document.addEventListener('DOMContentLoaded', function() {
    // DOM Elements
    const dropZone = document.getElementById('dropZone');
    const fileInput = document.getElementById('fileInput');
    const imagePreview = document.getElementById('imagePreview');
    const imagePreviewContainer = document.getElementById('imagePreviewContainer');
    const annotationCanvas = document.getElementById('annotationCanvas');
    const analyzeBtn = document.getElementById('analyzeBtn');
    const exportBtn = document.getElementById('exportBtn');
    const detectedFields = document.getElementById('detectedFields');
    const noFieldsMessage = document.getElementById('noFieldsMessage');
    const templateField = document.getElementById('templateField');
    // Enhanced chemical label field patterns with better matching
    const FIELD_PATTERNS = {
        productName: /(product|item|name|chemical)\s*[:：]\s*/i,
        manufacturer: /(manufacturer|producer|supplier|made by|company)\s*[:：]\s*/i,
        casNumber: /(cas\s*(no|number|#)|chemical\s*abstracts\s*service)\s*[:：]\s*/i,
        unNumber: /(un\s*(no|number|#)|un\s*id|transport\s*id)\s*[:：]\s*/i,
        hazardSymbols: /(ghs|hazard|warning|symbol|pictogram|danger)\s*[:：]\s*/i,
        concentration: /(concentration|purity|grade|assay|content)\s*[:：]\s*/i,
        batchNumber: /(batch\s*(no|number|#)|lot\s*(no|number|#)|serial)\s*[:：]\s*/i,
        expiryDate: /(expiry|expiration|best\s*before|use\s*by|valid\s*until)\s*[:：]\s*/i,
        hazardStatements: /(hazard\s*statement|h\s*phrase|risk\s*phrase)\s*[:：]\s*/i,
        precautionaryStatements: /(precautionary\s*statement|p\s*phrase|safety\s*phrase)\s*[:：]\s*/i,
        signalWord: /(signal\s*word|warning|danger|caution)\s*[:：]\s*/i,
        molecularFormula: /(molecular\s*formula|formula)\s*[:：]\s*/i,
        molecularWeight: /(molecular\s*weight|m\.w\.|mw)\s*[:：]\s*/i,
        density: /(density|specific\s*gravity)\s*[:：]\s*/i,
        storageConditions: /(storage|store)\s*[:：]\s*/i
    };
// Event listeners for drag and drop
    ['dragenter', 'dragover', 'dragleave', 'drop'].forEach(eventName => {
        dropZone.addEventListener(eventName, preventDefaults, false);
    });

    function preventDefaults(e) {
        e.preventDefault();
        e.stopPropagation();
    }

    ['dragenter', 'dragover'].forEach(eventName => {
        dropZone.addEventListener(eventName, highlight, false);
    });

    ['dragleave', 'drop'].forEach(eventName => {
        dropZone.addEventListener(eventName, unhighlight, false);
    });

    function highlight() {
        dropZone.classList.add('drag-over');
    }

    function unhighlight() {
        dropZone.classList.remove('drag-over');
    }

    dropZone.addEventListener('drop', handleDrop, false);
    fileInput.addEventListener('change', handleFiles, false);

    function handleDrop(e) {
        const dt = e.dataTransfer;
        const files = dt.files;
        handleFiles({target: {files}});
    }

    function handleFiles(e) {
        const files = e.target.files;
        if (!files.length) return;

        const file = files[0];
        if (!file.type.match('image.*')) {
            alert('Please upload an image file');
            return;
        }

        const reader = new FileReader();
        reader.onload = function(e) {
            imagePreview.src = e.target.result;
            imagePreview.onload = function() {
                imagePreviewContainer.classList.remove('hidden');
                dropZone.classList.add('hidden');
                
                // Set canvas dimensions to match the image
                annotationCanvas.width = imagePreview.width;
                annotationCanvas.height = imagePreview.height;
                
                analyzeBtn.disabled = false;
            };
        };
        reader.readAsDataURL(file);
    }
    // Analyze button click handler
    analyzeBtn.addEventListener('click', async function() {
        analyzeBtn.disabled = true;
        analyzeBtn.textContent = 'Analyzing...';
        
        try {
            // Get the image data
            const imageData = await getImageData();
            
