import { ILogger } from '@node-dlc/logger';

import { GossipTimestampFilterMessage } from '../messages/GossipTimestampFilterMessage';
import { IMessageSender } from '../Peer';

export enum GossipQueriesReceiverState {
  Idle,
  Receiving,
}

/**
 * This class is used to activate / deactivate receiving of gossip messages
 * when the gossip_queries or gossip_queries_ex gossip sync strategies are used.
 */
export class GossipQueriesReceiver {
  private _state: GossipQueriesReceiverState;
  private _firstTimestamp: number;
  private _timestampRange: number;

  constructor(
    readonly chainHash: Buffer,
    readonly peer: IMessageSender,
    readonly logger: ILogger,
  ) {
    this._state = GossipQueriesReceiverState.Idle;
    this._firstTimestamp = 0xffffffff;
    this._timestampRange = 0;
  }

  public get state(): GossipQueriesReceiverState {
    return this._state;
  }

  public get firstTimestamp(): number {
    return this._firstTimestamp;
  }

  public get timestampRange(): number {
    return this._timestampRange;
  }

  /**
   * Deactivates gossip with the remote peer by sending a
   * gossip_timestamp_filter message that disables broadcast. In particular this
   * message will use a first_timestamp of uint32_max and a timestamp_range of
   * 0 to prevent the remote peer from sending information.
   */
  public deactivate(): void {
    this.logger.info('deactivating gossip');

    // reset params
    this._firstTimestamp = 0xffffffff;
    this._timestampRange = 0;

    // send message
    const msg = new GossipTimestampFilterMessage();
    msg.chainHash = this.chainHash;
    msg.firstTimestamp = 0xffffffff;
    msg.timestampRange = 0;
    this.peer.sendMessage(msg);

    // change state
    this._state = GossipQueriesReceiverState.Idle;
  }

  /**
   * Activates gossip with the remote peer by sending a gossip_timestamp_filter
   * message with the specified first timestamp and range. By default, this
   * starts gossip with the current timestamp and uint32_max as the range.
   * @param start
   * @param range
   */
  public activate(
    start: number = Math.trunc(Date.now() / 1000),
    range = 0xffffffff,
  ): void {
    this.logger.info('activating gossip for range %d to %d', start, range);

    // set params
    this._firstTimestamp = start;
    this._timestampRange = range;

    // send message
    const msg = new GossipTimestampFilterMessage();
    msg.chainHash = this.chainHash;
    msg.firstTimestamp = start;
    msg.timestampRange = range;
    this.peer.sendMessage(msg);

    // change state
    this._state = GossipQueriesReceiverState.Receiving;
  }
}