/**
 * 在照片左下角叠加水印文字
 * @param {string} imagePath - 原始图片路径
 * @param {string} text - 水印文字（如 "2025/06/15 12:00 张三"）
 * @returns {Promise<string>} 带水印的临时文件路径（H5 返回 base64 dataURL）
 */
export function addWatermark(imagePath, text) {
  return new Promise((resolve, reject) => {
    // #ifdef APP-PLUS
    uni.getImageInfo({
      src: imagePath,
      success(imgInfo) {
        const width = imgInfo.width
        const height = imgInfo.height
        const bitmap = new plus.nativeObj.Bitmap('watermark')
        bitmap.load(imagePath, () => {
          const canvas = new plus.nativeObj.View('watermarkView', {
            left: '0px', top: '0px',
            width: width + 'px', height: height + 'px'
          })
          canvas.drawBitmap(bitmap, {}, { left: '0px', top: '0px', width: width + 'px', height: height + 'px' })
          const fontSize = Math.max(Math.floor(width * 0.03), 14)
          const padding = Math.floor(fontSize * 0.8)
          const textX = padding
          const bgHeight = fontSize + padding * 2
          canvas.drawRect(
            { color: 'rgba(0,0,0,0.4)' },
            { left: '0px', top: (height - bgHeight) + 'px', width: width + 'px', height: bgHeight + 'px' }
          )
          canvas.drawText(text, {
            left: textX + 'px',
            top: (height - bgHeight + padding) + 'px',
            width: (width - textX * 2) + 'px',
            height: fontSize + 'px'
          }, { size: fontSize + 'px', color: '#ffffff' })
          const tempPath = `_doc/watermark_${Date.now()}.jpg`
          canvas.toBitmap(tempPath, {}, () => {
            bitmap.clear()
            resolve(tempPath)
          }, (err) => {
            bitmap.clear()
            reject(err)
          })
        }, (err) => reject(err))
      },
      fail: reject
    })
    // #endif

    // #ifdef H5
    const img = new Image()
    img.crossOrigin = 'anonymous'
    img.onload = () => {
      const width = img.naturalWidth
      const height = img.naturalHeight
      const canvas = document.createElement('canvas')
      canvas.width = width
      canvas.height = height
      const ctx = canvas.getContext('2d')
      ctx.drawImage(img, 0, 0, width, height)
      const fontSize = Math.max(Math.floor(width * 0.03), 14)
      const padding = Math.floor(fontSize * 0.8)
      const bgHeight = fontSize + padding * 2
      ctx.fillStyle = 'rgba(0,0,0,0.4)'
      ctx.fillRect(0, height - bgHeight, width, bgHeight)
      ctx.fillStyle = '#ffffff'
      ctx.font = `${fontSize}px sans-serif`
      ctx.textBaseline = 'middle'
      ctx.fillText(text, padding, height - bgHeight / 2)
      resolve(canvas.toDataURL('image/jpeg', 0.9))
    }
    img.onerror = (err) => reject(err || new Error('图片加载失败'))
    img.src = imagePath
    // #endif

    // #ifdef MP-WEIXIN || MP-ALIPAY || MP-BAIDU || MP-TOUTIAO || MP-QQ
    // 小程序端：跳过水印，直接返回原图
    // resolve(imagePath)
    // #endif
  })
}