#include <glib-object.h>
#include <gtk/gtk.h>
#include <string.h>
#include <stdlib.h>

#include "gm-text-scroller.h"
#include "gm-debug.h"
#include "gm-support.h"

#define GM_TEXT_SCROLLER_GET_PRIVATE(object)(G_TYPE_INSTANCE_GET_PRIVATE((object),	GM_TYPE_TEXT_SCROLLER, GmTextScrollerPrivate))

struct _GmTextScrollerPrivate {
	GtkTextView *text_view;
	GtkTextBuffer *text_buffer;
	GtkScrolledWindow *scrolled_window;
	
	gint character_height;
	gboolean end_scrolled;
	gint idle_handler;
	
	GtkAllocation allocation;
};

void on_gm_text_scroller_text_view_style_set(GtkTextView *view, 
		GtkStyle *previous_style, GmTextScroller *scroller);
void on_gm_text_scroller_text_buffer_changed(GtkTextBuffer *text_buffer, 
		GmTextScroller *scroller);
void on_gm_text_scroller_text_view_notify(GtkTextView *text_view, GParamSpec *arg1,
		GmTextScroller *scroller);
void on_gm_text_scroller_text_view_destroy(GtkTextView *text_view, 
		GmTextScroller *scroller);

/* Signals

enum {
	PROTO
	NUM_SIGNALS
};

static guint gm_text_scroller_signals[NUM_SIGNALS] = {0};*/

G_DEFINE_TYPE(GmTextScroller, gm_text_scroller, G_TYPE_OBJECT)

static void
gm_text_scroller_finalize(GObject *object) {
	GmTextScroller *obj = GM_TEXT_SCROLLER(object);

	if (obj->priv->text_buffer != NULL) {
		g_signal_handlers_disconnect_by_func(obj->priv->text_buffer,
				G_CALLBACK(on_gm_text_scroller_text_buffer_changed), 
				obj);

		g_object_unref(obj->priv->text_buffer);
	}
	
	if (obj->priv->idle_handler) {
		g_source_remove(obj->priv->idle_handler);
	}
	
	g_signal_handlers_disconnect_by_func(obj->priv->text_view,
			G_CALLBACK(on_gm_text_scroller_text_view_notify), obj);
	g_signal_handlers_disconnect_by_func(obj->priv->text_view,
			G_CALLBACK(on_gm_text_scroller_text_view_style_set), obj);
	g_signal_handlers_disconnect_by_func(obj->priv->text_view,
			G_CALLBACK(on_gm_text_scroller_text_view_destroy), obj);

	G_OBJECT_CLASS(gm_text_scroller_parent_class)->finalize(object);
}

static void
gm_text_scroller_class_init(GmTextScrollerClass *klass) {
	GObjectClass *object_class = G_OBJECT_CLASS(klass);
	
	object_class->finalize = gm_text_scroller_finalize;

	/*gm_text_scroller_signals[PROTO] = 
		g_signal_new("proto",
			G_OBJECT_CLASS_TYPE(object_class),
			G_SIGNAL_RUN_LAST,
			G_STRUCT_OFFSET(GmTextScrollerClass, proto),
			NULL, NULL,
			g_cclosure_marshal_VOID__VOID,
			G_TYPE_NONE,
			0);*/
				
	g_type_class_add_private(object_class, sizeof(GmTextScrollerPrivate));
}

static void
gm_text_scroller_init(GmTextScroller *obj) {
	obj->priv = GM_TEXT_SCROLLER_GET_PRIVATE(obj);
	
	obj->priv->character_height = 10;
	obj->priv->end_scrolled = FALSE;
}

void
gm_text_scroller_update_text_buffer(GmTextScroller *scroller) {
	if (scroller->priv->text_buffer != NULL) {
		g_signal_handlers_disconnect_by_func(scroller->priv->text_buffer,
				G_CALLBACK(on_gm_text_scroller_text_buffer_changed), 
				scroller);

		g_object_unref(scroller->priv->text_buffer);
	}
	
	scroller->priv->text_buffer = 
			gtk_text_view_get_buffer(scroller->priv->text_view);
	
	if (scroller->priv->text_buffer != NULL) {
		g_object_ref(scroller->priv->text_buffer);
		
		g_signal_connect(scroller->priv->text_buffer, "changed",
				G_CALLBACK(on_gm_text_scroller_text_buffer_changed), scroller);
	}
	