            // Call Google Cloud Vision API (or your preferred vision service)
            const results = await analyzeImageWithVisionAPI(imageData);
            
            // Process the results
            processVisionResults(results);
            
            // Enable export button
            exportBtn.disabled = false;
        } catch (error) {
            console.error('Analysis error:', error);
            alert('Analysis failed. Please try again.');
        } finally {
            analyzeBtn.disabled = false;
            analyzeBtn.textContent = 'Analyze Label';
        }
    });

    // Export button click handler
    exportBtn.addEventListener('click', function() {
        exportData();
    });

    // Get image data as base64
    async function getImageData() {
        return new Promise((resolve) => {
            const reader = new FileReader();
            reader.onload = function(e) {
                // Remove data URL prefix
                const base64Data = e.target.result.split(',')[1];
                resolve(base64Data);
            };
            reader.readAsDataURL(fileInput.files[0]);
        });
    }
    // Analyze image with OCR.space API
    async function analyzeImageWithVisionAPI(imageData) {
        const apiKey = 'K87299170688957'; // Free public demo key (rate limited)
        const apiUrl = 'https://api.ocr.space/parse/image';
        
        try {
            const formData = new FormData();
            formData.append('base64Image', `data:image/jpeg;base64,${imageData}`);
            formData.append('language', 'eng');
            formData.append('isOverlayRequired', 'true');
            formData.append('OCREngine', '2'); // Engine 2 is more accurate
            
            const response = await fetch(apiUrl, {
                method: 'POST',
                headers: {
                    'apikey': apiKey
                },
                body: formData
            });
            
            const data = await response.json();
            
            if (!data.IsErroredOnProcessing) {
                // Format response to match our expected structure
                const parsedText = data.ParsedResults[0].ParsedText;
                const textOverlay = data.ParsedResults[0].TextOverlay;
                
                // Get bounding box of all text
                let minX = Infinity, minY = Infinity, maxX = 0, maxY = 0;
                textOverlay.Lines.forEach(line => {
                    line.Words.forEach(word => {
                        minX = Math.min(minX, word.Left);
                        minY = Math.min(minY, word.Top);
                        maxX = Math.max(maxX, word.Left + word.Width);
                        maxY = Math.max(maxY, word.Top + word.Height);
                    });
                });
                
                return {
                    textAnnotations: [{
                        description: parsedText,
                        boundingPoly: {
                            vertices: [
                                {x: minX, y: minY},
                                {x: maxX, y: minY},
                                {x: maxX, y: maxY},
                                {x: minX, y: maxY}
                            ]
                        }
                    }]
                };
            } else {
                throw new Error(data.ErrorMessage || 'OCR processing failed');
            }
        } catch (error) {
            console.error('OCR API error:', error);
            throw error;
        }
    }
    // Process vision API results
    function processVisionResults(results) {
        // Clear previous fields
        detectedFields.innerHTML = '';
        noFieldsMessage.classList.add('hidden');
        
        // Extract full text
        const fullText = results.textAnnotations[0].description;
        
        // Split into lines and process each line
        const lines = fullText.split('\n');
        const detectedFieldsMap = new Map();
        
        // Improved text processing with better pattern matching
        lines.forEach(line => {
            if (!line.trim()) return;
            
            // Try to match against known field patterns
            let matched = false;
            for (const [fieldType, pattern] of Object.entries(FIELD_PATTERNS)) {
                const match = line.match(pattern);
                if (match) {
                    // Extract the field value (text after the label)
                    let value = line.substring(match.index + match[0].length).trim();
                    
                    // Clean up value (remove special characters at start/end)
                    value = value.replace(/^[^a-zA-Z0-9]+/, '').replace(/[^a-zA-Z0-9]+$/, '');
                    
                    if (value) {
                        detectedFieldsMap.set(fieldType, {
                            label: match[0].trim(),
                            value: value
                        });
                        matched = true;
                        break;
                    }
                }
            }
            
