/*
 * 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.
 */

namespace Budgie {

public class SettingsWindow : Gtk.Window {

    Gtk.HeaderBar header;
    Gtk.ListBox sidebar;
    Gtk.Stack content;
    Gtk.Box layout;
    HashTable<string,string> group_map;
    HashTable<string,SettingsPage?> page_map;
    HashTable<string,SettingsItem?> sidebar_map;

    public Budgie.DesktopManager? manager { public set ; public get ; }

    /* Special item that allows us to add new items to the display */
    SettingsItem? item_add_panel;
    bool new_panel_requested = false;

    public SettingsWindow(Budgie.DesktopManager? manager)
    {
        Object(type: Gtk.WindowType.TOPLEVEL, manager: manager);

        header = new Gtk.HeaderBar();
        header.set_show_close_button(true);
        set_titlebar(header);

        group_map = new HashTable<string,string>(str_hash, str_equal);
        group_map["appearance"] = _("Appearance");
        group_map["panel"] = _("Panels");
        group_map["session"] = _("Session");
        page_map = new HashTable<string,SettingsPage?>(str_hash, str_equal);
        sidebar_map = new HashTable<string,SettingsItem?>(str_hash, str_equal);

        layout = new Gtk.Box(Gtk.Orientation.HORIZONTAL, 0);
        add(layout);

        /* Have to override wmclass for pinning support */
        set_icon_name("preferences-desktop");
        set_title(_("Budgie Desktop Settings"));
        set_wmclass("budgie-desktop-settings", "budgie-desktop-settings");

        /* Fit even on a spud resolution */
        set_default_size(750, 550);

        /* Sidebar navigation */
        var scroll = new Gtk.ScrolledWindow(null, null);
        scroll.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.AUTOMATIC);
        sidebar = new Gtk.ListBox();
        sidebar.set_header_func(this.do_headers);
        sidebar.set_sort_func(this.do_sort);
        sidebar.row_activated.connect(this.on_row_activate);
        sidebar.set_activate_on_single_click(true);
        scroll.add(sidebar);
        layout.pack_start(scroll, false, false, 0);
        scroll.margin_end = 24;

        /* Where actual Things go */
        content = new Gtk.Stack();
        content.set_transition_type(Gtk.StackTransitionType.CROSSFADE);
        layout.pack_start(content, true, true, 0);

        /* Help our theming community out */
        get_style_context().add_class("budgie-settings-window");
        sidebar.get_style_context().add_class(Gtk.STYLE_CLASS_SIDEBAR);

        this.build_content();

        this.item_add_panel = new SettingsItem(SETTINGS_GROUP_PANEL,
                                               "x-add-panel",
                                               _("Create new panel"),
                                               "list-add-symbolic");

        this.sidebar.add(this.item_add_panel);

        /* We'll need to build panel items for each toplevel */
        this.manager.panel_added.connect(this.on_panel_added);
        this.manager.panel_deleted.connect(this.on_panel_deleted);
        this.manager.panels_changed.connect_after(this.on_panels_changed);

        this.on_panels_changed();

        layout.show_all();
        header.show_all();
    }

    /**
     * Static pages that will always be part of the UI
     */
    void build_content()
    {
        this.add_page(new Budgie.StylePage());

#if HAVE_NAUTILUS
        if (Environment.find_program_in_path("nautilus") != null) {
            this.add_page(new Budgie.DesktopPage());
        }
#endif

        this.add_page(new Budgie.FontPage());
        this.add_page(new Budgie.WindowsPage());
        this.add_page(new Budgie.AutostartPage());
        this.add_page(new Budgie.RavenPage());
    }

    /**
     * Update the state of the add-panel button in relation to slots
     */
    void on_panels_changed()
    {
        item_add_panel.set_sensitive(this.manager.slots_available() >= 1);
        Idle.add(()=> {
            this.sidebar.invalidate_sort();
            this.sidebar.invalidate_filter();
            return false;
        });
    }

    /**
     * Handle transition between various pages
     */
    void on_row_activate(Gtk.ListBoxRow? row)
    {
        if (row == null) {
            return;
        }
        SettingsItem? item = row.get_child() as SettingsItem;
        if (item != this.item_add_panel) {
            this.content.set_visible_child_name(item.content_id);
            return;
        }
        this.new_panel_requested = true;
        if (this.manager.slots_available() >= 1) {
            this.manager.create_new_panel();
        }
    }

