Image Government Classified Document Creator

async function processImage(
    originalImg,
    classificationLevel = "TOP SECRET",
    classificationColor = "red",
    headerTextTop = "", // Example: "CLASSIFIED BY ORDER OF..."
    footerTextBottom = "", // Example: "DECLASSIFY ON:..."
    documentId = "", // Auto-generates if empty. Example: "DOCID-XYZ-2023"
    fontFamilyClassification = "Impact, Arial Black, sans-serif",
    fontFamilyDetails = "Courier New, monospace",
    classificationTextOpacity = 0.7
) {
    const imgWidth = originalImg.naturalWidth || originalImg.width;
    const imgHeight = originalImg.naturalHeight || originalImg.height;

    if (imgWidth === 0 || imgHeight === 0) {
        const errorCanvas = document.createElement('canvas');
        errorCanvas.width = 300;
        errorCanvas.height = 100;
        const errorCtx = errorCanvas.getContext('2d');
        errorCtx.fillStyle = '#f0f0f0';
        errorCtx.fillRect(0, 0, errorCanvas.width, errorCanvas.height);
        errorCtx.fillStyle = 'red';
        errorCtx.font = '16px Arial';
        errorCtx.textAlign = 'center';
        errorCtx.textBaseline = 'middle';
        errorCtx.fillText('Error: Image not loaded or invalid.', errorCanvas.width / 2, errorCanvas.height / 2);
        console.error("Image Government Classified Document Creator: Image has zero dimensions.");
        return errorCanvas;
    }

    const canvas = document.createElement('canvas');
    canvas.width = imgWidth;
    canvas.height = imgHeight;
    const ctx = canvas.getContext('2d');

    // 1. Draw Original Image
    ctx.drawImage(originalImg, 0, 0, imgWidth, imgHeight);

    // Auto-generate Document ID if not provided
    if (!documentId) {
        documentId = `DOCID-${Math.random().toString(36).substring(2, 10).toUpperCase()}-${new Date().getFullYear()}`;
    }

    // --- Define layout constants ---
    // Padding from the absolute edges of the canvas for items like Doc ID
    const edgePadding = Math.max(5, Math.round(Math.min(imgWidth, imgHeight) * 0.01));

    // Zone for small detail texts (headerTextTop, footerTextBottom, documentId)
    // This zone is at the very top and very bottom of the image.
    const detailZoneHeight = Math.max(12, Math.round(imgHeight * 0.035));
    const fontSizeDetails = Math.max(8, Math.round(detailZoneHeight * 0.7)); // Font size for detail text

    // Zone for main classification text (e.g., "TOP SECRET")
    // This zone is located just inside the detail zones.
    const classificationZoneHeight = Math.max(15, Math.round(imgHeight * 0.08));
    const fontSizeClassification = Math.max(10, Math.round(classificationZoneHeight * 0.85));

    // --- Draw detail texts (header, footer, docID) ---
    ctx.font = `${fontSizeDetails}px ${fontFamilyDetails}`;
    ctx.fillStyle = 'black'; // Detail texts are typically black
    ctx.globalAlpha = 1.0;   // Ensure full opacity for details

    // Top details zone: Y position calculated from top edge
    const topDetailCenterY = detailZoneHeight / 2;
    if (headerTextTop) {
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(headerTextTop.toUpperCase(), imgWidth / 2, topDetailCenterY);
    }
    if (documentId) {
        ctx.textAlign = 'right';
        ctx.textBaseline = 'middle';
        ctx.fillText(documentId.toUpperCase(), imgWidth - edgePadding, topDetailCenterY);
    }

    // Bottom details zone: Y position calculated from bottom edge
    const bottomDetailCenterY = imgHeight - (detailZoneHeight / 2);
    if (footerTextBottom) {
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(footerTextBottom.toUpperCase(), imgWidth / 2, bottomDetailCenterY);
    }

    // --- Draw Main Classification Text ---
    ctx.font = `bold ${fontSizeClassification}px ${fontFamilyClassification}`;
    ctx.fillStyle = classificationColor;
    ctx.globalAlpha = classificationTextOpacity;
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';

    // Top Classification Text: positioned below the top detail zone
    const topClassificationCenterY = detailZoneHeight + (classificationZoneHeight / 2);
    ctx.fillText(classificationLevel.toUpperCase(), imgWidth / 2, topClassificationCenterY);

    // Bottom Classification Text: positioned above the bottom detail zone
    const bottomClassificationCenterY = imgHeight - detailZoneHeight - (classificationZoneHeight / 2);
    ctx.fillText(classificationLevel.toUpperCase(), imgWidth / 2, bottomClassificationCenterY);

    // Reset globalAlpha if it was changed by classification text
    ctx.globalAlpha = 1.0;

    return canvas;
}