new FormData();
            formData.append('file', file);
            formData.append('src_lang', srcLang);
            formData.append('tgt_lang', tgtLang);
            formData.append('translator', 'google');
            
            // Submit form data to API
            try {
                // Call the translation endpoint with streaming response
                await handlePdfTranslation('/translate/pdf', formData);
                
            } catch (error) {
                debug(`Error during PDF translation: ${error}`);
                showError("An error occurred during translation. Please try again.");
            }
        });
    }
    
    // Function to handle URL translation with streaming response
    async function handleTranslation(endpoint, requestBody) {
        try {
            const response = await fetch(endpoint, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify(requestBody)
            });
            
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            
            const reader = response.body.getReader();
            const decoder = new TextDecoder();
            
            let receivedImages = 0;
            let totalImages = 5; // Default assumption, will be updated if more info is available
            
            while (true) {
                const { value, done } = await reader.read();
                
                if (done) {
                    break;
                }
                
                // Process the streamed response
                const text = decoder.decode(value, { stream: true });
                const lines = text.split('\n\n');
                
                for (const line of lines) {
                    if (line.startsWith('data: ')) {
                        try {
                            const data = JSON.parse(line.substring(6));
                            processTranslationUpdate(data, receivedImages, totalImages);
                            
                            if (data.status === 'success' && data.image_url) {
                                receivedImages++;
                                updateProgress(receivedImages, totalImages);
                            } else if (data.status === 'complete') {
                                progressContainer.style.display = 'none';
                            }
                        } catch (e) {
                            debug(`Error parsing JSON: ${e}`);
                        }
                    }
                }
            }
            
        } catch (error) {
            debug(`Error during translation: ${error}`);
            showError("An error occurred during translation. Please try again.");
        }
    }
    
    // Function to handle PDF translation with streaming response
    async function handlePdfTranslation(endpoint, formData) {
        try {
            const response = await fetch(endpoint, {
                method: 'POST',
                body: formData
            });
            
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            
            const reader = response.body.getReader();
            const decoder = new TextDecoder();
            
            let receivedImages = 0;
            let totalImages = 5; // Default assumption, will be updated if more info is available
            
            while (true) {
                const { value, done } = await reader.read();
                
                if (done) {
                    break;
                }
                
                // Process the streamed response
                const text = decoder.decode(value, { stream: true });
                const lines = text.split('\n\n');
                
                for (const line of lines) {
                    if (line.startsWith('data: ')) {
                        try {
                            const data = JSON.parse(line.substring(6));
                            processTranslationUpdate(data, receivedImages, totalImages);
                            
                            if (data.status === 'success' && data.image_url) {
                                receivedImages++;
                                updateProgress(receivedImages, totalImages);
                            } else if (data.status === 'complete') {
                                progressContainer.style.display = 'none';
                            }
                        } catch (e) {
                            debug(`Error parsing JSON: ${e}`);
                        }
                    }
                }
            }
            
        } catch (error) {
            debug(`Error during translation: ${error}`);
            showError("An error occurred during translation. Please try again.");
        }
    }
    
    // Process translation updates
    function processTranslationUpdate(data, currentImage, totalImages) {
        debug(`Received update: ${JSON.stringify(data)}`);
        
        if (data.status === 'error') {
            showError(data.message || "An error occurred during translation.");
            progressContainer.style.display = 'none';
            return;
        }
        
        if (data.status === 'processing') {
            progressText.textContent = data.message || `Processing image ${currentImage + 1}/${totalImages}...`;
            return;
        }
        
        if (data.status === 'success' && data.image_url) {
            // Add the translated image to the results
            addImageToResults(data.image_url);
        }
        
        if (data.status === 'complete') {
            progressText.textContent = 'Translation complete!';
            progressFill.style.width = '100%';
            setTimeout(() => {
                progressContainer.style.display = 'none';
            }, 1000);
        }
    }
    
    // Update progress bar
    function updateProgress(current, total) {
        const percentage = Math.min(Math.round((current / total) * 100), 100);
        progressFill.style.width = `${percentage}%`;
        progressText.textContent = `Processing page ${current}/${total}...`;
    }
    
    // Add an image to the results grid
    function addImageToResults(imageUrl) {
        // Create result card
        const resultCard = document.createElement('div');
        resultCard.className = 'result-card';
        
        // Create image
        const img = document.createElement('img');
        img.className = 'result-image';
        img.src = imageUrl;
        img.alt = 'Translated Image';
        img.loading = 'lazy';
        
        // Create actions div
        const actionsDiv = document.createElement('div');
        actionsDiv.className = 'result-actions';
        
        // Create download link
        const downloadLink = document.createElement('a');
        downloadLink.href = imageUrl;
        downloadLink.download = 'translated-' + imageUrl.split('/').pop();
        downloadLink.className = 'btn';
        downloadLink.innerHTML = '<i class="fas fa-download"></i> Download';
        
        // Create view link
        const viewLink = document.createElement('a');
        viewLink.href = imageUrl;
        viewLink.target = '_blank';
        viewLink.className = 'btn';
        viewLink.innerHTML = '<i class="fas fa-external-link-alt"></i> View';
        
        // Append elements
        actionsDiv.appendChild(downloadLink);
        actionsDiv.appendChild(viewLink);
        resultCard.appendChild(img);
        resultCard.appendChild(actionsDiv);
        resultsGrid.appendChild(resultCard);
    }
    
    // Show error message
    function showError(message) {
        resultsGrid.innerHTML = `
            <div class="error-message">
                <i class="fas fa-exclamation-circle"></i>
                <p>${message}</p>
            </div>
        `;
    }
    
    // Create placeholder image on page load for visual preview
    function createPlaceholderImage() {
        const placeholderUrl = '/static/ui/placeholder.png';
        debug('Creating placeholder UI example');
        
        // Only add placeholder if no results yet
        if (resultsGrid.children.length === 0) {
            addImageToResults(placeholderUrl);
            addImageToResults(placeholderUrl);
        }
    }
    
    // Optional: Add placeholder images for demo purposes
    // Uncomment to enable placeholders on page load
    // createPlaceholderImage();
});