/**
 * 通过后端代理获取图片并转换为Base64
 * @param imageUrl 原始图片URL
 * @param maxSize 最大尺寸，默认80px
 * @returns Promise<string | null> Base64字符串或null
 */
export async function convertImageToBase64ViaProxy(imageUrl: string, maxSize: number = 80): Promise<string | null> {
  if (!imageUrl) return null
  try {
    const proxyUrl = `http://127.0.0.1:8081/api/system/proxy/image?url=${encodeURIComponent(imageUrl)}`
    const response = await fetch(proxyUrl)
    if (!response.ok) return null

    const contentType = response.headers.get('Content-Type')
    const arrayBuffer = await response.arrayBuffer()
    if (!arrayBuffer || arrayBuffer.byteLength === 0) return null
    if (arrayBuffer.byteLength < 1000) return null

    const mimeType = contentType && contentType.startsWith('image/') ? contentType : 'image/jpeg'
    const imageBlob = new Blob([arrayBuffer], { type: mimeType })
    const objectUrl = URL.createObjectURL(imageBlob)

    return new Promise((resolve) => {
      const img = new Image()

      img.onload = () => {
        try {
          const canvas = document.createElement('canvas')
          const ratio = Math.min(maxSize / img.width, maxSize / img.height)
          canvas.width = img.width * ratio
          canvas.height = img.height * ratio

          const ctx = canvas.getContext('2d')
          if (!ctx) {
            URL.revokeObjectURL(objectUrl)
            resolve(null)
            return
          }

          ctx.drawImage(img, 0, 0, canvas.width, canvas.height)
          const base64 = canvas.toDataURL('image/jpeg', 0.8)
          URL.revokeObjectURL(objectUrl)
          resolve(base64)
        } catch (error) {
          URL.revokeObjectURL(objectUrl)
          resolve(null)
        }
      }

      img.onerror = () => {
        URL.revokeObjectURL(objectUrl)
        resolve(null)
      }

      img.src = objectUrl
    })

  } catch (error) {
    return null
  }
}


/**
 * 批量处理图片转换
 * @param imageUrls 图片URL数组
 * @param maxSize 最大尺寸
 * @returns Promise<(string | null)[]> Base64数组
 */
export async function batchConvertImages(imageUrls: string[], maxSize: number = 80): Promise<(string | null)[]> {
  const promises = imageUrls.map(async (url) => {
    if (!url) return null
    return await convertImageToBase64ViaProxy(url, maxSize)
  })

  return await Promise.all(promises)
}