import { BufferReader, BufferWriter } from '@node-dlc/bufio';
import { ChannelId } from '@node-dlc/common';

import { MessageType } from '../MessageType';
import { IWireMessage } from './IWireMessage';

/**
 * The `funding_signed` message is sent by the channel acceptor after
 * they have recieved a `funding_created` message from the initiator.
 * This message includes the signature for the initiator's first
 * commitment transaction. After the initiator receives this message
 * the channel can be broadcast to the Bitcoin network as both
 * participants can spend the outputs of the funding transaction. This
 * message also is the first instance of the `channel_id` and both sides
 * can transition from using the `temporary_channel_id` to the actual
 * `channel_id`.
 */
export class FundingSignedMessage implements IWireMessage {
  public static type: MessageType = MessageType.FundingSigned;

  /**
   * Deserializes the funding_signed message
   * @param buf
   * @returns
   */
  public static deserialize(buf: Buffer): FundingSignedMessage {
    const instance = new FundingSignedMessage();
    const reader = new BufferReader(buf);

    reader.readUInt16BE(); // read type
    instance.channelId = new ChannelId(reader.readBytes(32));
    instance.signature = reader.readBytes(64);

    return instance;
  }

  /**
   * The type for message. funding_signed = 35
   */
  public readonly type: MessageType = FundingSignedMessage.type;

  /**
   * ChannelId generated from the funding transactions outpoint.
   */
  public channelId: ChannelId;

  /**
   * Signature for the counterpary's first commitment transaction.
   * This signature allows the counterparty to spend the commitment
   * using their own signature. The signature must be 64-bytes
   * representing the 32-byte (r,s) values for an ECDSA signature.
   */
  public signature: Buffer;

  /**
   * Serializes the message into a Buffer
   */
  public serialize(): Buffer {
    const writer = new BufferWriter();
    writer.writeUInt16BE(this.type);
    writer.writeBytes(this.channelId.toBuffer());
    writer.writeBytes(this.signature);
    return writer.toBuffer();
  }
}