import {compose, EventEmitter} from '@avocado/core';
import {QuadTree, Rectangle, Vector} from '@avocado/math';
import {
  SynchronizedCreatePacket,
  SynchronizedDestroyPacket,
} from '@avocado/net';

import {EntityListUpdateEntityPacket} from '../packets/entity-list-update-entity.packet';
import {Entity} from '../entity.synchronized';

const decorate = compose(
  EventEmitter,
);

export class EntityList extends decorate(class {}) {

  constructor() {
    super();
    this._afterDestructionTickers = [];
    this._entities = {};
    this._entityTickers = []
    this._flatEntities = [];
    this._informedEntities = new Map();
    this._quadTree = new QuadTree();
  }

  *[Symbol.iterator]() {
    for (const uuid in this._entities) {
      const entity = this._entities[uuid];
      yield entity;
    }
  }

  acceptPacket(packet) {
    if (packet instanceof EntityListUpdateEntityPacket) {
      for (let i = 0; i < packet.data.length; i++) {
        const {uuid, packets} = packet.data[i];
        for (let j = 0; j < packets.length; j++) {
          if (this._entities[uuid]) {
            this._entities[uuid].acceptPacket(packets[j]);
          }
        }
      }
    }
    if (packet instanceof SynchronizedCreatePacket) {
      Entity.loadOrInstance(packet.data.spec).then((entity) => {
        entity.hydrate().then(() => {
          this.addEntity(entity);
        });
      });
    }
    if (packet instanceof SynchronizedDestroyPacket) {
      const uuid = packet.data.synchronized.id;
      if (this._entities[uuid]) {
        this._entities[uuid].destroy();
      }
    }
  }

  addEntity(entity) {
    const uuid = entity.instanceUuid;
    // Already exists?
    if (this._entities[uuid]) {
      return;
    }
    this._entities[uuid] = entity;
    this._flatEntities.push(entity);
    this._entityTickers.push(entity.tick);
    if (AVOCADO_SERVER) {
      this._informedEntities.set(entity, []);
    }
    entity.attachToList(this);
    entity.once('destroy', () => {
      this.removeEntity(entity);
      // In the process of destroying, allow entities to specify tickers that
      // must live on past destruction.
      const tickers = entity.invokeHookFlat('afterDestructionTickers');
      for (let i = 0; i < tickers.length; i++) {
        const ticker = tickers[i];
        this._afterDestructionTickers.push(ticker);
      }
    });
    this.emit('entityAdded', entity);
  }

  cleanPackets() {
    for (let i = 0; i < this._flatEntities.length; i++) {
      this._flatEntities[i].cleanPackets();
    }
  }

  destroy() {
    for (let i = 0; i < this._flatEntities.length; i++) {
      this._flatEntities[i].destroy();
    }
  }

  findEntity(uuid) {
    if (uuid in this._entities) {
      return this._entities[uuid];
    }
  }

  fromJSON(json) {
    for (let i = 0; i < json.length; i++) {
      const entityJSON = json[i];
      if (entityJSON.uri) {
        Entity.read(entityJSON.uri).then((readJSON) => {
          this.addEntity(new Entity(readJSON, entityJSON));
        });
      }
      else {
        this.addEntity(new Entity(json[i]));
      }
    }
  }

  packets(informed) {
    const packets = [];
    // Visible entities.
    const {areaToInform} = informed;
    const previousVisibleEntities = this._informedEntities.get(informed);
    const visibleEntities = this.visibleEntities(areaToInform);
    const updates = [];
    for (let i = 0; i < visibleEntities.length; i++) {
      const entity = visibleEntities[i];
      // Newly visible entity.
      const index = previousVisibleEntities.indexOf(entity);
      if (-1 === index) {
        packets.push(entity.createPacket(informed));
      }
      // Still visible entity.
      else {
        const entityPackets = entity.packets(informed);
        if (entityPackets.length > 0) {
          updates.push({
            uuid: entity.instanceUuid,
            packets: entityPackets,
          });
        }
        previousVisibleEntities.splice(index, 1);
      }
    }
    // Send updates.
    this._informedEntities.set(informed, visibleEntities);
    if (updates.length > 0) {
      packets.push(new EntityListUpdateEntityPacket(updates));
    }
    // Send destroys.
    for (let i = 0; i < previousVisibleEntities.length; i++) {
      const entity = previousVisibleEntities[i];
      // Newly removed entity.
      if (-1 === visibleEntities.indexOf(entity)) {
        packets.push(entity.destroyPacket(informed));
      }
    }
    return packets;
  }

  get quadTree() {
    return this._quadTree;
  }

  removeEntity(entity) {
    const uuid = entity.instanceUuid;
    if (!(uuid in this._entities)) {
      return;
    }
    if (AVOCADO_SERVER) {
      this._informedEntities.delete(entity);
    }
    entity.detachFromList();
    delete this._entities[uuid];
    this._flatEntities.splice(this._flatEntities.indexOf(entity), 1);
    this._entityTickers.splice(this._entityTickers.indexOf(entity.tick), 1);
    this.emit('entityRemoved', entity);
  }

  tick(elapsed) {
    // Run after destruction tickers.
    if (this._afterDestructionTickers.length > 0) {
      this.tickAfterDestructionTickers(elapsed);
    }
    // Run normal tickers.
    this.tickEntities(elapsed)
  }

  tickAfterDestructionTickers(elapsed) {
    const finishedTickers = [];
    for (let i = 0; i < this._afterDestructionTickers.length; ++i) {
      const ticker = this._afterDestructionTickers[i];
      if (ticker(elapsed)) {
        finishedTickers.push(ticker);
      }
    }
    for (let i = 0; i < finishedTickers.length; ++i) {
      const ticker = finishedTickers[i];
      const index = this._afterDestructionTickers.indexOf(ticker);
      this._afterDestructionTickers.splice(index, 1);
    }
  }

  tickEntities(elapsed) {
    for (let i = 0; i < this._entityTickers.length; i++) {
      this._entityTickers[i](elapsed);
    }
  }

  toNetwork(informed) {
    const {areaToInform} = informed;
    const visibleEntities = this.visibleEntities(areaToInform);
    // Mark as notified.
    this._informedEntities.set(informed, visibleEntities);
    return visibleEntities.map((entity) => {
      return entity.toNetwork(informed);
    });
  }

  toJSON() {
    const json = [];
    for (let i = 0; i < this._flatEntities.length; i++) {
      const entity = this._flatEntities[i];
      json.push(entity.mergeDiff(entity.toJSON()));
    }
    return json;
  }

  visibleEntities(query) {
    const entities = [];
    const entitiesChecked = [];
    const quadTree = this._quadTree;
    const nodes = quadTree.search(query);
    // Check all nodes.
    for (let i = 0; i < nodes.length; ++i) {
      const node = nodes[i];
      const entity = node.data[2];
      const aabb = node.data[3];
      if (-1 === entitiesChecked.indexOf(entity)) {
        entitiesChecked.push(entity);
        // Make sure the AABB is actually in the query due to expansion.
        if (entity.isVisible && Rectangle.intersects(query, aabb)) {
          entities.push(entity);
        }
      }
    }
    return entities;
  }

  visibleEntitiesWithUri(query, uri) {
    return this.visibleEntities(query).filter((entity) => {
      return entity.uri === uri;
    });
  }

}

export {EntityListView} from './view';