/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8; coding: utf-8 -*- */
/*
 * This file is part of GtkSourceView
 *
 * Copyright (C) 2013, 2014, 2016 - Sébastien Wilmet <swilmet@gnome.org>
 *
 * GtkSourceView 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 2.1 of the License, or (at your option) any later version.
 *
 * GtkSourceView 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 this library; if not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Custom sizing of the scrolled window containing the GtkTreeView containing
 * the completion proposals. If the GtkTreeView is small enough, the scrolled
 * window returns the natural size of the GtkTreeView. If it exceeds a certain
 * size, the scrolled window returns a smaller size, with the height at a row
 * boundary of the GtkTreeView.
 *
 * The purpose is to have a compact completion window, with a certain size
 * limit.
 */

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

#include "gtksourcecompletioncontainer.h"

#define UNREALIZED_WIDTH  350
#define MAX_HEIGHT        180

G_DEFINE_TYPE (GtkSourceCompletionContainer,
	       _gtk_source_completion_container,
	       GTK_TYPE_SCROLLED_WINDOW);

static gint
get_max_width (GtkSourceCompletionContainer *container)
{
	if (gtk_widget_get_realized (GTK_WIDGET (container)))
	{
		GtkWidget *toplevel;
		GdkWindow *window;
		GdkScreen *screen;
		gint max_width;
		gint xorigin;

		toplevel = gtk_widget_get_toplevel (GTK_WIDGET (container));
		window = gtk_widget_get_window (toplevel);
		screen = gdk_window_get_screen (window);

		gdk_window_get_origin (window, &xorigin, NULL);
		max_width = gdk_screen_get_width (screen) - xorigin;

		return MAX (max_width, UNREALIZED_WIDTH);
	}

	return UNREALIZED_WIDTH;
}

static void
_gtk_source_completion_container_get_preferred_width (GtkWidget *widget,
						      gint      *min_width,
						      gint      *nat_width)
{
	GtkSourceCompletionContainer *container = GTK_SOURCE_COMPLETION_CONTAINER (widget);
	GtkWidget *child;
	GtkRequisition nat_size;
	gint width;

	child = gtk_bin_get_child (GTK_BIN (container));
	gtk_widget_get_preferred_size (child, NULL, &nat_size);

	width = MIN (nat_size.width, get_max_width (container));

	if (GTK_WIDGET_CLASS (_gtk_source_completion_container_parent_class)->get_preferred_width != NULL)
	{
		gint min_width_parent = 0;

		GTK_WIDGET_CLASS (_gtk_source_completion_container_parent_class)->get_preferred_width (widget,
												       &min_width_parent,
												       NULL);

		width = MAX (width, min_width_parent);
	}

	if (min_width != NULL)
	{
		*min_width = width;
	}

	if (nat_width != NULL)
	{
		*nat_width = width;
	}

	g_return_if_fail (width >= 0);
}

static gint
get_row_height (GtkSourceCompletionContainer *container,
		gint                          tree_view_height)
{
	GtkWidget *tree_view;
	GtkTreeModel *model;
	gint nb_rows;

	/* For another possible implementation, see gtkentrycompletion.c in the
	 * GTK+ source code (the _gtk_entry_completion_resize_popup() function).
	 * It uses gtk_tree_view_column_cell_get_size() for retrieving the
	 * height, plus gtk_widget_style_get() to retrieve the
	 * "vertical-separator" height (note that the vertical separator must
	 * probably be counted one less time than the number or rows).
	 * But using that technique is buggy, it returns a smaller height (it's
	 * maybe a bug in GtkTreeView, or there are other missing parameters).
	 *
	 * Note that the following implementation doesn't take into account
	 * "vertical-separator". If there are some sizing bugs, it's maybe the
	 * source of the problem. (note that on my system the separator size was
	 * 0).
	 */

	tree_view = gtk_bin_get_child (GTK_BIN (container));
	model = gtk_tree_view_get_model (GTK_TREE_VIEW (tree_view));

	if (model == NULL)
	{
		return 0;
	}

	nb_rows = gtk_tree_model_iter_n_children (model, NULL);

	if (nb_rows == 0)
	{
		return 0;
	}

	return tree_view_height / nb_rows;
}

/* Return a height at a row boundary of the GtkTreeView. */
static void
_gtk_source_completion_container_get_preferred_height (GtkWidget *widget,
						       gint	 *min_height,
						       gint	 *nat_height)
{
	GtkSourceCompletionContainer *container = GTK_SOURCE_COMPLETION_CONTAINER (widget);
	GtkWidget *child;
	GtkRequisition nat_size;
	gint height;

	child = gtk_bin_get_child (GTK_BIN (container));
	gtk_widget_get_preferred_size (child, NULL, &nat_size);

	if (nat_size.height <= MAX_HEIGHT)
	{
		height = nat_size.height;
	}
	else
	{
		gint row_height = get_row_height (container, nat_size.height);
		gint n_rows_allowed = row_height != 0 ? MAX_HEIGHT / row_height : 0;

		height = n_rows_allowed * row_height;
	}

	if (GTK_WIDGET_CLASS (_gtk_source_completion_container_parent_class)->get_preferred_height != NULL)
	{
		gint min_height_parent = 0;

		GTK_WIDGET_CLASS (_gtk_source_completion_container_parent_class)->get_preferred_height (widget,
													&min_height_parent,
													NULL);

		height = MAX (height, min_height_parent);
	}

	if (min_height != NULL)
	{
		*min_height = height;
	}

	if (nat_height != NULL)
	{
		*nat_height = height;
	}

	g_return_if_fail (height >= 0);
}

static void
_gtk_source_completion_container_class_init (GtkSourceCompletionContainerClass *klass)
{
	GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

	widget_class->get_preferred_width = _gtk_source_completion_container_get_preferred_width;
	widget_class->get_preferred_height = _gtk_source_completion_container_get_preferred_height;
}

static void
_gtk_source_completion_container_init (GtkSourceCompletionContainer *container)
{
}

GtkSourceCompletionContainer *
_gtk_source_completion_container_new (void)
{
	return g_object_new (GTK_SOURCE_TYPE_COMPLETION_CONTAINER, NULL);
}