document.addEventListener('DOMContentLoaded', () => {
    const API = window.location.origin;

    // ── Toast ────────────────────────────────────────────────
    function toast(msg, type = 'info') {
        const el = document.createElement('div');
        el.className = `toast ${type}`;
        el.textContent = msg;
        document.getElementById('toasts').appendChild(el);
        setTimeout(() => el.remove(), 3500);
    }

    // ── Backend status ───────────────────────────────────────
    const dot = document.getElementById('connection-badge');
    function checkStatus() {
        fetch(`${API}/api/status`)
            .then(() => { dot.className = 'status-dot online'; })
            .catch(() => { dot.className = 'status-dot offline'; });
    }
    checkStatus();
    setInterval(checkStatus, 20000);

    // ── PWA install ──────────────────────────────────────────
    let installPrompt;
    const installBtn = document.getElementById('pwa-install-btn');
    window.addEventListener('beforeinstallprompt', e => {
        e.preventDefault();
        installPrompt = e;
        installBtn.classList.remove('hidden');
    });
    installBtn.addEventListener('click', async () => {
        if (!installPrompt) return;
        installPrompt.prompt();
        const { outcome } = await installPrompt.userChoice;
        if (outcome === 'accepted') toast('App installed!', 'success');
        installPrompt = null;
        installBtn.classList.add('hidden');
    });

    // ── Mode switching ───────────────────────────────────────
    let currentMode = 'dataset';
    let chassisBlob = null;
    let barcodeBlob = null;

    document.querySelectorAll('.seg-btn').forEach(btn => {
        btn.addEventListener('click', () => {
            document.querySelectorAll('.seg-btn').forEach(b => b.classList.remove('active'));
            btn.classList.add('active');
            currentMode = btn.dataset.mode;
            ['dataset', 'upload', 'camera'].forEach(m =>
                document.getElementById(`mode-${m}`).classList.add('hidden')
            );
            document.getElementById(`mode-${currentMode}`).classList.remove('hidden');
            stopAllCameras();
            validate();
        });
    });

    // ── Dataset pairs ────────────────────────────────────────
    const pairSelect = document.getElementById('dataset-pair-select');
    const barcodeValInput = document.getElementById('barcode-val');

    fetch(`${API}/api/test-pairs`)
        .then(r => r.json())
        .then(pairs => {
            pairSelect.innerHTML = '<option value="">— Choose a pair —</option>';
            pairs.forEach(p => {
                const o = document.createElement('option');
                o.value = o.textContent = p;
                pairSelect.appendChild(o);
            });
        })
        .catch(() => toast('Could not load dataset pairs', 'error'));

    pairSelect.addEventListener('change', () => {
        const key = pairSelect.value;
        if (!key) { barcodeValInput.value = ''; validate(); return; }
        barcodeValInput.value = 'Decoding…';
        barcodeValInput.disabled = true;
        fetch(`${API}/api/scan-barcode/${encodeURIComponent(key)}`)
            .then(r => r.json())
            .then(d => {
                barcodeValInput.value = d.success ? d.barcode : '';
                if (!d.success) toast('Barcode not decoded. Enter manually.', 'info');
            })
            .catch(() => { barcodeValInput.value = ''; toast('Barcode scan failed', 'error'); })
            .finally(() => { barcodeValInput.disabled = false; validate(); });
    });

    // ── Upload dropzones ─────────────────────────────────────
    function setupDropzone(dzId, inputId, nameId, isBarcode) {
        const dz = document.getElementById(dzId);
        const inp = document.getElementById(inputId);
        const nm = document.getElementById(nameId);

        dz.addEventListener('click', () => inp.click());
        dz.addEventListener('dragover', e => { e.preventDefault(); dz.classList.add('active'); });
        dz.addEventListener('dragleave', () => dz.classList.remove('active'));
        dz.addEventListener('drop', e => {
            e.preventDefault();
            dz.classList.remove('active');
            if (e.dataTransfer.files[0]) handleFile(e.dataTransfer.files[0], nm, isBarcode);
        });
        inp.addEventListener('change', () => {
            if (inp.files[0]) handleFile(inp.files[0], nm, isBarcode);
        });
    }

    function handleFile(file, nameEl, isBarcode) {
        nameEl.textContent = file.name;
        if (isBarcode) {
            barcodeBlob = file;
            barcodeValInput.value = 'Decoding…';
            barcodeValInput.disabled = true;
            const fd = new FormData();
            fd.append('file', file);
            fetch(`${API}/api/scan-barcode`, { method: 'POST', body: fd })
                .then(r => r.json())
                .then(d => {
                    barcodeValInput.value = d.success ? d.barcode : '';
                    if (d.success) toast('Barcode decoded', 'success');
                    else toast('Could not decode barcode. Enter manually.', 'info');
                })
                .catch(() => { barcodeValInput.value = ''; toast('Barcode scan error', 'error'); })
                .finally(() => { barcodeValInput.disabled = false; validate(); });
        } else {
            chassisBlob = file;
            validate();
        }
    }

    setupDropzone('barcode-dropzone', 'barcode-file', 'barcode-file-name', true);
    setupDropzone('chassis-dropzone', 'chassis-file', 'chassis-file-name', false);