}

void
gm_text_scroller_scroll_end(GmTextScroller *scroller) {
	GtkTextMark *mark;
	GtkTextIter iter;
	
	g_return_if_fail(GTK_IS_TEXT_BUFFER(scroller->priv->text_buffer));
	
	mark = gtk_text_buffer_get_mark(scroller->priv->text_buffer, 
			"end-of-buffer");
  
	if (mark == NULL) {
		gtk_text_buffer_get_end_iter(scroller->priv->text_buffer, &iter);
		mark = gtk_text_buffer_create_mark(scroller->priv->text_buffer, 
				"end-of-buffer", &iter, FALSE);
	}
  
	gtk_text_view_scroll_to_mark(scroller->priv->text_view, mark, 0.0, 
				TRUE, 1.0, 1.0);
}

void
gm_text_scroller_scroll_begin(GmTextScroller *scroller) {
	GtkTextMark *mark;
	GtkTextIter iter;
	
	g_return_if_fail(GTK_IS_TEXT_BUFFER(scroller->priv->text_buffer));

	mark = gtk_text_buffer_get_mark(scroller->priv->text_buffer, 
			"begin-of-buffer");
  
	if (mark == NULL) {
		gtk_text_buffer_get_start_iter(scroller->priv->text_buffer, &iter);
		mark = gtk_text_buffer_create_mark(scroller->priv->text_buffer, 
				"begin-of-buffer", &iter, TRUE);
	}
  
	gtk_text_view_scroll_to_mark(scroller->priv->text_view, mark, 0.0, 
				TRUE, 0.0, 0.0);
}

gboolean
gm_text_scroller_scroll_end_idle(GmTextScroller *scroller) {
	scroller->priv->idle_handler = 0;
	gm_text_scroller_scroll_end(scroller);
	scroller->priv->end_scrolled = FALSE;
	
	return FALSE;
}


gboolean
gm_text_scroller_is_end_scrolled_margin(GmTextScroller *scroller,
		gint margin) {
	GtkAdjustment *ad = gtk_scrolled_window_get_vadjustment(
			scroller->priv->scrolled_window);

	return scroller->priv->end_scrolled ||
			((ad->page_size + ad->value) >= ad->upper - 
			(double)(scroller->priv->character_height) - margin);
}

gboolean
gm_text_scroller_is_end_scrolled(GmTextScroller *scroller) {
	return gm_text_scroller_is_end_scrolled_margin(scroller, 0);
}

void
gm_text_scroller_prepare(GmTextScroller *scroller) {
	scroller->priv->end_scrolled = gm_text_scroller_is_end_scrolled(scroller);
	
	if (scroller->priv->idle_handler == 0 && scroller->priv->end_scrolled) {
		gm_text_scroller_scroll_end(scroller);
		
		// Ensure the end scroll for large texts
		scroller->priv->idle_handler = g_idle_add((GSourceFunc)
				gm_text_scroller_scroll_end_idle, scroller);
	}
}

void
gm_text_scroller_update_character_height(GmTextScroller *scroller) {
	GtkRcStyle *style = gtk_widget_get_modifier_style(GTK_WIDGET(
			scroller->priv->text_view));
	PangoContext *pc = gtk_widget_create_pango_context(GTK_WIDGET(
			scroller->priv->text_view));
	PangoLayout *pl;
	gint cwidth, cheight;

	if (style->font_desc != NULL) {
		pango_context_set_font_description(pc, style->font_desc);
		pl = pango_layout_new(pc);

		pango_layout_set_text(pl, "G", 1);
		pango_layout_get_pixel_size(pl, &(cwidth), 
				&(cheight));

