/*
 * This program 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 2 of the License, or (at your option) version 3.
 *
 * 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 *
 * Authors:
 *		Damon Chaplin <damon@ximian.com>
 *		Bolian Yin <bolian.yin@sun.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 */

/*
 * ECalendar - displays a table of monthly calendars, allowing highlighting
 * and selection of one or more days. Like GtkCalendar with more features.
 * Most of the functionality is in the ECalendarItem canvas item, though
 * we also add GnomeCanvasWidget buttons to go to the previous/next month and
 * to got to the current day.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "e-calendar.h"

#include <gtk/gtk.h>
#include <libgnomecanvas/gnome-canvas-widget.h>
#include <glib/gi18n.h>

#define E_CALENDAR_SMALL_FONT_PTSIZE 6

#define E_CALENDAR_SMALL_FONT	\
	"-adobe-utopia-regular-r-normal-*-*-100-*-*-p-*-iso8859-*"
#define E_CALENDAR_SMALL_FONT_FALLBACK	\
	"-adobe-helvetica-medium-r-normal-*-*-80-*-*-p-*-iso8859-*"

/* The space between the arrow buttons and the edge of the widget. */
#define E_CALENDAR_ARROW_BUTTON_X_PAD	2
#define E_CALENDAR_ARROW_BUTTON_Y_PAD	0

/* Vertical padding. The padding above the button includes the space for the
   horizontal line. */
#define	E_CALENDAR_YPAD_ABOVE_LOWER_BUTTONS		4
#define	E_CALENDAR_YPAD_BELOW_LOWER_BUTTONS		3

/* Horizontal padding inside & between buttons. */
#define E_CALENDAR_IXPAD_BUTTONS			4
#define E_CALENDAR_XPAD_BUTTONS				8

/* The time between steps when the prev/next buttons is pressed, in 1/1000ths
   of a second, and the number of timeouts we skip before we start
   automatically moving back/forward. */
#define E_CALENDAR_AUTO_MOVE_TIMEOUT		150
#define E_CALENDAR_AUTO_MOVE_TIMEOUT_DELAY	2

static void e_calendar_destroy		(GtkObject	*object);
static void e_calendar_realize		(GtkWidget	*widget);
static void e_calendar_style_set	(GtkWidget	*widget,
					 GtkStyle	*previous_style);
static void e_calendar_size_request	(GtkWidget      *widget,
					 GtkRequisition *requisition);
static void e_calendar_size_allocate	(GtkWidget	*widget,
					 GtkAllocation	*allocation);
static gint e_calendar_drag_motion	(GtkWidget      *widget,
					 GdkDragContext *context,
					 gint            x,
					 gint            y,
					 guint           time);
static void e_calendar_drag_leave	(GtkWidget      *widget,
					 GdkDragContext *context,
					 guint           time);
static gboolean e_calendar_button_has_focus (ECalendar	*cal);
static gboolean e_calendar_focus (GtkWidget *widget,
				  GtkDirectionType direction);

static void e_calendar_on_prev_pressed	(ECalendar	*cal);
static void e_calendar_on_prev_released	(ECalendar	*cal);
static void e_calendar_on_prev_clicked  (ECalendar      *cal);
static void e_calendar_on_next_pressed	(ECalendar	*cal);
static void e_calendar_on_next_released	(ECalendar	*cal);
static void e_calendar_on_next_clicked  (ECalendar      *cal);

static void e_calendar_start_auto_move	(ECalendar	*cal,
					 gboolean	 moving_forward);
static gboolean e_calendar_auto_move_handler	(gpointer	 data);
static void e_calendar_stop_auto_move	(ECalendar	*cal);

G_DEFINE_TYPE (
	ECalendar,
	e_calendar,
	E_TYPE_CANVAS)

static void
e_calendar_class_init (ECalendarClass *class)
{
	GtkObjectClass *object_class;
	GtkWidgetClass *widget_class;

	object_class = (GtkObjectClass *) class;
	widget_class = (GtkWidgetClass *) class;

	object_class->destroy = e_calendar_destroy;

	widget_class->realize		   = e_calendar_realize;
	widget_class->style_set		   = e_calendar_style_set;
	widget_class->size_request	   = e_calendar_size_request;
	widget_class->size_allocate	   = e_calendar_size_allocate;
	widget_class->drag_motion	   = e_calendar_drag_motion;
	widget_class->drag_leave	   = e_calendar_drag_leave;
	widget_class->focus                = e_calendar_focus;
}

static void
e_calendar_init (ECalendar *cal)
{
	GnomeCanvasGroup *canvas_group;
	PangoFontDescription *small_font_desc;
	GtkWidget *button, *pixmap;
	AtkObject *a11y;