    // ── Camera — barcode ─────────────────────────────────────
    let qr = null;
    const startBarcodeCam = document.getElementById('start-barcode-cam');
    const camStep2 = document.getElementById('cam-step-2');

    startBarcodeCam.addEventListener('click', () => {
        if (qr) {
            qr.stop().finally(() => { qr = null; startBarcodeCam.textContent = 'Start Camera'; });
            return;
        }
        startBarcodeCam.textContent = 'Stop';
        qr = new Html5Qrcode('barcode-reader');
        qr.start(
            { facingMode: 'environment' },
            { fps: 10, qrbox: { width: 240, height: 100 } },
            decoded => {
                barcodeValInput.value = decoded;
                toast(`Barcode: ${decoded}`, 'success');
                qr.stop().finally(() => {
                    qr = null;
                    startBarcodeCam.textContent = 'Start Camera';
                    camStep2.classList.remove('disabled');
                    document.getElementById('start-chassis-cam').disabled = false;
                    validate();
                });
            },
            () => { }
        ).catch(e => { toast(`Camera error: ${e}`, 'error'); startBarcodeCam.textContent = 'Start Camera'; qr = null; });
    });

    // ── Camera — chassis ─────────────────────────────────────
    let chassisStream = null;
    const chassisVideo = document.getElementById('chassis-video');
    const chassisCanvas = document.getElementById('chassis-canvas');
    const snapContainer = document.getElementById('chassis-snap-container');
    const snapImg = document.getElementById('chassis-snap-img');
    const startChassisCam = document.getElementById('start-chassis-cam');
    const captureBtn = document.getElementById('capture-chassis');
    const retakeBtn = document.getElementById('reset-chassis-snap');
    const guideBox = document.getElementById('chassis-guide-box');

    // Guide box region as fractions of the video frame (matches CSS: 70% wide, 22% tall, centered)
    const GUIDE_BOX_FRACTION = { widthFrac: 0.70, heightFrac: 0.22, xFrac: 0.15, yFrac: 0.39 };

    startChassisCam.addEventListener('click', async () => {
        if (chassisStream) { stopChassisCamera(); return; }
        try {
            chassisStream = await navigator.mediaDevices.getUserMedia({
                video: { facingMode: 'environment', width: { ideal: 1280 } }, audio: false
            });
            chassisVideo.srcObject = chassisStream;
            chassisVideo.classList.remove('hidden');
            guideBox.classList.remove('hidden');
            captureBtn.classList.remove('hidden');
            snapContainer.classList.add('hidden');
            retakeBtn.classList.add('hidden');
            startChassisCam.textContent = 'Stop';
        } catch (e) { toast(`Camera error: ${e.message}`, 'error'); }
    });

    captureBtn.addEventListener('click', () => {
        const vw = chassisVideo.videoWidth;
        const vh = chassisVideo.videoHeight;

        // Crop to just the guide box region so OCR only sees the framed chassis strip
        const cropX = vw * GUIDE_BOX_FRACTION.xFrac;
        const cropY = vh * GUIDE_BOX_FRACTION.yFrac;
        const cropW = vw * GUIDE_BOX_FRACTION.widthFrac;
        const cropH = vh * GUIDE_BOX_FRACTION.heightFrac;

        chassisCanvas.width = cropW;
        chassisCanvas.height = cropH;
        chassisCanvas.getContext('2d').drawImage(
            chassisVideo,
            cropX, cropY, cropW, cropH,   // source rect (the guide box area)
            0, 0, cropW, cropH            // destination rect (full canvas)
        );

        chassisCanvas.toBlob(blob => {
            chassisBlob = blob;
            snapImg.src = URL.createObjectURL(blob);
            chassisVideo.classList.add('hidden');
            guideBox.classList.add('hidden');
            captureBtn.classList.add('hidden');
            snapContainer.classList.remove('hidden');
            retakeBtn.classList.remove('hidden');
            stopChassisCamera();
            validate();
        }, 'image/jpeg');
    });

    retakeBtn.addEventListener('click', () => {
        chassisBlob = null;
        snapContainer.classList.add('hidden');
        retakeBtn.classList.add('hidden');
        startChassisCam.click();
        validate();
    });

    function stopChassisCamera() {
        if (chassisStream) { chassisStream.getTracks().forEach(t => t.stop()); chassisStream = null; }
        chassisVideo.srcObject = null;
        chassisVideo.classList.add('hidden');
        guideBox.classList.add('hidden');
        captureBtn.classList.add('hidden');
        startChassisCam.textContent = 'Start Camera';
    }

    function stopAllCameras() {
        if (qr) { qr.stop().catch(() => { }); qr = null; startBarcodeCam.textContent = 'Start Camera'; }
        stopChassisCamera();
    }

