function isTouchDevice() {
  return (
    "ontouchstart" in window ||
    navigator.maxTouchPoints > 0 ||
    navigator.msMaxTouchPoints > 0
  );
}

class WindowObject {
  windowObject;

  windowManager;
  windowManagerLabel;
  windowContent;

  #orig_mousePosX;
  #orig_mousePosY;
  #orig_selfPosX;
  #orig_selfPosY;
  #isDragging;

  constructor(parent, content, srcdoc, w, h) {
    this.parentElement = parent;
    this.windowObject = WindowObject.createWindow(this, content, srcdoc, w, h);
    this.parentElement.appendChild(this.windowObject);

    WindowObject.raiseWindow(this.windowObject);

    if (isTouchDevice()) this.maximizeWindow();

    this.windowManager = this.windowObject.querySelector(".window-manager");
    this.windowManagerLabel = this.windowObject.querySelector(
      ".window-manager-label"
    );
    this.windowContent = this.windowObject.querySelector(".window-content");

    this.windowManager.addEventListener("mousedown", (e) =>
      this.event__dragMouseDown(e)
    );
    this.windowManager.addEventListener("mousemove", (e) =>
      this.event__dragMouseMove(e)
    );
    this.windowManager.addEventListener("mouseup", (e) =>
      this.event__dragMouseUp(e)
    );
    this.windowManager.addEventListener("mouseout", (e) =>
      this.event__dragMouseMove(e)
    );
    this.windowManager.addEventListener("touchstart", (e) =>
      this.event__dragMouseDown(e, true)
    );
    this.windowManager.addEventListener("touchmove", (e) =>
      this.event__dragMouseMove(e, true)
    );
    this.windowManager.addEventListener("touchend", (e) =>
      this.event__dragMouseUp(e, true)
    );

    this.windowObject.addEventListener("mousedown", (e) =>
      WindowObject.raiseWindow(this.windowObject)
    );

    this.windowContent.contentWindow.addEventListener("mousedown", (e) =>
      WindowObject.raiseWindow(this.windowObject)
    );

    window.addEventListener("beforeunload", () => this.destroy());

    this.windowContent.addEventListener("load", () => {
      this.title = this.windowContent.contentWindow.document.title;
      if (!srcdoc) {
        const nb = this.windowManager.querySelector(".window-new-button");
        nb.addEventListener("click", () => {
          window.open(this.content);
        });
        nb.addEventListener("touchstart", (e) => e.stopPropagation());
        nb.addEventListener("touchend", (e) => e.stopPropagation());
      }
    });
  }

  get title() {
    return this.windowManagerLabel.textContent;
  }

  get content() {
    return this.windowContent.src;
  }

  set title(content) {
    this.windowManagerLabel.textContent = content;
  }

  set content(src) {
    this.windowContent.src = src;
  }

  minimizeWindow() {
    if (this.windowObject.classList.contains("minimized")) {
      this.windowObject.classList.remove("minimized");

      WindowObject.raiseWindow(this.windowObject);
    } else {
      this.windowObject.classList.add("minimized");
      this.windowObject.style.zIndex = 50;
    }
  }

  maximizeWindow() {
    this.windowObject.classList.toggle("maximized");

    WindowObject.raiseWindow(this.windowObject);
  }

  destroy() {
    if (this.windowContent.contentWindow != null) {
      const unloadEvent = new Event("beforeunload");
      this.windowContent.contentWindow.dispatchEvent(unloadEvent);
    }

    this.windowObject.classList.add("closed");
    setTimeout(() => {
      this.windowObject.remove();
      var someWindow = this.parentElement.querySelector(
        `.window-object:last-child`
      );
      if (someWindow != null) WindowObject.raiseWindow(someWindow);
    }, 250);
  }

  event__dragMouseDown(e, touch) {
    e.preventDefault();

    this.#orig_mousePosX = touch ? e.touches[0].clientX : e.clientX;
    this.#orig_mousePosY = touch ? e.touches[0].clientY : e.clientY;
    this.#orig_selfPosX = this.windowObject.offsetLeft;
    this.#orig_selfPosY = this.windowObject.offsetTop;
    this.windowContent.style.userSelect = "none";
    this.windowContent.style.pointerEvents = "none";
    this.windowManager.style.cursor = "move";
    this.#isDragging = true;
    if (this.windowObject.style.zIndex != 100)
      WindowObject.raiseWindow(this.windowObject);
  }

