signer.ts

import { encodeUnsignedSimulateTransaction, Transaction } from './transaction';
import Account from './types/account';
import { LogicSigAccount, signLogicSigTransactionObject } from './logicsig';
import { MultisigMetadata } from './types/multisig';
import { signMultisigTransaction, mergeMultisigTransactions } from './multisig';

/**
 * This type represents a function which can sign transactions from an atomic transaction group.
 * @param txnGroup - The atomic group containing transactions to be signed
 * @param indexesToSign - An array of indexes in the atomic transaction group that should be signed
 * @returns A promise which resolves an array of encoded signed transactions. The length of the
 *   array will be the same as the length of indexesToSign, and each index i in the array
 *   corresponds to the signed transaction from txnGroup[indexesToSign[i]]
 */
export type TransactionSigner = (
  txnGroup: Transaction[],
  indexesToSign: number[]
) => Promise<Uint8Array[]>;

/**
 * Create a TransactionSigner that can sign transactions for the provided basic Account.
 */
export function makeBasicAccountTransactionSigner(
  account: Account
): TransactionSigner {
  return (txnGroup: Transaction[], indexesToSign: number[]) => {
    const signed: Uint8Array[] = [];

    for (const index of indexesToSign) {
      signed.push(txnGroup[index].signTxn(account.sk));
    }

    return Promise.resolve(signed);
  };
}

/**
 * Create a TransactionSigner that can sign transactions for the provided LogicSigAccount.
 */
export function makeLogicSigAccountTransactionSigner(
  account: LogicSigAccount
): TransactionSigner {
  return (txnGroup: Transaction[], indexesToSign: number[]) => {
    const signed: Uint8Array[] = [];

    for (const index of indexesToSign) {
      const { blob } = signLogicSigTransactionObject(txnGroup[index], account);
      signed.push(blob);
    }

    return Promise.resolve(signed);
  };
}

/**
 * Create a TransactionSigner that can sign transactions for the provided Multisig account.
 * @param msig - The Multisig account metadata
 * @param sks - An array of private keys belonging to the msig which should sign the transactions.
 */
export function makeMultiSigAccountTransactionSigner(
  msig: MultisigMetadata,
  sks: Uint8Array[]
): TransactionSigner {
  return (txnGroup: Transaction[], indexesToSign: number[]) => {
    const signed: Uint8Array[] = [];

    for (const index of indexesToSign) {
      const txn = txnGroup[index];
      const partialSigs: Uint8Array[] = [];

      for (const sk of sks) {
        const { blob } = signMultisigTransaction(txn, msig, sk);
        partialSigs.push(blob);
      }

      if (partialSigs.length > 1) {
        signed.push(mergeMultisigTransactions(partialSigs));
      } else {
        signed.push(partialSigs[0]);
      }
    }

    return Promise.resolve(signed);
  };
}

/**
 * Create a makeEmptyTransactionSigner that does not specify any signer or
 * signing capabilities. This should only be used to simulate transactions.
 */
export function makeEmptyTransactionSigner(): TransactionSigner {
  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  return (txnGroup: Transaction[], indexesToSign: number[]) => {
    const unsigned: Uint8Array[] = [];

    for (const index of indexesToSign) {
      unsigned.push(encodeUnsignedSimulateTransaction(txnGroup[index]));
    }

    return Promise.resolve(unsigned);
  };
}

/** Represents an unsigned transactions and a signer that can authorize that transaction. */
export interface TransactionWithSigner {
  /** An unsigned transaction */
  txn: Transaction;
  /** A transaction signer that can authorize txn */
  signer: TransactionSigner;
}

/**
 * Check if a value conforms to the TransactionWithSigner structure.
 * @param value - The value to check.
 * @returns True if an only if the value has the structure of a TransactionWithSigner.
 */
export function isTransactionWithSigner(
  value: any
): value is TransactionWithSigner {
  return (
    typeof value === 'object' &&
    Object.keys(value).length === 2 &&
    typeof value.txn === 'object' &&
    typeof value.signer === 'function'
  );
}