#!/usr/bin/env node
/**
 * chipnet-attack-negatives.mjs — attempts to break the contract that
 * are EXPECTED to fail. If any of these succeed, that's a bug.
 *
 * Tests:
 *  N1. Reservoir lockingBytecode swap: redirect the reservoir output to
 *      a non-contract address. Should fail at the contract's
 *      `require(tx.outputs[0].lockingBytecode == input.lockingBytecode)`.
 *  N2. FT overflow: pick a tokenAmount large enough that
 *      tokenAmount * rate overflows 64-bit signed. Should fail at the
 *      Script multiplication opcode.
 *  N3. Negative tokenAmount: claim a negative number of tokens. Should
 *      fail at `require(tokenAmount > 0)`.
 *
 * Each test builds the tx but does NOT broadcast (uses .build() not
 * .send()). Validation errors are reported as expected results.
 */
import { readFileSync } from 'node:fs';
import { join } from 'node:path';
import { TestNetWallet } from 'mainnet-js';
import {
  Contract,
  ElectrumNetworkProvider,
  TransactionBuilder,
  SignatureTemplate,
} from 'cashscript';

const ROOT = join(import.meta.dirname, '..');
const KEYS_B = join(ROOT, '.chipnet-keys-b.json');
const TOKENS_FILE = join(ROOT, '.chipnet-tokens.json');
const ARTIFACT_PATH = join(ROOT, 'contracts/dist/DeviantOpenMintFT.json');

function hexToBin(hex) {
  if (hex.length % 2 !== 0) throw new Error(`odd hex length: ${hex.length}`);
  const out = new Uint8Array(hex.length / 2);
  for (let i = 0; i < out.length; i++) out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);
  return out;
}
function txidToConsensusBytes(txidHex) {
  const display = hexToBin(txidHex);
  const out = new Uint8Array(display.length);
  for (let i = 0; i < display.length; i++) out[i] = display[display.length - 1 - i];
  return out;
}
function p2pkhLockingBytecode(pkh) {
  const out = new Uint8Array(25);
  out[0] = 0x76; out[1] = 0xa9; out[2] = 0x14;
  out.set(pkh, 3);
  out[23] = 0x88; out[24] = 0xac;
  return out;
}
function divider() { console.log('-'.repeat(72)); }

async function runTest(name, expectedFailurePatterns, buildFn) {
  console.log('');
  console.log(`[${name}] expected failure matching: ${expectedFailurePatterns.join(' OR ')}`);
  divider();
  try {
    await buildFn();
    console.log(`  RESULT: DEBUG SUCCEEDED. UNEXPECTED — this attack should fail!`);
    return { name, status: 'unexpected-success' };
  } catch (err) {
    const msg = err?.message ?? String(err);
    const expected = expectedFailurePatterns.some((p) => msg.toLowerCase().includes(p.toLowerCase()));
    const status = expected ? 'expected-failure' : 'unexpected-failure';
    console.log(`  RESULT: ${status}`);
    console.log(`  Error excerpt: ${msg.split('\n')[0].slice(0, 220)}`);
    return { name, status, error: msg };
  }
}

async function main() {
  const { wif } = JSON.parse(readFileSync(KEYS_B, 'utf8'));
  const tokens = JSON.parse(readFileSync(TOKENS_FILE, 'utf8'));
  const tokenA = tokens.tokens.find((t) => t.name === 'TokenA');
  const artifact = JSON.parse(readFileSync(ARTIFACT_PATH, 'utf8'));

  const attacker = await TestNetWallet.fromWIF(wif);
  const provider = new ElectrumNetworkProvider('chipnet');
  const sigTemplate = new SignatureTemplate(attacker.privateKey);

  const tokenCategory = txidToConsensusBytes(tokenA.categoryId);
  const founderLockingBytecode = hexToBin(tokenA.founderLockingBytecodeHex);
  const contract = new Contract(
    artifact,
    [tokenCategory, BigInt(tokenA.rateSats), BigInt(tokenA.founderFeeBps), founderLockingBytecode],
    { provider },
  );

  const reservoirUtxos = await provider.getUtxos(contract.tokenAddress);
  const reservoir = reservoirUtxos.find(
    (u) => u.token?.nft?.capability === 'minting' && u.token?.category === tokenA.categoryId,
  );
  if (!reservoir) throw new Error('Reservoir not found');

  const attackerUtxos = await provider.getUtxos(attacker.cashaddr);
  const bchUtxos = attackerUtxos.filter((u) => !u.token);
  if (bchUtxos.length === 0) throw new Error('Attacker has no BCH UTXO');
  const feeInput = bchUtxos.reduce((a, b) => BigInt(a.satoshis) > BigInt(b.satoshis) ? a : b);

  const rateSats = BigInt(tokenA.rateSats);
  const attackerLB = p2pkhLockingBytecode(attacker.publicKeyHash);

  console.log('='.repeat(72));
  console.log('CONTRACT NEGATIVE TESTS — should ALL fail at local validation');
  console.log('='.repeat(72));
  console.log(`  Reservoir: ${reservoir.token.amount} FTs, ${reservoir.satoshis} sats`);
  console.log(`  Attacker BCH: ${feeInput.satoshis} sats`);

  const results = [];

