@apocentre/bc-ur
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A JS implementation of the Uniform Resources (UR) specification from Blockchain Commons
115 lines • 5.96 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const assert_1 = __importDefault(require("assert"));
const utils_1 = require("./utils");
const bytewords = 'ableacidalsoapexaquaarchatomauntawayaxisbackbaldbarnbeltbetabiasbluebodybragbrewbulbbuzzcalmcashcatschefcityclawcodecolacookcostcruxcurlcuspcyandarkdatadaysdelidicedietdoordowndrawdropdrumdulldutyeacheasyechoedgeepicevenexamexiteyesfactfairfernfigsfilmfishfizzflapflewfluxfoxyfreefrogfuelfundgalagamegeargemsgiftgirlglowgoodgraygrimgurugushgyrohalfhanghardhawkheathelphighhillholyhopehornhutsicedideaidleinchinkyintoirisironitemjadejazzjoinjoltjowljudojugsjumpjunkjurykeepkenokeptkeyskickkilnkingkitekiwiknoblamblavalazyleaflegsliarlimplionlistlogoloudloveluaulucklungmainmanymathmazememomenumeowmildmintmissmonknailnavyneednewsnextnoonnotenumbobeyoboeomitonyxopenovalowlspaidpartpeckplaypluspoempoolposepuffpumapurrquadquizraceramprealredorichroadrockroofrubyruinrunsrustsafesagascarsetssilkskewslotsoapsolosongstubsurfswantacotasktaxitenttiedtimetinytoiltombtoystriptunatwinuglyundouniturgeuservastveryvetovialvibeviewvisavoidvowswallwandwarmwaspwavewaxywebswhatwhenwhizwolfworkyankyawnyellyogayurtzapszerozestzinczonezoom';
let bytewordsLookUpTable = [];
const BYTEWORDS_NUM = 256;
const BYTEWORD_LENGTH = 4;
const MINIMAL_BYTEWORD_LENGTH = 2;
var STYLES;
(function (STYLES) {
STYLES["STANDARD"] = "standard";
STYLES["URI"] = "uri";
STYLES["MINIMAL"] = "minimal";
})(STYLES || (STYLES = {}));
const getWord = (index) => {
return bytewords.slice(index * BYTEWORD_LENGTH, (index * BYTEWORD_LENGTH) + BYTEWORD_LENGTH);
};
const getMinimalWord = (index) => {
const byteword = getWord(index);
return `${byteword[0]}${byteword[BYTEWORD_LENGTH - 1]}`;
};
const addCRC = (string) => {
const crc = utils_1.getCRCHex(Buffer.from(string, 'hex'));
return `${string}${crc}`;
};
const encodeWithSeparator = (word, separator) => {
const crcAppendedWord = addCRC(word);
const crcWordBuff = Buffer.from(crcAppendedWord, 'hex');
const result = crcWordBuff.reduce((result, w) => ([...result, getWord(w)]), []);
return result.join(separator);
};
const encodeMinimal = (word) => {
const crcAppendedWord = addCRC(word);
const crcWordBuff = Buffer.from(crcAppendedWord, 'hex');
const result = crcWordBuff.reduce((result, w) => result + getMinimalWord(w), '');
return result;
};
const decodeWord = (word, wordLength) => {
assert_1.default(word.length === wordLength, 'Invalid Bytewords: word.length does not match wordLength provided');
const dim = 26;
// Since the first and last letters of each Byteword are unique,
// we can use them as indexes into a two-dimensional lookup table.
// This table is generated lazily.
if (bytewordsLookUpTable.length === 0) {
const array_len = dim * dim;
bytewordsLookUpTable = [...new Array(array_len)].map(() => -1);
for (let i = 0; i < BYTEWORDS_NUM; i++) {
const byteword = getWord(i);
let x = byteword[0].charCodeAt(0) - 'a'.charCodeAt(0);
let y = byteword[3].charCodeAt(0) - 'a'.charCodeAt(0);
let offset = y * dim + x;
bytewordsLookUpTable[offset] = i;
}
}
// If the coordinates generated by the first and last letters are out of bounds,
// or the lookup table contains -1 at the coordinates, then the word is not valid.
let x = (word[0]).toLowerCase().charCodeAt(0) - 'a'.charCodeAt(0);
let y = (word[wordLength == 4 ? 3 : 1]).toLowerCase().charCodeAt(0) - 'a'.charCodeAt(0);
assert_1.default(0 <= x && x < dim && 0 <= y && y < dim, 'Invalid Bytewords: invalid word');
let offset = y * dim + x;
let value = bytewordsLookUpTable[offset];
assert_1.default(value !== -1, 'Invalid Bytewords: value not in lookup table');
// If we're decoding a full four-letter word, verify that the two middle letters are correct.
if (wordLength == BYTEWORD_LENGTH) {
const byteword = getWord(value);
let c1 = word[1].toLowerCase();
let c2 = word[2].toLowerCase();
assert_1.default(c1 === byteword[1] && c2 === byteword[2], 'Invalid Bytewords: invalid middle letters of word');
}
// Successful decode.
return Buffer.from([value]).toString('hex');
};
const _decode = (string, separator, wordLength) => {
const words = wordLength == BYTEWORD_LENGTH ? string.split(separator) : utils_1.partition(string, 2);
const decodedString = words.map((word) => decodeWord(word, wordLength)).join('');
assert_1.default(decodedString.length >= 5, 'Invalid Bytewords: invalid decoded string length');
const [body, bodyChecksum] = utils_1.split(Buffer.from(decodedString, 'hex'), 4);
const checksum = utils_1.getCRCHex(body); // convert to hex
assert_1.default(checksum === bodyChecksum.toString('hex'), 'Invalid Checksum');
return body.toString('hex');
};
const decode = (string, style = STYLES.MINIMAL) => {
switch (style) {
case STYLES.STANDARD:
return _decode(string, ' ', BYTEWORD_LENGTH);
case STYLES.URI:
return _decode(string, '-', BYTEWORD_LENGTH);
case STYLES.MINIMAL:
return _decode(string, '', MINIMAL_BYTEWORD_LENGTH);
default:
throw new Error(`Invalid style ${style}`);
}
};
const encode = (string, style = STYLES.MINIMAL) => {
switch (style) {
case STYLES.STANDARD:
return encodeWithSeparator(string, ' ');
case STYLES.URI:
return encodeWithSeparator(string, '-');
case STYLES.MINIMAL:
return encodeMinimal(string);
default:
throw new Error(`Invalid style ${style}`);
}
};
exports.default = {
decode,
encode,
STYLES
};
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