import {
  assembleBytecodeBCH,
  disassembleBytecodeBCH,
  base58AddressToLockingBytecode,
  cashAddressToLockingBytecode,
  binToHex,
  hexToBin,
  isHex,
} from '@bitauth/libauth';

/**
 * Script Entity.
 */
export class Script {
  public readonly bytes: Uint8Array;

  /**
   * Construct a new Script
   *
   * @param bytes {Uint8Array} The raw bytes of the Script.
   */
  constructor(bytes: Uint8Array) {
    this.bytes = bytes;
  }

  /**
   * Create a Script Entity from the given Assembly String.
   *
   * @param asm {string} String of assembly code.
   *
   * @throws {Error} If script cannot be decoded.
   *
   * @returns {Script} The created Script Entity.
   */
  public static fromASM(asm: string): Script {
    // Attempt to convert the given ASM to bytecode.
    const assembleResult = assembleBytecodeBCH(asm);

    // If a string is returned, this indicates an error...
    if (typeof assembleResult === 'string') {
      throw new Error(assembleResult);
    }

    // If the success flag is not marked, this indicates an error...
    if (!assembleResult.success) {
      throw new Error('Could not assemble bytecode from assembly.');
    }

    // Return new Script Entity from the assembled bytecode.
    return new Script(assembleResult.bytecode);
  }

  /**
   * Create a Script Entity from the given bytes (as hexadecimal string).
   *
   * @param hex {string} Raw script bytes encoded as hexadecimal.
   *
   * @throws {Error} If script cannot be decoded.
   *
   * @returns {Script} The created Script Entity.
   */
  public static fromHex(hex: string): Script {
    // Ensure that the given string is hex.
    if (!isHex(hex)) {
      throw new Error(`The given string (${hex}) is not valid hexadecimal.`);
    }

    // Conver the given hex to binary (Uint8Array).
    const scriptBin = hexToBin(hex);

    // Return new Script entity constructed from the binary.
    return new Script(scriptBin);
  }

  /**
   * Create a Script Entity from the given CashAddr.
   *
   * @param cashAddr {string} The Address in CashAddr format.
   *
   * @throws {Error} If address cannot be decoded.
   *
   * @returns {Script} The created Script Entity.
   */
  public static fromCashAddr(cashAddr: string): Script {
    const decodeResult = cashAddressToLockingBytecode(cashAddr);

    if (typeof decodeResult === 'string') {
      throw new Error(decodeResult);
    }

    return new Script(decodeResult.bytecode);
  }

  /**
   * Create a Script Entity from the given Legacy Address.
   *
   * @param legacyAddress {string} The Address in Legacy format.
   *
   * @throws {Error} If address cannot be decoded.
   *
   * @returns {Script} The created Script Entity.
   */
  public static fromLegacyAddress(legacyAddress: string): Script {
    const decodeResult = base58AddressToLockingBytecode(legacyAddress);

    if (typeof decodeResult === 'string') {
      throw new Error(decodeResult);
    }

    return new Script(decodeResult.bytecode);
  }

  /**
   * Convert this script to a human-readable string of assembly.
   *
   * @returns {string} Human-readable assembly.
   */
  public toASM(joinWith = '\n'): string {
    const disassembledBytecode = disassembleBytecodeBCH(this.bytes);

    if (joinWith) {
      return disassembledBytecode.split(' ').join(joinWith);
    }

    return disassembledBytecode;
  }

  /**
   * Get the raw bytecode for this script.
   *
   * @returns {Uint8Array} The compiled bytes.
   */
  public toBytes(): Uint8Array {
    return this.bytes;
  }

  /**
   * Get the raw bytecode for this script as a hex string.
   *
   * @returns {string} The compiled bytes as a hex string.
   */
  public toHex(): string {
    return binToHex(this.bytes);
  }
}