zulip/web/src/ui_util.ts

import $ from "jquery";

import * as blueslip from "./blueslip";
import * as keydown_util from "./keydown_util";

// Add functions to this that have no non-trivial
// dependencies other than jQuery.

// https://stackoverflow.com/questions/4233265/contenteditable-set-caret-at-the-end-of-the-text-cross-browser
export function place_caret_at_end(el: HTMLElement): void {
    el.focus();
    if (el instanceof HTMLInputElement) {
        el.setSelectionRange(el.value.length, el.value.length);
    } else {
        const range = document.createRange();
        range.selectNodeContents(el);
        range.collapse(false);
        const sel = window.getSelection();
        sel?.removeAllRanges();
        sel?.addRange(range);
    }
}

export function replace_emoji_with_text($element: JQuery): void {
    $element.find(".emoji").replaceWith(function () {
        if ($(this).is("img")) {
            return $(this).attr("alt") ?? "";
        }
        return $(this).text();
    });
}

export function blur_active_element(): void {
    // this blurs anything that may perhaps be actively focused on.
    if (document.activeElement instanceof HTMLElement) {
        document.activeElement.blur();
    }
}

export function convert_enter_to_click(e: JQuery.KeyDownEvent): void {
    if (keydown_util.is_enter_event(e)) {
        e.preventDefault();
        e.stopPropagation();
        $(e.currentTarget).trigger("click");
    }
}

export function update_unread_count_in_dom($unread_count_elem: JQuery, count: number): void {
    // This function is used to update unread count in top left corner
    // elements.
    const $unread_count_span = $unread_count_elem.find(".unread_count");

    if (count === 0) {
        $unread_count_span.hide();
        $unread_count_span.text("");
        return;
    }

    $unread_count_span.show();
    $unread_count_span.text(count);
}

export function update_unread_mention_info_in_dom(
    $unread_mention_info_elem: JQuery,
    stream_has_any_unread_mention_messages: boolean,
): void {
    const $unread_mention_info_span = $unread_mention_info_elem.find(".unread_mention_info");
    if (!stream_has_any_unread_mention_messages) {
        $unread_mention_info_span.hide();
        $unread_mention_info_span.text("");
        return;
    }

    $unread_mention_info_span.show();
    $unread_mention_info_span.text("@");
}

/**
 * Parse HTML and return a DocumentFragment.
 *
 * Like any consumer of HTML, this function must only be given input
 * from trusted producers of safe HTML, such as auto-escaping
 * templates; violating this expectation will introduce bugs that are
 * likely to be security vulnerabilities.
 */
export function parse_html(html: string): DocumentFragment {
    const template = document.createElement("template");
    template.innerHTML = html;
    return template.content;
}

/*
 * Handle permission denied to play audio by the browser.
 * This can happen due to two reasons: user denied permission to play audio
 * unconditionally and browser denying permission to play audio without
 * any interactive trigger like a button. See
 * https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/play for more details.
 */
export async function play_audio(elem: HTMLVideoElement): Promise<void> {
    try {
        await elem.play();
    } catch (error) {
        if (!(error instanceof DOMException)) {
            throw error;
        }
        blueslip.debug(`Unable to play audio. ${error.name}: ${error.message}`);
    }
}

export function listener_for_preferred_color_scheme_change(callback: () => void): void {
    const media_query_list = window.matchMedia("(prefers-color-scheme: dark)");
    // MediaQueryList.addEventListener is missing in Safari < 14
    const listener: () => void = () => {
        if ($(":root").hasClass("color-scheme-automatic")) {
            callback();
        }
    };
    if ("addEventListener" in media_query_list) {
        media_query_list.addEventListener("change", listener);
    } else {
        (media_query_list as MediaQueryList).addListener(listener);
    }
}