# node.js implementation of atob and btoa

if typeof atob is 'function' and typeof btoa is 'function'
  # Modern browsers and workers.
  atob = (string) -> window.atob string
  btoa = (base64) -> window.btoa base64

else if (typeof window isnt 'undefined' or typeof self isnt 'undefined') and
    (typeof navigator isnt 'undefined' and
     typeof navigator.userAgent is 'string')
  # IE < 10, no standard atob / btoa functions.
  base64Digits =
      'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

  btoaNibble = (accumulator, bytes, result) ->
    limit = 3 - bytes
    accumulator <<= limit * 8
    i = 3
    while i >= limit
      result.push base64Digits.charAt((accumulator >> (i * 6)) & 0x3F)
      i -= 1
    i = bytes
    while i < 3
      result.push '='
      i += 1
    null
  atobNibble = (accumulator, digits, result) ->
    limit = 4 - digits
    accumulator <<= limit * 6
    i = 2
    while i >= limit
      result.push String.fromCharCode((accumulator >> (8 * i)) & 0xFF)
      i -= 1
    null

  btoa = (string) ->
    result = []
    accumulator = 0
    bytes = 0
    for i in [0...string.length]
      accumulator = (accumulator << 8) | string.charCodeAt(i)
      bytes += 1
      if bytes is 3
        btoaNibble accumulator, bytes, result
        accumulator = bytes = 0

    if bytes > 0
      btoaNibble accumulator, bytes, result
    result.join ''

  atob = (base64) ->
    result = []
    accumulator = 0
    digits = 0
    for i in [0...base64.length]
      digit = base64.charAt i
      break if digit is '='
      accumulator = (accumulator << 6) | base64Digits.indexOf(digit)
      digits += 1
      if digits is 4
        atobNibble accumulator, digits, result
        accumulator = digits = 0

    if digits > 0
      atobNibble accumulator, digits, result
    result.join ''

else
  # Node.js.

  # NOTE: the npm packages atob and btoa don't do base64-encoding correctly.
  atob = (arg) ->
    buffer = new Buffer arg, 'base64'
    (String.fromCharCode(buffer[i]) for i in [0...buffer.length]).join ''
  btoa = (arg) ->
    buffer = new Buffer(arg.charCodeAt(i) for i in [0...arg.length])
    buffer.toString 'base64'

Dropbox.Util.atob = atob
Dropbox.Util.btoa = btoa