/*
 * This file is part of budgie-desktop
 * 
 * Copyright © 2015-2019 Budgie Desktop Developers
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

const string APPS_ID = "gnome-applications.menu";
const string LOGOUT_BINARY = "budgie-session-dialog";

/**
 * Return a string suitable for working on.
 * This works around the issue of GNOME Control Center and others deciding to
 * use soft hyphens in their .desktop files.
 */
static string? searchable_string(string input)
{
    /* Force dup in vala */
    string mod = "" + input;
    return mod.replace("\u00AD", "").ascii_down().strip();
}

public class BudgieMenuWindow : Budgie.Popover
{
    protected Gtk.SearchEntry search_entry;
    protected Gtk.Box categories;
    protected Gtk.ListBox content;
    private GMenu.Tree tree;
    private GMenu.TreeDirectory other_tree;
    private bool attempted_other_search = false;
    protected Gtk.ScrolledWindow categories_scroll;
    protected Gtk.ScrolledWindow content_scroll;
    protected CategoryButton all_categories;

    /* Mapped id -> button */
    protected HashTable<string,MenuButton?> menu_buttons = null;

    // The current group 
    protected GMenu.TreeDirectory? group = null;
    protected bool compact_mode;
    protected bool headers_visible;

    /* Whether we allow rollover category switch */
    protected bool rollover_menus = true;

    // Current search term
    protected string search_term = "";

    protected int icon_size = 24;

    public Settings settings { public get; public set; }

    private bool reloading = false;

    /* Reload menus, essentially. */
    public void refresh_tree()
    {
        lock (reloading) {
            if (reloading) {
                return;
            }
            reloading = true;
        }
        foreach (var child in content.get_children()) {
            child.destroy();
        }
        menu_buttons.remove_all();
        foreach (var child in categories.get_children()) {
            if (child != all_categories) {
                SignalHandler.disconnect_by_func(child, (void*)on_mouse_enter, this);
                child.destroy();
            }
        }
        SignalHandler.disconnect_by_func(tree, (void*)refresh_tree, this);
        this.tree = null;
        Idle.add(()=> { 
            load_menus(null);
            content.invalidate_headers();
            content.invalidate_filter();
            content.invalidate_sort();
            return false;
        });
        lock (reloading) {
            reloading = false;
        }
    }

    /**
     * Permits "rolling" over categories
     */
    private bool on_mouse_enter(Gtk.Widget source_widget, Gdk.EventCrossing e)
    {
        if (!this.rollover_menus) {
            return Gdk.EVENT_PROPAGATE;
        }
        /* If it's not valid, don't use it. */
        Gtk.ToggleButton? b = source_widget as Gtk.ToggleButton;
        if (!b.get_sensitive() || !b.get_visible()) {
            return Gdk.EVENT_PROPAGATE;
        }

        /* Activate the source_widget category */
        (source_widget as Gtk.ToggleButton).set_active(true);
        return Gdk.EVENT_PROPAGATE;
    }


    /**
     * Load "menus" (.desktop's) recursively (ripped from our RunDialog)
     * 
     * @param tree_root Initialised GMenu.TreeDirectory, or null
     */
    private void load_menus(GMenu.TreeDirectory? tree_root = null)
    {
        GMenu.TreeDirectory root;
    
        // Load the tree for the first time
        if (tree == null) {
            tree = new GMenu.Tree(APPS_ID, GMenu.TreeFlags.SORT_DISPLAY_NAME);

            try {
                tree.load_sync();
            } catch (Error e) {
                stderr.printf("Error: %s\n", e.message);
                lock (reloading) {
                    reloading = false;
                }
                return;
            }
            /* Think of deferred routines.. */
            Idle.add(()=> {
                tree.changed.connect(refresh_tree);
                return false;
            });
        }
        if (tree_root == null) {
            root = tree.get_root_directory();
        } else {
            root = tree_root;
        }

