// Worker for processing video frames off the main thread

interface ProcessMessage {
    type: 'process';
    bitmap: ImageBitmap;
    targetWidth: number;
    targetHeight: number;
    sourceRect: {
        x: number;
        y: number;
        width: number;
        height: number;
    };
    mirror: boolean;
}

let offscreenCanvas: OffscreenCanvas | null = null;
let ctx: OffscreenCanvasRenderingContext2D | null = null;

self.onmessage = (e: MessageEvent<ProcessMessage>) => {
    const { bitmap, targetWidth, targetHeight, sourceRect, mirror } = e.data;

    try {
        // Create or resize canvas
        if (!offscreenCanvas || offscreenCanvas.width !== targetWidth || offscreenCanvas.height !== targetHeight) {
            offscreenCanvas = new OffscreenCanvas(targetWidth, targetHeight);
            ctx = offscreenCanvas.getContext('2d', {
                alpha: false,
                desynchronized: true,
                willReadFrequently: true
            });
        }

        if (!ctx) {
            throw new Error('Failed to get canvas context');
        }

        // Enable high-quality smoothing
        ctx.imageSmoothingEnabled = true;
        ctx.imageSmoothingQuality = 'medium';

        // Draw with optional mirroring
        ctx.resetTransform();
        if (mirror) {
            ctx.translate(targetWidth, 0);
            ctx.scale(-1, 1);
        }
        ctx.drawImage(bitmap, sourceRect.x, sourceRect.y, sourceRect.width, sourceRect.height,
            0, 0, targetWidth, targetHeight);

        // Extract pixel data
        const imageData = ctx.getImageData(0, 0, targetWidth, targetHeight);

        // Send back (transfer the buffer for zero-copy)
        const response = {
            type: 'result',
            data: imageData.data,
            width: targetWidth,
            height: targetHeight
        };

        self.postMessage(response, [imageData.data.buffer]);

    } catch (error) {
        self.postMessage({ type: 'error', error: String(error) });
    } finally {
        // Clean up bitmap
        bitmap.close();
    }
};