Chris@35: 'use strict'
Chris@35: 
Chris@35: if (typeof document === "undefined") {
Chris@35:     exports.byteLength = byteLength
Chris@35:     exports.toByteArray = toByteArray
Chris@35:     exports.fromByteArray = fromByteArray
Chris@35: }
Chris@35: 
Chris@35: var lookup = []
Chris@35: var revLookup = []
Chris@35: var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
Chris@35: 
Chris@35: var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
Chris@35: for (var i = 0, len = code.length; i < len; ++i) {
Chris@35:   lookup[i] = code[i]
Chris@35:   revLookup[code.charCodeAt(i)] = i
Chris@35: }
Chris@35: 
Chris@35: revLookup['-'.charCodeAt(0)] = 62
Chris@35: revLookup['_'.charCodeAt(0)] = 63
Chris@35: 
Chris@35: function placeHoldersCount (b64) {
Chris@35:   var len = b64.length
Chris@35:   if (len % 4 > 0) {
Chris@35:     throw new Error('Invalid string. Length must be a multiple of 4')
Chris@35:   }
Chris@35: 
Chris@35:   // the number of equal signs (place holders)
Chris@35:   // if there are two placeholders, than the two characters before it
Chris@35:   // represent one byte
Chris@35:   // if there is only one, then the three characters before it represent 2 bytes
Chris@35:   // this is just a cheap hack to not do indexOf twice
Chris@35:   return b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0
Chris@35: }
Chris@35: 
Chris@35: function byteLength (b64) {
Chris@35:   // base64 is 4/3 + up to two characters of the original data
Chris@35:   return b64.length * 3 / 4 - placeHoldersCount(b64)
Chris@35: }
Chris@35: 
Chris@35: function toByteArray (b64) {
Chris@35:   var i, j, l, tmp, placeHolders, arr
Chris@35:   var len = b64.length
Chris@35:   placeHolders = placeHoldersCount(b64)
Chris@35: 
Chris@35:   arr = new Arr(len * 3 / 4 - placeHolders)
Chris@35: 
Chris@35:   // if there are placeholders, only get up to the last complete 4 chars
Chris@35:   l = placeHolders > 0 ? len - 4 : len
Chris@35: 
Chris@35:   var L = 0
Chris@35: 
Chris@35:   for (i = 0, j = 0; i < l; i += 4, j += 3) {
Chris@35:     tmp = (revLookup[b64.charCodeAt(i)] << 18) | (revLookup[b64.charCodeAt(i + 1)] << 12) | (revLookup[b64.charCodeAt(i + 2)] << 6) | revLookup[b64.charCodeAt(i + 3)]
Chris@35:     arr[L++] = (tmp >> 16) & 0xFF
Chris@35:     arr[L++] = (tmp >> 8) & 0xFF
Chris@35:     arr[L++] = tmp & 0xFF
Chris@35:   }
Chris@35: 
Chris@35:   if (placeHolders === 2) {
Chris@35:     tmp = (revLookup[b64.charCodeAt(i)] << 2) | (revLookup[b64.charCodeAt(i + 1)] >> 4)
Chris@35:     arr[L++] = tmp & 0xFF
Chris@35:   } else if (placeHolders === 1) {
Chris@35:     tmp = (revLookup[b64.charCodeAt(i)] << 10) | (revLookup[b64.charCodeAt(i + 1)] << 4) | (revLookup[b64.charCodeAt(i + 2)] >> 2)
Chris@35:     arr[L++] = (tmp >> 8) & 0xFF
Chris@35:     arr[L++] = tmp & 0xFF
Chris@35:   }
Chris@35: 
Chris@35:   return arr
Chris@35: }
Chris@35: 
Chris@35: function tripletToBase64 (num) {
Chris@35:   return lookup[num >> 18 & 0x3F] + lookup[num >> 12 & 0x3F] + lookup[num >> 6 & 0x3F] + lookup[num & 0x3F]
Chris@35: }
Chris@35: 
Chris@35: function encodeChunk (uint8, start, end) {
Chris@35:   var tmp
Chris@35:   var output = []
Chris@35:   for (var i = start; i < end; i += 3) {
Chris@35:     tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2])
Chris@35:     output.push(tripletToBase64(tmp))
Chris@35:   }
Chris@35:   return output.join('')
Chris@35: }
Chris@35: 
Chris@35: function fromByteArray (uint8) {
Chris@35:   var tmp
Chris@35:   var len = uint8.length
Chris@35:   var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
Chris@35:   var output = ''
Chris@35:   var parts = []
Chris@35:   var maxChunkLength = 16383 // must be multiple of 3
Chris@35: 
Chris@35:   // go through the array every three bytes, we'll deal with trailing stuff later
Chris@35:   for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
Chris@35:     parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)))
Chris@35:   }
Chris@35: 
Chris@35:   // pad the end with zeros, but make sure to not forget the extra bytes
Chris@35:   if (extraBytes === 1) {
Chris@35:     tmp = uint8[len - 1]
Chris@35:     output += lookup[tmp >> 2]
Chris@35:     output += lookup[(tmp << 4) & 0x3F]
Chris@35:     output += '=='
Chris@35:   } else if (extraBytes === 2) {
Chris@35:     tmp = (uint8[len - 2] << 8) + (uint8[len - 1])
Chris@35:     output += lookup[tmp >> 10]
Chris@35:     output += lookup[(tmp >> 4) & 0x3F]
Chris@35:     output += lookup[(tmp << 2) & 0x3F]
Chris@35:     output += '='
Chris@35:   }
Chris@35: 
Chris@35:   parts.push(output)
Chris@35: 
Chris@35:   return parts.join('')
Chris@35: }