	/* Create the small font. */

	small_font_desc =
		pango_font_description_copy (gtk_widget_get_style (GTK_WIDGET (cal))->font_desc);
	pango_font_description_set_size (small_font_desc,
					 E_CALENDAR_SMALL_FONT_PTSIZE * PANGO_SCALE);

	canvas_group = GNOME_CANVAS_GROUP (GNOME_CANVAS (cal)->root);

	cal->calitem = E_CALENDAR_ITEM (gnome_canvas_item_new (canvas_group,
							       e_calendar_item_get_type (),
							       "week_number_font_desc", small_font_desc,
							       NULL));

	pango_font_description_free (small_font_desc);

	/* Create the arrow buttons to move to the previous/next month. */
	button = gtk_button_new ();
	gtk_button_set_relief (GTK_BUTTON (button), GTK_RELIEF_NONE);
	gtk_widget_show (button);
	g_signal_connect_swapped (
		button, "pressed",
		G_CALLBACK (e_calendar_on_prev_pressed), cal);
	g_signal_connect_swapped (
		button, "released",
		G_CALLBACK (e_calendar_on_prev_released), cal);
	g_signal_connect_swapped (
		button, "clicked",
		G_CALLBACK (e_calendar_on_prev_clicked), cal);

	pixmap = gtk_arrow_new (GTK_ARROW_LEFT, GTK_SHADOW_NONE);
	gtk_widget_show (pixmap);
	gtk_container_add (GTK_CONTAINER (button), pixmap);

	cal->prev_item = gnome_canvas_item_new (canvas_group,
						gnome_canvas_widget_get_type (),
						"widget", button,
						NULL);
	a11y = gtk_widget_get_accessible (button);
	atk_object_set_name (a11y, _("Previous"));

	button = gtk_button_new ();
	gtk_button_set_relief (GTK_BUTTON (button), GTK_RELIEF_NONE);
	gtk_widget_show (button);
	g_signal_connect_swapped (
		button, "pressed",
		G_CALLBACK (e_calendar_on_next_pressed), cal);
	g_signal_connect_swapped (
		button, "released",
		G_CALLBACK (e_calendar_on_next_released), cal);
	g_signal_connect_swapped (
		button, "clicked",
		G_CALLBACK (e_calendar_on_next_clicked), cal);

	pixmap = gtk_arrow_new (GTK_ARROW_RIGHT, GTK_SHADOW_NONE);
	gtk_widget_show (pixmap);
	gtk_container_add (GTK_CONTAINER (button), pixmap);

	cal->next_item = gnome_canvas_item_new (canvas_group,
						gnome_canvas_widget_get_type (),
						"widget", button,
						NULL);
	a11y = gtk_widget_get_accessible (button);
	atk_object_set_name (a11y, _("Next"));

	cal->min_rows = 1;
	cal->min_cols = 1;
	cal->max_rows = -1;
	cal->max_cols = -1;

	cal->timeout_id = 0;
}

/**
 * e_calendar_new:
 * @Returns: a new #ECalendar.
 *
 * Creates a new #ECalendar.
 **/
GtkWidget *
e_calendar_new			(void)
{
	GtkWidget *cal;
	AtkObject *a11y;

	cal = g_object_new (e_calendar_get_type (), NULL);
	a11y = gtk_widget_get_accessible (cal);
	atk_object_set_name (a11y, _("Month Calendar"));

	return cal;
}

static void
e_calendar_destroy		(GtkObject *object)
{
	ECalendar *cal;

	g_return_if_fail (object != NULL);
	g_return_if_fail (E_IS_CALENDAR (object));

	cal = E_CALENDAR (object);

	if (cal->timeout_id != 0) {
		g_source_remove (cal->timeout_id);
		cal->timeout_id = 0;
	}

	if (GTK_OBJECT_CLASS (e_calendar_parent_class)->destroy)
		(* GTK_OBJECT_CLASS (e_calendar_parent_class)->destroy) (object);
}

static void
e_calendar_realize (GtkWidget *widget)
{
	GtkStyle *style;
	GdkWindow *window;

	(*GTK_WIDGET_CLASS (e_calendar_parent_class)->realize) (widget);

