import { System } from '@serpentity/serpentity';

import ControllableNode from '../nodes/controllable';

const internals = {
  gamepadState: {
  },
  keyboardState: {
  }
};

/**
 * Updates control status based on the controller map
 *
 * @extends {external:Serpentity.System}
 * @class ControlMapperSystem
 * @param {object} config a configuration object to extend.
 */
export default class ControlMapperSystem extends System {

  constructor(config = {}) {

    super();

    /**
     * The node collection of controllable entities
     *
     * @property {external:Serpentity.NodeCollection} controllables
     * @instance
     * @memberof RenderSystem
     */
    this.controllables = null;

    this._initializeKeyboard();
    this._initializeGamepad();
  }

  /**
   * Initializes system when added. Requests controllable nodes.
   *
   * @function added
   * @memberof RenderSystem
   * @instance
   * @param {external:Serpentity.Engine} engine the serpentity engine to
   * which we are getting added
   */
  added(engine) {

    this.controllables = engine.getNodes(ControllableNode);
  }

  /**
   * Clears system resources when removed.
   *
   * @function removed
   * @instance
   * @memberof RenderSystem
   */
  removed() {

    this.controllables = null;
  }

  /**
   * Runs on every update of the loop. Maps the actions given the current state of the inputs
   *
   * @function update
   * @instance
   * @param {Number} currentFrameDuration the duration of the current
   * frame
   * @memberof RenderSystem
   */
  update(currentFrameDuration) {

    this._updateGamepads();

    for (const controllable of this.controllables) {
      for (const map of controllable.controlMap.map) {
        if (map.source.type === 'keyboard') {
          this._setValue(controllable.entity, map.target, !!internals.keyboardState[map.source.index]);
        }

        if (map.source.type === 'gamepad') {
          const gamepad = internals.gamepadState[map.source.gamepadNumber];
          if (gamepad) {
            const source = gamepad[map.source.gamepadInputSource];
            source && this._setValue(controllable.entity, map.target, source[map.source.index]);
          }
        }
      }
    }
  }

  // Listens to keyboard to update internal map

  _initializeKeyboard() {

    window.addEventListener('keydown', (event) => {

      internals.keyboardState[event.keyCode] = true;
    });

    window.addEventListener('keyup', (event) => {

      internals.keyboardState[event.keyCode] = false;
    });
  }

  // Requests gamepad access and binds to the events

  _initializeGamepad() {

    window.addEventListener('gamepadconnected', (event) => {

      internals.gamepadState[event.gamepad.index] = event.gamepad;
      window.gamepad = event.gamepad;
    });

    window.addEventListener('gamepaddisconnected', (event) => {

      delete internals.gamepadState[event.gamepad.index];
    });
  }

  // Update Gamepad

  _updateGamepads() {

    const gamepads = navigator.getGamepads();
    for (const index of Object.keys(internals.gamepadState)) {
      internals.gamepadState[index] = gamepads[index];
    }
  }

  // Sets the value to a target

  _setValue(entity, target, value) {

    const component = entity.getComponent(target.component);

    if (component) {
      const keyFragments = target.property.split('.');
      let currentObject = component;
      for (const keyFragment of keyFragments.slice(0, keyFragments.length - 1)) {
        currentObject = currentObject[keyFragment] = currentObject[keyFragment] || {};
      }


      const finalValue = !!target.value ? target.value(value) : value;
      const finalProperty = keyFragments.pop();
      currentObject[finalProperty] += finalValue;
    }
  }
}