const request = require("superagent");
const fs = require("fs");

function isEncrypted(file) {
   const magic = Buffer.from([0x00, 0x00, 0x5b, 0x00, 0xe5]);

   if (file?.buffer && Buffer.isBuffer(file.buffer)) {
      if (file.buffer.length < 5) {
         return false;
      }
      return file.buffer.subarray(0, 5).equals(magic);
   }

   if (file?.path) {
      const fd = fs.openSync(file.path, "r");
      try {
         const buffer = Buffer.alloc(5);
         const bytesRead = fs.readSync(fd, buffer, 0, 5, 0);
         if (bytesRead < 5) {
            return false;
         }
         return buffer.equals(magic);
      } finally {
         fs.closeSync(fd);
      }
   }

   return false;
}

module.exports.decryption = async (ctx, next) => {
   try {
      const { xunruan } = ctx.config;
      const { file } = ctx.request;
      const fileBuffer = file?.buffer || (file?.path ? fs.readFileSync(file.path) : null);

      if (!fileBuffer) {
         ctx.status = 400;
         ctx.body = { message: "file is required." };
         return;
      }

      if (!isEncrypted(file)) {
         ctx.status = 200;
         ctx.body = fileBuffer;
         return;
      }

      let url = `${xunruan.host}/uploadSecret`;
      let res_ = await request
         .post(url)
         .set("Content-Type", "application/octet-stream")
         .send(fileBuffer)
         .responseType("binary");
      ctx.status = 200;
      ctx.body = res_.body;
   } catch (error) {
      console.error(error, "error");
      ctx.status = 400;
      ctx.body = { message: "decryption error." };
   }
};