import * as I from 'immutable';
import immutablediff from 'immutablediff';
import isPlainObject from 'is-plain-object';

import {compose} from '@avocado/core';
import {Trait} from '@avocado/entity';
import {Packer, Synchronizer} from '@avocado/state';

const decorate = compose(
);

export class Informed extends decorate(Trait) {

  initialize() {
    this._packer = new Packer();
    this._socket = undefined;
    this._state = I.Map();
  }

  destroy() {
    if (this._socket) {
      delete this._socket.entity;
      delete this._socket;
    }
  }

  reduceState(state) {
    // Set client's self entity.
    state = state.set('selfEntity', this.entity.instanceUuid);
    // Reduce entity list to visible.
    const room = this.entity.room;
    const camera = this.entity.camera;
    for (const {index, layer} of room.layers) {
      const visibleEntities = layer.visibleEntities(
        camera.rectangle
      );
      let reducedEntityList = I.Map();
      for (const entity of visibleEntities) {
        reducedEntityList = reducedEntityList.set(
          entity.instanceUuid,
          entity.state,
        );
      }
      const entityListPath = ['room', 'layers', index, 'entityList'];
      state = state.setIn(entityListPath, reducedEntityList);
    }
    return state;
  }

  get socket() {
    return this._socket;
  }

  set socket(socket) {
    socket.entity = this.entity;
    this._socket = socket;
  }

  methods() {
    return {

      inform: (state) => {
        // Reduce state.
        const reducedState = this.reduceState(state);
        // Take a pure JS diff.
        const steps = immutablediff(this._state, reducedState).toJS();
        this._state = reducedState;
        if (0 === steps.length) {
          return;
        }
        // Emit!
        const keys = this._packer.computeNewKeys(steps);
        if (0 !== keys[0].length) {
          this._socket.send({
            type: 'keys',
            payload: keys,
          });
        }
        const packed = this._packer.pack(steps);
        this._socket.send(packed);
      },

    };
  }

}