/*
 * Copyright 2014-2015 Javier S. Pedro <dev.git@javispedro.com>
 *
 * This file is part of TopMenu.
 *
 * TopMenu is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * TopMenu 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with TopMenu.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <math.h>
#include <cairo-xlib.h>
#include "topmenu-background.h"

struct _TopMenuBackgroundPrivate
{
	double red, green, blue, alpha;
	Pixmap pixmap;
	gint width, height, depth;
	gboolean has_color;
};

enum {
	SIGNAL_CHANGED,
	N_SIGNALS
};

G_DEFINE_TYPE(TopMenuBackground, topmenu_background, G_TYPE_OBJECT)

#define TOPMENU_BACKGROUND_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE((obj), TOPMENU_TYPE_BACKGROUND, TopMenuBackgroundPrivate))

static guint signals[N_SIGNALS];

#if GTK_MAJOR_VERSION == 3
#define TOPMENU_BACKGROUND_CSS_STYLE_CLASS    "topmenu-background"
static GtkCssProvider *topmenu_provider;
#endif

static inline GdkDisplay * topmenu_background_get_display(TopMenuBackground *self)
{
	return gdk_display_get_default();
}

static gboolean topmenu_background_reset(TopMenuBackground *self)
{
	gboolean had_contents = self->priv->has_color || self->priv->pixmap;
	self->priv->has_color = FALSE;
	if (self->priv->pixmap) {
		GdkDisplay *display = topmenu_background_get_display(self);
		XFreePixmap(GDK_DISPLAY_XDISPLAY(display), self->priv->pixmap);
		self->priv->pixmap = None;
	}
	return had_contents;
}

static void topmenu_background_finalize(GObject *obj)
{
	TopMenuBackground *self = TOPMENU_BACKGROUND(obj);
	topmenu_background_clear(self);
	G_OBJECT_CLASS(topmenu_background_parent_class)->finalize(obj);
}

static void topmenu_background_class_init(TopMenuBackgroundClass *klass)
{
	GObjectClass *obj_class = G_OBJECT_CLASS(klass);
	obj_class->finalize = topmenu_background_finalize;

	signals[SIGNAL_CHANGED] = g_signal_newv("changed",
	                                        G_TYPE_FROM_CLASS(obj_class),
	                                        G_SIGNAL_NO_RECURSE,
	                                        NULL,
	                                        NULL,
	                                        NULL,
	                                        g_cclosure_marshal_VOID__VOID,
	                                        G_TYPE_NONE,
	                                        0, NULL);

	g_type_class_add_private(klass, sizeof(TopMenuBackgroundPrivate));
}

static void topmenu_background_init(TopMenuBackground *self)
{
	self->priv = TOPMENU_BACKGROUND_GET_PRIVATE(self);
}

TopMenuBackground *topmenu_background_new(void)
{
	return TOPMENU_BACKGROUND(g_object_new(TOPMENU_TYPE_BACKGROUND, NULL));
}

void topmenu_background_set_from_color(TopMenuBackground *self, double red, double green, double blue, double alpha)
{
	topmenu_background_reset(self);

	self->priv->has_color = TRUE;
	self->priv->red = red;
	self->priv->green = green;
	self->priv->blue = blue;
	self->priv->alpha = alpha;
	g_signal_emit(self, signals[SIGNAL_CHANGED], 0);
}

void topmenu_background_set_from_drawable(TopMenuBackground *self, Drawable drawable)
{
	gboolean had_contents = topmenu_background_reset(self);

	g_return_if_fail(drawable);

	GdkDisplay *display = topmenu_background_get_display(self);
	GdkScreen *screen = gdk_display_get_default_screen(display);
	Display *xdpy = GDK_DISPLAY_XDISPLAY(display);
	int err;

	gdk_error_trap_push();

	Window root;
	int x, y;
	unsigned int width, height, border_width, depth;
	if (!XGetGeometry(xdpy, drawable, &root,
	                 &x, &y, &width, &height, &border_width, &depth)) {
		g_debug("could not get geometry of drawable: 0x%lx", drawable);
		goto err_out;
	}

	self->priv->width = width;
	self->priv->height = height;
	self->priv->depth = depth;

	cairo_surface_t *orig_surface = cairo_xlib_surface_create(xdpy, drawable,
	            GDK_VISUAL_XVISUAL(gdk_screen_get_system_visual(screen)),
	            width, height);
	if (!orig_surface) {
		g_debug("could not create orig surface");
		goto err_out;
	}

	self->priv->pixmap = XCreatePixmap(xdpy, drawable, width, height, depth);
	cairo_surface_t *new_surface = cairo_xlib_surface_create(xdpy, self->priv->pixmap,
	            GDK_VISUAL_XVISUAL(gdk_screen_get_system_visual(screen)),
				width, height);
	if (!new_surface) {
		g_debug("could not create new surface");
		XFreePixmap(xdpy, self->priv->pixmap);
		goto err_out;
	}

	cairo_t *cr = cairo_create(new_surface);
	cairo_set_source_surface(cr, orig_surface, 0, 0);
	cairo_paint(cr);
	cairo_destroy(cr);

