// Node.
import msgpack from 'msgpack-lite';
import {performance} from 'perf_hooks';
// 3rd party.
// 2nd party.
import {EntityPacketSynchronizer} from '@avocado/entity';
import {InputPacket} from '@avocado/input';
import {Synchronizer} from '@avocado/state';
import {Ticker} from '@avocado/timing';
// 1st party.
import {WorldTime} from '../common/world-time';
import {createEntityForConnection} from './create-entity-for-connection';
import {createRoom} from './create-server-room';
// Create game.
export default class Game {

  constructor() {
    const config = this.readConfig();
    // Packets.
    this.entityPacketSynchronizer = new EntityPacketSynchronizer();
    // Room.
    this.room = createRoom();
    this.room.world.stepTime = config.simulationInterval;
    for (const entity of this.room.allEntities()) {
      this.onEntityAddedToRoom(entity);
    }
    this.room.on('entityAdded', this.onEntityAddedToRoom, this);
    // World time. Start at 10 am for testing.
    this.worldTime = new WorldTime();
    this.worldTime.hour = 10;
    // Entity tracking.
    this.informables = [];
    // State synchronization.
    this.synchronizer = new Synchronizer({
      room: this.room,
      worldTime: this.worldTime,
    });
    this.informTicker = new Ticker(config.informInterval);
    this.informTicker.on('tick', this.inform, this);
    // Simulation.
    this.mainLoopHandle = setInterval(
      this.createMainLoop(),
      1000 * config.simulationInterval
    );
  }

  destroy(fn) {
    clearInterval(this.mainLoopHandle);
    this.room.destroy();
    fn();
  }

  bundleEntityPackets() {
    const bundledEntityPackets = new Map();
    this.entityPacketSynchronizer.flushPackets((packetEntity, packets) => {
      for (let i = 0; i < this.informables.length; ++i) {
        const entity = this.informables[i];
        if (!entity.seesEntity(packetEntity)) {
          return;
        }
        if (!bundledEntityPackets.has(entity)) {
          bundledEntityPackets.set(entity, new Map());
        }
        for (let j = 0; j < packets.length; j++) {
          const packet = packets[j];
          const Packet = packet.constructor;
          if (!bundledEntityPackets.get(entity).has(Packet)) {
            bundledEntityPackets.get(entity).set(Packet, packet);
          }
          else {
            bundledEntityPackets.get(entity).get(Packet).bundleWith(packet);
          }
        }
      }
    });
    return bundledEntityPackets;
  }

  acceptConnection(socket) {
    // Create and track a new entity for the connection.
    const entity = createEntityForConnection(socket);
    // Track informables.
    this.informables.push(entity);
    entity.on('destroyed', () => {
      const index = this.informables.indexOf(entity);
      if (-1 !== index) {
        this.informables.splice(index, 1);
      }
    });
    // Add entity to room.
    this.room.addEntityToLayer(entity, 'everything');
    // Initial information.
    entity.inform(this.synchronizer.state);
    // Listen for events.
    socket.on('packet', this.createPacketListener(socket));
    socket.on('disconnect', this.createDisconnectionListener(socket));
  }

  createDisconnectionListener(socket) {
    const {entity} = socket;
    return () => {
      if (entity.is('existent')) {
        entity.destroy();
      }
    };
  }

  createMainLoop() {
    let lastTime = performance.now();
    return () => {
      const now = performance.now();
      const elapsed = (now - lastTime) / 1000;
      lastTime = now;
      // Tick synchronized.
      this.synchronizer.tick(elapsed);
      // Tick informer.
      this.informTicker.tick(elapsed);
    }
  }

  createPacketListener(socket) {
    const {entity} = socket;
    return (packet) => {
      this.entityPacketSynchronizer.acceptPacket(packet);
      if (packet instanceof InputPacket) {
        entity.inputState = packet.toState();
      }
    };
  }

  flushEntityPackets() {
    const bundledEntityPackets = this.bundleEntityPackets();
    const entities = Array.from(bundledEntityPackets.keys());
    for (let i = 0; i < entities.length; i++) {
      const entity = entities[i];
      const packets = Array.from(bundledEntityPackets.get(entity).values());
      for (let j = 0; j < packets.length; j++) {
        const packet = packets[j];
        entity.socket.send(packet);
      }
    }
  }

  inform() {
    // Inform entities of the new state.
    for (let i = 0; i < this.informables.length; ++i) {
      const entity = this.informables[i];
      entity.inform(this.synchronizer.state);
    }
    // Flush entity packets.
    this.flushEntityPackets();
  }

  onEntityAddedToRoom(entity) {
    this.entityPacketSynchronizer.trackEntity(entity);
  }

  readConfig() {
    return {
      informInterval: 1 / 60,
      simulationInterval: 1 / 60,
    };
  }

}