import { queryAll } from "../utils/util.js";
import { isAndroid } from "../utils/device.js";

/**
 * Manages our presentation controls. This includes both
 * the built-in control arrows as well as event monitoring
 * of any elements within the presentation with either of the
 * following helper classes:
 * - .navigate-up
 * - .navigate-right
 * - .navigate-down
 * - .navigate-left
 * - .navigate-next
 * - .navigate-prev
 */
export default class Controls {
  constructor(Reveal) {
    this.Reveal = Reveal;

    this.onNavigateLeftClicked = this.onNavigateLeftClicked.bind(this);
    this.onNavigateRightClicked = this.onNavigateRightClicked.bind(this);
    this.onNavigateUpClicked = this.onNavigateUpClicked.bind(this);
    this.onNavigateDownClicked = this.onNavigateDownClicked.bind(this);
    this.onNavigatePrevClicked = this.onNavigatePrevClicked.bind(this);
    this.onNavigateNextClicked = this.onNavigateNextClicked.bind(this);
  }

  render() {
    const rtl = this.Reveal.getConfig().rtl;
    const revealElement = this.Reveal.getRevealElement();

    this.element = document.createElement("aside");
    this.element.className = "controls";
    this.element.innerHTML = `<button class="navigate-left" aria-label="${
      rtl ? "next slide" : "previous slide"
    }"><div class="controls-arrow"></div></button>
			<button class="navigate-right" aria-label="${
        rtl ? "previous slide" : "next slide"
      }"><div class="controls-arrow"></div></button>
			<button class="navigate-up" aria-label="above slide"><div class="controls-arrow"></div></button>
			<button class="navigate-down" aria-label="below slide"><div class="controls-arrow"></div></button>`;

    this.Reveal.getRevealElement().appendChild(this.element);

    // There can be multiple instances of controls throughout the page
    this.controlsLeft = queryAll(revealElement, ".navigate-left");
    this.controlsRight = queryAll(revealElement, ".navigate-right");
    this.controlsUp = queryAll(revealElement, ".navigate-up");
    this.controlsDown = queryAll(revealElement, ".navigate-down");
    this.controlsPrev = queryAll(revealElement, ".navigate-prev");
    this.controlsNext = queryAll(revealElement, ".navigate-next");

    // The left, right and down arrows in the standard reveal.js controls
    this.controlsRightArrow = this.element.querySelector(".navigate-right");
    this.controlsLeftArrow = this.element.querySelector(".navigate-left");
    this.controlsDownArrow = this.element.querySelector(".navigate-down");
  }

  /**
   * Called when the reveal.js config is updated.
   */
  configure(config, oldConfig) {
    this.element.style.display = config.controls ? "block" : "none";

    this.element.setAttribute("data-controls-layout", config.controlsLayout);
    this.element.setAttribute(
      "data-controls-back-arrows",
      config.controlsBackArrows
    );
  }

  bind() {
    // Listen to both touch and click events, in case the device
    // supports both
    let pointerEvents = ["touchstart", "click"];

    // Only support touch for Android, fixes double navigations in
    // stock browser
    if (isAndroid) {
      pointerEvents = ["touchstart"];
    }

    pointerEvents.forEach((eventName) => {
      this.controlsLeft.forEach((el) =>
        el.addEventListener(eventName, this.onNavigateLeftClicked, false)
      );
      this.controlsRight.forEach((el) =>
        el.addEventListener(eventName, this.onNavigateRightClicked, false)
      );
      this.controlsUp.forEach((el) =>
        el.addEventListener(eventName, this.onNavigateUpClicked, false)
      );
      this.controlsDown.forEach((el) =>
        el.addEventListener(eventName, this.onNavigateDownClicked, false)
      );
      this.controlsPrev.forEach((el) =>
        el.addEventListener(eventName, this.onNavigatePrevClicked, false)
      );
      this.controlsNext.forEach((el) =>
        el.addEventListener(eventName, this.onNavigateNextClicked, false)
      );
    });
  }

  unbind() {
    ["touchstart", "click"].forEach((eventName) => {
      this.controlsLeft.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigateLeftClicked, false)
      );
      this.controlsRight.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigateRightClicked, false)
      );
      this.controlsUp.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigateUpClicked, false)
      );
      this.controlsDown.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigateDownClicked, false)
      );
      this.controlsPrev.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigatePrevClicked, false)
      );
      this.controlsNext.forEach((el) =>
        el.removeEventListener(eventName, this.onNavigateNextClicked, false)
      );
    });
  }

