Feat/nft parser util

src/lib/engine/engine.ts

@@ -1,6 +1,7 @@
 export * from './types/bcmr-types.js';
 // export * from './types/draft-transaction-workspace-types.js';
 export * from './types/template-types.js';
+export * from './parse-nft.js';
 /*
  * export * from './types/wallet-types.js';
  * export * from './types/wallet-activity-types.js';

src/lib/engine/parse-nft.spec.ts

@@ -0,0 +1,76 @@
+import test from 'ava';
+
+import {
+  binToHex,
+  createVirtualMachineBCH,
+  hexToBin,
+  NonFungibleTokenCapability,
+  parseNft,
+} from '../lib.js';
+
+test('parseNft: returns the expected value of altstack', (t) => {
+  // Example parsable NFT from https://www.bitcoincashsite.com/blog/token-pioneers-cashtokens-tutorial-4/
+  const nft1 = {
+    lockingBytecode: hexToBin(''),
+    token: {
+      amount: BigInt(0),
+      category: hexToBin(''),
+      nft: {
+        capability: NonFungibleTokenCapability.none,
+        commitment: hexToBin(
+          '30313130313031303131323032333132313231393030313034333030303030',
+        ),
+      },
+    },
+    valueSatoshis: BigInt(1000),
+  };
+  const bytecode =
+    '00cf527f780230348763786b587f786b6b67780230378763786b5c7f786b6b67786b587f786b5c7f786b6b7568687575';
+  const nft1AltStack: Uint8Array[] = parseNft(nft1, bytecode);
+  t.is(binToHex(nft1AltStack[0] ?? new Uint8Array()), '3031');
+  t.is(binToHex(nft1AltStack[1] ?? new Uint8Array()), '3130313031303131');
+  t.is(
+    binToHex(nft1AltStack[2] ?? new Uint8Array()),
+    '323032333132313231393030',
+  );
+  t.is(binToHex(nft1AltStack[3] ?? new Uint8Array()), '313034333030303030');
+});
+
+test('parseNft: bottom of altstack contains the commitment if bytecode is 00cf6b', (t) => {
+  // Example from bcmr-v2.schema.ts
+  const nft2 = {
+    lockingBytecode: hexToBin(''),
+    token: {
+      amount: BigInt(0),
+      category: hexToBin(''),
+      nft: {
+        capability: NonFungibleTokenCapability.none,
+        commitment: hexToBin('2021'),
+      },
+    },
+    valueSatoshis: BigInt(1000),
+  };
+  const bytecode = '00cf6b';
+  const nft2AltStack: Uint8Array[] = parseNft(nft2, bytecode);
+  t.is(binToHex(nft2AltStack[0] ?? new Uint8Array()), '2021');
+});
+
+test('parseNft: works with compatible vm', (t) => {
+  // Example from bcmr-v2.schema.ts
+  const nft2 = {
+    lockingBytecode: hexToBin(''),
+    token: {
+      amount: BigInt(0),
+      category: hexToBin(''),
+      nft: {
+        capability: NonFungibleTokenCapability.none,
+        commitment: hexToBin('2021'),
+      },
+    },
+    valueSatoshis: BigInt(1000),
+  };
+  const bytecode = '00cf6b';
+  const vmCreator = () => createVirtualMachineBCH();
+  const nft2AltStack: Uint8Array[] = parseNft(nft2, bytecode, vmCreator);
+  t.is(binToHex(nft2AltStack[0] ?? new Uint8Array()), '2021');
+});

src/lib/engine/parse-nft.ts

@@ -0,0 +1,69 @@
+import { hexToBin } from '../format/format.js';
+import type {
+  AuthenticationProgramCommon,
+  AuthenticationProgramStateCommon,
+  AuthenticationVirtualMachine,
+  Output,
+  ResolvedTransactionCommon,
+} from '../lib.js';
+import { createVirtualMachineBCHCHIPs } from '../vm/instruction-sets/bch/chips/bch-chips-vm.js';
+
+export type VMCreator = () => AuthenticationVirtualMachine<
+  ResolvedTransactionCommon,
+  AuthenticationProgramCommon,
+  AuthenticationProgramStateCommon
+>;
+
+/**
+ * Returns the altstack as a result of parsing the NFT's commitment using the
+ * provided bytecode.
+ *
+ * @param utxo - the NFT to parse
+ * @param bytecode - the bytecode as hex string
+ * @param createVirtualMachine - a function that returns an {@link AuthenticationVirtualMachine}
+ */
+export const parseNft = (
+  utxo: Output,
+  bytecode: string,
+  createVirtualMachine?: VMCreator,
+): Uint8Array[] => {
+  const vm = createVirtualMachine
+    ? createVirtualMachine()
+    : createVirtualMachineBCHCHIPs();
+
+  const { alternateStack } = vm.evaluate({
+    inputIndex: 1,
+    sourceOutputs: [
+      utxo,
+      {
+        lockingBytecode: hexToBin(bytecode),
+        valueSatoshis: BigInt(0),
+      },
+    ],
+    transaction: {
+      inputs: [
+        {
+          outpointIndex: 0,
+          outpointTransactionHash: hexToBin(''),
+          sequenceNumber: 0,
+          unlockingBytecode: hexToBin(''),
+        },
+        {
+          outpointIndex: 0,
+          outpointTransactionHash: hexToBin(''),
+          sequenceNumber: 0,
+          unlockingBytecode: hexToBin('51'),
+        },
+      ],
+      locktime: 0,
+      outputs: [
+        {
+          lockingBytecode: hexToBin('6a'),
+          valueSatoshis: BigInt(0),
+        },
+      ],
+      version: 2,
+    },
+  });
+  return alternateStack;
+};