/**
 * @module ol/interaction/KeyboardZoom
 */
import {inherits} from '../index.js';
import EventType from '../events/EventType.js';
import {targetNotEditable} from '../events/condition.js';
import Interaction, {zoomByDelta} from '../interaction/Interaction.js';


/**
 * @typedef {Object} Options
 * @property {number} [duration=100] Animation duration in milliseconds.
 * @property {module:ol/events/condition~Condition} [condition] A function that
 * takes an {@link module:ol/MapBrowserEvent~MapBrowserEvent} and returns a
 * boolean to indicate whether that event should be handled. Default is
 * {@link module:ol/events/condition~targetNotEditable}.
 * @property {number} [delta=1] The zoom level delta on each key press.
 */


/**
 * @classdesc
 * Allows the user to zoom the map using keyboard + and -.
 * Note that, although this interaction is by default included in maps,
 * the keys can only be used when browser focus is on the element to which
 * the keyboard events are attached. By default, this is the map div,
 * though you can change this with the `keyboardEventTarget` in
 * {@link module:ol/Map~Map}. `document` never loses focus but, for any other
 * element, focus will have to be on, and returned to, this element if the keys
 * are to function.
 * See also {@link moudle:ol/interaction/KeyboardPan~KeyboardPan}.
 *
 * @constructor
 * @param {module:ol/interaction/KeyboardZoom~Options=} opt_options Options.
 * @extends {module:ol/interaction/Interaction~Interaction}
 * @api
 */
const KeyboardZoom = function(opt_options) {

  Interaction.call(this, {
    handleEvent: handleEvent
  });

  const options = opt_options ? opt_options : {};

  /**
   * @private
   * @type {module:ol/events/condition~Condition}
   */
  this.condition_ = options.condition ? options.condition : targetNotEditable;

  /**
   * @private
   * @type {number}
   */
  this.delta_ = options.delta ? options.delta : 1;

  /**
   * @private
   * @type {number}
   */
  this.duration_ = options.duration !== undefined ? options.duration : 100;

};

inherits(KeyboardZoom, Interaction);


/**
 * Handles the {@link module:ol/MapBrowserEvent~MapBrowserEvent map browser event} if it was a
 * `KeyEvent`, and decides whether to zoom in or out (depending on whether the
 * key pressed was '+' or '-').
 * @param {module:ol/MapBrowserEvent~MapBrowserEvent} mapBrowserEvent Map browser event.
 * @return {boolean} `false` to stop event propagation.
 * @this {module:ol/interaction/KeyboardZoom~KeyboardZoom}
 */
function handleEvent(mapBrowserEvent) {
  let stopEvent = false;
  if (mapBrowserEvent.type == EventType.KEYDOWN ||
      mapBrowserEvent.type == EventType.KEYPRESS) {
    const keyEvent = mapBrowserEvent.originalEvent;
    const charCode = keyEvent.charCode;
    if (this.condition_(mapBrowserEvent) &&
        (charCode == '+'.charCodeAt(0) || charCode == '-'.charCodeAt(0))) {
      const map = mapBrowserEvent.map;
      const delta = (charCode == '+'.charCodeAt(0)) ? this.delta_ : -this.delta_;
      const view = map.getView();
      zoomByDelta(view, delta, undefined, this.duration_);
      mapBrowserEvent.preventDefault();
      stopEvent = true;
    }
  }
  return !stopEvent;
}

export default KeyboardZoom;