import * as I from 'immutable';

import {compose} from '@avocado/core';
import {Entity, EntityList} from '@avocado/entity';
import {Vector} from '@avocado/math';
import {EventEmitter, Property} from '@avocado/mixins';
import {ShapeList} from '@avocado/physics';
import {Synchronized} from '@avocado/state';

import {Tiles} from './tiles';
import {Tileset} from './tileset';

const decorate = compose(
  EventEmitter,
  Property('tilesetUri', {
    track: true,
  }),
  Property('tileset', {
    track: true,
  }),
  Property('world', {
    track: true,
  }),
  Synchronized,
);

export class Layer extends decorate(class {}) {

  constructor() {
    super();
    this.entityList = new EntityList();
    this.tileGeometry = [];
    this.tiles = new Tiles();
    // Listeners.
    this.entityList.on('entityAdded', this.onEntityAddedToLayer, this);
    this.entityList.on('entityRemoved', this.onEntityRemovedFromLayer, this);
    this.tiles.on('dataChanged', this.onTileDataChanged, this);
    this.on('tilesetChanged', this.onTilesetChanged, this);
    this.on('tilesetUriChanged', this.onTilesetUriChanged, this);
    this.onTilesetUriChanged();
    this.on('worldChanged', this.onWorldChanged, this);
  }

  addEntity(entity) {
    this.entityList.addEntity(entity);
  }

  addTileGeometry() {
    const tileset = this.tileset;
    if (!tileset) {
      return false;
    }
    const world = this.world;
    if (!world) {
      return false;
    }
    const halfTileSize = Vector.scale(tileset.tileSize, 0.5);
    this.tiles.forEachTile((tile, x, y, i) => {
      const shape = this.tileset.geometry(tile);
      if (!shape) {
        return;
      }
      shape.position = Vector.add(
        halfTileSize,
        Vector.mul([x, y], tileset.tileSize),
      );
      const body = world.createBody(shape);
      body.static = true;
      world.addBody(body);
      this.tileGeometry.push(body);
    });
    return true;
  }

  destroy() {
    this.entityList.destroy();
    this.entityList.off('entityAdded', this.onEntityAddedToLayer);
    this.entityList.off('entityRemoved', this.onEntityRemovedFromLayer);
    this.tiles.off('dataChanged', this.onTileDataChanged);
    this.off('tilesetUriChanged', this.onTilesetUriChanged);
    if (this.tileset) {
      this.tileset.destroy();
    }
  }

  findEntity(uuid) {
    return this.entityList.findEntity(uuid);
  }

  fromJSON(json) {
    if (json.entities) {
      json.entities.forEach((entityJSON) => {
        const entity = new Entity();
        this.entityList.addEntity(entity.fromJSON(entityJSON));
      });
    }
    if (json.tiles) {
      this.tiles.fromJSON(json.tiles)
    }
    if (json.tilesetUri) {
      this.tilesetUri = json.tilesetUri;
    }
    return this;
  }

  onEntityAddedToLayer(entity) {
    entity.addTrait('layered');
    entity.layer = this;
    this.emit('entityAdded', entity)
  }

  onEntityRemovedFromLayer(entity) {
    if (entity.is('layered')) {
      entity.removeTrait('layered');
    }
    this.emit('entityRemoved', entity);
  }

  onTileDataChanged() {
    this.emit('tileDataChanged');
  }

  onTilesetChanged(oldTileset) {
    let didChange = false;
    if (oldTileset) {
      this.removeTileGeometry();
      didChange = true;
    }
    if (this.addTileGeometry()) {
      didChange = true;
    }
    if (didChange) {
      this.emit('tileGeometryChanged');
    }
  }

  onTilesetUriChanged() {
    if (!this.tilesetUri) {
      return;
    }
    Tileset.load(this.tilesetUri).then((tileset) => {
      this.tileset = tileset;
    });
  }

  onWorldChanged(oldWorld) {
    let didChange = false;
    if (oldWorld) {
      this.removeTileGeometry();
      didChange = true;
    }
    if (this.addTileGeometry()) {
      didChange = true;
    }
    if (didChange) {
      this.emit('tileGeometryChanged');
    }
  }

  removeEntity(entity) {
    this.entityList.removeEntity(entity);
  }

  removeTileGeometry() {
     // ... tag geometry in world for removal?
  }

  setTileAt(x, y, tile) {
    this.tiles.setTileAt(x, y, tile);
  }

  synchronizedChildren() {
    return [
      'entityList',
      'tiles',
      'tilesetUri',
    ];
  }

  visibleEntities(query) {
    return this.entityList.visibleEntities(query);
  }

}