	cairo_surface_destroy(new_surface);
	cairo_surface_destroy(orig_surface);

err_out:
	err = gdk_error_trap_pop();
	if (err) g_debug("X error: %d", err);

	if (had_contents || self->priv->pixmap) {
		g_signal_emit(self, signals[SIGNAL_CHANGED], 0);
	}
}

void topmenu_background_set_from_cairo_pattern(TopMenuBackground *self, cairo_pattern_t *pattern)
{
	if (!pattern) {
		topmenu_background_clear(self);
		return;
	}

	gboolean had_contents = topmenu_background_reset(self);

	cairo_surface_t *surface;
	double red, green, blue, alpha;
	if (cairo_pattern_get_rgba(pattern, &red, &green, &blue, &alpha) == CAIRO_STATUS_SUCCESS) {
		topmenu_background_set_from_color(self, red, green, blue, alpha);
	} else if (cairo_pattern_get_surface(pattern, &surface) == CAIRO_STATUS_SUCCESS) {
		cairo_surface_type_t type = cairo_surface_get_type(surface);
		if (type == CAIRO_SURFACE_TYPE_XLIB) {
			Drawable drawable = cairo_xlib_surface_get_drawable(surface);
			topmenu_background_set_from_drawable(self, drawable);
			return;
		} else {
			g_warning("no idea how to handle this cairo pattern type");
		}
	} else {
		g_warning("no idea how to handle this cairo surface type");
	}

	if (had_contents) {
		g_signal_emit(self, signals[SIGNAL_CHANGED], 0);
	}
}

void topmenu_background_clear(TopMenuBackground *self)
{
	if (topmenu_background_reset(self)) {
		g_signal_emit(self, signals[SIGNAL_CHANGED], 0);
	}
}

gboolean topmenu_background_get_color(TopMenuBackground *self, double *red, double *green, double *blue, double *alpha)
{
	if (self->priv->has_color) {
		if (red) *red = self->priv->red;
		if (green) *green = self->priv->green;
		if (blue) *blue = self->priv->blue;
		if (alpha) *alpha = self->priv->alpha;
		return TRUE;
	} else {
		return FALSE;
	}
}

gboolean topmenu_background_get_pixmap(TopMenuBackground *self, Pixmap *pixmap)
{
	if (self->priv->pixmap) {
		if (pixmap) *pixmap = self->priv->pixmap;
		return TRUE;
	} else {
		return FALSE;
	}
}

cairo_pattern_t * topmenu_background_get_cairo_pattern(TopMenuBackground *self)
{
	if (self->priv->has_color) {
		return cairo_pattern_create_rgba(self->priv->red, self->priv->green,
		                                 self->priv->blue, self->priv->alpha);
	} else if (self->priv->pixmap) {
		GdkDisplay *display = topmenu_background_get_display(self);
		GdkScreen *screen = gdk_display_get_default_screen(display);
		Display *xdpy = GDK_DISPLAY_XDISPLAY(display);

		cairo_surface_t * surface = cairo_xlib_surface_create(xdpy, self->priv->pixmap,
			GDK_VISUAL_XVISUAL(gdk_screen_get_system_visual(screen)),
			self->priv->width, self->priv->height);

		cairo_pattern_t * pattern = cairo_pattern_create_for_surface(surface);
		cairo_surface_destroy(surface);

		return pattern;
	} else {
		return NULL;
	}
}

void topmenu_background_fill_client_message(TopMenuBackground *self, XClientMessageEvent *event)
{
	event->format = 32;
	event->data.l[0] = self->priv->has_color ? 1 : 0;
	if (self->priv->has_color) {
		// Encode color as a 32-bit RGBA value
		guint32 rgba = (lround(self->priv->red   * 255.0) & 0xFF) << 24
		             | (lround(self->priv->green * 255.0) & 0xFF) << 16
		             | (lround(self->priv->blue  * 255.0) & 0xFF) << 8
		             | (lround(self->priv->alpha * 255.0) & 0xFF) << 0;
		event->data.l[1] = rgba;
	} else {
		event->data.l[1] = 0;
	}
	event->data.l[2] = self->priv->pixmap;
	event->data.l[3] = 0;
	event->data.l[4] = 0;
}

void topmenu_background_set_from_client_message(TopMenuBackground *self, XClientMessageEvent *event)
{
	g_return_if_fail(event->format == 32);
	g_warn_if_fail(event->data.l[3] == 0);
	if (event->data.l[0] & 1) {
		const guint32 rgba = event->data.l[1];
		double red   = ((rgba >> 24) & 0xFF) / 255.0,
		       green = ((rgba >> 16) & 0xFF) / 255.0,
		       blue = ((rgba >> 8) & 0xFF) / 255.0,
		       alpha = ((rgba >> 0) & 0xFF) / 255.0;
		topmenu_background_set_from_color(self, red, green, blue, alpha);
	} else if (event->data.l[2] != None) {
		topmenu_background_set_from_drawable(self, event->data.l[2]);
	} else {
		topmenu_background_clear(self);
	}
}

