132 lines
4 KiB
TypeScript
132 lines
4 KiB
TypeScript
/// Based on https://github.com/beatgammit/base64-js, MIT license
|
|
const lookup: string[] = []
|
|
const revLookup: number[] = []
|
|
|
|
const code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
|
|
|
|
for (let i = 0, len = code.length; i < len; ++i) {
|
|
lookup[i] = code[i]
|
|
revLookup[code.charCodeAt(i)] = i
|
|
}
|
|
|
|
function getLens(b64: string): [number, number] {
|
|
const len = b64.length
|
|
|
|
if (len % 4 > 0) {
|
|
throw new Error('Invalid string. Length must be a multiple of 4')
|
|
}
|
|
|
|
// Trim off extra bytes after placeholder bytes are found
|
|
// See: https://github.com/beatgammit/base64-js/issues/42
|
|
let validLen = b64.indexOf('=')
|
|
if (validLen === -1) validLen = len
|
|
|
|
const placeHoldersLen = validLen === len ? 0 : 4 - (validLen % 4)
|
|
|
|
return [validLen, placeHoldersLen]
|
|
}
|
|
|
|
function _byteLength(b64: string, validLen: number, placeHoldersLen: number) {
|
|
return ((validLen + placeHoldersLen) * 3) / 4 - placeHoldersLen
|
|
}
|
|
|
|
function toByteArray(b64: string, arr: Uint8Array) {
|
|
let tmp
|
|
const lens = getLens(b64)
|
|
const validLen = lens[0]
|
|
const placeHoldersLen = lens[1]
|
|
|
|
let curByte = 0
|
|
|
|
// if there are placeholders, only get up to the last complete 4 chars
|
|
const len = placeHoldersLen > 0 ? validLen - 4 : validLen
|
|
|
|
let i
|
|
|
|
for (i = 0; i < len; i += 4) {
|
|
tmp =
|
|
(revLookup[b64.charCodeAt(i)] << 18) |
|
|
(revLookup[b64.charCodeAt(i + 1)] << 12) |
|
|
(revLookup[b64.charCodeAt(i + 2)] << 6) |
|
|
revLookup[b64.charCodeAt(i + 3)]
|
|
arr[curByte++] = (tmp >> 16) & 0xff
|
|
arr[curByte++] = (tmp >> 8) & 0xff
|
|
arr[curByte++] = tmp & 0xff
|
|
}
|
|
|
|
if (placeHoldersLen === 2) {
|
|
tmp = (revLookup[b64.charCodeAt(i)] << 2) | (revLookup[b64.charCodeAt(i + 1)] >> 4)
|
|
arr[curByte++] = tmp & 0xff
|
|
}
|
|
|
|
if (placeHoldersLen === 1) {
|
|
tmp =
|
|
(revLookup[b64.charCodeAt(i)] << 10) |
|
|
(revLookup[b64.charCodeAt(i + 1)] << 4) |
|
|
(revLookup[b64.charCodeAt(i + 2)] >> 2)
|
|
arr[curByte++] = (tmp >> 8) & 0xff
|
|
arr[curByte++] = tmp & 0xff
|
|
}
|
|
|
|
return arr
|
|
}
|
|
|
|
function tripletToBase64(num: number) {
|
|
return lookup[(num >> 18) & 0x3f] + lookup[(num >> 12) & 0x3f] + lookup[(num >> 6) & 0x3f] + lookup[num & 0x3f]
|
|
}
|
|
|
|
function encodeChunk(uint8: Uint8Array, start: number, end: number) {
|
|
let tmp
|
|
const output = []
|
|
|
|
for (let i = start; i < end; i += 3) {
|
|
tmp = ((uint8[i] << 16) & 0xff0000) + ((uint8[i + 1] << 8) & 0xff00) + (uint8[i + 2] & 0xff)
|
|
output.push(tripletToBase64(tmp))
|
|
}
|
|
|
|
return output.join('')
|
|
}
|
|
|
|
function fromByteArray(uint8: Uint8Array) {
|
|
let tmp
|
|
const len = uint8.length
|
|
const extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
|
|
const parts = []
|
|
const maxChunkLength = 16383 // must be multiple of 3
|
|
|
|
// go through the array every three bytes, we'll deal with trailing stuff later
|
|
for (let i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
|
|
parts.push(encodeChunk(uint8, i, i + maxChunkLength > len2 ? len2 : i + maxChunkLength))
|
|
}
|
|
|
|
// pad the end with zeros, but make sure to not forget the extra bytes
|
|
if (extraBytes === 1) {
|
|
tmp = uint8[len - 1]
|
|
parts.push(lookup[tmp >> 2] + lookup[(tmp << 4) & 0x3f] + '==')
|
|
} else if (extraBytes === 2) {
|
|
tmp = (uint8[len - 2] << 8) + uint8[len - 1]
|
|
parts.push(lookup[tmp >> 10] + lookup[(tmp >> 4) & 0x3f] + lookup[(tmp << 2) & 0x3f] + '=')
|
|
}
|
|
|
|
return parts.join('')
|
|
}
|
|
|
|
export function base64Encode(buf: Uint8Array, url: boolean = false): string {
|
|
const str = fromByteArray(buf)
|
|
if (url) return str.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '')
|
|
|
|
return str
|
|
}
|
|
|
|
export function base64Decode(string: string, url: boolean = false): Uint8Array {
|
|
if (url) {
|
|
string = string.replace(/-/g, '+').replace(/_/g, '/')
|
|
while (string.length % 4) string += '='
|
|
}
|
|
|
|
const buf = new Uint8Array(_byteLength(string, ...getLens(string)))
|
|
|
|
toByteArray(string, buf)
|
|
|
|
return buf
|
|
}
|