		if (scroller->priv->character_height != cheight) {
			scroller->priv->character_height = cheight;
		}

		g_object_unref(pl);
	}

	g_object_unref(pc);
}

void
on_gm_text_scroller_text_view_size_allocate(GtkWidget *widget,
		GtkAllocation *allocation, GmTextScroller *scroller) {
	if (gm_text_scroller_is_end_scrolled_margin(scroller, 
			abs(allocation->height - scroller->priv->allocation.height))) {
		if (scroller->priv->idle_handler == 0) {
			gm_text_scroller_scroll_end(scroller);
		
			// Ensure the end scroll for large texts
			scroller->priv->idle_handler = g_idle_add((GSourceFunc)
					gm_text_scroller_scroll_end_idle, scroller);
		}
	}
	
	scroller->priv->allocation = *allocation;
}

GmTextScroller *
gm_text_scroller_new(GtkTextView *text_view) {
	GmTextScroller *obj;
	GtkWidget *parent = gtk_widget_get_parent(GTK_WIDGET(text_view));
	
	if (parent == NULL || !GTK_IS_SCROLLED_WINDOW(parent)) {
		return NULL;
	}
	
	obj = GM_TEXT_SCROLLER(g_object_new(GM_TYPE_TEXT_SCROLLER, 
			NULL));
	
	obj->priv->text_view = text_view;
	obj->priv->scrolled_window = GTK_SCROLLED_WINDOW(parent);
	
	obj->priv->allocation = (GTK_WIDGET(text_view)->allocation);
	
	gm_text_scroller_update_text_buffer(obj);
	gm_text_scroller_update_character_height(obj);
	
	g_signal_connect(text_view, "notify::buffer", 
			G_CALLBACK(on_gm_text_scroller_text_view_notify), obj);
	g_signal_connect(text_view, "style-set", 
			G_CALLBACK(on_gm_text_scroller_text_view_style_set), obj);
	g_signal_connect(text_view, "destroy",
			G_CALLBACK(on_gm_text_scroller_text_view_destroy), obj);
	
	g_signal_connect(text_view, "size-allocate",
			G_CALLBACK(on_gm_text_scroller_text_view_size_allocate), obj);

	obj->priv->idle_handler = g_idle_add((GSourceFunc)
			gm_text_scroller_scroll_end_idle, obj);

	return obj;
}

void
gm_text_scroller_scroll_page(GmTextScroller *scroller, gint direction) {
	GtkScrolledWindow *srl = scroller->priv->scrolled_window;
	GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(srl);
	double value = adj->value + (adj->page_size * direction);

	if (value > adj->upper - adj->page_size) {
		gtk_adjustment_set_value(adj, adj->upper - adj->page_size);
	} else if (value < adj->lower) {
		gtk_adjustment_set_value(adj, adj->lower);
	} else {
		gtk_adjustment_set_value(adj, value);
	}
}

// Callbacks

void
on_gm_text_scroller_text_view_notify(GtkTextView *text_view, GParamSpec *arg1,
		GmTextScroller *scroller) {
	// Buffer changed
	gm_text_scroller_update_text_buffer(scroller);
}

void
on_gm_text_scroller_text_view_style_set(GtkTextView *view, 
		GtkStyle *previous_style, GmTextScroller *scroller) {
		
	g_return_if_fail(GM_IS_TEXT_SCROLLER(scroller));
	
	gm_text_scroller_update_character_height(scroller);
}

void
on_gm_text_scroller_text_buffer_changed(GtkTextBuffer *text_buffer, 
		GmTextScroller *scroller) {
		
	g_return_if_fail(GM_IS_TEXT_SCROLLER(scroller));
	
	gm_text_scroller_prepare(scroller);
}

void
on_gm_text_scroller_text_view_destroy(GtkTextView *text_view, 
		GmTextScroller *scroller) {
	// Remove ourselfs when the text view dies
	
	g_object_unref(scroller);
}