Image Personal Information Remover

async function processImage(originalImg, censorColor = "#222222") {
    // Create the final canvas to be returned
    const canvas = document.createElement('canvas');
    canvas.width = originalImg.width;
    canvas.height = originalImg.height;
    const ctx = canvas.getContext('2d');
    
    // Draw the original image onto the canvas
    ctx.drawImage(originalImg, 0, 0);

    // Limit image size for OCR to avoid browser crashes and speed up processing
    const MAX_OCR_DIMENSION = 1200;
    let scale = 1;
    let ocrCanvas = canvas;

    if (canvas.width > MAX_OCR_DIMENSION || canvas.height > MAX_OCR_DIMENSION) {
        scale = MAX_OCR_DIMENSION / Math.max(canvas.width, canvas.height);
        ocrCanvas = document.createElement('canvas');
        ocrCanvas.width = canvas.width * scale;
        ocrCanvas.height = canvas.height * scale;
        const ocrCtx = ocrCanvas.getContext('2d');
        ocrCtx.drawImage(originalImg, 0, 0, ocrCanvas.width, ocrCanvas.height);
    }

    // Dynamically load Tesseract.js if not already present
    if (typeof Tesseract === 'undefined') {
        await new Promise((resolve, reject) => {
            const script = document.createElement('script');
            script.src = 'https://cdn.jsdelivr.net/npm/tesseract.js@5/dist/tesseract.min.js';
            script.onload = resolve;
            script.onerror = reject;
            document.head.appendChild(script);
        });
    }

    // Initialize Tesseract Worker
    const worker = await Tesseract.createWorker('eng');
    
    // Perform Optical Character Recognition
    const { data } = await worker.recognize(ocrCanvas);
    await worker.terminate();

    const lines = data.lines;
    const keywordBBoxes = { name: [], dob: [], address: [] };

    // Helper to translate bounding box back to original image scale
    const adjustBBox = (b) => ({
        x0: b.x0 / scale,
        y0: b.y0 / scale,
        x1: b.x1 / scale,
        y1: b.y1 / scale
    });

    // Pass 1: Identify keywords and map their locations
    for (const line of lines) {
        for (const word of line.words) {
            const cleanText = word.text.replace(/[^a-z]/gi, '').toLowerCase();
            
            if (['name', 'first', 'last', 'full'].includes(cleanText)) {
                keywordBBoxes.name.push(adjustBBox(word.bbox));
            } else if (['dob', 'birth', 'date'].includes(cleanText)) {
                keywordBBoxes.dob.push(adjustBBox(word.bbox));
            } else if (['address', 'addr'].includes(cleanText)) {
                keywordBBoxes.address.push(adjustBBox(word.bbox));
            }
        }
    }

    // Helper function used to check if a word is contextually placed next to or immediately below a keyword
    const isRelatedLocally = (targetBbox, keywordBbox) => {
        const height = keywordBbox.y1 - keywordBbox.y0;
        const wordYCenter = (targetBbox.y0 + targetBbox.y1) / 2;
        
        // Checks if the target is to the right of the keyword explicitly on the same line
        const isRight = wordYCenter >= keywordBbox.y0 - 10 && 
                        wordYCenter <= keywordBbox.y1 + 10 && 
                        targetBbox.x0 > keywordBbox.x0;
                        
        // Checks if the target is placed on the line immediately below the keyword label
        const isBelow = targetBbox.y0 >= keywordBbox.y1 - 5 && 
                        targetBbox.y0 <= keywordBbox.y1 + (height * 3) && 
                        targetBbox.x0 >= keywordBbox.x0 - (height * 5) && 
                        targetBbox.x0 <= keywordBbox.x1 + (height * 20);
                        
        return isRight || isBelow;
    };

    ctx.fillStyle = censorColor;

    // RegEx patterns for standard Personal Identifiable Information details (PII)
    const addressLine1Regex = /\b\d{1,5}\s+[a-z0-9\s]+\s+(st|street|ave|avenue|blvd|boulevard|rd|road|dr|drive|ln|lane|ct|court|apt|suite|unit|pl|place|hw|hwy|highway|pkwy)\b/i;
    const poBoxRegex = /\bp\.?o\.?\s*box\s+\d+\b/i;

    // Pass 2: Analyze & redact matched details
    for (const line of lines) {
        const lineText = line.text;
        
        // Address checks (street address, po box, or zip code format states)
        const hasAddress = addressLine1Regex.test(lineText) || 
                           poBoxRegex.test(lineText) || 
                           /\b[A-Z]{2}[,]?\s+\d{5}(-\d{4})?\b/.test(lineText);
                           
        // General Date checks                
        const hasMonth = /\b(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[a-z]*\b/i.test(lineText);
        const has4Digits = /\b\d{4}\b/.test(lineText);

        for (const word of line.words) {
            const wordText = word.text.trim();
            const cleanWord = wordText.replace(/[^a-z]/gi, '').toLowerCase();

            // Do not paint over structural document labels to maintain visibility of layout context
            if (/^(name|first|last|dob|birth|date|address|addr|street|city|state|zip|sex|gender|height|weight|eyes|hair|class|exp|expires|issued)$/i.test(cleanWord)) {
                continue;
            }

            let shouldCensor = false;

            // 1. Redact Address lines completely
            if (hasAddress) shouldCensor = true;
            
            // 2. Redact strictly numerical Dates (e.g. DD/MM/YYYY)
            if (/\b(\d{1,2}[/-]\d{1,2}[/-]\d{2,4}|\d{4}[/-]\d{1,2}[/-]\d{1,2})\b/.test(wordText)) {
                shouldCensor = true;
            }
            
            // 3. Redact descriptive string formatted dates (e.g. Month Day Year)
            if (hasMonth && has4Digits && (/\b(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[a-z]*\b/i.test(wordText) || /\d/.test(wordText))) {
                shouldCensor = true;
            }
            
            // 4. Redact numbers that resemble Zip Codes or SSNs
            if (/\b\d{5}(-\d{4})?\b/.test(wordText) || /\b\d{3}-\d{2}-\d{4}\b/.test(wordText)) {
                shouldCensor = true;
            }

            const adjustedBBox = adjustBBox(word.bbox);

            // 5. Redact contextually via logical alignment (placed directly right or accurately below a label indicator)
            for (const kb of keywordBBoxes.name) if (isRelatedLocally(adjustedBBox, kb)) shouldCensor = true;
            for (const kb of keywordBBoxes.dob) if (isRelatedLocally(adjustedBBox, kb)) shouldCensor = true;
            for (const kb of keywordBBoxes.address) if (isRelatedLocally(adjustedBBox, kb)) shouldCensor = true;

            // Paint Censor block with minor 3px padding
            if (shouldCensor) {
                const { x0, y0, x1, y1 } = adjustedBBox;
                ctx.fillRect(Math.max(0, x0 - 3), Math.max(0, y0 - 3), (x1 - x0) + 6, (y1 - y0) + 6);
            }
        }
    }

    return canvas;
}