import * as I from 'immutable';

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

const decorate = compose(
  EventEmitter,
);

export class ActionRegistry extends decorate(class {}) {

  constructor() {
    super();
    this.actionKeys = new Map();
    this.keyActions = {};
    this.normalizer = undefined;
    this._actionIds = {};
    this._stream = [];
    this._actionTransformers = {};
  }

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

  drain() {
    const stream = this._stream;
    this._stream = [];
    return stream;
  }

  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.actionKeys[action];
  }

  mapKeysToActions(map) {
    for (const action in map) {
      const key = map[action];
      this.keyActions[key] = action;
      this.actionKeys[action] = key;
    }
  }

  onKeyDown(key) {
    if (this.keyActions[key]) {
      const action = this.keyActions[key];
      let value;
      if (this._actionTransformers[action]) {
        value = this._actionTransformers[action]('keyDown');
      }
      else {
        value = 1;
      }
      this._stream.push({action, value});
    }
  }

  onKeyUp(key) {
    if (this.keyActions[key]) {
      const action = this.keyActions[key];
      let value;
      if (this._actionTransformers[action]) {
        value = this._actionTransformers[action]('keyUp');
      }
      else {
        value = 0;
      }
      this._stream.push({action, value});
    }
  }

  setActionTransformerFor(action, transformer) {
    this._actionTransformers[action] = transformer;
  }

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

}