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

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

/**
 * This message is sent by both participants in the channel after
 * the funding transaction has reached a sufficient depth (as specified
 * in `accept_channel` via the `minimum_depth` property). This message
 * enables normal operation for the channel by providing the
 * next `per_commitment_point` needed to generate a new commitment
 * transaction signature. This message may get resent upon reconnections
 * if no additional updates have occurred for the channel.
 */
export class FundingLockedMessage implements IWireMessage {
  public static type: MessageType = MessageType.FundingLocked;

  /**
   * Deserializes the `funding_signed` message per BOLT2
   */
  public static deserialize(buf: Buffer): FundingLockedMessage {
    const instance = new FundingLockedMessage();
    const reader = new BufferReader(buf);

    reader.readUInt16BE(); // read type
    instance.channelId = new ChannelId(reader.readBytes(32));
    instance.nextPerCommitmentPoint = reader.readBytes(33);

    return instance;
  }

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

  /**
   * Unique channel identifier for the channel based on the funding
   * transactions UTXO.
   */
  public channelId: ChannelId;

  /**
   * Provides the next_per_commitment_point that the peer should use
   * for the next commitment transaction. For this message, this is
   * the commitment transaction in the first update.
   */
  public nextPerCommitmentPoint: Buffer;

  /**
   * Serializes the `funding_locked` message per BOLT2
   * @returns
   */
  public serialize(): Buffer {
    const writer = new BufferWriter();
    writer.writeUInt16BE(this.type);
    writer.writeBytes(this.channelId.toBuffer());
    writer.writeBytes(this.nextPerCommitmentPoint);
    return writer.toBuffer();
  }
}