Base64

// https://stackoverflow.com/questions/42829838/react-native-atob-btoa-not-working-without-remote-js-debugging
const chars =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
const Base64 = {
  btoa: (input: string = "") => {
    let str = input;
    let output = "";

    for (
      let block = 0, charCode, i = 0, map = chars;
      str.charAt(i | 0) || ((map = "="), i % 1);
      output += map.charAt(63 & (block >> (8 - (i % 1) * 8)))
    ) {
      charCode = str.charCodeAt((i += 3 / 4));

      if (charCode > 0xff) {
        throw new Error(
          "'btoa' failed: The string to be encoded contains characters outside of the Latin1 range."
        );
      }

      block = (block << 8) | charCode;
    }

    return output;
  },

  atob: (input: string = "") => {
    let str = input.replace(/=+$/, "");
    let output = "";

    if (str.length % 4 == 1) {
      throw new Error(
        "'atob' failed: The string to be decoded is not correctly encoded."
      );
    }
    for (
      let bc = 0, bs = 0, buffer, i = 0;
      (buffer = str.charAt(i++));
      ~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
        ? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
        : 0
    ) {
      buffer = chars.indexOf(buffer);
    }

    return output;
  },
};

FileReader.prototype.readAsArrayBuffer = function (blob) {
  if (this.readyState === this.LOADING) throw new Error("InvalidStateError");
  this._setReadyState(this.LOADING);
  this._result = null;
  this._error = null;
  const fr = new FileReader();
  fr.onloadend = () => {
    const content = Base64.atob(
      fr.result.substr("data:application/octet-stream;base64,".length)
    );
    const buffer = new ArrayBuffer(content.length);
    const view = new Uint8Array(buffer);
    view.set(Array.from(content).map((c) => c.charCodeAt(0)));
    this._result = buffer;
    this._setReadyState(this.DONE);
  };
  fr.readAsDataURL(blob);
};

// from: https://stackoverflow.com/questions/42829838/react-native-atob-btoa-not-working-without-remote-js-debugging
// const chars =
//   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
// const atob = (input = "") => {
//   let str = input.replace(/=+$/, "");
//   let output = "";

//   if (str.length % 4 == 1) {
//     throw new Error(
//       "'atob' failed: The string to be decoded is not correctly encoded."
//     );
//   }
//   for (
//     let bc = 0, bs = 0, buffer, i = 0;
//     (buffer = str.charAt(i++));
//     ~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
//       ? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
//       : 0
//   ) {
//     buffer = chars.indexOf(buffer);
//   }

//   return output;
// };

export default Base64;