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

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

/**
 * This is a direct messagee between two endpoints of a channel
 * and serves as an opt-in mechanism to allow the
 * announcement of the channel to the rest of the network. It
 * contains the necessary signatuures, by the sender, to construct
 * the channel_announcement message.
 *
 * The message constructed by constructing a channel_announcement
 * message, corresponding to the newly created channel, and signing
 * it with the secrets matching an endpoint's node_id and
 * bitcoin_key.
 */
export class AnnouncementSignaturesMessage implements IWireMessage {
  /**
   * Deserializes a Buffer into an AnnouncementSignaturesMessage.
   */
  public static deserialize(payload: Buffer): AnnouncementSignaturesMessage {
    const reader = new BufferReader(payload);
    reader.readUInt16BE(); // read off type

    const instance = new AnnouncementSignaturesMessage();
    instance.channelId = reader.readBytes(32);
    instance.shortChannelId = shortChannelIdFromBuffer(reader.readBytes(8));
    instance.nodeSignature = reader.readBytes(64);
    instance.bitcoinSignature = reader.readBytes(64);
    return instance;
  }

  /**
   * Message type - 259
   */
  public type: MessageType = MessageType.AnnouncementSignatures;

  /**
   * Buffer of the channel_id for the message.
   */
  public channelId: Buffer = Buffer.alloc(0);

  /**
   * ShortChannelId is a unique reference to the funding output of
   * the channel.
   */
  public shortChannelId: ShortChannelId;

  /**
   * Buffer containing the signature of the channel_announcement message
   * signed by the endpoint's node_id.
   */
  public nodeSignature: Buffer = Buffer.alloc(0);

  /**
   * Buffer containing the signaturee of the channel_announcment message
   * signed by the endpoint's bitcoin_key.
   */
  public bitcoinSignature: Buffer = Buffer.alloc(0);

  /**
   * Serializes the instance into a Buffer suitable for
   * transmission on the wire.
   */
  public serialize(): Buffer {
    const len =
      2 + // type
      32 + // channel_id
      8 + // short_channel_id
      64 + // node_signature
      64; // bitcoin_signaturee
    const writer = new BufferWriter(Buffer.alloc(len));
    writer.writeUInt16BE(this.type);
    writer.writeBytes(this.channelId);
    writer.writeBytes(this.shortChannelId.toBuffer());
    writer.writeBytes(this.nodeSignature);
    writer.writeBytes(this.bitcoinSignature);
    return writer.toBuffer();
  }
}