const EventEmitter = require('events');
const { strToIv } = require('./utils');

class FileReceiver extends EventEmitter {
  constructor() {
    super();
    this.salt = strToIv(location.pathname.slice(10, -1));
  }
  

  download() {
    return Promise.all([
      new Promise((resolve, reject) => {
        let xhr = new XMLHttpRequest();
        
        xhr.onprogress = e => {
          if (e.lengthComputable) {
            let percentComplete = Math.floor(e.loaded / e.total * 100);
            this.emit('progress', percentComplete);
          }
        };

        xhr.onload = function(e) {
          let blob = new Blob([this.response]);
          let fileReader = new FileReader();
          fileReader.onload = function() {
            resolve({
              data: this.result,
              fname: xhr.getResponseHeader('Content-Disposition').match(/filename="(.+)"/)[1]
            });
          }

          fileReader.readAsArrayBuffer(blob);
        }
        
        xhr.open('get', '/assets' + location.pathname.slice(0, -1), true);
        xhr.responseType = 'blob';
        xhr.send();
      }),
      window.crypto.subtle
        .importKey(
          'jwk',
          {
            kty: 'oct',
            k: location.hash.slice(1),
            alg: 'A128CBC',
            ext: true
          },
          {
            name: 'AES-CBC'
          },
          true,
          ['encrypt', 'decrypt']
        )
    ])
      .then(([fdata, key]) => {
        let salt = this.salt;
        return Promise.all([
          window.crypto.subtle.decrypt(
            {
            name: 'AES-CBC',
            iv: salt
            },
            key,
            fdata.data
          ),
          new Promise((resolve, reject) => {
            resolve(fdata.fname);
          })
        ]);
      })
  }
}

module.exports = FileReceiver;