        // This is almost certainly the least optimal way of doing this. However, couldn't get the TreeDirectory lookup for Other to work.
        if ((other_tree == null) && !attempted_other_search) {
            var it = root.iter();
            GMenu.TreeItemType? type;

            while ((type = it.next()) != GMenu.TreeItemType.INVALID) {
                if (type == GMenu.TreeItemType.DIRECTORY) {
                    var dir = it.get_directory();

                    if (dir.get_desktop_file_path().has_suffix("X-GNOME-Other.directory")) {
                        other_tree = dir;
                        break;
                    }
                }
            }

            attempted_other_search = true;
        }

        var it = root.iter();
        GMenu.TreeItemType? type;

        while ((type = it.next()) != GMenu.TreeItemType.INVALID) {
            if (type == GMenu.TreeItemType.DIRECTORY) {
                var dir = it.get_directory();
                bool is_sundry = dir.get_desktop_file_path().has_suffix("X-GNOME-Sundry.directory");

                if (!is_sundry || (is_sundry && (other_tree == null))) { // Create a button if not Sundry or is Sundry and Other tree is null
                    var btn = new CategoryButton(dir);
                    btn.join_group(all_categories);
                    btn.enter_notify_event.connect(this.on_mouse_enter);
                    categories.pack_start(btn, false, false, 0);

                    // Ensures we find the correct button
                    btn.toggled.connect(()=>{
                        update_category(btn);
                    });
                }

                load_menus(dir);
            } else if (type == GMenu.TreeItemType.ENTRY) {
                // store the entry by its command line (without path)
                var appinfo = it.get_entry().get_app_info();
                if (tree_root == null) {
                    warning("%s has no parent directory, not adding to menu\n", appinfo.get_display_name());
                } else {
                    var use_root = root;
                    var app_id = appinfo.get_id();

                    if (root.get_desktop_file_path().has_suffix("X-GNOME-Sundry.directory")) { // If we're iterating over desktop entries in Sundry
                        if (other_tree != null)  {
                            use_root = other_tree;
                        }
                    }

                    if (!menu_buttons.contains(app_id)) { // If we haven't already added this button
                        var btn = new MenuButton(appinfo, use_root, icon_size);

                        btn.clicked.connect(()=> {
                            hide();
                            launch_app(btn.info);
                        });
                        menu_buttons.insert(app_id, btn);
                        btn.show_all();
                        content.add(btn);
                    }
                }
            }
        }
    }

    public BudgieMenuWindow(Settings? settings, Gtk.Widget? leparent)
    {
        Object(settings: settings, relative_to: leparent);
        get_style_context().add_class("budgie-menu");
        var master_layout = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
        add(master_layout);

        menu_buttons = new HashTable<string,MenuButton?>(GLib.str_hash, GLib.str_equal);

        icon_size = settings.get_int("menu-icons-size");

        // search entry up north
        search_entry = new Gtk.SearchEntry();
        master_layout.pack_start(search_entry, false, false, 0);

        // middle holds the categories and applications
        var middle = new Gtk.Box(Gtk.Orientation.HORIZONTAL, 0);
        master_layout.pack_start(middle, true, true, 0);

        // clickable categories
        categories = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
        categories.margin_top = 3;
        categories.margin_bottom = 3;
        categories_scroll = new Gtk.ScrolledWindow(null, null);
        categories_scroll.set_overlay_scrolling(false);
        categories_scroll.set_shadow_type(Gtk.ShadowType.ETCHED_IN);
        categories_scroll.get_style_context().add_class("categories");
        categories_scroll.get_style_context().add_class("sidebar");
        categories_scroll.add(categories);
        categories_scroll.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.NEVER);
        middle.pack_start(categories_scroll, false, false, 0);

        // "All" button"
        all_categories = new CategoryButton(null);
        all_categories.enter_notify_event.connect(this.on_mouse_enter);
        all_categories.toggled.connect(()=> {
            update_category(all_categories);
        });
        categories.pack_start(all_categories, false, false, 0);

        var right_layout = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
        middle.pack_start(right_layout, true, true, 0);

        // holds all the applications
        content = new Gtk.ListBox();
        content.row_activated.connect(on_row_activate);
        content.set_selection_mode(Gtk.SelectionMode.NONE);
        content_scroll = new Gtk.ScrolledWindow(null, null);
        content_scroll.set_overlay_scrolling(true);
        content_scroll.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.AUTOMATIC);
        content_scroll.add(content);
        right_layout.pack_start(content_scroll, true, true, 0);

