#include <math.h>
#include "indicator-image-helper.h"

const gchar * INDICATOR_NAMES_DATA = "indicator-names-data";

static void
refresh_image (GtkImage * image)
{
	g_return_if_fail(GTK_IS_IMAGE(image));

	GIcon * icon_names = (GIcon *)g_object_get_data(G_OBJECT(image), INDICATOR_NAMES_DATA);
	g_return_if_fail(icon_names != NULL);

	/* Get the default theme */
	GtkIconTheme * default_theme = gtk_icon_theme_get_default();
	g_return_if_fail(default_theme != NULL);

	gint icon_size = 22;

	GtkStyle * style = gtk_widget_get_style(GTK_WIDGET(image));
	GValue styleprop = {0};
	gtk_style_get_style_property(style, GTK_TYPE_IMAGE, "x-ayatana-indicator-dynamic", &styleprop);

	if (G_VALUE_HOLDS_BOOLEAN(&styleprop) && g_value_get_boolean(&styleprop)) {
		PangoContext * context = gtk_widget_get_pango_context(GTK_WIDGET(image));
		PangoFontMetrics * metrics = pango_context_get_metrics(context, style->font_desc, pango_context_get_language(context));
		icon_size = PANGO_PIXELS(pango_font_metrics_get_ascent(metrics)) + PANGO_PIXELS(pango_font_metrics_get_descent(metrics));
		g_debug("Looking for icon size %d", icon_size);
		pango_font_metrics_unref(metrics);
	}

	/* Look through the themes for that icon */
	GtkIconInfo * icon_info = gtk_icon_theme_lookup_by_gicon(default_theme, icon_names, icon_size, 0);
	if (icon_info == NULL) {
		g_warning("Unable to find icon in theme.");
		return;
	}

	/* Grab the filename */
	const gchar * icon_filename = gtk_icon_info_get_filename(icon_info);
	g_return_if_fail(icon_filename != NULL); /* An error because we shouldn't get info without a filename */

	/* Build a pixbuf */
	GError * error = NULL;
	GdkPixbuf * pixbuf = gdk_pixbuf_new_from_file(icon_filename, &error);
	gtk_icon_info_free(icon_info);

	if (pixbuf == NULL) {
		g_error("Unable to load icon from file '%s' because: %s", icon_filename, error == NULL ? "I don't know" : error->message);
		return;
	}

	/* Scale icon if all we get is something too big. */
	if (gdk_pixbuf_get_height(pixbuf) > icon_size) {
		gfloat scale = (gfloat)icon_size / (gfloat)gdk_pixbuf_get_height(pixbuf);
		gint width = round(gdk_pixbuf_get_width(pixbuf) * scale);

		GdkPixbuf * scaled = gdk_pixbuf_scale_simple(pixbuf, width, icon_size, GDK_INTERP_BILINEAR);
		g_object_unref(G_OBJECT(pixbuf));
		pixbuf = scaled;
	}

	/* Put the pixbuf on the image */
	gtk_image_set_from_pixbuf(image, pixbuf);
	g_object_unref(G_OBJECT(pixbuf));

	return;
}

/* Handles the theme changed signal to refresh the icon to make
   sure that it changes appropriately */
static void
theme_changed_cb (GtkIconTheme * theme, gpointer user_data)
{
	GtkImage * image = GTK_IMAGE(user_data);
	refresh_image(image);
	return;
}

/* Removes the signal on the theme that was calling update on this
   image. */
static void
image_destroyed_cb (GtkImage * image, gpointer user_data)
{
	g_signal_handlers_disconnect_by_func(gtk_icon_theme_get_default(), theme_changed_cb, image);
	return;
}

GtkImage *
indicator_image_helper (const gchar * name)
{
	g_return_val_if_fail(name != NULL, NULL);
	g_return_val_if_fail(name[0] != '\0', NULL);

	/* Build us a GIcon */
	GIcon * icon_names = g_themed_icon_new_with_default_fallbacks(name);
	g_return_val_if_fail(icon_names != NULL, NULL);

	/* Build us an image */
	GtkImage * image = GTK_IMAGE(gtk_image_new());

	if (image == NULL) {
		g_error("Unable to create image from pixbuf on icon name '%s'", name);
		g_object_unref(icon_names);
		return NULL;
	}

	/* Attach our names to the image */
	g_object_set_data_full(G_OBJECT(image), INDICATOR_NAMES_DATA, icon_names, g_object_unref);

	/* Put the pixbuf in */
	refresh_image(image);

	/* Connect to all changes */
	g_signal_connect(G_OBJECT(gtk_icon_theme_get_default()), "changed", G_CALLBACK(theme_changed_cb), image);
	g_signal_connect(G_OBJECT(image), "destroy", G_CALLBACK(image_destroyed_cb), NULL);

	/* Return our built image */
	return image;
}