function gradioApp() {
    const elems = document.getElementsByTagName('gradio-app');
    const elem = elems.length == 0 ? document : elems[0];

    if (elem !== document) {
        elem.getElementById = function(id) {
            return document.getElementById(id);
        };
    }
    return elem.shadowRoot ? elem.shadowRoot : elem;
}

/**
 * Get the currently selected top-level UI tab button (e.g. the button that says "Extras").
 */
function get_uiCurrentTab() {
    return gradioApp().querySelector('#tabs > .tab-nav > button.selected');
}

/**
 * Get the first currently visible top-level UI tab content (e.g. the div hosting the "txt2img" UI).
 */
function get_uiCurrentTabContent() {
    return gradioApp().querySelector('#tabs > .tabitem[id^=tab_]:not([style*="display: none"])');
}

var uiUpdateCallbacks = [];
var uiAfterUpdateCallbacks = [];
var uiLoadedCallbacks = [];
var uiTabChangeCallbacks = [];
var optionsChangedCallbacks = [];
var uiAfterUpdateTimeout = null;
var uiCurrentTab = null;

/**
 * Register callback to be called at each UI update.
 * The callback receives an array of MutationRecords as an argument.
 */
function onUiUpdate(callback) {
    uiUpdateCallbacks.push(callback);
}

/**
 * Register callback to be called soon after UI updates.
 * The callback receives no arguments.
 *
 * This is preferred over `onUiUpdate` if you don't need
 * access to the MutationRecords, as your function will
 * not be called quite as often.
 */
function onAfterUiUpdate(callback) {
    uiAfterUpdateCallbacks.push(callback);
}

/**
 * Register callback to be called when the UI is loaded.
 * The callback receives no arguments.
 */
function onUiLoaded(callback) {
    uiLoadedCallbacks.push(callback);
}

/**
 * Register callback to be called when the UI tab is changed.
 * The callback receives no arguments.
 */
function onUiTabChange(callback) {
    uiTabChangeCallbacks.push(callback);
}

/**
 * Register callback to be called when the options are changed.
 * The callback receives no arguments.
 * @param callback
 */
function onOptionsChanged(callback) {
    optionsChangedCallbacks.push(callback);
}

function executeCallbacks(queue, arg) {
    for (const callback of queue) {
        try {
            callback(arg);
        } catch (e) {
            console.error("error running callback", callback, ":", e);
        }
    }
}

/**
 * Schedule the execution of the callbacks registered with onAfterUiUpdate.
 * The callbacks are executed after a short while, unless another call to this function
 * is made before that time. IOW, the callbacks are executed only once, even
 * when there are multiple mutations observed.
 */
function scheduleAfterUiUpdateCallbacks() {
    clearTimeout(uiAfterUpdateTimeout);
    uiAfterUpdateTimeout = setTimeout(function() {
        executeCallbacks(uiAfterUpdateCallbacks);
    }, 200);
}

var executedOnLoaded = false;

document.addEventListener("DOMContentLoaded", function() {
    var mutationObserver = new MutationObserver(function(m) {
        if (!executedOnLoaded && gradioApp().querySelector('#txt2img_prompt')) {
            executedOnLoaded = true;
            executeCallbacks(uiLoadedCallbacks);
        }

        executeCallbacks(uiUpdateCallbacks, m);
        scheduleAfterUiUpdateCallbacks();
        const newTab = get_uiCurrentTab();
        if (newTab && (newTab !== uiCurrentTab)) {
            uiCurrentTab = newTab;
            executeCallbacks(uiTabChangeCallbacks);
        }
    });
    mutationObserver.observe(gradioApp(), {childList: true, subtree: true});
});

/**
 * Add a ctrl+enter as a shortcut to start a generation
 */
document.addEventListener('keydown', function(e) {
    var handled = false;
    if (e.key !== undefined) {
        if ((e.key == "Enter" && (e.metaKey || e.ctrlKey || e.altKey))) handled = true;
    } else if (e.keyCode !== undefined) {
        if ((e.keyCode == 13 && (e.metaKey || e.ctrlKey || e.altKey))) handled = true;
    }
    if (handled) {
        var button = get_uiCurrentTabContent().querySelector('button[id$=_generate]');
        if (button) {
            button.click();
        }
        e.preventDefault();
    }
});

/**
 * checks that a UI element is not in another hidden element or tab content
 */
function uiElementIsVisible(el) {
    if (el === document) {
        return true;
    }

    const computedStyle = getComputedStyle(el);
    const isVisible = computedStyle.display !== 'none';

    if (!isVisible) return false;
    return uiElementIsVisible(el.parentNode);
}

function uiElementInSight(el) {
    const clRect = el.getBoundingClientRect();
    const windowHeight = window.innerHeight;
    const isOnScreen = clRect.bottom > 0 && clRect.top < windowHeight;

    return isOnScreen;
}
