const HEIC_MIME_TYPES = [
  'image/heic',
  'image/heif',
  'image/heic-sequence',
  'image/heif-sequence',
]

export function isHeicOrHeif(file: File): boolean {
  const name = file.name.toLowerCase()
  const type = (file.type || '').toLowerCase()
  return (
    name.endsWith('.heic') ||
    name.endsWith('.heif') ||
    HEIC_MIME_TYPES.includes(type)
  )
}

function replaceExtension(fileName: string, extension: string): string {
  const lastDot = fileName.lastIndexOf('.')
  if (lastDot <= 0) return `${fileName}.${extension}`
  return `${fileName.slice(0, lastDot)}.${extension}`
}

export async function convertHeicHeifToWebp(file: File): Promise<File> {
  const type = (file.type || '').toLowerCase()

  // If the blob already has a browser-readable image MIME (and it's not a HEIC MIME),
  // skip conversion and return the original file.
  if (type && type.startsWith('image/') && !HEIC_MIME_TYPES.includes(type)) {
    return file
  }

  const { default: heic2any } = await import('heic2any')
  try {
    const result = await heic2any({
      blob: file,
      toType: 'image/webp',
      quality: 0.92,
    })

    const blob = Array.isArray(result) ? result[0] : result
    if (!(blob instanceof Blob)) {
      throw new Error('HEIC/HEIF 转换失败')
    }

    const targetFileName = replaceExtension(file.name, 'webp')
    return new File([blob], targetFileName, {
      type: 'image/webp',
      lastModified: Date.now(),
    })
  } catch (err: any) {
    // heic2any may throw when the provided blob is already browser-readable
    // (e.g. it contains image/jpeg despite .heic extension). In that case,
    // treat it as already-converted and return the original file.
    const msg = String(err?.message || '')
    if (err && (err.code === 1 || /already browser readable/i.test(msg))) {
      return file
    }
    throw err instanceof Error ? err : new Error('HEIC/HEIF 转换失败')
  }
}