// Basic front-end logic

document.addEventListener('DOMContentLoaded', () => {
    const inputMode = document.getElementById('input-mode');
    const fileInput = document.getElementById('file-input');
    const startProcessingBtn = document.getElementById('start-processing');
    const confidenceSlider = document.getElementById('confidence-threshold');
    const confidenceValue = document.getElementById('confidence-value');
    const progress = document.getElementById('progress');
    const progressText = document.getElementById('progress-text');
    const processingStatus = document.getElementById('processing-status');
    const statusOutput = document.getElementById('status-output');
    const resultsTableBody = document.querySelector('#results-table tbody');
    const previewImage = document.getElementById('preview-image');
    const imageInfo = document.getElementById('image-info');
    const prevBtn = document.getElementById('prev-image');
    const nextBtn = document.getElementById('next-image');
    const exportCsvBtn = document.getElementById('export-csv');
    const exportImagesBtn = document.getElementById('export-images');
    const zoomInBtn = document.getElementById('zoom-in');
    const zoomOutBtn = document.getElementById('zoom-out');

    let currentResults = [];
    let currentImageIndex = -1;
    let currentJobId = null;

    // Update confidence value display
    confidenceSlider.addEventListener('input', () => {
        confidenceValue.textContent = confidenceSlider.value;
    });

    // Handle input mode change (single file vs multiple)
    inputMode.addEventListener('change', () => {
        if (inputMode.value === 'single') {
            fileInput.removeAttribute('multiple');
        } else {
            fileInput.setAttribute('multiple', '');
        }
    });

    // --- Updated Start Processing Logic ---
    startProcessingBtn.addEventListener('click', async () => {
        const files = fileInput.files;
        if (!files || files.length === 0) {
            logStatus('Error: No files selected.');
            alert('Please select one or more image files.');
            return;
        }

        const mode = inputMode.value;
        if (mode === 'single' && files.length > 1) {
            logStatus('Error: Single File mode selected, but multiple files chosen.');
            alert('Single File mode allows only one file. Please select one file or switch to Directory mode.');
            return;
        }

        logStatus('Starting upload and processing...');
        processingStatus.textContent = 'Uploading...';
        startProcessingBtn.disabled = true;
        progress.value = 0;
        progressText.textContent = '0%';
        resultsTableBody.innerHTML = ''; // Clear previous results
        clearPreview(); // Clear image preview

        const formData = new FormData();
        for (const file of files) {
            formData.append('files', file);
        }
        formData.append('input_mode', mode);
        formData.append('confidence_threshold', confidenceSlider.value);

        // Basic progress simulation for upload (replace with XHR progress if needed)
        progress.value = 50;
        progressText.textContent = '50%';
        processingStatus.textContent = 'Processing...';

        try {
            const response = await fetch('/process', {
                method: 'POST',
                body: formData,
            });

            progress.value = 100;
            progressText.textContent = '100%';

            // First check if the response is valid
            const contentType = response.headers.get('content-type');
            if (!contentType || !contentType.includes('application/json')) {
                // Handle non-JSON response
                const textResponse = await response.text();
                logStatus(`Error: Server returned non-JSON response: ${textResponse.substring(0, 200)}...`);
                processingStatus.textContent = 'Error: Server returned invalid format';
                throw new Error('Server returned non-JSON response');
            }

            // Now we can safely parse JSON
            const data = await response.json();

            if (response.ok) {
                logStatus('Processing successful.');
                processingStatus.textContent = 'Processing finished.';
                currentJobId = data.job_id; // Store the job ID
                logStatus(`Job ID: ${currentJobId}`);
                if (data.log) {
                    logStatus("--- Server Log ---");
                    logStatus(data.log);
                    logStatus("--- End Log ---");
                }
                if (data.error_files && data.error_files.length > 0) {
                    logStatus(`Warning: Skipped invalid files: ${data.error_files.join(', ')}`);
                }
                displayResults(data.results || []);
            } else {
                logStatus(`Error: ${data.error || 'Unknown processing error.'}`);
                if (data.log) {
                    logStatus("--- Server Log ---");
                    logStatus(data.log);
                    logStatus("--- End Log ---");
                }
                processingStatus.textContent = 'Error during processing.';
                alert(`Processing failed: ${data.error || 'Unknown error'}`);
            }

        } catch (error) {
            console.error('Fetch Error:', error);
            logStatus(`Network or Server Error: ${error.message}`);
            processingStatus.textContent = 'Network Error.';
            progress.value = 0;
            progressText.textContent = 'Error';
            alert(`An error occurred while communicating with the server: ${error.message}`);
        } finally {
            startProcessingBtn.disabled = false; // Re-enable button
        }
    });

    function logStatus(message) {
        statusOutput.value += message + '\n';
        statusOutput.scrollTop = statusOutput.scrollHeight; // Auto-scroll
    }

    function displayResults(results) {
        currentResults = results; // Store results
        resultsTableBody.innerHTML = ''; // Clear existing results
        currentImageIndex = -1; // Reset index
        currentJobId = currentJobId; // Ensure job ID is current

        if (!results || results.length === 0) {
            logStatus("No results returned from processing.");
            clearPreview();
            exportCsvBtn.disabled = true;
            exportImagesBtn.disabled = true;
            updateNavButtons(); // Ensure nav buttons are disabled
            return; // Exit early
        }

