// image-processor.worker.js
self.onmessage = async function (e) {
  const { imageUrl, text, options, id } = e.data;

  try {
    // Загружаем изображение как Blob
    const response = await fetch(imageUrl, { 
      mode: 'cors',
      credentials: 'same-origin' 
    });
    
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    
    const imageBlob = await response.blob();
    const imageBitmap = await createImageBitmap(imageBlob);

    // Создаём OffscreenCanvas
    const offscreen = new OffscreenCanvas(
      options.width ?? imageBitmap.width,
      options.height ?? imageBitmap.height
    );
    
    const ctx = offscreen.getContext('2d', { alpha: true });

    // Рисуем изображение
    ctx.drawImage(imageBitmap, 0, 0, offscreen.width, offscreen.height);

    if (!text?.trim()) {
      const blob = await offscreen.convertToBlob({
        type: options.type ?? 'image/png',
        quality: options.quality ?? 0.92
      });
      self.postMessage({ id, blob }, [blob]);
      return;
    }

    // === Отрисовка текста ===
    const basePadding = 6;
    const fontSize = options.fontSize ?? Math.round(offscreen.width * 0.05);
    ctx.font = `${fontSize}px ${options.fontFamily ?? 'sans-serif'}`;
    ctx.textBaseline = 'bottom';
    ctx.textAlign = 'center';

    const textColor = options.textColor ?? '#5F1798';
    const bgColor = options.bgColor ?? '#fff';
    const strokeColor = options.strokeColor ?? 'rgba(0,0,0,0.35)';
    const shadowBlur = options.shadowBlur ?? 6;
    const maxWidth = offscreen.width - basePadding * 2 - (options.extraPadding ?? 0);

    // Разбивка текста на строки
    const words = text.split(' ');
    let line = '';
    const lines = [];
    for (const word of words) {
      const testLine = line ? line + ' ' + word : word;
      if (ctx.measureText(testLine).width > maxWidth && line) {
        lines.push(line);
        line = word;
      } else {
        line = testLine;
      }
    }
    if (line) lines.push(line);

    const lineHeight = fontSize + (options.lineGap ?? 6);
    const boxHeight = lines.length * lineHeight + basePadding * 2;
    const maxLineWidth = Math.max(...lines.map(l => ctx.measureText(l).width));
    const boxWidth = maxLineWidth + basePadding * 2;

    const bottomPadding = options.bottomPadding ?? Math.round(fontSize * 0.6);
    const boxX = (offscreen.width - boxWidth) / 2;
    const boxY = offscreen.height - bottomPadding - boxHeight;
    const radius = options.radius ?? 8;

    // Фон под текстом
    ctx.save();
    ctx.fillStyle = bgColor;
    ctx.shadowColor = strokeColor;
    ctx.shadowBlur = shadowBlur;
    roundRect(ctx, boxX, boxY, boxWidth, boxHeight, radius, true, false);
    ctx.restore();

    // Текст
    ctx.fillStyle = textColor;
    ctx.shadowColor = 'transparent';
    for (let i = 0; i < lines.length; i++) {
      const lineY = boxY + basePadding + (i + 1) * lineHeight - (lineHeight - fontSize) / 2;
      const lineX = offscreen.width / 2;

      if (options.outline) {
        ctx.lineWidth = options.outlineWidth ?? 2;
        ctx.strokeStyle = options.outlineColor ?? 'rgba(255,255,255,0.8)';
        ctx.strokeText(lines[i], lineX, lineY);
      }
      ctx.fillText(lines[i], lineX, lineY);
    }

    const blob = await offscreen.convertToBlob({
      type: options.type ?? 'image/png',
      quality: options.quality ?? 0.92
    });

    self.postMessage({ id, blob }, [blob]); // Transferable object

  } catch (err) {
    self.postMessage({ id, error: err.message });
  }
};

function roundRect(ctx, x, y, w, h, r, fill, stroke) {
  if (typeof r === 'number') r = { tl: r, tr: r, br: r, bl: r };
  ctx.beginPath();
  ctx.moveTo(x + r.tl, y);
  ctx.lineTo(x + w - r.tr, y);
  ctx.quadraticCurveTo(x + w, y, x + w, y + r.tr);
  ctx.lineTo(x + w, y + h - r.br);
  ctx.quadraticCurveTo(x + w, y + h, x + w - r.br, y + h);
  ctx.lineTo(x + r.bl, y + h);
  ctx.quadraticCurveTo(x, y + h, x, y + h - r.bl);
  ctx.lineTo(x, y + r.tl);
  ctx.quadraticCurveTo(x, y, x + r.tl, y);
  ctx.closePath();
  if (fill) ctx.fill();
  if (stroke) ctx.stroke();
}