#if GTK_MAJOR_VERSION == 2
static GdkPixmap * get_pixmap(GdkDisplay *display, Pixmap pixmap)
{
	gdk_error_trap_push();
	GdkPixmap *gp = gdk_pixmap_lookup_for_display(display, pixmap);
	if (!gp) {
		gp = gdk_pixmap_foreign_new_for_display(display, pixmap);
	}
	gdk_error_trap_pop();
	return gp;
}
#endif

void topmenu_background_apply(TopMenuBackground *self, GtkWidget *widget)
{
#if GTK_MAJOR_VERSION == 3
	if (!topmenu_provider) {
		topmenu_provider = gtk_css_provider_new();
		gtk_css_provider_load_from_data(topmenu_provider,
			"." TOPMENU_BACKGROUND_CSS_STYLE_CLASS " {\n"
				" background-color: rgba (0, 0, 0, 0);\n"
				" background-image: none;\n"
			"}", -1, NULL);
	}

	GtkStyleContext *context = gtk_widget_get_style_context(widget);

	GdkWindow *widget_window = gtk_widget_get_window(widget);
	double red, green, blue, alpha;
	Pixmap pixmap;
	if (topmenu_background_get_color(self, &red, &green, &blue, &alpha)) {
		gtk_style_context_add_class(context, TOPMENU_BACKGROUND_CSS_STYLE_CLASS);
		if (widget_window) {
			GdkRGBA color = {red, green, blue, alpha};
			gdk_window_set_background_rgba(widget_window, &color);
			g_debug("do color");

		}
	} else if (topmenu_background_get_pixmap(self, &pixmap)) {
		gtk_style_context_add_class(context, TOPMENU_BACKGROUND_CSS_STYLE_CLASS);
		if (widget_window) {
			cairo_pattern_t * pattern = topmenu_background_get_cairo_pattern(self);
			gdk_window_set_background_pattern(widget_window, pattern);
			cairo_pattern_destroy(pattern);
		}
	} else {
		gtk_style_context_remove_class(context, TOPMENU_BACKGROUND_CSS_STYLE_CLASS);
	}

	gtk_style_context_add_provider(context, GTK_STYLE_PROVIDER(topmenu_provider),
	                               GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
#elif GTK_MAJOR_VERSION == 2
	// Clear current background
	GtkRcStyle *rc_style;
	gtk_widget_set_style(widget, NULL);
	rc_style = gtk_rc_style_new();
	gtk_widget_modify_style(widget, rc_style);
	g_object_unref(rc_style);

	double red, green, blue, alpha;
	Pixmap pixmap;
	if (topmenu_background_get_color(self, &red, &green, &blue, &alpha)) {
		if (alpha >= 1.0) {
			// Opaque
			GdkColor color = { 0, red * 65535U, green * 65535U, blue * 65535U };
			gtk_widget_modify_bg(widget, GTK_STATE_NORMAL, &color);
		} else {
			// TODO Alpha color
			g_warning("Alpha colors not yet supported (alpha=%f)", alpha);
		}
	} else if (topmenu_background_get_pixmap(self, &pixmap)) {
		GdkDisplay *display = gtk_widget_get_display(widget);
		GdkPixmap *gpixmap = get_pixmap(display, pixmap);

		if (gpixmap) {
			if (!gdk_drawable_get_colormap(gpixmap)) {
				gdk_drawable_set_colormap(GDK_DRAWABLE (gpixmap),
										  gtk_widget_get_colormap(widget));
			}

			GtkStyle *style = gtk_style_copy(gtk_widget_get_style(widget));
			g_clear_object(&style->bg_pixmap[GTK_STATE_NORMAL]);
			style->bg_pixmap[GTK_STATE_NORMAL] = g_object_ref_sink(gpixmap);
			gtk_widget_set_style(widget, style);
			g_object_unref(style);
		}
	}
#endif
	gtk_widget_queue_draw(widget);
}

void topmenu_background_unapply(TopMenuBackground *self, GtkWidget *widget)
{
#if GTK_MAJOR_VERSION == 3
	GtkStyleContext *context = gtk_widget_get_style_context(widget);
	gtk_style_context_remove_class(context, TOPMENU_BACKGROUND_CSS_STYLE_CLASS);
	gtk_style_context_remove_provider(context, GTK_STYLE_PROVIDER(topmenu_provider));
#elif GTK_MAJOR_VERSION == 2
	// Clear current background
	GtkRcStyle *rc_style;
	gtk_widget_set_style(widget, NULL);
	rc_style = gtk_rc_style_new();
	gtk_widget_modify_style(widget, rc_style);
	g_object_unref(rc_style);
#endif
	gtk_widget_queue_draw(widget);
}

void topmenu_background_connect(TopMenuBackground *self, GtkWidget *widget)
{
	g_signal_connect(self, "changed",
	                 G_CALLBACK(topmenu_background_apply), widget);
	if (gtk_widget_get_realized(widget)) {
		topmenu_background_apply(self, widget);
	}
}

void topmenu_background_disconnect(TopMenuBackground *self, GtkWidget *widget)
{
	g_signal_handlers_disconnect_by_func(self,
	                                     G_CALLBACK(topmenu_background_apply), widget);
}