        results.forEach((result, index) => {
            const row = resultsTableBody.insertRow();
            row.classList.add('result-row'); // Add class for styling/selection
            row.innerHTML = `<td>${result.filename}</td><td>${result.num_eggs}</td>`;
            // Add data attributes for easy access
            row.dataset.index = index;
            row.dataset.filename = result.filename;
            row.dataset.annotatedFilename = result.annotated_filename;

            row.addEventListener('click', () => {
                displayImage(index);
            });
        });

        displayImage(0); // Show the first image initially
        // Enable export buttons IF there are results
        exportCsvBtn.disabled = !results.some(r => r.filename); // Enable if at least one result has a filename
        exportImagesBtn.disabled = !results.some(r => r.annotated_filename); // Enable if at least one result has an annotated image
    }

    function displayImage(index) {
        if (index < 0 || index >= currentResults.length || !currentJobId) {
            clearPreview();
            return;
        }

        currentImageIndex = index;
        const result = currentResults[index];

        if (result.annotated_filename) {
            const imageUrl = `/results/${currentJobId}/${result.annotated_filename}`;
            previewImage.src = imageUrl;
            previewImage.alt = `Annotated ${result.filename}`;
            imageInfo.textContent = `Filename: ${result.filename} - Eggs detected: ${result.num_eggs}`;
            logStatus(`Displaying image: ${result.annotated_filename}`);
        } else {
            // Handle cases where annotation failed or wasn't produced
            previewImage.src = ''; // Clear image
            previewImage.alt = 'Annotated image not available';
            imageInfo.textContent = `Filename: ${result.filename} - Eggs detected: ${result.num_eggs} (Annotation N/A)`;
            logStatus(`Annotated image not available for: ${result.filename}`);
        }

        updateNavButtons();

        // Highlight selected row
        document.querySelectorAll('.result-row').forEach(row => {
            row.classList.remove('selected');
        });
        const selectedRow = resultsTableBody.querySelector(`tr[data-index="${index}"]`);
        if (selectedRow) {
            selectedRow.classList.add('selected');
        }
    }

    function clearPreview() {
        previewImage.src = '';
        previewImage.alt = 'Annotated image preview';
        imageInfo.textContent = 'Filename: - Eggs detected: -';
        currentImageIndex = -1;
        updateNavButtons();
    }

    function updateNavButtons() {
        prevBtn.disabled = currentImageIndex <= 0;
        nextBtn.disabled = currentImageIndex < 0 || currentImageIndex >= currentResults.length - 1;
    }

    prevBtn.addEventListener('click', () => {
        if (currentImageIndex > 0) {
            displayImage(currentImageIndex - 1);
        }
    });

    nextBtn.addEventListener('click', () => {
        if (currentImageIndex < currentResults.length - 1) {
            displayImage(currentImageIndex + 1);
        }
    });

    // --- Export Logic (Placeholders - requires backend implementation) ---
    exportCsvBtn.addEventListener('click', () => {
        if (!currentJobId) {
            alert("No job processed yet.");
            return;
        }
        // Construct the CSV download URL
        const csvFilename = `${currentJobId}_results.csv`;
        const downloadUrl = `/results/${currentJobId}/${csvFilename}`;
        logStatus(`Triggering CSV download: ${csvFilename}`);
        // Create a temporary link and click it
        const link = document.createElement('a');
        link.href = downloadUrl;
        link.download = csvFilename; // Suggest filename to browser
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    });

    exportImagesBtn.addEventListener('click', () => {
        if (!currentJobId) {
            alert("No job processed yet.");
            return;
        }
        // This is more complex. Ideally, the backend would provide a zip file.
        // For now, just log and maybe open the first image?
        logStatus('Image export clicked. Downloading individual images or a zip file is needed.');
        alert('Image export functionality requires backend support to create a downloadable archive (zip file).');
        // Example: trigger download of the currently viewed image
        if (currentImageIndex !== -1 && currentResults[currentImageIndex].annotated_filename) {
            const imgFilename = currentResults[currentImageIndex].annotated_filename;
            const downloadUrl = `/results/${currentJobId}/${imgFilename}`;
            const link = document.createElement('a');
            link.href = downloadUrl;
            link.download = imgFilename;
            document.body.appendChild(link);
            link.click();
            document.body.removeChild(link);
        }
    });

    // --- Zoom Logic (Placeholder - requires a library or complex CSS/JS) ---
    zoomInBtn.addEventListener('click', () => {
        console.log('Zoom In clicked');
        logStatus('Zoom functionality not yet implemented.');
        alert('Zoom functionality is not yet implemented.');
    });

    zoomOutBtn.addEventListener('click', () => {
        console.log('Zoom Out clicked');
        logStatus('Zoom functionality not yet implemented.');
        alert('Zoom functionality is not yet implemented.');
    });

    // Initial setup
    if (inputMode.value === 'single') {
        fileInput.removeAttribute('multiple');
    }
    logStatus('Application initialized. Ready for file selection.');
    exportCsvBtn.disabled = true;
    exportImagesBtn.disabled = true;
    clearPreview(); // Ensure preview is cleared on load
});