	/* Set the background of the canvas window to the normal color,
	   or the arrow buttons are not displayed properly. */
	style = gtk_widget_get_style (widget);
	window = gtk_layout_get_bin_window (GTK_LAYOUT (widget));
	gdk_window_set_background (window, &style->bg[GTK_STATE_NORMAL]);
}

static void
e_calendar_style_set		(GtkWidget	*widget,
				 GtkStyle	*previous_style)
{
	ECalendar *e_calendar;

	e_calendar = E_CALENDAR (widget);
	if (GTK_WIDGET_CLASS (e_calendar_parent_class)->style_set)
		(*GTK_WIDGET_CLASS (e_calendar_parent_class)->style_set) (widget,
							       previous_style);

	/* Set the background of the canvas window to the normal color,
	   or the arrow buttons are not displayed properly. */
	if (gtk_widget_get_realized (widget)) {
		GtkStyle *style;
		GdkWindow *window;

		style = gtk_widget_get_style (widget);
		window = gtk_layout_get_bin_window (GTK_LAYOUT (widget));
		gdk_window_set_background (window, &style->bg[GTK_STATE_NORMAL]);
	}
	e_calendar_item_style_set (widget, e_calendar->calitem);
}

static void
e_calendar_size_request		(GtkWidget      *widget,
				 GtkRequisition *requisition)
{
	ECalendar *cal;
	GtkStyle *style;
	gint col_width, row_height, width, height;

	cal = E_CALENDAR (widget);
	style = gtk_widget_get_style (GTK_WIDGET (cal));

	g_object_get ((cal->calitem),
			"row_height", &row_height,
			"column_width", &col_width,
			NULL);

	height = row_height * cal->min_rows;
	width = col_width * cal->min_cols;

	requisition->width = width + style->xthickness * 2;
	requisition->height = height + style->ythickness * 2;
}

static void
e_calendar_size_allocate	(GtkWidget	*widget,
				 GtkAllocation	*allocation)
{
	ECalendar *cal;
	GtkStyle *style;
	GtkAllocation old_allocation;
	PangoFontDescription *font_desc;
	PangoContext *pango_context;
	PangoFontMetrics *font_metrics;
	gdouble old_x2, old_y2, new_x2, new_y2;
	gdouble xthickness, ythickness, arrow_button_size;

	cal = E_CALENDAR (widget);
	style = gtk_widget_get_style (widget);
	xthickness = style->xthickness;
	ythickness = style->ythickness;

	(*GTK_WIDGET_CLASS (e_calendar_parent_class)->size_allocate) (widget, allocation);

	/* Set up Pango prerequisites */
	font_desc = gtk_widget_get_style (widget)->font_desc;
	pango_context = gtk_widget_get_pango_context (widget);
	font_metrics = pango_context_get_metrics (pango_context, font_desc,
						  pango_context_get_language (pango_context));

	/* Set the scroll region to its allocated size, if changed. */
	gnome_canvas_get_scroll_region (GNOME_CANVAS (cal),
					NULL, NULL, &old_x2, &old_y2);
	gtk_widget_get_allocation (widget, &old_allocation);
	new_x2 = old_allocation.width - 1;
	new_y2 = old_allocation.height - 1;
	if (old_x2 != new_x2 || old_y2 != new_y2)
		gnome_canvas_set_scroll_region (GNOME_CANVAS (cal),
						0, 0, new_x2, new_y2);

	/* Take off space for line & buttons if shown. */
	gnome_canvas_item_set (GNOME_CANVAS_ITEM (cal->calitem),
			       "x1", 0.0,
			       "y1", 0.0,
			       "x2", new_x2,
			       "y2", new_y2,
			       NULL);

	/* Position the arrow buttons. */
	arrow_button_size =
		PANGO_PIXELS (pango_font_metrics_get_ascent (font_metrics))
		+ PANGO_PIXELS (pango_font_metrics_get_descent (font_metrics))
		+ E_CALENDAR_ITEM_YPAD_ABOVE_MONTH_NAME
		+ E_CALENDAR_ITEM_YPAD_BELOW_MONTH_NAME
		- E_CALENDAR_ARROW_BUTTON_Y_PAD * 2;

	gnome_canvas_item_set (cal->prev_item,
			       "x", (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL)
			       ? new_x2 + 1 - xthickness * 2 - E_CALENDAR_ARROW_BUTTON_X_PAD
				 - arrow_button_size
			       : xthickness * 2 + E_CALENDAR_ARROW_BUTTON_X_PAD,
			       "y", ythickness * 2
			       + E_CALENDAR_ARROW_BUTTON_Y_PAD,
			       "width", arrow_button_size,
			       "height", arrow_button_size,
			       NULL);