  // N1: redirect reservoir output to attacker's address.
  results.push(await runTest(
    'N1: reservoir lockingBytecode swap',
    ['lockingBytecode', 'Require statement failed', 'line 64', 'line 65'],
    async () => {
      const tb = new TransactionBuilder({ provider });
      tb.addInput(reservoir, contract.unlock.claim(1n, attackerLB));
      tb.addInput(feeInput, sigTemplate.unlockP2PKH());
      // EVIL: reservoir-back output going to attacker, not contract
      tb.addOutput({
        to: attacker.tokenaddr,
        amount: 1000n,
        token: {
          amount: reservoir.token.amount - 1n,
          category: tokenA.categoryId,
          nft: { capability: 'minting', commitment: '' },
        },
      });
      tb.addOutput({ to: attacker.tokenaddr, amount: rateSats, token: { amount: 1n, category: tokenA.categoryId } });
      tb.addOutput({ to: attacker.cashaddr, amount: BigInt(feeInput.satoshis) - 4000n });
      tb.debug();
    },
  ));

  // N2: FT overflow — pick tokenAmount × rate > 2^63 - 1.
  // rate=1000, so tokenAmount > 9.22e15 overflows. Pick 10^17.
  results.push(await runTest(
    'N2: FT overflow on grossSats',
    ['overflow', 'out of range', 'too large', 'Number overflow', 'arithmetic'],
    async () => {
      const overflowAmount = 10n ** 17n;
      const tb = new TransactionBuilder({ provider });
      tb.addInput(reservoir, contract.unlock.claim(overflowAmount, attackerLB));
      tb.addInput(feeInput, sigTemplate.unlockP2PKH());
      tb.addOutput({
        to: contract.tokenAddress,
        amount: 1000n,
        token: {
          amount: reservoir.token.amount - overflowAmount,
          category: tokenA.categoryId,
          nft: { capability: 'minting', commitment: '' },
        },
      });
      // tokenAmount * rate would overflow. We don't even need a valid
      // grossSats here — the contract will throw at the multiplication.
      tb.addOutput({
        to: attacker.tokenaddr,
        amount: 1000n,
        token: { amount: overflowAmount, category: tokenA.categoryId },
      });
      tb.addOutput({ to: attacker.cashaddr, amount: BigInt(feeInput.satoshis) - 4000n });
      tb.debug();
    },
  ));

  // N3: negative tokenAmount. The SDK refuses to construct an output with
  // negative `tokens` at addOutput() time, so we don't even reach the
  // contract's own `require(tokenAmount > 0)` line. Either failure mode
  // counts as guarded.
  results.push(await runTest(
    'N3: negative tokenAmount',
    ['invalid', 'tokenAmount', 'tokens', 'Require statement failed'],
    async () => {
      const tb = new TransactionBuilder({ provider });
      tb.addInput(reservoir, contract.unlock.claim(-1n, attackerLB));
      tb.addInput(feeInput, sigTemplate.unlockP2PKH());
      tb.addOutput({
        to: contract.tokenAddress,
        amount: 1000n,
        token: {
          amount: reservoir.token.amount + 1n,
          category: tokenA.categoryId,
          nft: { capability: 'minting', commitment: '' },
        },
      });
      tb.addOutput({
        to: attacker.tokenaddr,
        amount: 1000n,
        token: { amount: -1n, category: tokenA.categoryId },
      });
      tb.addOutput({ to: attacker.cashaddr, amount: BigInt(feeInput.satoshis) - 4000n });
      tb.debug();
    },
  ));

  console.log('');
  console.log('='.repeat(72));
  console.log('SUMMARY');
  console.log('='.repeat(72));
  for (const r of results) {
    console.log(`  ${r.name}: ${r.status}`);
  }
  const allExpected = results.every((r) => r.status === 'expected-failure');
  console.log('');
  console.log(allExpected
    ? 'ALL NEGATIVE TESTS FAILED AS EXPECTED — contract guards work.'
    : 'WARNING: some tests did not fail as expected. Review individually.');
}

main().catch((err) => {
  console.error('SCRIPT FAILED:', err?.message ?? err);
  if (err?.stack) console.error(err.stack);
  process.exit(1);
});