/**
 * Handles the showing of speaker notes
 */
export default class Notes {
  constructor(Reveal) {
    this.Reveal = Reveal;
  }

  render() {
    this.element = document.createElement("div");
    this.element.className = "speaker-notes";
    this.element.setAttribute("data-prevent-swipe", "");
    this.element.setAttribute("tabindex", "0");
    this.Reveal.getRevealElement().appendChild(this.element);
  }

  /**
   * Called when the reveal.js config is updated.
   */
  configure(config, oldConfig) {
    if (config.showNotes) {
      this.element.setAttribute(
        "data-layout",
        typeof config.showNotes === "string" ? config.showNotes : "inline"
      );
    }
  }

  /**
   * Pick up notes from the current slide and display them
   * to the viewer.
   *
   * @see {@link config.showNotes}
   */
  update() {
    if (
      this.Reveal.getConfig().showNotes &&
      this.element &&
      this.Reveal.getCurrentSlide() &&
      !this.Reveal.print.isPrintingPDF()
    ) {
      this.element.innerHTML =
        this.getSlideNotes() ||
        '<span class="notes-placeholder">No notes on this slide.</span>';
    }
  }

  /**
   * Updates the visibility of the speaker notes sidebar that
   * is used to share annotated slides. The notes sidebar is
   * only visible if showNotes is true and there are notes on
   * one or more slides in the deck.
   */
  updateVisibility() {
    if (
      this.Reveal.getConfig().showNotes &&
      this.hasNotes() &&
      !this.Reveal.print.isPrintingPDF()
    ) {
      this.Reveal.getRevealElement().classList.add("show-notes");
    } else {
      this.Reveal.getRevealElement().classList.remove("show-notes");
    }
  }

  /**
   * Checks if there are speaker notes for ANY slide in the
   * presentation.
   */
  hasNotes() {
    return (
      this.Reveal.getSlidesElement().querySelectorAll(
        "[data-notes], aside.notes"
      ).length > 0
    );
  }

  /**
   * Checks if this presentation is running inside of the
   * speaker notes window.
   *
   * @return {boolean}
   */
  isSpeakerNotesWindow() {
    return !!window.location.search.match(/receiver/gi);
  }

  /**
   * Retrieves the speaker notes from a slide. Notes can be
   * defined in two ways:
   * 1. As a data-notes attribute on the slide <section>
   * 2. With <aside class="notes"> elements inside the slide
   *
   * @param {HTMLElement} [slide=currentSlide]
   * @return {(string|null)}
   */
  getSlideNotes(slide = this.Reveal.getCurrentSlide()) {
    // Notes can be specified via the data-notes attribute...
    if (slide.hasAttribute("data-notes")) {
      return slide.getAttribute("data-notes");
    }

    // ... or using <aside class="notes"> elements
    let notesElements = slide.querySelectorAll("aside.notes");
    if (notesElements) {
      return Array.from(notesElements)
        .map((notesElement) => notesElement.innerHTML)
        .join("\n");
    }

    return null;
  }

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