	gnome_canvas_item_set (cal->next_item,
			       "x", (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL)
			       ? xthickness * 2 + E_CALENDAR_ARROW_BUTTON_X_PAD
			       : new_x2 + 1 - xthickness * 2 - E_CALENDAR_ARROW_BUTTON_X_PAD
				 - arrow_button_size,
			       "y", ythickness * 2
			       + E_CALENDAR_ARROW_BUTTON_Y_PAD,
			       "width", arrow_button_size,
			       "height", arrow_button_size,
			       NULL);

	pango_font_metrics_unref (font_metrics);
}

void
e_calendar_set_minimum_size	(ECalendar	*cal,
				 gint		 rows,
				 gint		 cols)
{
	g_return_if_fail (E_IS_CALENDAR (cal));

	cal->min_rows = rows;
	cal->min_cols = cols;

	gnome_canvas_item_set (GNOME_CANVAS_ITEM (cal->calitem),
			       "minimum_rows", rows,
			       "minimum_columns", cols,
			       NULL);

	gtk_widget_queue_resize (GTK_WIDGET (cal));
}

void
e_calendar_set_maximum_size	(ECalendar	*cal,
				 gint		 rows,
				 gint		 cols)
{
	g_return_if_fail (E_IS_CALENDAR (cal));

	cal->max_rows = rows;
	cal->max_cols = cols;

	gnome_canvas_item_set (GNOME_CANVAS_ITEM (cal->calitem),
			       "maximum_rows", rows,
			       "maximum_columns", cols,
			       NULL);

	gtk_widget_queue_resize (GTK_WIDGET (cal));
}

/* Returns the border size on each side of the month displays. */
void
e_calendar_get_border_size	(ECalendar	*cal,
				 gint		*top,
				 gint		*bottom,
				 gint		*left,
				 gint		*right)
{
	GtkStyle *style;

	g_return_if_fail (E_IS_CALENDAR (cal));

	style = gtk_widget_get_style (GTK_WIDGET (cal));

	if (style) {
		*top    = style->ythickness;
		*bottom = style->ythickness;
		*left   = style->xthickness;
		*right  = style->xthickness;
	} else {
		*top = *bottom = *left = *right = 0;
	}
}

static void
e_calendar_on_prev_pressed	(ECalendar	*cal)
{
	e_calendar_start_auto_move (cal, FALSE);
}

static void
e_calendar_on_next_pressed	(ECalendar	*cal)
{
	e_calendar_start_auto_move (cal, TRUE);
}

static void
e_calendar_start_auto_move	(ECalendar	*cal,
				 gboolean	 moving_forward)
{
	if (cal->timeout_id == 0) {
		cal->timeout_id = g_timeout_add (E_CALENDAR_AUTO_MOVE_TIMEOUT,
						 e_calendar_auto_move_handler,
						 cal);
	}
	cal->timeout_delay = E_CALENDAR_AUTO_MOVE_TIMEOUT_DELAY;
	cal->moving_forward = moving_forward;

}

static gboolean
e_calendar_auto_move_handler	(gpointer	 data)
{
	ECalendar *cal;
	ECalendarItem *calitem;
	gint offset;

	g_return_val_if_fail (E_IS_CALENDAR (data), FALSE);

	cal = E_CALENDAR (data);
	calitem = cal->calitem;

	GDK_THREADS_ENTER ();

	if (cal->timeout_delay > 0) {
		cal->timeout_delay--;
	} else {
		offset = cal->moving_forward ? 1 : -1;
		e_calendar_item_set_first_month (calitem, calitem->year,
						 calitem->month + offset);
	}

	GDK_THREADS_LEAVE ();
	return TRUE;
}

static void
e_calendar_on_prev_released	(ECalendar	*cal)
{
	e_calendar_stop_auto_move (cal);
}

static void
e_calendar_on_next_released	(ECalendar	*cal)
{
	e_calendar_stop_auto_move (cal);
}

static void
e_calendar_stop_auto_move	(ECalendar	*cal)
{
	if (cal->timeout_id != 0) {
		g_source_remove (cal->timeout_id);
		cal->timeout_id = 0;
	}
}

static void
e_calendar_on_prev_clicked      (ECalendar      *cal)
{
	e_calendar_item_set_first_month (cal->calitem, cal->calitem->year,
		cal->calitem->month - 1);
}

