display.js

// Microsoft ATP Safe Links Cleaner
// Copyright 2021 David Byers <david.byers@liu.se>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

// Display script


let currentPopupTarget = null;
let hidePopupTimeout = null;


/**
 * Return the popup div element, creating it if necessary.
 * @returns {Element} The popup element.
 */
function getPopup() {
    let popup = document.getElementById(safelinksPopupId);
    if (!popup) {
	popupElementLocked = false;
	popup = document.createElement('div');
	popup.id = safelinksPopupId;
	popup.addEventListener('mouseenter', cancelHidePopup, {passive: true});
	popup.addEventListener('mouseleave', scheduleHidePopup, {passive: true});
	document.body.appendChild(popup);
    }
    return popup;
}


/**
 * Cancel hiding the popup (if it has been scheduled) and set
 * hidePopupTimeout to null.
 */
function cancelHidePopup() {
    if (hidePopupTimeout) {
	clearTimeout(hidePopupTimeout);
	hidePopupTimeout = null;
    }
}


/**
 * Hide the current popup. If there is no popup, one will be created.
 */
function hidePopup() {
    cancelHidePopup();
    getPopup().classList.remove(safelinksPopupVisibleClass);
    currentPopupTarget = undefined;
}


/**
 * Schedule hiding the current popup.
 */
function scheduleHidePopup() {
    if (!hidePopupTimeout) {
	hidePopupTimeout = setTimeout(hidePopup, 100);
    }
}


/**
 * Get the absolute bounds of an element.
 * @param {Element} elem - The element for which to return bounds.
 * @returns {{top: number, left: number, right: number, bottom:
 *   number}} The top, left, right, and bottom coordinates of the
 *   element.
 */
function getAbsoluteBoundingRect(elem) {
    let rect = elem.getBoundingClientRect();
    let scrollLeft = window.scrollX;
    let scrollTop = window.scrollY;
    return {
	top: rect.top + window.scrollY,
	left: rect.left + window.scrollX,
	bottom: rect.bottom + window.scrollY,
	right: rect.right + window.scrollX,
    }
}

/**
 * Attempt to ensure that at least part of an element is visible. If
 * the element's right-hand coordinate is off-screen, move it
 * on-screen without moving the left-hand side off-screen. If the
 * bottom of the element is off-screen, move it on-screen.
 * @param {Element} elem - The element to show.
 */
function clampElementToDocument(elem) {
    let elemBounds = getAbsoluteBoundingRect(elem);

    if (elemBounds.bottom > document.documentElement.scrollHeight) {
	elem.style.removeProperty('top');
	elem.style.bottom = 0;
    }

    if (elemBounds.right > document.documentElement.scrollWidth) {
	elem.style.removeProperty('left');
	elem.style.right = 0;
	if (getAbsoluteBoundingRect(elem).left < 0) {
	    elem.style.left = 0;
	}
    }
}

/**
 * Show the original URL of a link.
 * @param {MouseEvent} event - The event triggering this handler.
 */
function showOriginalUrl(event) {
    let popup = getPopup();
    cancelHidePopup();
    if (event.target != currentPopupTarget || !popup.classList.contains(safelinksPopupVisibleClass)) {
	currentPopupTarget = event.target;
	popup.textContent = untangleLink(event.target.href);
	popup.style.removeProperty('bottom');
	popup.style.removeProperty('right');
	popup.style.left = event.clientX;
	popup.style.top = event.clientY;
	popup.classList.add(safelinksPopupVisibleClass);
	//clampElementToDocument(popup);
    }
}

/**
 * Add event handlers to a link so it will show the original url.
 * @param {Element} link - The link to add the popup to.
 */
function addLinkPopup(link) {
    link.addEventListener('mouseenter', showOriginalUrl, {passive: true});
    link.addEventListener('mouseleave', scheduleHidePopup, {passive: true});
}


for (const link of document.links) {
    // Untangle link text
    for (const node of getTextNodes(link)) {
	node.textContent = untangleLink(node.textContent);
    }

    // Create popup event handlers
    if (isTangledLink(link.href)) {
	addLinkPopup(link);
    }
}