Profile picture upload.

// W, H: the photo's size after EXIF orientation (3024 × 4032 for Kavya).
// V: the viewport square in CSS px (320). zoom: 1 to maxZoom.
// pan: how far the photo was dragged from centred, in CSS px (positive y = dragged down).
export function cropRect(W: number, H: number, V: number, zoom: number, pan: { x: number; y: number }) {
  const short = Math.min(W, H);
  const perCssPx = short / (V * zoom);   // image px under one CSS px
  const size = Math.round(short / zoom); // the square we keep
  const clamp = (v: number, max: number) => Math.min(Math.max(v, 0), max);
  return {
    size,
    x: clamp(Math.round((W - size) / 2 - pan.x * perCssPx), W - size),
    y: clamp(Math.round((H - size) / 2 - pan.y * perCssPx), H - size),
  };
}
// Kavya: zoom 1.6, pan.y 78 → { size: 1890, x: 567, y: 610 }
// maxZoom = min(4, short / 320), so the kept square is never under 320 px.

self.onmessage = async ({ data: { jobId, file, crop, out, quality } }) => {
  let bmp;
  try {
    // Decodes here, off the main thread; EXIF orientation is applied by default.
    bmp = await createImageBitmap(file, { imageOrientation: 'from-image' });
    const canvas = new OffscreenCanvas(out, out);
    const ctx = canvas.getContext('2d');
    ctx.imageSmoothingQuality = 'high';
    ctx.drawImage(bmp, crop.x, crop.y, crop.size, crop.size, 0, 0, out, out);
    bmp.close(); // frees about 49 MB now, not at the next GC
    bmp = undefined;
    let blob = await canvas.convertToBlob({ type: 'image/webp', quality });
    // An unsupported type silently comes back as PNG: check, then fall back.
    if (blob.type !== 'image/webp') {
      blob = await canvas.convertToBlob({ type: 'image/jpeg', quality: 0.85 });
    }
    self.postMessage({ jobId, ok: true, blob });
  } catch {
    bmp?.close();
    self.postMessage({ jobId, ok: false, code: 'decode_failed' });
  }
};

export function uploadOnce(blob: Blob, key: string, csrf: string,
                           signal: AbortSignal, onProgress: (p: number) => void) {
  return new Promise<Response202 | Ready>((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    let stall = setTimeout(() => xhr.abort(), 20_000);
    const touch = () => { clearTimeout(stall); stall = setTimeout(() => xhr.abort(), 20_000); };
    xhr.upload.onprogress = (e) => { touch(); if (e.lengthComputable) onProgress(e.loaded / e.total); };
    xhr.onload = () => { clearTimeout(stall); xhr.status < 300 ? resolve(JSON.parse(xhr.responseText))
                                                             : reject(httpError(xhr)); };
    xhr.onerror = () => { clearTimeout(stall); reject({ code: 'network', retryable: true }); };
    xhr.onabort = () => { clearTimeout(stall);
      reject(signal.aborted ? { code: 'cancelled' } : { code: 'stalled', retryable: true }); };
    signal.addEventListener('abort', () => xhr.abort(), { once: true });
    xhr.open('POST', '/api/me/avatar');
    xhr.setRequestHeader('Content-Type', blob.type);
    xhr.setRequestHeader('X-CSRF-Token', csrf);
    xhr.setRequestHeader('Idempotency-Key', `"${key}"`); // a quoted string; the same key on every attempt
    xhr.send(blob);
  });
}