/**
 * @file Move windows on mouse drag.
 *
 * @licstart The following is the entire license notice for the JavaScript code
 * in this page.
 *
 * Copyright (C) 2026 Madison L.
 *
 * The JavaScript code in this page is free software: you can redistribute it
 * and/or modify it under the terms of the GNU General Public License (GNU GPL)
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version. The code is distributed
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you may
 * distribute non-source (e.g., minimized or compacted) forms of that code
 * without the copy of the GNU GPL normally required by section 4, provided you
 * include this license notice and a URL through which recipients can access the
 * Corresponding Source.
 *
 * @licend The above is the entire license notice for the JavaScript code in
 * this page.
 */

// TODO: Rewrite to support more than one window per page.

const subwindow = document.getElementById("window");
const titlebar = document.getElementById("window-titlebar");

let dragging = false;
let prevPosX;
let prevPosY;

titlebar.addEventListener("mousedown", (event) => {
    dragging = true;
    prevPosX = event.clientX;
    prevPosY = event.clientY;
});

window.addEventListener("mousemove", (event) => {
    if (!dragging)
        return;
    const newPosX = subwindow.offsetLeft - (prevPosX - event.clientX);
    const newPosY = subwindow.offsetTop  - (prevPosY - event.clientY);
    subwindow.style.left = newPosX + "px";
    subwindow.style.top  = newPosY + "px";
    prevPosX = event.clientX;
    prevPosY = event.clientY;
});

window.addEventListener("mouseup", (_event) => {
    dragging = false;
});