document.addEventListener('DOMContentLoaded', function() {
    let html5QrCode;
    const btnScanBarcode = document.getElementById('btnScanBarcode');
    const btnTakePhoto = document.getElementById('btnTakePhoto');
    const reader = document.getElementById('reader');
    const aiLoading = document.getElementById('aiLoading');

    const pName = document.getElementById('p_name');
    const pCategory = document.getElementById('p_category');
    const pQuantity = document.getElementById('p_quantity');
    const pExpiration = document.getElementById('p_expiration');

    function checkHttps() {
        if (location.protocol !== 'https:' && location.hostname !== 'localhost' && location.hostname !== '127.0.0.1') {
            alert("Camera access requires HTTPS. Please ensure you are using a secure connection.");
            return false;
        }
        return true;
    }

    function stopScanner() {
        return new Promise((resolve) => {
            console.log("Stopping scanner...");
            cleanupUI();
            if (html5QrCode && html5QrCode.isScanning) {
                html5QrCode.stop().then(() => {
                    console.log("Scanner stopped.");
                    reader.style.display = 'none';
                    resolve();
                }).catch(err => {
                    console.error("Failed to stop scanner", err);
                    reader.style.display = 'none';
                    resolve();
                });
            } else {
                console.log("Scanner was not active.");
                reader.style.display = 'none';
                resolve();
            }
        });
    }

    function cleanupUI() {
        const capBtn = document.getElementById('btnCaptureFrame');
        if (capBtn) capBtn.remove();
        const stopBtn = document.getElementById('btnStopScanner');
        if (stopBtn) stopBtn.remove();
        const flash = document.querySelector('.shutter-flash');
        if (flash) flash.classList.remove('active');
        reader.classList.remove('camera-mode');
    }

    function addStopButton() {
        if (!document.getElementById('btnStopScanner')) {
            const stopBtn = document.createElement('button');
            stopBtn.id = 'btnStopScanner';
            stopBtn.innerText = "Stop Camera";
            stopBtn.className = "btn btn-danger btn-sm w-100 mt-2";
            stopBtn.onclick = stopScanner;
            reader.after(stopBtn);
        }
    }

    function triggerFlash() {
        let flash = document.querySelector('.shutter-flash');
        if (!flash) {
            flash = document.createElement('div');
            flash.className = 'shutter-flash';
            reader.appendChild(flash);
        }
        flash.classList.add('active');
        setTimeout(() => flash.classList.remove('active'), 150);
    }

    btnScanBarcode.addEventListener('click', function() {
        if (!checkHttps()) return;
        
        stopScanner().then(() => {
            reader.style.display = 'block';
            if (!html5QrCode) {
                html5QrCode = new Html5Qrcode("reader");
            }
            
            addStopButton();

            const config = { 
                fps: 10, 
                qrbox: (viewfinderWidth, viewfinderHeight) => {
                    return { width: viewfinderWidth * 0.8, height: viewfinderHeight * 0.4 };
                }
            };

            html5QrCode.start(
                { facingMode: "environment" }, 
                config, 
                (decodedText) => {
                    console.log(`Barcode detected: ${decodedText}`);
                    triggerFlash();
                    stopScanner().then(() => {
                        analyzeProduct({ barcode: decodedText });
                    });
                }
            ).catch(err => {
                console.error("Scanner start error:", err);
                alert("Could not start camera. Please check permissions.");
                reader.style.display = 'none';
                cleanupUI();
            });
        });
    });

    btnTakePhoto.addEventListener('click', function() {
        if (!checkHttps()) return;

        stopScanner().then(() => {
            reader.style.display = 'block';
            reader.classList.add('camera-mode');
            if (!html5QrCode) {
                html5QrCode = new Html5Qrcode("reader");
            }

            addStopButton();