  /**
   * Updates the state of all control/navigation arrows.
   */
  update() {
    let routes = this.Reveal.availableRoutes();

    // Remove the 'enabled' class from all directions
    [
      ...this.controlsLeft,
      ...this.controlsRight,
      ...this.controlsUp,
      ...this.controlsDown,
      ...this.controlsPrev,
      ...this.controlsNext,
    ].forEach((node) => {
      node.classList.remove("enabled", "fragmented");

      // Set 'disabled' attribute on all directions
      node.setAttribute("disabled", "disabled");
    });

    // Add the 'enabled' class to the available routes; remove 'disabled' attribute to enable buttons
    if (routes.left)
      this.controlsLeft.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });
    if (routes.right)
      this.controlsRight.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });
    if (routes.up)
      this.controlsUp.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });
    if (routes.down)
      this.controlsDown.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });

    // Prev/next buttons
    if (routes.left || routes.up)
      this.controlsPrev.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });
    if (routes.right || routes.down)
      this.controlsNext.forEach((el) => {
        el.classList.add("enabled");
        el.removeAttribute("disabled");
      });

    // Highlight fragment directions
    let currentSlide = this.Reveal.getCurrentSlide();
    if (currentSlide) {
      let fragmentsRoutes = this.Reveal.fragments.availableRoutes();

      // Always apply fragment decorator to prev/next buttons
      if (fragmentsRoutes.prev)
        this.controlsPrev.forEach((el) => {
          el.classList.add("fragmented", "enabled");
          el.removeAttribute("disabled");
        });
      if (fragmentsRoutes.next)
        this.controlsNext.forEach((el) => {
          el.classList.add("fragmented", "enabled");
          el.removeAttribute("disabled");
        });

      // Apply fragment decorators to directional buttons based on
      // what slide axis they are in
      if (this.Reveal.isVerticalSlide(currentSlide)) {
        if (fragmentsRoutes.prev)
          this.controlsUp.forEach((el) => {
            el.classList.add("fragmented", "enabled");
            el.removeAttribute("disabled");
          });
        if (fragmentsRoutes.next)
          this.controlsDown.forEach((el) => {
            el.classList.add("fragmented", "enabled");
            el.removeAttribute("disabled");
          });
      } else {
        if (fragmentsRoutes.prev)
          this.controlsLeft.forEach((el) => {
            el.classList.add("fragmented", "enabled");
            el.removeAttribute("disabled");
          });
        if (fragmentsRoutes.next)
          this.controlsRight.forEach((el) => {
            el.classList.add("fragmented", "enabled");
            el.removeAttribute("disabled");
          });
      }
    }

    if (this.Reveal.getConfig().controlsTutorial) {
      let indices = this.Reveal.getIndices();

      // Highlight control arrows with an animation to ensure
      // that the viewer knows how to navigate
      if (!this.Reveal.hasNavigatedVertically() && routes.down) {
        this.controlsDownArrow.classList.add("highlight");
      } else {
        this.controlsDownArrow.classList.remove("highlight");

        if (this.Reveal.getConfig().rtl) {
          if (
            !this.Reveal.hasNavigatedHorizontally() &&
            routes.left &&
            indices.v === 0
          ) {
            this.controlsLeftArrow.classList.add("highlight");
          } else {
            this.controlsLeftArrow.classList.remove("highlight");
          }
        } else {
          if (
            !this.Reveal.hasNavigatedHorizontally() &&
            routes.right &&
            indices.v === 0
          ) {
            this.controlsRightArrow.classList.add("highlight");
          } else {
            this.controlsRightArrow.classList.remove("highlight");
          }
        }
      }
    }
  }

  destroy() {
    this.unbind();
    this.element.remove();
  }

  /**
   * Event handlers for navigation control buttons.
   */
  onNavigateLeftClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    if (this.Reveal.getConfig().navigationMode === "linear") {
      this.Reveal.prev();
    } else {
      this.Reveal.left();
    }
  }

  onNavigateRightClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    if (this.Reveal.getConfig().navigationMode === "linear") {
      this.Reveal.next();
    } else {
      this.Reveal.right();
    }
  }

  onNavigateUpClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    this.Reveal.up();
  }

  onNavigateDownClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    this.Reveal.down();
  }

  onNavigatePrevClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    this.Reveal.prev();
  }

  onNavigateNextClicked(event) {
    event.preventDefault();
    this.Reveal.onUserInput();

    this.Reveal.next();
  }
}