    /**
     * Add a new page to our sidebar + stack
     */
    void add_page(Budgie.SettingsPage? page)
    {
        var settings_item = new SettingsItem(page.group, page.content_id, page.title, page.icon_name);
        settings_item.show_all();
        sidebar.add(settings_item);

        page.bind_property("title", settings_item, "label", BindingFlags.DEFAULT);
        page.bind_property("display-weight", settings_item, "display-weight", BindingFlags.DEFAULT|BindingFlags.SYNC_CREATE);

        this.sidebar_map[page.content_id] = settings_item;
        this.page_map[page.content_id] = page;

        if (page.want_scroll) {
            var scroll = new Gtk.ScrolledWindow(null, null);
            scroll.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.AUTOMATIC);
            scroll.add(page);
            scroll.show();
            content.add_named(scroll, page.content_id);
        } else {
            page.show();
            content.add_named(page, page.content_id);
        }
        this.sidebar.invalidate_sort();
        this.sidebar.invalidate_headers();
    }

    /**
     * Remove a page from the sidebar and content stack
     */
    void remove_page(string content_id)
    {
        Budgie.SettingsPage? page = this.page_map.lookup(content_id);
        Budgie.SettingsItem? item = this.sidebar_map.lookup(content_id);

        /* Remove from listbox */
        if (item != null) {
            item.get_parent().destroy();
        }

        /* Remove from content view */
        if (page != null) {
            page.destroy();
        }
        this.sidebar.invalidate_sort();
        this.sidebar.invalidate_headers();
    }

    /**
     * Provide categorisation for our sidebar items
     */
    void do_headers(Gtk.ListBoxRow? before, Gtk.ListBoxRow? after)
    {
        SettingsItem? child = null;
        string? prev = null;
        string? next = null;

        if (before != null) {
            child = before.get_child() as SettingsItem;
            prev = child.group;
        }

        if (after != null) {
            child = after.get_child() as SettingsItem;
            next = child.group;
        }

        if (after == null || prev != next) {
            string? title = group_map.lookup(prev);
            Gtk.Label label = new Gtk.Label(title);
            label.get_style_context().add_class(Gtk.STYLE_CLASS_DIM_LABEL);
            label.halign = Gtk.Align.START;
            label.use_markup = true;
            label.margin_top = 8;
            label.margin_bottom = 8;
            label.margin_start = 12;
            before.set_header(label);
        } else {
            before.set_header(null);
        }
    }

    /**
     * Sort the sidebar items, enforcing clustering of the same groups
     */
    int do_sort(Gtk.ListBoxRow? before, Gtk.ListBoxRow? after)
    {
        SettingsItem? child_before = null;
        SettingsItem? child_after = null;

        child_before = before.get_child() as SettingsItem;
        child_after = after.get_child() as SettingsItem;

        /* Match untranslated group string only */
        if (child_before.group != child_after.group) {
            return strcmp(child_before.group, child_after.group);
        }

        /* Always ensure the "new panel" button is last, at the tail of panels group */
        if (child_after == this.item_add_panel) {
            return -1;
        } else if (child_before == this.item_add_panel) {
            return 1;
        }

        if (child_before.display_weight > child_after.display_weight) {
            return 1;
        } else if (child_before.display_weight < child_after.display_weight) {
            return -1;
        }
        return 0;
    }

    /**
     * Emulate sidebar activation for the user
     */
    void force_select_page(string content_id)
    {
        Idle.add(()=> {
            Gtk.ListBoxRow? row = this.sidebar_map[content_id].get_parent() as Gtk.ListBoxRow;
            sidebar.select_row(row);
            row.grab_focus();
            content.set_visible_child_name(content_id);
            return false;
        });
    }

    /**
     * New panel added, let's make a page for it
     */
    private void on_panel_added(string uuid, Budgie.Toplevel? toplevel)
    {
        string content_id = "panel-" + uuid;
        if (content_id in this.page_map) {
            return;
        }
        this.add_page(new PanelPage(this.manager, toplevel));
        if (new_panel_requested) {
            this.force_select_page(content_id);
        }
    }

    /**
     * A panel was destroyed, remove our knowledge of it
     */
    private void on_panel_deleted(string uuid)
    {
        string content_id = "panel-" + uuid;

        /* TODO: Set the visible name to another panel that isn't the
         * one being deleted, only when already looking at the panel.
         */
        if (this.content.get_visible_child_name() == content_id) {
            this.force_select_page("style");
        }

        /* Nuke from orbit */
        this.remove_page("panel-" + uuid);
    }
} /* End SettingsWindow */


} /* End namespace Budgie */
