Image Top Secret Military File Creator

async function processImage(
    originalImg,
    classificationText = "TOP SECRET",
    headerDetails = "FOR OFFICIAL USE ONLY",
    footerLeftText = "", // Auto-generates if empty
    footerRightText = "", // Auto-generates if empty
    stampColor = "rgb(200, 0, 0)",
    docTextColor = "black",
    pageColor = "#F0E68C" // Khaki/Manila like color
) {
    const canvas = document.createElement('canvas');
    const ctx = canvas.getContext('2d');

    const img = originalImg;

    // --- Calculate dynamic sizes ---
    const outerMargin = 30;
    const elementSpacing = 15;
    const stampRotation = -0.03; // Radians, approx -1.7 degrees

    // Base size for font calculation, capped to prevent excessively large fonts for huge images
    const referenceDim = Math.min(img.width, img.height); // Use smaller dimension of image
    const baseSizeForFontCalc = Math.min(referenceDim, 800); // Cap this reference to 800px

    const stampAreaNominalHeight = Math.max(40, baseSizeForFontCalc * 0.12 + img.height * 0.03);
    const detailsAreaNominalHeight = Math.max(25, baseSizeForFontCalc * 0.06 + img.height * 0.015);

    const stampFontPixels = Math.floor(stampAreaNominalHeight * 0.75);
    const detailsFontPixels = Math.floor(detailsAreaNominalHeight * 0.70);

    // --- Determine canvas dimensions ---
    canvas.width = img.width + 2 * outerMargin;

    let currentProjectedHeight = 0;
    currentProjectedHeight += outerMargin; // Top margin

    if (classificationText) {
        currentProjectedHeight += stampAreaNominalHeight;
        currentProjectedHeight += elementSpacing;
    }

    if (headerDetails) {
        currentProjectedHeight += detailsAreaNominalHeight;
        currentProjectedHeight += elementSpacing;
    }

    currentProjectedHeight += img.height; // Image
    currentProjectedHeight += elementSpacing;
    currentProjectedHeight += detailsAreaNominalHeight; // Footer details area (always present due to defaults)
    
    if (classificationText) {
        currentProjectedHeight += elementSpacing;
        currentProjectedHeight += stampAreaNominalHeight; // Bottom stamp
    }
    
    currentProjectedHeight += outerMargin; // Bottom margin
    canvas.height = currentProjectedHeight;

    // --- Fill background ---
    ctx.fillStyle = pageColor;
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    let currentY = outerMargin;

    // --- Helper function to draw rotated stamp text ---
    function drawStampText(text, yPos, height, fontSize) {
        if (!text) return;
        const centerX = canvas.width / 2;
        const centerY = yPos + height / 2;

        ctx.save();
        ctx.translate(centerX, centerY);
        ctx.rotate(stampRotation);
        ctx.font = `bold ${fontSize}px Impact, Arial Black, sans-serif`;
        ctx.fillStyle = stampColor;
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(text, 0, 0);
        ctx.restore();
    }
    
    // --- Draw Top Stamp (classificationText) ---
    if (classificationText) {
        drawStampText(classificationText, currentY, stampAreaNominalHeight, stampFontPixels);
        currentY += stampAreaNominalHeight + elementSpacing;
    }

    // --- Draw Header Details (headerDetails) ---
    if (headerDetails) {
        ctx.font = `${detailsFontPixels}px 'Courier New', Courier, monospace`;
        ctx.fillStyle = docTextColor;
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(headerDetails, canvas.width / 2, currentY + detailsAreaNominalHeight / 2);
        currentY += detailsAreaNominalHeight + elementSpacing;
    }

    // --- Draw Original Image ---
    ctx.drawImage(img, outerMargin, currentY, img.width, img.height);
    // Add a thin border around the image
    ctx.strokeStyle = docTextColor;
    ctx.lineWidth = 1;
    ctx.strokeRect(outerMargin, currentY, img.width, img.height);
    currentY += img.height + elementSpacing;

    // --- Draw Footer Details (footerLeftText, footerRightText) ---
    const randomFileSuffix = Math.random().toString(36).substring(2, 7).toUpperCase();
    const randomNumber = Math.floor(Math.random() * 899 + 100); // 100-999
    const finalFooterLeft = footerLeftText || `FILE REF: ${randomFileSuffix}-${randomNumber}`;
    const finalFooterRight = footerRightText || `DATE: ${new Date().toLocaleDateString('en-GB', { day: '2-digit', month: 'short', year: 'numeric' }).toUpperCase()}`;

    ctx.font = `${detailsFontPixels}px 'Courier New', Courier, monospace`;
    ctx.fillStyle = docTextColor;
    ctx.textBaseline = 'middle';
    
    const footerY = currentY + detailsAreaNominalHeight / 2;
    ctx.textAlign = 'left';
    ctx.fillText(finalFooterLeft, outerMargin, footerY);
    
    ctx.textAlign = 'right';
    ctx.fillText(finalFooterRight, canvas.width - outerMargin, footerY);
    
    currentY += detailsAreaNominalHeight; // Spacing added only if bottom stamp exists

    // --- Draw Bottom Stamp (classificationText) ---
    if (classificationText) {
        currentY += elementSpacing; // Add spacing before bottom stamp
        drawStampText(classificationText, currentY, stampAreaNominalHeight, stampFontPixels);
        // currentY += stampAreaNominalHeight; // Not needed as it's the last element before bottom margin
    }

    return canvas;
}