let active_overlay;
let close_handler;
let open_overlay_name;

function reset_state() {
    active_overlay = undefined;
    close_handler = undefined;
    open_overlay_name = undefined;
}

exports.is_active = function () {
    return !!open_overlay_name;
};

exports.is_modal_open = function () {
    return $(".modal").hasClass("in");
};

exports.info_overlay_open = function () {
    return open_overlay_name === 'informationalOverlays';
};

exports.settings_open = function () {
    return open_overlay_name === 'settings';
};

exports.streams_open = function () {
    return open_overlay_name === 'subscriptions';
};

exports.lightbox_open = function () {
    return open_overlay_name === 'lightbox';
};

exports.drafts_open = function () {
    return open_overlay_name === 'drafts';
};

// To address bugs where mouse might apply to the streams/settings
// overlays underneath an open modal within those settings UI, we add
// this inline style to '.overlay.show', overriding the
// "pointer-events: all" style in app_components.scss.
//
// This is kinda hacky; it only works for modals within overlays, and
// we need to make sure it gets re-enabled when the modal closes.
exports.disable_background_mouse_events = function () {
    $('.overlay.show').attr("style", "pointer-events: none");
};

// This removes only the inline-style of the element that
// was added in disable_background_mouse_events and
// enables the background mouse events.
exports.enable_background_mouse_events = function () {
    $('.overlay.show').attr("style", null);
};

exports.active_modal = function () {
    if (!exports.is_modal_open()) {
        blueslip.error("Programming error — Called active_modal when there is no modal open");
        return;
    }
    return '#' + $(".modal.in").attr("id");
};

exports.open_overlay = function (opts) {
    popovers.hide_all();

    if (!opts.name || !opts.overlay || !opts.on_close) {
        blueslip.error('Programming error in open_overlay');
        return;
    }

    if (active_overlay || open_overlay_name || close_handler) {
        blueslip.error('Programming error — trying to open ' + opts.name +
            ' before closing ' + open_overlay_name);
        return;
    }

    blueslip.debug('open overlay: ' + opts.name);

    // Our overlays are kind of crufty...we have an HTML id
    // attribute for them and then a data-overlay attribute for
    // them.  Make sure they match.
    if (opts.overlay.attr('data-overlay') !== opts.name) {
        blueslip.error('Bad overlay setup for ' + opts.name);
        return;
    }

    open_overlay_name = opts.name;
    active_overlay = opts.overlay;
    opts.overlay.addClass('show');

    opts.overlay.attr("aria-hidden", "false");
    $('.app').attr("aria-hidden", "true");
    $('.fixed-app').attr("aria-hidden", "true");
    $('.header').attr("aria-hidden", "true");

    close_handler = function () {
        opts.on_close();
        reset_state();
    };
};

exports.open_modal = function (selector) {
    if (selector === undefined) {
        blueslip.error('Undefined selector was passed into open_modal');
        return;
    }

    if (selector[0] !== '#') {
        blueslip.error('Non-id-based selector passed in to open_modal: ' + selector);
        return;
    }

    if (exports.is_modal_open()) {
        blueslip.error('open_modal() was called while ' + exports.active_modal() +
            ' modal was open.');
        return;
    }

    blueslip.debug('open modal: ' + selector);

    const elem = $(selector).expectOne();
    elem.modal("show").attr("aria-hidden", false);
    // Disable background mouse events when modal is active
    exports.disable_background_mouse_events();
    // Remove previous alert messages from modal, if exists.
    elem.find(".alert").hide();
    elem.find(".alert-notification").html("");
};

exports.close_overlay = function (name) {
    if (name !== open_overlay_name) {
        blueslip.error("Trying to close " + name + " when " + open_overlay_name + " is open.");
        return;
    }

    if (name === undefined) {
        blueslip.error('Undefined name was passed into close_overlay');
        return;
    }

    blueslip.debug('close overlay: ' + name);

    active_overlay.removeClass("show");

    active_overlay.attr("aria-hidden", "true");
    $('.app').attr("aria-hidden", "false");
    $('.fixed-app').attr("aria-hidden", "false");
    $('.header').attr("aria-hidden", "false");

    if (!close_handler) {
        blueslip.error("Overlay close handler for " + name + " not properly setup.");
        return;
    }

    close_handler();
};

exports.close_active = function () {
    if (!open_overlay_name) {
        blueslip.warn('close_active() called without checking is_active()');
        return;
    }

    exports.close_overlay(open_overlay_name);
};

exports.close_modal = function (selector) {
    if (selector === undefined) {
        blueslip.error('Undefined selector was passed into close_modal');
        return;
    }

    if (!exports.is_modal_open()) {
        blueslip.warn('close_active_modal() called without checking is_modal_open()');
        return;
    }

    if (exports.active_modal() !== selector) {
        blueslip.error("Trying to close " + selector +
            " modal when " + exports.active_modal() + " is open.");
        return;
    }

    blueslip.debug('close modal: ' + selector);

    const elem = $(selector).expectOne();
    elem.modal("hide").attr("aria-hidden", true);
    // Enable mouse events for the background as the modal closes.
    exports.enable_background_mouse_events();

};

exports.close_active_modal = function () {
    if (!exports.is_modal_open()) {
        blueslip.warn('close_active_modal() called without checking is_modal_open()');
        return;
    }

    $(".modal.in").modal("hide").attr("aria-hidden", true);
};

exports.close_for_hash_change = function () {
    $(".overlay.show").removeClass("show");
    reset_state();
};

exports.open_settings = function () {
    exports.open_overlay({
        name: 'settings',
        overlay: $("#settings_overlay_container"),
        on_close: function () {
            hashchange.exit_overlay();
        },
    });
};

exports.initialize = function () {
    $("body").on("click", ".overlay, .overlay .exit", function (e) {
        let $target = $(e.target);

        // if the target is not the .overlay element, search up the node tree
        // until it is found.
        if ($target.is(".exit, .exit-sign, .overlay-content, .exit span")) {
            $target = $target.closest("[data-overlay]");
        } else if (!$target.is(".overlay")) {
            // not a valid click target then.
            return;
        }

        const target_name = $target.attr("data-overlay");

        exports.close_overlay(target_name);

        e.preventDefault();
        e.stopPropagation();
    });
};

window.overlays = exports;