        // placeholder in case of no results
        var placeholder = new Gtk.Label("<big>%s</big>".printf(_("Sorry, no items found")));
        placeholder.use_markup = true;
        placeholder.get_style_context().add_class("dim-label");
        placeholder.show();
        placeholder.margin = 6;
        content.valign = Gtk.Align.START;
        content.set_placeholder(placeholder);

        settings.changed.connect(on_settings_changed);
        on_settings_changed("menu-compact");
        on_settings_changed("menu-headers");
        on_settings_changed("menu-categories-hover");

        // management of our listbox
        content.set_filter_func(do_filter_list);
        content.set_sort_func(do_sort_list);

        // searching functionality :)
        search_entry.changed.connect(()=> {
            search_term = searchable_string(search_entry.text);
            content.invalidate_headers();
            content.invalidate_filter();
            content.invalidate_sort();
        });

        search_entry.grab_focus();

        // Enabling activation by search entry
        search_entry.activate.connect(on_entry_activate);
        // sensible vertical height
        set_size_request(300, 510);
        // load them in the background
        Idle.add(()=> {
            load_menus(null);
            content.invalidate_headers();
            content.invalidate_filter();
            content.invalidate_sort();
            queue_resize();
            if (!get_realized()) {
                realize();
            }
            return false;
        });
    }

    protected void on_settings_changed(string key)
    {
        switch (key) {
            case "menu-compact":
                var vis = settings.get_boolean(key);
                categories_scroll.no_show_all = vis;
                categories_scroll.set_visible(vis);
                compact_mode = vis;
                content.invalidate_headers();
                content.invalidate_filter();
                content.invalidate_sort();
                break;
            case "menu-headers":
                var hed = settings.get_boolean(key);
                headers_visible = hed;
                if (hed) {
                    content.set_header_func(do_list_header);
                } else {
                    content.set_header_func(null);
                }
                content.invalidate_headers();
                content.invalidate_filter();
                content.invalidate_sort();
                break;
            case "menu-categories-hover":
                /* Category hover */
                this.rollover_menus = settings.get_boolean(key);
                break;
            default:
                // not interested
                break;
        }
    }


    protected void on_entry_activate()
    {
        Gtk.ListBoxRow? selected = null;

        var rows = content.get_selected_rows();
        if (rows != null) {
            selected = rows.data;
        } else {
            foreach (var child in content.get_children()) {
                if (child.get_visible() && child.get_child_visible()) {
                    selected = child as Gtk.ListBoxRow;
                    break;
                }
            }
        }
        if (selected == null) {
            return;
        }

        MenuButton btn = selected.get_child() as MenuButton;
        launch_app(btn.info);
    }

    protected void on_row_activate(Gtk.ListBoxRow? row)
    {
        if (row == null) {
            return;
        }
        /* Launch this item, i.e. keyboard access. */
        MenuButton btn = row.get_child() as MenuButton;
        launch_app(btn.info);
    }

    /**
     * Provide category headers in the "All" category
     */
    protected void do_list_header(Gtk.ListBoxRow? before, Gtk.ListBoxRow? after)
    {
        MenuButton? child = null;
        string? prev = null;
        string? next = null;

        // In a category listing, kill headers
        if (group != null) {
            if (before != null) {
                before.set_header(null);
            }
            if (after != null) {
                after.set_header(null);
            }
            return;
        }

        // Just retrieve the category names
        if (before != null) {
            child = before.get_child() as MenuButton;
            prev = child.parent_menu.get_name();
        }

        if (after != null) {
            child = after.get_child() as MenuButton;
            next = child.parent_menu.get_name();
        }
        
        // Only add one if we need one!
        if (before == null || after == null || prev != next) {
            var label = new Gtk.Label(Markup.printf_escaped("<big>%s</big>", prev));
            label.get_style_context().add_class("dim-label");
            label.halign = Gtk.Align.START;
            label.use_markup = true;
            before.set_header(label);
            label.margin = 6;
        } else {
            before.set_header(null);
        }
    }

    /* Helper ported from Brisk */
    private bool array_contains(string?[] array, string term)
    {
        foreach (string? field in array) {
            if (field == null) {
                continue;
            }
            string ct = searchable_string(field);
            if (term.match_string(ct, true)) {
                return true;
            }
            if (term in ct) {
                return true;
            }
        }
        return false;
    }

