"use strict";

/*\
|*|
|*|  Base64 / binary data / UTF-8 strings utilities
|*|
|*|  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding
|*|
\*/


/// Adapted for url-safe character set without padding

/* Array of bytes to Base64 string decoding */

function b64ToUint6 (nChr) {

  return nChr > 64 && nChr < 91 ?
      nChr - 65
    : nChr > 96 && nChr < 123 ?
      nChr - 71
    : nChr > 47 && nChr < 58 ?
      nChr + 4
    : nChr === 45 ?
      62
    : nChr === 95 ?
      63
    :
      0;

}

export function base64DecToArr (sBase64, taBytes) {

  var
    sB64Enc = sBase64.replace(/[^A-Za-z0-9-_]/g, ""),
    nInLen = sB64Enc.length,
    nOutLen = nInLen * 3 + 1 >> 2;

  for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) {
    nMod4 = nInIdx & 3;
    nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 6 * (3 - nMod4);
    if (nMod4 === 3 || nInLen - nInIdx === 1) {
      for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
        taBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255;
      }
      nUint24 = 0;

    }
  }

  return nOutLen;
}

/* Base64 string to array encoding */

function uint6ToB64 (nUint6) {

  return nUint6 < 26 ?
      nUint6 + 65
    : nUint6 < 52 ?
      nUint6 + 71
    : nUint6 < 62 ?
      nUint6 - 4
    : nUint6 === 62 ?
      45
    : nUint6 === 63 ?
      95
    :
      65;

}

export function base64EncArr (aBytes) {

  var nMod3 = 2, sB64Enc = "";

  for (var nLen = aBytes.length, nUint24 = 0, nIdx = 0; nIdx < nLen; nIdx++) {
    nMod3 = nIdx % 3;
    nUint24 |= aBytes[nIdx] << (16 >>> nMod3 & 24);
    if (nMod3 === 2 || aBytes.length - nIdx === 1) {
      sB64Enc += String.fromCodePoint(uint6ToB64(nUint24 >>> 18 & 63), uint6ToB64(nUint24 >>> 12 & 63), uint6ToB64(nUint24 >>> 6 & 63), uint6ToB64(nUint24 & 63));
      nUint24 = 0;
    }
  }

  //return sB64Enc.substr(0, sB64Enc.length - 2 + nMod3) + (nMod3 === 2 ? '' : nMod3 === 1 ? '=' : '==');
  return sB64Enc.substr(0, sB64Enc.length - 2 + nMod3);

}