// Always redraw to JPEG: native compressImage changes quality, not dimensions.
var MAX_SIDE = 1280;
function compressToBase64(src, page) {
  return new Promise(function (resolve, reject) {
    my.getImageInfo({ src: src, success: function (info) {
      if (page.alive === false) { reject({ canceled: true }); return; }
      if (!(info.width > 0 && info.height > 0)) { reject(new Error('无法读取照片尺寸，请重新选择')); return; }
      var scale = Math.min(1, MAX_SIDE / Math.max(info.width, info.height));
      var w = Math.max(1, Math.round(info.width * scale)), h = Math.max(1, Math.round(info.height * scale));
      page.setData({ compressWidth: w, compressHeight: h }, function () {
        if (page.alive === false) { reject({ canceled: true }); return; }
        try {
          var ctx = my.createCanvasContext('compress-canvas');
          ctx.clearRect(0, 0, w, h);
          ctx.drawImage(src, 0, 0, w, h);
          ctx.draw(false, function () {
            if (page.alive === false) { reject({ canceled: true }); return; }
            ctx.toTempFilePath({ x: 0, y: 0, width: w, height: h, destWidth: w, destHeight: h, fileType: 'jpg', quality: 0.88,
              success: function (result) {
                var file = result.apFilePath || result.tempFilePath;
                if (!file) { reject(new Error('照片处理失败，请重试')); return; }
                try {
                  my.getFileSystemManager().readFile({ filePath: file, encoding: 'base64',
                    success: function (r) { resolve('data:image/jpeg;base64,' + r.data); }, fail: reject });
                } catch (e) { reject(new Error('当前淘宝版本不支持照片读取，请升级后重试')); }
              }, fail: reject });
          });
        } catch (e) { reject(new Error('照片处理不可用，请升级淘宝后重试')); }
      });
    }, fail: reject });
  });
}
module.exports = { MAX_SIDE: MAX_SIDE, compressToBase64: compressToBase64 };