    /* Helper ported from brisk */
    private bool info_matches_term(AppInfo? info, string term)
    {
        string?[] fields = {
            info.get_display_name(),
            info.get_description(),
            info.get_name(),
            info.get_executable()
        };

        if (array_contains(fields, term)) {
            return true;
        }

        var keywords = (info as DesktopAppInfo).get_keywords();
        if (keywords == null || keywords.length < 1) {
            return false;
        }

        return array_contains(keywords, term);
    }

    private bool is_item_dupe(MenuButton? button)
    {
        MenuButton? compare_item = menu_buttons.lookup(button.info.get_id());
        if (compare_item != null && compare_item != button) {
            return true;
        }
        return false;
    }

    /**
     * Filter out results in the list according to whatever the current filter is,
     * i.e. group based or search based
     */
    protected bool do_filter_list(Gtk.ListBoxRow row)
    {
        MenuButton child = row.get_child() as MenuButton;

        string term = search_term.strip();
        if (term.length > 0) {
            // "disable" categories while searching
            categories.sensitive = false;
            // Items must be unique across the search
            if (this.is_item_dupe(child)) {
                return false;
            }

            return info_matches_term(child.info, term);
        }

        // "enable" categories if not searching
        categories.sensitive = true;

        // No more filtering, show all
        if (group == null) {
            if (this.headers_visible) { // If we are going to be showing headers
                return true;
            } else { // Not showing headers
                return !this.is_item_dupe(child);
            }
        }

        // If the GMenu.TreeDirectory isn't the same as the current filter, hide it
        if (child.parent_menu != group) {
            return false;
        }
        return true;
    }

    protected int do_sort_list(Gtk.ListBoxRow row1, Gtk.ListBoxRow row2)
    {
        MenuButton child1 = row1.get_child() as MenuButton;
        MenuButton child2 = row2.get_child() as MenuButton;

        string term = search_term.strip();

        if (term.length > 0) {
            int sc1 = child1.get_score(term);
            int sc2 = child2.get_score(term);
            /* Vala can't do this: return (sc1 > sc2) - (sc1 - sc2); */
            if (sc1 < sc2) {
                return 1;
            } else if (sc1 > sc2) {
                return -1;
            }
            return 0;
        }

        // Only perform category grouping if headers are visible
        string parentA = searchable_string(child1.parent_menu.get_name());
        string parentB = searchable_string(child2.parent_menu.get_name());
        if (child1.parent_menu != child2.parent_menu && this.headers_visible) {
            return GLib.strcmp(parentA, parentB);
        }

        string nameA = searchable_string(child1.info.get_display_name());
        string nameB = searchable_string(child2.info.get_display_name());
        return GLib.strcmp(nameA, nameB);
    }


    /**
     * Change the current group/category
     */
    protected void update_category(CategoryButton btn)
    {
        if (btn.active) {
            group = btn.group;
            content.invalidate_filter();
            content.invalidate_headers();
            content.invalidate_sort();
        }
    }

    /**
     * Launch an application
     */
    protected void launch_app(DesktopAppInfo info)
    {
        hide();
        // Do it on the idle thread to make sure we don't have focus wars
        Idle.add(()=> {
            try {
                info.launch(null,null);
            } catch (Error e) {
                stdout.printf("Error launching application: %s\n", e.message);
            }
            return false;
        });
    }

    /**
     * We need to make some changes to our display before we go showing ourselves
     * again! :)
     */
    public override void show()
    {
        search_term = "";
        search_entry.text = "";
        group = null;
        all_categories.set_active(true);
        content.select_row(null);
        content_scroll.get_vadjustment().set_value(0);
        categories_scroll.get_vadjustment().set_value(0);
        categories.sensitive = true;
        Idle.add(()=> {
            /* grab focus when we're not busy, ensuring it works.. */
            search_entry.grab_focus();
            return false;
        });
        base.show();
        if (!compact_mode) {
            categories_scroll.show_all();
        } else {
            categories_scroll.hide();
        }
    }

}// End BudgieMenuWindow class

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=4 expandtab:
 * :indentSize=4:tabSize=4:noTabs=true:
 */
