import { binToHex, hexToBin, hashTransaction, isHex } from '@bitauth/libauth';

/**
 * Transaction Hash Primitive.
 */
export class TransactionHash {
  public readonly bytes: Uint8Array;

  /**
   * Instantiates TransactionHash from a Transaction Hash's bytes.
   *
   * @param bytes {Uint8Array} The Transaction Hash's bytes.
   */
  constructor(bytes: Uint8Array) {
    // If bytes is not exactly 32, then this is an invalid transaction hash...
    if (bytes.length !== 32) {
      throw new Error(
        `Invalid Transaction Hash: Expected 32 bytes but received ${bytes.length}`,
      );
    }

    this.bytes = bytes;
  }

  /**
   * Instantiates TransactionHash from a hex string.
   *
   * @param hex {string} The hex string.
   *
   * @throws {Error} If hex is invalid.
   *
   * @returns {TransactionHash} Instance of TransactionHash.
   */
  public static fromHex(hex: string): TransactionHash {
    if (!isHex(hex)) {
      throw new Error('Invalid hex provided');
    }

    const bytes = hexToBin(hex);

    return new TransactionHash(bytes);
  }

  /**
   * Instantiates TransactionHash from a Transaction's bytes.
   *
   * @param transactionBytes {Uint8Array} The Transaction's bytes.
   *
   * @returns {TransactionHash} Instance of TransactionHash.
   */
  public static fromTransactionBytes(
    transactionBytes: Uint8Array,
  ): TransactionHash {
    const transactionHash = hashTransaction(transactionBytes);

    return new TransactionHash(hexToBin(transactionHash));
  }

  /**
   * Instantiates TransactionHash from a Transaction's bytes in hex.
   *
   * @param transactionHex {Uint8Array} The Transaction's bytes in hex.
   *
   * @throws {Error} If hex is invalid.
   *
   * @returns {TransactionHash} Instance of TransactionHash.
   */
  public static fromTransactionHex(transactionHex: string): TransactionHash {
    if (!isHex(transactionHex)) {
      throw new Error('Invalid hex provided');
    }

    const bytes = hexToBin(transactionHex);

    return TransactionHash.fromTransactionBytes(bytes);
  }

  /**
   * Returns transaction hash as a hex string.
   *
   * @returns {string} Hex string of the Transaction Hash.
   */
  public toHex(): string {
    return binToHex(this.bytes);
  }

  /**
   * Returns transaction hash as a Uint8Array.
   *
   * @returns {Uint8Array} Uint8Array of the Transaction Hash.
   */
  public toBytes(): Uint8Array {
    return this.bytes;
  }
}