/* Upload handling — drag-drop, file validation, check flow */

let currentJobId = null;
let pollInterval = null;
let pollCount = 0;

function initUpload() {
    const uploadArea = document.getElementById('uploadArea');
    const fileInput = document.getElementById('fileInput');

    uploadArea.addEventListener('click', () => fileInput.click());
    uploadArea.addEventListener('keydown', (e) => {
        if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); fileInput.click(); }
    });

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

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

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

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

async function handleFile(file) {
    if (!file.name.toLowerCase().endsWith('.pdf')) {
        alert('Please select a PDF file');
        return;
    }

    if (file.size > 50 * 1024 * 1024) {
        alert('File too large. Maximum size is 50MB.');
        return;
    }

    clearLog();
    document.getElementById('progressContainer').style.display = 'block';
    updateProgress(0, 'Preparing upload...');
    addLog('File selected: ' + file.name + ' (' + (file.size / 1024 / 1024).toFixed(2) + ' MB)', 'info');

    try {
        updateProgress(10, 'Uploading file...');
        addLog('Uploading to server...', 'info');

        const result = await uploadFile(file);

        if (result.success) {
            currentJobId = result.data.job_id;
            updateProgress(20, 'Upload complete');
            addLog('Upload successful — Job ID: ' + currentJobId, 'success');
            document.getElementById('progressContainer').style.display = 'none';
            showReadyState(file);
        } else {
            addLog('Upload failed: ' + result.error, 'error');
            alert('Upload failed: ' + result.error);
            document.getElementById('progressContainer').style.display = 'none';
        }
    } catch (error) {
        addLog('Upload error: ' + error.message, 'error');
        alert('Upload failed: ' + error.message);
        document.getElementById('progressContainer').style.display = 'none';
    }
}

function showReadyState(file) {
    const readyDiv = document.getElementById('uploadReadyState');
    if (!readyDiv) return;
    document.getElementById('readyFilename').textContent = file.name;
    document.getElementById('readyFilesize').textContent = (file.size / 1024 / 1024).toFixed(2) + ' MB';
    readyDiv.style.display = 'block';
    document.getElementById('singleUploadArea').querySelector('.upload-area').style.display = 'none';
}

function removeFile() {
    currentJobId = null;
    const readyDiv = document.getElementById('uploadReadyState');
    if (readyDiv) readyDiv.style.display = 'none';
    document.getElementById('singleUploadArea').querySelector('.upload-area').style.display = '';
    document.getElementById('fileInput').value = '';
    clearLog();
}

async function beginCheck() {
    // Hide ready state, show progress
    const readyDiv = document.getElementById('uploadReadyState');
    if (readyDiv) readyDiv.style.display = 'none';
    document.getElementById('progressContainer').style.display = 'block';
    updateProgress(25, 'Initializing accessibility check...');
    addLog('Preparing accessibility analysis...', 'info');

    const quickMode = document.getElementById('quickMode').checked;
    if (quickMode) addLog('Quick mode enabled — skipping expensive checks', 'info');

    // Animate progress while Cloud Run processes synchronously (can take 2-5 min)
    const progressStages = [
        { pct: 35, msg: 'Loading PDF structure...', log: 'Reading PDF metadata and tagging' },
        { pct: 45, msg: 'Checking document structure...', log: 'Validating PDF tags and structure tree' },
        { pct: 55, msg: 'Analyzing images with AI...', log: 'Running AI vision analysis on images' },
        { pct: 65, msg: 'Checking color contrast...', log: 'Calculating WCAG contrast ratios' },
        { pct: 72, msg: 'Analyzing readability...', log: 'Computing Flesch reading scores' },
        { pct: 80, msg: 'Checking headings & links...', log: 'Heading hierarchy, tab order, role mapping' },
        { pct: 88, msg: 'Running PDF/UA validation...', log: 'veraPDF structure validation' },
        { pct: 94, msg: 'Compiling results...', log: 'Generating accessibility report' },
    ];
    let stageIdx = 0;
    const progressTimer = setInterval(() => {
        if (stageIdx < progressStages.length) {
            const s = progressStages[stageIdx++];
            updateProgress(s.pct, s.msg);
            addLog(s.log, 'info');
        }
    }, 18000); // advance every 18s → covers ~2.5 min of processing

    updateProgress(30, 'Analyzing PDF (this may take a few minutes)...');
    addLog('Sent to Cloud Run for processing...', 'info');

    try {
        const result = await startCheck(currentJobId, quickMode);
        clearInterval(progressTimer);