  event__dragMouseUp(e, touch) {
    e.preventDefault();

    this.#orig_mousePosX = 0;
    this.#orig_mousePosY = 0;
    this.windowContent.style.userSelect = "auto";
    this.windowContent.style.pointerEvents = "auto";
    this.windowManager.style.cursor = "default";
    this.#isDragging = false;
  }

  event__dragMouseMove(e, touch) {
    e.preventDefault();

    if (this.#isDragging) {
      var cX = touch ? e.touches[0].clientX : e.clientX;
      var cY = touch ? e.touches[0].clientY : e.clientY;
      this.windowObject.style.left =
        this.#orig_selfPosX - (this.#orig_mousePosX - cX) + "px";
      this.windowObject.style.top =
        this.#orig_selfPosY - (this.#orig_mousePosY - cY) + "px";
    }
  }

  static raiseWindow(windowObj) {
    windowObj.parentElement.querySelectorAll(".window-object").forEach((x) => {
      if (x.style.zIndex > 50) x.style.zIndex -= 1;
      x.classList.add("unfocused");
    });
    windowObj.style.zIndex = 100;
    windowObj.classList.remove("unfocused");
    windowObj.focus();
  }

  static createWindow(windowRef, content, srcdoc, w, h) {
    const windowObject = document.createElement("div");
    windowObject.classList.add("window-object");
    windowObject.style.width = `calc(${w}px + 1.5em)`;
    windowObject.style.height = `calc(${h}px + 3.5em)`;

    {
      const windowManager = document.createElement("div");
      windowManager.classList.add("window-manager");

      {
        const windowManagerStart = document.createElement("div");
        windowManagerStart.classList.add("window-manager-start");

        {
          const windowManagerLabel = document.createElement("span");
          windowManagerLabel.textContent = "";
          windowManagerLabel.classList.add("window-manager-label");

          windowManagerStart.appendChild(windowManagerLabel);
        }

        windowManager.appendChild(windowManagerStart);
      }

      {
        const windowManagerEnd = document.createElement("div");
        windowManagerEnd.classList.add("window-manager-end");

        if (!srcdoc) {
          const windowNewButton = document.createElement("button");
          windowNewButton.innerHTML = "open_in_new";
          windowNewButton.classList.add("window-new-button");

          windowManagerEnd.appendChild(windowNewButton);
        }

        {
          const windowMaximizeButton = document.createElement("button");
          windowMaximizeButton.innerHTML = "maximize";
          windowMaximizeButton.classList.add("window-maximize-button");
          windowMaximizeButton.ariaHidden = true; // esoteric operation to screen-reader users
          windowMaximizeButton.addEventListener("click", () =>
            windowRef.maximizeWindow()
          );
          windowMaximizeButton.addEventListener("touchstart", (e) =>
            e.stopPropagation()
          );
          windowMaximizeButton.addEventListener("touchend", (e) =>
            e.stopPropagation()
          );

          windowManagerEnd.appendChild(windowMaximizeButton);
        }

        {
          const windowDestroyButton = document.createElement("button");
          windowDestroyButton.innerHTML = "close";
          windowDestroyButton.classList.add("window-destroy-button");
          windowDestroyButton.ariaHidden = true;
          windowDestroyButton.addEventListener("click", () =>
            windowRef.destroy()
          );
          windowDestroyButton.addEventListener("touchstart", (e) =>
            e.stopPropagation()
          );
          windowDestroyButton.addEventListener("touchend", (e) =>
            e.stopPropagation()
          );

          windowManagerEnd.appendChild(windowDestroyButton);
        }

        windowManager.appendChild(windowManagerEnd);
      }

      windowObject.appendChild(windowManager);
    }

    {
      const windowContent = document.createElement("iframe");
      windowContent.classList.add("window-content");

      {
        if (srcdoc) windowContent.srcdoc = content;
        else windowContent.src = content;
      }

      windowObject.appendChild(windowContent);
    }

    return windowObject;
  }
}