import * as I from 'immutable';

import {compose, EventEmitter} from '@avocado/core';

const decorate = compose(
  EventEmitter,
);

export class ActionRegistry extends decorate(class {}) {

  constructor() {
    super();
    this.mapActionToKey = new Map();
    this.mapKeyToAction = {};
    this.normalizer = undefined;
    this._state = I.Map();
  }

  actionForKey(key) {
    return this.mapKeyToAction[key];
  }

  listen(normalizer) {
    // Only listen once.
    if (this.normalizer) {
      return;
    }
    this.normalizer = normalizer;
    this.normalizer.on('keyUp', this.onKeyUp, this);
    this.normalizer.on('keyDown', this.onKeyDown, this);
  }

  keyForAction(action) {
    return this.mapActionToKey.get(action);
  }

  mapKeysToActions(map) {
    for (const key in map) {
      const action = map[key];
      this.mapKeyToAction[key] = action;
      this.mapActionToKey.set(action, key);
    }
  }

  onKeyDown(key) {
    if (this.mapKeyToAction[key]) {
      const action = this.mapKeyToAction[key];
      this._state = this._state.set(action, true);
    }
  }

  onKeyUp(key) {
    if (this.mapKeyToAction[key]) {
      const action = this.mapKeyToAction[key];
      this._state = this._state.delete(action);
    }
  }

  get state() {
    return this._state;
  }

  set state(state) {
    this._state = state;
  }

  stopListening(normalizer) {
    if (!this.normalizer) {
      return;
    }
    this.normalizer.off('keyUp', this.onKeyUp);
    this.normalizer.off('keyDown', this.onKeyDown);
    this.normalizer = undefined;
  }

}

export {InputPacket} from './packet/input.packet';