//
//  Copyright (C) 2012 Tom Beckmann, Rico Tzschichholz
//
//  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 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

namespace Gala
{
	public class Utils
	{
		// Cache xid:pixbuf and icon:pixbuf pairs to provide a faster way aquiring icons
		static HashTable<string, Gdk.Pixbuf> xid_pixbuf_cache;
		static HashTable<string, Gdk.Pixbuf> icon_pixbuf_cache;
		static uint cache_clear_timeout = 0;

		static Gdk.Pixbuf? close_pixbuf = null;
		static Gdk.Pixbuf? resize_pixbuf = null;

		static construct
		{
			xid_pixbuf_cache = new HashTable<string, Gdk.Pixbuf> (str_hash, str_equal);
			icon_pixbuf_cache = new HashTable<string, Gdk.Pixbuf> (str_hash, str_equal);
		}

		Utils ()
		{
		}

		/**
		 * Clean icon caches
		 */
		static void clean_icon_cache (uint32[] xids)
		{
			var list = xid_pixbuf_cache.get_keys ();
			var pixbuf_list = icon_pixbuf_cache.get_values ();
			var icon_list = icon_pixbuf_cache.get_keys ();

			foreach (var xid_key in list) {
				var xid = (uint32)uint64.parse (xid_key.split ("::")[0]);
				if (!(xid in xids)) {
					var pixbuf = xid_pixbuf_cache.get (xid_key);
					for (var j = 0; j < pixbuf_list.length (); j++) {
						if (pixbuf_list.nth_data (j) == pixbuf) {
							xid_pixbuf_cache.remove (icon_list.nth_data (j));
						}
					}

					xid_pixbuf_cache.remove (xid_key);
				}
			}
		}

		/**
		 * Marks the given xids as no longer needed, the corresponding icons
		 * may be freed now. Mainly for internal purposes.
		 *
		 * @param xids The xids of the window that no longer need icons
		 */
		public static void request_clean_icon_cache (uint32[] xids)
		{
			if (cache_clear_timeout > 0)
				GLib.Source.remove (cache_clear_timeout);

			cache_clear_timeout = Timeout.add_seconds (30, () => {
				cache_clear_timeout = 0;
				Idle.add (() => {
					clean_icon_cache (xids);
					return false;
				});
				return false;
			});
		}

		/**
		 * Returns a pixbuf for the application of this window or a default icon
		 *
		 * @param window       The window to get an icon for
		 * @param size         The size of the icon
		 * @param ignore_cache Should not be necessary in most cases, if you care about the icon
		 *                     being loaded correctly, you should consider using the WindowIcon class
		 */
		public static Gdk.Pixbuf get_icon_for_window (Meta.Window window, int size, bool ignore_cache = false)
		{
			return get_icon_for_xid ((uint32)window.get_xwindow (), size, ignore_cache);
		}

		/**
		 * Returns a pixbuf for a given xid or a default icon
		 *
		 * @see get_icon_for_window
		 */
		public static Gdk.Pixbuf get_icon_for_xid (uint32 xid, int size, bool ignore_cache = false)
		{
			Gdk.Pixbuf? result = null;
			var xid_key = "%u::%i".printf (xid, size);

			if (!ignore_cache && (result = xid_pixbuf_cache.get (xid_key)) != null)
				return result;

			var app = Bamf.Matcher.get_default ().get_application_for_xid (xid);
			result = get_icon_for_application (app, size, ignore_cache);

			xid_pixbuf_cache.set (xid_key, result);

			return result;
		}

		/**
		 * Returns a pixbuf for this application or a default icon
		 *
		 * @see get_icon_for_window
		 */
		static Gdk.Pixbuf get_icon_for_application (Bamf.Application? app, int size,
			bool ignore_cache = false)
		{
			Gdk.Pixbuf? image = null;
			bool not_cached = false;

			string? icon = null;
			string? icon_key = null;

			if (app != null && app.get_desktop_file () != null) {
				var appinfo = new DesktopAppInfo.from_filename (app.get_desktop_file ());
				if (appinfo != null) {
					icon = Plank.DrawingService.get_icon_from_gicon (appinfo.get_icon ());
					icon_key = "%s::%i".printf (icon, size);
					if (ignore_cache || (image = icon_pixbuf_cache.get (icon_key)) == null) {
						image = Plank.DrawingService.load_icon (icon, size, size);
						not_cached = true;
					}
				}
			}

			if (image == null) {
				try {
					unowned Gtk.IconTheme icon_theme = Gtk.IconTheme.get_default ();
					icon = "application-default-icon";
					icon_key = "%s::%i".printf (icon, size);
					if ((image = icon_pixbuf_cache.get (icon_key)) == null) {
						image = icon_theme.load_icon (icon, size, 0);
						not_cached = true;
					}
				} catch (Error e) {
					warning (e.message);
				}
			}

			if (image == null) {
				icon = "";
				icon_key = "::%i".printf (size);
				if ((image = icon_pixbuf_cache.get (icon_key)) == null) {
					image = new Gdk.Pixbuf (Gdk.Colorspace.RGB, true, 8, size, size);
					image.fill (0x00000000);
					not_cached = true;
				}
			}

			if (size != image.width || size != image.height)
				image = Plank.DrawingService.ar_scale (image, size, size);

			if (not_cached)
				icon_pixbuf_cache.set (icon_key, image);

			return image;
		}

		/**
		 * Get the next window that should be active on a workspace right now. Based on
		 * stacking order
		 *
		 * @param workspace The workspace on which to find the window
		 * @param backward  Whether to get the previous one instead
		 */
		public static Meta.Window get_next_window (Meta.Workspace workspace, bool backward = false)
		{
			var screen = workspace.get_screen ();
			var display = screen.get_display ();

