// 移动端拍照原图常 5–12MB，1500–1800px 长边 + JPEG 0.85 已经够看清楚音符。
// 用 createImageBitmap 的 imageOrientation: 'from-image' 自动按 EXIF 旋转，
// 否则横拍照在 canvas 里会变成竖图。

export async function compressImage(file, { maxEdge = 1800, quality = 0.85 } = {}) {
  if (!file || !file.type || !file.type.startsWith('image/')) return file

  let bitmap
  try {
    bitmap = await createImageBitmap(file, { imageOrientation: 'from-image' })
  } catch {
    return file
  }

  const { width, height } = bitmap
  const scale = Math.min(1, maxEdge / Math.max(width, height))
  const w = Math.max(1, Math.round(width * scale))
  const h = Math.max(1, Math.round(height * scale))

  const canvas = document.createElement('canvas')
  canvas.width = w
  canvas.height = h
  const ctx = canvas.getContext('2d')
  ctx.drawImage(bitmap, 0, 0, w, h)
  bitmap.close?.()

  const blob = await new Promise((res) => canvas.toBlob(res, 'image/jpeg', quality))
  if (!blob || blob.size >= file.size) return file

  const baseName = file.name?.replace(/\.[^.]+$/, '') || 'photo'
  return new File([blob], `${baseName}.jpg`, { type: 'image/jpeg', lastModified: Date.now() })
}