static void
e_calendar_on_next_clicked      (ECalendar      *cal)
{
	e_calendar_item_set_first_month (cal->calitem, cal->calitem->year,
		cal->calitem->month + 1);
}

static gint
e_calendar_drag_motion (GtkWidget      *widget,
			GdkDragContext *context,
			gint            x,
			gint            y,
			guint           time)
{
#if 0
	g_print ("In e_calendar_drag_motion\n");
#endif

	return FALSE;
}

static void
e_calendar_drag_leave (GtkWidget      *widget,
		       GdkDragContext *context,
		       guint           time)
{
#if 0
	g_print ("In e_calendar_drag_leave\n");
#endif
}

static gboolean
e_calendar_button_has_focus (ECalendar	*cal)
{
	GtkWidget *prev_widget, *next_widget;
	gboolean ret_val;

	g_return_val_if_fail (E_IS_CALENDAR (cal), FALSE);

	prev_widget = GNOME_CANVAS_WIDGET (cal->prev_item)->widget;
	next_widget = GNOME_CANVAS_WIDGET (cal->next_item)->widget;
	ret_val = gtk_widget_has_focus (prev_widget) ||
		gtk_widget_has_focus (next_widget);
	return ret_val;
}

static gboolean
e_calendar_focus (GtkWidget *widget, GtkDirectionType direction)
{
#define E_CALENDAR_FOCUS_CHILDREN_NUM 3
	ECalendar *cal;
	GnomeCanvas *canvas;
	GnomeCanvasItem *children[E_CALENDAR_FOCUS_CHILDREN_NUM];
	gint focused_index = -1;
	gint index;

	g_return_val_if_fail (widget != NULL, FALSE);
	g_return_val_if_fail (E_IS_CALENDAR (widget), FALSE);
	cal = E_CALENDAR (widget);
	canvas = GNOME_CANVAS (widget);

	if (!gtk_widget_get_can_focus (widget))
		return FALSE;

	children[0] = GNOME_CANVAS_ITEM (cal->calitem);
	children[1] = cal->prev_item;
	children[2] = cal->next_item;

	/* get current focused item, if e-calendar has had focus */
	if (gtk_widget_has_focus (widget) || e_calendar_button_has_focus (cal))
		for (index = 0; index < E_CALENDAR_FOCUS_CHILDREN_NUM; ++index) {
			if (canvas->focused_item == NULL)
				break;

			if (children[index] == canvas->focused_item) {
				focused_index = index;
				break;
			}
		}

	if (focused_index == -1)
		if (direction == GTK_DIR_TAB_FORWARD)
			focused_index = 0;
		else
			focused_index = E_CALENDAR_FOCUS_CHILDREN_NUM - 1;
	else
		if (direction == GTK_DIR_TAB_FORWARD)
			++focused_index;
		else
			--focused_index;

	if (focused_index < 0 ||
	    focused_index >= E_CALENDAR_FOCUS_CHILDREN_NUM)
		/* move out of e-calendar */
		return FALSE;
	gnome_canvas_item_grab_focus (children[focused_index]);
	if (GNOME_IS_CANVAS_WIDGET (children[focused_index])) {
		widget = GNOME_CANVAS_WIDGET (children[focused_index])->widget;
		gtk_widget_grab_focus (widget);
	}
	return TRUE;
}

void
e_calendar_set_focusable (ECalendar *cal, gboolean focusable)
{
	GtkWidget *widget;
	GtkWidget *prev_widget, *next_widget;
	GtkWidget *toplevel;

	g_return_if_fail (E_IS_CALENDAR (cal));

	widget = GTK_WIDGET (cal);
	prev_widget = GNOME_CANVAS_WIDGET (cal->prev_item)->widget;
	next_widget = GNOME_CANVAS_WIDGET (cal->next_item)->widget;

	if (focusable) {
		gtk_widget_set_can_focus (widget, TRUE);
		gtk_widget_set_can_focus (prev_widget, TRUE);
		gtk_widget_set_can_focus (next_widget, TRUE);
	}
	else {
		if (gtk_widget_has_focus (GTK_WIDGET (cal)) || e_calendar_button_has_focus (cal)) {
			toplevel = gtk_widget_get_toplevel (widget);
			if (toplevel)
				gtk_widget_grab_focus (toplevel);
		}
		gtk_widget_set_can_focus (widget, FALSE);
		gtk_widget_set_can_focus (prev_widget, FALSE);
		gtk_widget_set_can_focus (next_widget, FALSE);
	}
}