import {Address, Cell, Builder, beginCell} from "ton"; const ONCHAIN_CONTENT_PREFIX = 0x00; const SNAKE_PREFIX = 0x00; export type JettonMetaDataKeys = "name" | "description" | "image" | "symbol"; const jettonOnChainMetadataSpec: { [key in JettonMetaDataKeys]: "utf8" | "ascii" | undefined; } = { name: "utf8", description: "utf8", image: "ascii", symbol: "utf8", }; const sha256 = (str: string) => { const sha = new Sha256(); sha.update(str); return Buffer.from(sha.digestSync()); }; export function buildTokenMetadataCell(data: { [s: string]: string | undefined }): Cell { const KEYLEN = 256; let rootCell = beginCell(); let dict = new Cell(); Object.entries(data).forEach(([k, v]: [string, string | undefined]) => { if (!jettonOnChainMetadataSpec[k as JettonMetaDataKeys]) throw new Error(`Unsupported onchain key: ${k}`); if (v === undefined || v === "") return; let bufferToStore = Buffer.from(v, jettonOnChainMetadataSpec[k as JettonMetaDataKeys]); const CELL_MAX_SIZE_BYTES = Math.floor((1023 - 8) / 8); rootCell.storeUint(SNAKE_PREFIX, 16); let currentCell = rootCell; //TODO need fix dictionary writing while (bufferToStore.length > 0) { currentCell.storeBits(bufferToStore.read(CELL_MAX_SIZE_BYTES)) // how to read from Buffer??? //currentCell.bits.writeBuffer(bufferToStore.slice(0, CELL_MAX_SIZE_BYTES)); //bufferToStore = bufferToStore.slice(CELL_MAX_SIZE_BYTES); if (bufferToStore.length > 0) { const newCell = new Builder(); newCell.storeRef(currentCell); currentCell = newCell; } } let dict = currentCell.endCell(); }); return beginCell().storeInt(ONCHAIN_CONTENT_PREFIX, 8).storeDict(dict).endCell(); } export function parseTokenMetadataCell(contentCell: Cell): { [s in JettonMetaDataKeys]?: string; } { // Note that this relies on what is (perhaps) an internal implementation detail: // "ton" library dict parser converts: key (provided as buffer) => BN(base10) // and upon parsing, it reads it back to a BN(base10) // tl;dr if we want to read the map back to a JSON with string keys, we have to convert BN(10) back to hex const toKey = (str: string) => new BN(str, "hex").toString(10); const KEYLEN = 256; const contentSlice = contentCell.beginParse(); if (contentSlice.readUint(8).toNumber() !== ONCHAIN_CONTENT_PREFIX) throw new Error("Expected onchain content marker"); const dict = contentSlice.readDict(KEYLEN, (s) => { const buffer = Buffer.from(""); const sliceToVal = (s: Slice, v: Buffer, isFirst: boolean) => { s.toCell().beginParse(); if (isFirst && s.readUint(8).toNumber() !== SNAKE_PREFIX) throw new Error("Only snake format is supported"); v = Buffer.concat([v, s.readRemainingBytes()]); if (s.remainingRefs === 1) { v = sliceToVal(s.readRef(), v, false); } return v; }; return sliceToVal(s.readRef(), buffer, true); }); const res: { [s in JettonMetaDataKeys]?: string } = {}; Object.keys(jettonOnChainMetadataSpec).forEach((k) => { const val = dict .get(toKey(sha256(k).toString("hex"))) ?.toString(jettonOnChainMetadataSpec[k as JettonMetaDataKeys]); if (val) res[k as JettonMetaDataKeys] = val; }); return res; }