// GetPolicy.js
const Base64 = require('js-base64');
function getPolicyEncode(policy) {
  // 传入表单上传的policy字段，对policy进行Base64编码
  const encodedPolicy = Base64.encode(JSON.stringify(policy));

  return encodedPolicy;

}
export default getSignature;

// GetSignature.js
const Crypto = require('crypto-js');
const Base64 = require('js-base64');
function getSignature(policyEncoded, SecretKey){
  // 利用SecretKey对Base64编码后的policy结果进行HMAC-SHA1签名计算
  const bytes = Crypto.HmacSHA1(policyEncoded, SecretKey);
  // 对计算结果进行Base64编码，得到最终的签名信息
  const signature = Crypto.enc.Base64.stringify(bytes);
  return signature;
}

export default getPolicyEncode;

// upload.vue 
<template>
          <uni-file-picker
                v-model="showUrl.activityInform"
                :limit="limit"
                :auto-upload="false"
                mode="list"
                title="xxxx"
                file-mediatype="all"
                file-extname="png,jpg,jpeg,pdf"
                @select="handleSelect($event, 'activityInform')"
          >
          </uni-file-picker>
</template>

data () {
  return {
     .... ,
    showUrl: {
        activityInform: [],
       //  .......
    },
  // 后端接口获得
    uploadOss: {
        Bucket: "", // oss桶
        Key: "", // 文件路径
        filePath: "", // oss 文件路径
        AWSAccessKeyId: "",
        SecretKey: "",
      },
   }
}
methods: {
  handleSelect（files, field）{
      if (!files.tempFiles.length) return;
      const date = new Date();
      const file = files.tempFiles[0]; // 获取第一个文件信息
      const timestamp = date.getTime();
      const parts = file.name.split(".");
      const name = parts.slice(0, parts.length - 1).join("."); // 获取文件名（不包括后缀）
      const extension = parts[parts.length - 1]; // 获取后缀名
      const fileName = `${name}_${timestamp}.${extension}`;

      const { url, Bucket, filePath, SecretKey, AWSAccessKeyId } =
        this.uploadOss;

      const toISOString = new Date(Date.now() + 600000).toISOString();
      const OSSPolicy = {
        expiration: toISOString,
        conditions: [
          { bucket: Bucket }, //
          { key: `${filePath}/${fileName}` },
        ],
      };
      const policyEncoded = getPolicyEncode(OSSPolicy); // 计算base64编码后的policy
      const signature = getSignature(policyEncoded, SecretKey); // 计算签名
      uni.uploadFile({
        url,
        filePath: file.path,
        name: "file",
        formData: {
          // 从配置文件中获取到的AccessKeyID信息、计算得到的编码后policy及signature信息
          AWSAccessKeyId,
          policy: policyEncoded,
          signature: signature,
          key: `${filePath}/${fileName}`,
        },
        success: (res) => {
          if (res.statusCode == 204) {
            uni.showToast({ title: "上传成功", icon: "success" });
            this.showUrl[field].push({
              extname: extension,
              name: fileName,
              url: `${filePath}/${fileName}`,
            });
            this.uploadUrl[field].push(`${filePath}/${fileName}`);
          } else {
            uni.showToast({ title: "上传失败", icon: "fail" });
          }
        },
        fail: (e) => {
          console.log(e, "e");
        },
      });
  }
}