off-chain_code_unlock_funds

import {
  Blockfrost,
  C,
  Data,
  Lucid,
  SpendingValidator,
  TxHash,
  fromHex,
  toHex,
} from "https://deno.land/x/lucid@0.8.3/mod.ts";
import * as cbor from "https://deno.land/x/cbor@v1.4.1/index.js";
 
const lucid = await Lucid.new(
  new Blockfrost(
    "https://cardano-preview.blockfrost.io/api/v0",
    Deno.env.get("BLOCKFROST_API_KEY"),
  ),
  "Preview",
);
 
lucid.selectWalletFromPrivateKey(await Deno.readTextFile("./beneficiary.sk"));
 
const beneficiaryPublicKeyHash = lucid.utils.getAddressDetails(
  await lucid.wallet.address()
).paymentCredential.hash;
 
const validator = await readValidator();
 
async function readValidator(): Promise<SpendingValidator> {
  const validator = JSON.parse(await Deno.readTextFile("plutus.json")).validators[0];
  return {
    type: "PlutusV2",
    script: toHex(cbor.encode(fromHex(validator.compiledCode))),
  };
}

const scriptAddress = lucid.utils.validatorToAddress(validator);
 
const scriptUtxos = await lucid.utxosAt(scriptAddress);
 
const Datum = Data.Object({
  lock_until: Data.BigInt, 
  return_time: Data.BigInt,
  owner: Data.String,
  beneficiary: Data.String,
});
 
type Datum = Data.Static<typeof Datum>;
 
const currentTime = new Date().getTime();
 
const utxos = scriptUtxos.filter((utxo) => {
    let datum = Data.from<Datum>(
      utxo.datum,
      Datum,
    );
 
    return datum.beneficiary === beneficiaryPublicKeyHash &&
      datum.lock_until <= currentTime;
});
 
if (utxos.length === 0) {
  console.log("No redeemable utxo found. You need to wait a little longer...");
  Deno.exit(1);
}
 
const redeemer = Data.empty();
 
const txUnlock = await unlock(utxos, currentTime, { from: validator, using: redeemer });
 
await lucid.awaitTx(txUnlock);
 
console.log(`1 ADA recovered from the contract
    Tx ID: ${txUnlock}
    Redeemer: ${redeemer}
`);

async function unlock(utxos, currentTime, { from, using }): Promise<TxHash> {
  const laterTime = new Date(currentTime + 2 * 60 * 60 * 1000).getTime(); // add two hours (TTL: time to live)
 
  const tx = await lucid
    .newTx()
    .collectFrom(utxos, using)
    .addSigner(await lucid.wallet.address()) 
    .validFrom(currentTime)
    .validTo(laterTime)
    .attachSpendingValidator(from)
    .complete();
 
  const signedTx = await tx
    .sign()
    .complete();
 
  return signedTx.submit();
}