        if (result.success) {
            if (result.data && result.data.status === 'completed') {
                // Synchronous Cloud Run response — results are ready
                updateProgress(98, 'Loading results...');
                addLog('Analysis complete!', 'success');
                loadResults();
            } else {
                // Async/local mode fallback — poll for status
                updateProgress(35, 'Analysis started');
                addLog('Job processing...', 'success');
                pollJobStatus();
            }
        } else {
            addLog('Check failed: ' + result.error, 'error');
            alert('Check failed: ' + result.error);
            document.getElementById('progressContainer').style.display = 'none';
        }
    } catch (error) {
        clearInterval(progressTimer);
        addLog('Check error: ' + error.message, 'error');
        alert('Check failed: ' + error.message);
        document.getElementById('progressContainer').style.display = 'none';
    }
}

async function pollJobStatus() {
    pollCount = 0;

    const simStages = [
        { percent: 40, message: 'Loading PDF...', log: 'Reading PDF structure and metadata' },
        { percent: 50, message: 'Analyzing document structure...', log: 'Checking PDF tagging and structure' },
        { percent: 60, message: 'Analyzing images...', log: 'Processing images with AI' },
        { percent: 70, message: 'Checking color contrast...', log: 'Calculating WCAG contrast ratios' },
        { percent: 80, message: 'Analyzing readability...', log: 'Computing readability scores' },
        { percent: 90, message: 'Running final checks...', log: 'Font embedding, bookmarks, headings, tab order' },
        { percent: 95, message: 'Compiling results...', log: 'Generating accessibility report' }
    ];

    let stageIdx = 0;

    const tick = async () => {
        pollCount++;

        try {
            const result = await checkStatus(currentJobId);

            if (result.success) {
                const data = result.data;

                // Use real progress from Redis if available
                if (data.progress && data.progress > 0) {
                    updateProgress(data.progress, data.status_message || data.status);
                } else if (stageIdx < simStages.length && pollCount % 3 === 0) {
                    const s = simStages[stageIdx];
                    updateProgress(s.percent, s.message);
                    addLog(s.log, 'info');
                    stageIdx++;
                }

                if (data.status === 'completed') {
                    clearInterval(pollInterval);
                    updateProgress(98, 'Loading results...');
                    addLog('Analysis complete! Loading results...', 'success');
                    loadResults();
                } else if (data.status === 'failed' || data.status === 'error') {
                    clearInterval(pollInterval);
                    addLog('Analysis failed', 'error');
                    if (data.error_log) addLog('Error: ' + data.error_log.substring(0, 500), 'error');
                    document.getElementById('progressContainer').style.display = 'none';
                    alert('Analysis failed. Check the error log for details.');
                } else if (pollCount > 450) {
                    clearInterval(pollInterval);
                    addLog('Analysis timed out after 15 minutes', 'error');
                    addLog('Try using Quick Mode for faster results', 'info');
                    document.getElementById('progressContainer').style.display = 'none';
                }
            }
        } catch (error) {
            console.error('Status check failed:', error);
            addLog('Status check error (retrying...): ' + error.message, 'warning');
        }
    };

    tick();
    pollInterval = setInterval(tick, 2000);
}

async function loadResults() {
    updateProgress(100, 'Complete!');
    addLog('Fetching results from server...', 'info');

    try {
        const result = await getResult(currentJobId);
        if (result.success) {
            addLog('Results loaded — Score: ' + result.data.accessibility_score + '/100', 'success');
            await new Promise(r => setTimeout(r, 800));
            displayResults(result.data);
        } else {
            addLog('Failed to load results: ' + result.error, 'error');
        }
    } catch (error) {
        addLog('Error loading results: ' + error.message, 'error');
    }
}

function resetCheck() {
    if (pollInterval) { clearInterval(pollInterval); pollInterval = null; }
    if (batchPollInterval) { clearInterval(batchPollInterval); batchPollInterval = null; }
    pollCount = 0;
    document.getElementById('uploadSection').style.display = 'block';
    document.getElementById('resultsSection').style.display = 'none';
    document.getElementById('progressContainer').style.display = 'none';
    document.getElementById('pageViewerCard').style.display = 'none';
    document.getElementById('fileInput').value = '';
    var readyDiv = document.getElementById('uploadReadyState');
    if (readyDiv) readyDiv.style.display = 'none';
    var uploadArea = document.getElementById('singleUploadArea') && document.getElementById('singleUploadArea').querySelector('.upload-area');
    if (uploadArea) uploadArea.style.display = '';
    var remCard = document.getElementById('remediationCard');
    if (remCard) remCard.style.display = 'none';
    currentJobId = null;
    clearLog();
}