            // If no field label matched, check if it might be a value continuing from previous line
            if (!matched && detectedFieldsMap.size > 0) {
                const lastEntry = Array.from(detectedFieldsMap.entries()).pop();
                const lastValue = lastEntry[1].value;
                
                // If previous value ends with incomplete punctuation or looks truncated
                if (!/[.!?]$/.test(lastValue) || lastValue.length < 30) {
                    detectedFieldsMap.set(lastEntry[0], {
                        ...lastEntry[1],
                        value: `${lastValue} ${line.trim()}`
                    });
                }
            }
            
            // Check for GHS symbols (improved matching)
            const ghsMatch = line.match(/(corrosive|flammable|toxic|health hazard|environmental hazard|explosive|oxidizing|irritant|gas under pressure|acute toxicity)/i);
            if (ghsMatch) {
                const symbol = ghsMatch[0].toLowerCase().replace(/\s+/g, '_');
                detectedFieldsMap.set(`ghs_${symbol}`, {
                    label: 'GHS Symbol',
                    value: ghsMatch[0]
                });
            }
        });
// Add detected fields to UI
        detectedFieldsMap.forEach((fieldData, fieldName) => {
            addDetectedField(fieldName, fieldData.value);
        });
        
        // Draw bounding boxes (simplified for demo)
        drawBoundingBoxes(results.textAnnotations[0].boundingPoly.vertices);
    }
function addDetectedField(name, value) {
        const fieldElement = templateField.cloneNode(true);
        fieldElement.classList.remove('hidden');
        fieldElement.querySelector('#fieldName').textContent = name;
        fieldElement.querySelector('#fieldValue').textContent = value;
        fieldElement.removeAttribute('id');
        detectedFields.appendChild(fieldElement);
    }
    function drawBoundingBoxes(vertices) {
        const ctx = annotationCanvas.getContext('2d');
        ctx.clearRect(0, 0, annotationCanvas.width, annotationCanvas.height);
        
        // Calculate bounding box dimensions
        const minX = Math.min(...vertices.map(v => v.x || 0));
        const maxX = Math.max(...vertices.map(v => v.x || 0));
        const minY = Math.min(...vertices.map(v => v.y || 0));
        const maxY = Math.max(...vertices.map(v => v.y || 0));
        const width = maxX - minX;
        const height = maxY - minY;
        
        // Draw main bounding box
        ctx.strokeStyle = '#818cf8';
        ctx.lineWidth = 2;
        ctx.strokeRect(minX, minY, width, height);
        
        // Fill with semi-transparent color
        ctx.fillStyle = 'rgba(99, 102, 241, 0.1)';
        ctx.fillRect(minX, minY, width, height);
        
        // Draw label
        ctx.fillStyle = '#4b5563';
        ctx.fillRect(minX, minY - 20, 100, 20);
        ctx.fillStyle = 'white';
        ctx.font = '12px sans-serif';
        ctx.fillText('Detected Label', minX + 5, minY - 5);
    }
    function exportData() {
        const fields = [];
        document.querySelectorAll('#detectedFields > div').forEach(field => {
            const name = field.querySelector('span').textContent;
            const value = field.querySelector('div').textContent;
            fields.push({
                field: name,
                value: value,
                confidence: 0.95, // Would come from API in real implementation
                timestamp: new Date().toISOString()
            });
        });
        
        // Create more comprehensive JSON structure
        const exportData = {
            metadata: {
                analyzedAt: new Date().toISOString(),
                imageDimensions: {
                    width: imagePreview.naturalWidth,
                    height: imagePreview.naturalHeight
                },
                version: '1.0'
            },
            fields: fields
        };
        
        // Create JSON download
        const dataStr = JSON.stringify(exportData, null, 2);
        const dataUri = 'data:application/json;charset=utf-8,' + encodeURIComponent(dataStr);
        
        const exportFileDefaultName = `chemical_label_${Date.now()}.json`;
        const linkElement = document.createElement('a');
        linkElement.setAttribute('href', dataUri);
        linkElement.setAttribute('download', exportFileDefaultName);
        linkElement.click();
    }
// Initialize feather icons
    feather.replace();
});