    // ── Validation ───────────────────────────────────────────
    const runBtn = document.getElementById('run-ocr-btn');
    barcodeValInput.addEventListener('input', validate);

    function validate() {
        const hasBarcode = barcodeValInput.value.trim() !== '' && barcodeValInput.value !== 'Decoding…';
        let hasChassis = false;
        if (currentMode === 'dataset') hasChassis = pairSelect.value !== '';
        else hasChassis = chassisBlob !== null;
        runBtn.disabled = !(hasBarcode && hasChassis);
    }

    // ── Run OCR ──────────────────────────────────────────────
    let lastResult = null;

    runBtn.addEventListener('click', () => {
        runBtn.disabled = true;
        runBtn.querySelector('.spinner').classList.remove('hidden');

        const fd = new FormData();
        fd.append('barcode_val', barcodeValInput.value.trim().toUpperCase());

        if (currentMode === 'dataset') {
            fd.append('chassis_key', pairSelect.value);
        } else {
            fd.append('chassis_file', chassisBlob, currentMode === 'camera' ? 'chassis.jpg' : chassisBlob.name);
        }

        fetch(`${API}/api/match`, { method: 'POST', body: fd })
            .then(r => {
                if (!r.ok) return r.json().then(e => { throw new Error(e.detail); });
                return r.json();
            })
            .then(data => { lastResult = data; renderResult(data); toast('Scan complete', 'success'); })
            .catch(e => toast(e.message || 'OCR failed', 'error'))
            .finally(() => {
                runBtn.disabled = false;
                runBtn.querySelector('.spinner').classList.add('hidden');
            });
    });

    function renderResult(d) {
        document.getElementById('result-empty').classList.add('hidden');
        document.getElementById('result-content').classList.remove('hidden');

        // Banner
        const banner = document.getElementById('result-banner');
        banner.className = `result-banner ${d.status}`;
        const icons = {
            EXACT: '✓',
            CORRECTED: '~',
            FAILED: '✗'
        };
        const subs = {
            EXACT: 'Raw OCR matched the barcode exactly.',
            CORRECTED: 'Match achieved after error-correction.',
            FAILED: 'OCR output could not be matched.'
        };
        document.getElementById('banner-icon').textContent = icons[d.status];
        document.getElementById('banner-title').textContent = d.status === 'EXACT' ? 'Exact Match' : d.status === 'CORRECTED' ? 'Corrected Match' : 'No Match';
        document.getElementById('banner-sub').textContent = subs[d.status];

        // Table
        document.getElementById('res-expected').textContent = d.barcode_val;
        document.getElementById('res-raw').textContent = d.raw_ocr || '—';
        document.getElementById('res-corrected').textContent = d.corrected_ocr || '—';
        document.getElementById('res-conf').textContent = `${Math.round(d.confidence * 100)}%`;
        document.getElementById('res-filter').textContent = d.winning_label || '—';

        // Preprocessing carousel
        const tabs = document.querySelectorAll('.pre-tab');
        tabs.forEach(t => t.replaceWith(t.cloneNode(true)));
        const newTabs = document.querySelectorAll('.pre-tab');

        function setPreview(type) {
            const img = document.getElementById('pre-img');
            const lbl = document.getElementById('pre-ocr-text');
            if (type === 'original') {
                img.src = `data:image/jpeg;base64,${d.original}`;
                lbl.textContent = d.raw_ocr || '—';
            } else {
                const v = d.variations.find(x => x.label.toLowerCase() === type);
                const det = d.variation_details.find(x => x.label.toLowerCase() === type);
                if (v) img.src = `data:image/jpeg;base64,${v.base64}`;
                lbl.textContent = det ? (det.text || '—') : '—';
            }
        }

        newTabs.forEach(tab => {
            tab.addEventListener('click', () => {
                newTabs.forEach(t => t.classList.remove('active'));
                tab.classList.add('active');
                setPreview(tab.dataset.pre);
            });
        });

        // Set initial to original
        document.querySelector('.pre-tab[data-pre="original"]').classList.add('active');
        setPreview('original');
    }

    // ── Modal ────────────────────────────────────────────────
    const modal = document.getElementById('modal');
    const modalImg = document.getElementById('modal-img');
    const modalTitle = document.getElementById('modal-title');

    function openModal(url, title) {
        modalTitle.textContent = title;
        modalImg.src = `${url}?t=${Date.now()}`;
        modal.classList.remove('hidden');
    }

    document.getElementById('modal-close').addEventListener('click', () => modal.classList.add('hidden'));
    modal.addEventListener('click', e => { if (e.target === modal) modal.classList.add('hidden'); });

    // ── Service Worker ───────────────────────────────────────
    if ('serviceWorker' in navigator) {
        navigator.serviceWorker.register('/sw.js').catch(() => { });
    }
});