            html5QrCode.start(
                { facingMode: "environment" }, 
                { fps: 10 }, 
                () => { /* ignore QR scans in photo mode unless we want both */ }
            ).then(() => {
                if (!document.getElementById('btnCaptureFrame')) {
                    const capBtn = document.createElement('button');
                    capBtn.id = 'btnCaptureFrame';
                    capBtn.innerHTML = '<i class="bi bi-camera-fill me-1"></i> Take Photo & Identify';
                    capBtn.className = "btn btn-primary btn-lg w-100 mt-2 mb-1 py-3";
                    capBtn.onclick = capturePhoto;
                    // Insert before stop button if exists
                    const stopBtn = document.getElementById('btnStopScanner');
                    if (stopBtn) {
                        stopBtn.before(capBtn);
                    } else {
                        reader.after(capBtn);
                    }
                }
            }).catch(err => {
                console.error("Camera start error:", err);
                alert("Camera error: " + err);
                reader.style.display = 'none';
                cleanupUI();
            });
        });
    });

    function capturePhoto() {
        console.log("Capturing photo...");
        const video = document.querySelector('#reader video');
        if (!video) {
            console.error("Video element not found in reader");
            alert("Camera not ready. Video element missing.");
            return;
        }

        triggerFlash();

        const canvas = document.getElementById('photoCanvas');
        if (!canvas) {
            console.error("Canvas element #photoCanvas not found");
            alert("Application error: missing canvas.");
            return;
        }
        
        const MAX_DIM = 1024;
        let width = video.videoWidth;
        let height = video.videoHeight;

        if (width === 0 || height === 0) {
            console.error("Video dimensions are 0", {width, height});
            alert("Camera error: invalid video dimensions. Try moving the camera.");
            return;
        }

        if (width > height) {
            if (width > MAX_DIM) {
                height *= MAX_DIM / width;
                width = MAX_DIM;
            }
        } else {
            if (height > MAX_DIM) {
                width *= MAX_DIM / height;
                height = MAX_DIM;
            }
        }

        canvas.width = width;
        canvas.height = height;
        const context = canvas.getContext('2d');
        context.drawImage(video, 0, 0, width, height);
        
        const dataUrl = canvas.toDataURL('image/jpeg', 0.8);
        console.log("Data URL generated, length:", dataUrl.length);

        if (dataUrl.length < 1000) {
            console.error("Data URL seems too short, capture might have failed");
        }
        
        setTimeout(() => {
            console.log("Proceeding to identification...");
            stopScanner().then(() => {
                analyzeProduct({ image: dataUrl });
            });
        }, 300);
    }

    function analyzeProduct(params) {
        console.log("Sending request to api/analyze.php", params.barcode ? "with barcode" : "with image");
        aiLoading.style.display = 'block';
        pName.placeholder = "Identifying...";
        
        // Clear previous values to show something is happening
        pName.value = '';
        
        fetch('api/analyze.php', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(params)
        })
        .then(res => {
            console.log("Received response status:", res.status);
            return res.json();
        })
        .then(res => {
            console.log("Received data:", res);
            aiLoading.style.display = 'none';
            pName.placeholder = "e.g. Milk, Eggs, Bread";
            
            if (res.success && res.data) {
                const data = res.data;
                if (data.name) pName.value = data.name;
                if (data.category) pCategory.value = data.category;
                if (data.quantity) pQuantity.value = data.quantity;
                if (data.expiration_date) pExpiration.value = data.expiration_date;
                
                // Visual highlight of changed fields
                [pName, pCategory, pQuantity, pExpiration].forEach(el => {
                    if (el.value) {
                        el.classList.add('is-valid');
                        setTimeout(() => el.classList.remove('is-valid'), 2000);
                    }
                });

            } else {
                console.error("Identification failed:", res.error);
                alert("Could not identify the product: " + (res.error || "Please try again."));
            }
        })
        .catch(err => {
            aiLoading.style.display = 'none';
            pName.placeholder = "e.g. Milk, Eggs, Bread";
            console.error("Fetch error:", err);
            alert("Analysis failed. Connection error or server issue.");
        });
    }

    const addItemModal = document.getElementById('addItemModal');
    if (addItemModal) {
        addItemModal.addEventListener('hidden.bs.modal', function () {
            stopScanner();
        });
    }
});