			var window = display.get_tab_next (Meta.TabList.NORMAL,
				workspace, null, backward);

			if (window == null)
				window = display.get_tab_current (Meta.TabList.NORMAL, workspace);

			return window;
		}

		/**
		 * Get the number of toplevel windows on a workspace excluding those that are
		 * on all workspaces
		 *
		 * @param workspace The workspace on which to count the windows
		 */
		public static uint get_n_windows (Meta.Workspace workspace)
		{
			var n = 0;
			foreach (var window in workspace.list_windows ()) {
				if (window.is_on_all_workspaces ())
					continue;
				if (window.window_type == Meta.WindowType.NORMAL ||
					window.window_type == Meta.WindowType.DIALOG ||
					window.window_type == Meta.WindowType.MODAL_DIALOG)
					n ++;
			}

			return n;
		}

		/**
		 * Creates an actor showing the current contents of the given WindowActor.
		 *
		 * @param actor 	 The actor from which to create a shnapshot
		 * @param inner_rect The inner (actually visible) rectangle of the window
		 * @param outer_rect The outer (input region) rectangle of the window
		 *
		 * @return           A copy of the actor at that time or %NULL
		 */
		public static Clutter.Actor? get_window_actor_snapshot (Meta.WindowActor actor, Meta.Rectangle inner_rect, Meta.Rectangle outer_rect)
		{
			var texture = actor.get_texture () as Meta.ShapedTexture;

			if (texture == null)
				return null;

			var surface = texture.get_image ({
				inner_rect.x - outer_rect.x,
				inner_rect.y - outer_rect.y,
				inner_rect.width,
				inner_rect.height
			});

			if (surface == null)
				return null;

			var canvas = new Clutter.Canvas ();
			var handler = canvas.draw.connect ((cr) => {
				cr.set_source_surface (surface, 0, 0);
				cr.paint ();
				return false;
			});
			canvas.set_size (inner_rect.width, inner_rect.height);
			SignalHandler.disconnect (canvas, handler);

			var container = new Clutter.Actor ();
			container.set_size (inner_rect.width, inner_rect.height);
			container.content = canvas;

			return container;
		}

		/**
		 * Ring the system bell, will most likely emit a <beep> error sound or, if the
		 * audible bell is disabled, flash the screen
		 *
		 * @param screen The screen to flash, if necessary
		 */
		public static void bell (Meta.Screen screen)
		{
			if (Meta.Prefs.bell_is_audible ())
				Gdk.beep ();
			else
				screen.get_display ().get_compositor ().flash_screen (screen);
		}

		/**
		 * Returns the pixbuf that is used for close buttons throughout gala at a
		 * size of 36px
		 *
		 * @return the close button pixbuf or null if it failed to load
		 */
		public static Gdk.Pixbuf? get_close_button_pixbuf ()
		{
			if (close_pixbuf == null) {
				try {
					close_pixbuf = new Gdk.Pixbuf.from_resource_at_scale (Config.RESOURCEPATH + "/buttons/close.svg", -1, 36, true);
				} catch (Error e) {
					warning (e.message);
					return null;
				}
			}

			return close_pixbuf;
		}

		/**
		 * Creates a new reactive ClutterActor at 36px with the close pixbuf
		 *
		 * @return The close button actor
		 */
		public static Clutter.Actor create_close_button ()
		{
			var texture = new Clutter.Texture ();
			var pixbuf = get_close_button_pixbuf ();

			texture.reactive = true;

			if (pixbuf != null) {
				try {
					texture.set_from_rgb_data (pixbuf.get_pixels (), pixbuf.get_has_alpha (),
						pixbuf.get_width (), pixbuf.get_height (),
						pixbuf.get_rowstride (), (pixbuf.get_has_alpha () ? 4 : 3), 0);
				} catch (Error e) {}
			} else {
				// we'll just make this red so there's at least something as an 
				// indicator that loading failed. Should never happen and this
				// works as good as some weird fallback-image-failed-to-load pixbuf
				texture.set_size (36, 36);
				texture.background_color = { 255, 0, 0, 255 };
			}

			return texture;
		}
		/**
		 * Returns the pixbuf that is used for resize buttons throughout gala at a
		 * size of 36px
		 *
		 * @return the close button pixbuf or null if it failed to load
		 */
		public static Gdk.Pixbuf? get_resize_button_pixbuf ()
		{
			if (resize_pixbuf == null) {
				try {
					resize_pixbuf = new Gdk.Pixbuf.from_resource_at_scale (Config.RESOURCEPATH + "/buttons/resize.svg", -1, 36, true);
				} catch (Error e) {
					warning (e.message);
					return null;
				}
			}

			return resize_pixbuf;
		}

		/**
		 * Creates a new reactive ClutterActor at 36px with the resize pixbuf
		 *
		 * @return The resize button actor
		 */
		public static Clutter.Actor create_resize_button ()
		{
			var texture = new Clutter.Texture ();
			var pixbuf = get_resize_button_pixbuf ();

			texture.reactive = true;

			if (pixbuf != null) {
				try {
					texture.set_from_rgb_data (pixbuf.get_pixels (), pixbuf.get_has_alpha (),
						pixbuf.get_width (), pixbuf.get_height (),
						pixbuf.get_rowstride (), (pixbuf.get_has_alpha () ? 4 : 3), 0);
				} catch (Error e) {}
			} else {
				// we'll just make this red so there's at least something as an
				// indicator that loading failed. Should never happen and this
				// works as good as some weird fallback-image-failed-to-load pixbuf
				texture.set_size (36, 36);
				texture.background_color = { 255, 0, 0, 255 };
			}

			return texture;
		}
	}
}