nel-neo-thinsdk/neo-ts/thinneo/Base64.ts

NEL's NEO thinSDK

namespace ThinNeo {
    export class Base64 {
        static lookup = []
        static revLookup = []
        static code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
        static binited = false;
        static init(): void {
            if (Base64.binited)
                return;
            Base64.lookup = []
            Base64.revLookup = []

            for (var i = 0, len = Base64.code.length; i < len; ++i) {
                Base64.lookup[i] = Base64.code[i];
                Base64.revLookup[Base64.code.charCodeAt(i)] = i
            }

            Base64.revLookup['-'.charCodeAt(0)] = 62
            Base64.revLookup['_'.charCodeAt(0)] = 63
            Base64.binited = true;
        }
        static placeHoldersCount(b64: string): number {
            var len = b64.length
            if (len % 4 > 0) {
                throw new Error('Invalid string. Length must be a multiple of 4')
            }

            // the number of equal signs (place holders)
            // if there are two placeholders, than the two characters before it
            // represent one byte
            // if there is only one, then the three characters before it represent 2 bytes
            // this is just a cheap hack to not do indexOf twice
            return b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0
        }

        static byteLength(b64: string): number {
            // base64 is 4/3 + up to two characters of the original data
            return (b64.length * 3 / 4) - Base64.placeHoldersCount(b64);
        }

        public static toByteArray(b64: string): Uint8Array {
            Base64.init();

            var i, l, tmp, placeHolders, arr
            var len = b64.length
            placeHolders = Base64.placeHoldersCount(b64)

            arr = new Uint8Array((len * 3 / 4) - placeHolders)

            // if there are placeholders, only get up to the last complete 4 chars
            l = placeHolders > 0 ? len - 4 : len

            var L = 0

            for (i = 0; i < l; i += 4) {
                tmp = (Base64.revLookup[b64.charCodeAt(i)] << 18) | (Base64.revLookup[b64.charCodeAt(i + 1)] << 12) | (Base64.revLookup[b64.charCodeAt(i + 2)] << 6) | Base64.revLookup[b64.charCodeAt(i + 3)]
                arr[L++] = (tmp >> 16) & 0xFF
                arr[L++] = (tmp >> 8) & 0xFF
                arr[L++] = tmp & 0xFF
            }

            if (placeHolders === 2) {
                tmp = (Base64.revLookup[b64.charCodeAt(i)] << 2) | (Base64.revLookup[b64.charCodeAt(i + 1)] >> 4)
                arr[L++] = tmp & 0xFF
            } else if (placeHolders === 1) {
                tmp = (Base64.revLookup[b64.charCodeAt(i)] << 10) | (Base64.revLookup[b64.charCodeAt(i + 1)] << 4) | (Base64.revLookup[b64.charCodeAt(i + 2)] >> 2)
                arr[L++] = (tmp >> 8) & 0xFF
                arr[L++] = tmp & 0xFF
            }

            return arr
        }

        static tripletToBase64(num) {
            return Base64.lookup[num >> 18 & 0x3F] + Base64.lookup[num >> 12 & 0x3F] + Base64.lookup[num >> 6 & 0x3F] + Base64.lookup[num & 0x3F]
        }

        static encodeChunk(uint8, start, end) {
            var tmp
            var output = []
            for (var i = start; i < end; i += 3) {
                tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + (uint8[i + 2])
                output.push(Base64.tripletToBase64(tmp))
            }
            return output.join('')
        }

        public static fromByteArray(uint8: Uint8Array) {
            Base64.init();
            var tmp
            var len = uint8.length
            var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
            var output = ''
            var parts = []
            var maxChunkLength = 16383 // must be multiple of 3

            // go through the array every three bytes, we'll deal with trailing stuff later
            for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
                parts.push(Base64.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]
                output += Base64.lookup[tmp >> 2]
                output += Base64.lookup[(tmp << 4) & 0x3F]
                output += '=='
            } else if (extraBytes === 2) {
                tmp = (uint8[len - 2] << 8) + (uint8[len - 1])
                output += Base64.lookup[tmp >> 10]
                output += Base64.lookup[(tmp >> 4) & 0x3F]
                output += Base64.lookup[(tmp << 2) & 0x3F]
                output += '='
            }

            parts.push(output)

            return parts.join('')
        }

    }
}