/*
 * Beamer Viewer, a web-based PDF presentation viewer
 * Copyright 2018-2024 Pacien TRAN-GIRARD
 * SPDX-License-Identifier: EUPL-1.2
 */

"use strict";

class ActionEventHandler {
  constructor(onNext, onPrevious) {
    this.onNext = onNext;
    this.onPrevious = onPrevious;
  }
}

class KeyboardEventHandler extends ActionEventHandler {
  register(window) {
    window.addEventListener("keydown", event => this._onCommand(event));
  }

  _onCommand(keyboardEvent) {
    switch (keyboardEvent.key) {
      case "Enter":
      case " ":
      case "ArrowRight":
      case "ArrowDown":
      case "PageDown":
      case "n":
        return this.onNext();

      case "ArrowLeft":
      case "ArrowUp":
      case "PageUp":
      case "p":
        return this.onPrevious();
    }
  }
}

class MouseClickEventHandler extends ActionEventHandler {
  register(window) {
    window.addEventListener("click", event => this._onCommand(event));
  }

  _onCommand(mouseEvent) {
    this.onNext();
  }
}

class TouchSwipeEventHandler extends ActionEventHandler {
  constructor(onNext, onPrevious) {
    super(onNext, onPrevious);
    this.touchStartEvent = null;
    this.touchMoveEvent = null;
  }

  register(window) {
    window.addEventListener("touchstart", event => {
      event.preventDefault();
      this._onTouchStart(event);
    });

    window.addEventListener("touchmove", event => {
      event.preventDefault();
      this._onTouchMove(event);
    });

    window.addEventListener("touchend", event => {
      event.preventDefault();
      this._onTouchEnd();
    });

    window.addEventListener("touchcancel", event => {
      event.preventDefault();
    });
  }

  _onTouchStart(touchEvent) {
    this.touchStartEvent = touchEvent;
  }

  _onTouchMove(touchEvent) {
    this.touchMoveEvent = touchEvent;
  }

  _onTouchEnd() {
    if (this.touchStartEvent == null || this.touchMoveEvent == null) return;

    const touchDown = this._xCoordinate(this.touchStartEvent);
    const touchUp = this._xCoordinate(this.touchMoveEvent);
    const xDelta = touchDown - touchUp;

    if (xDelta > 0)
      this.onNext();
    else if (xDelta < 0)
      this.onPrevious();
    
    this.touchStartEvent = null;
    this.touchMoveEvent = null;
  }

  _xCoordinate(touchEvent) {
    return touchEvent.touches[0].clientX; // first finger
  }
}