/* See LICENSE file for copyright and license details. */
#include "common.h"

static char url_list_name[] = "text/uri-list";
static GtkTargetEntry url_list = {url_list_name, 0u, 0u};

static int dragging = 0;
static int drag_source_disabled = 0;
static int drag_x, drag_y;

static void
set_file_drag_source(GtkWidget *widget)
{
	gtk_drag_source_set(widget, GDK_BUTTON1_MASK, &url_list, 1u,
	                    GDK_ACTION_COPY | GDK_ACTION_MOVE | GDK_ACTION_LINK | GDK_ACTION_ASK);
}

static int
button_pressed(GtkWidget *widget, GdkEventButton *event, void *user)
{
	(void) user;
	if (event->button == 2u || (event->state & GDK_CONTROL_MASK)) {
		if (event->button == 1u) {
			gtk_drag_source_unset(widget);
			drag_source_disabled = 1;
		}
		dragging = 1;
		drag_x = (int)event->x_root;
		drag_y = (int)event->y_root;
	}
	return dragging;
}

static int
button_released(GtkWidget *widget, GdkEventButton *event, void *user)
{
	(void) event;
	(void) user;
	dragging = 0;
	if (drag_source_disabled) {
		set_file_drag_source(widget);
		drag_source_disabled = 0;
	}
	return 0;
}

static int
pointer_moved(GtkWidget *widget, GdkEventMotion *event, void *user)
{
	int x, y;
	(void) event;
	(void) user;
	if (dragging) {
		gdk_display_get_pointer(gtk_widget_get_display(widget), NULL, &x, &y, NULL);
		scroll_by(drag_x - x, drag_y - y);
		drag_x = x;
		drag_y = y;
	}
	return dragging;
}

static void
drag_begin(GtkWidget *widget, GdkDragContext *context, void *user)
{
	GdkPixbuf *image, *icon;
	intmax_t height, width;

	(void) widget;
	(void) user;

	image = get_original_image();
	if (!image)
		return;

	width = gdk_pixbuf_get_width(image);
	height = gdk_pixbuf_get_height(image);
	if (width <= DRAG_ICON_SIZE && height <= DRAG_ICON_SIZE) {
		gtk_drag_set_icon_pixbuf(context, image, 0, 0);
		return;
	}
	if (width >= height) {
		height = height * DRAG_ICON_SIZE / width;
		height = MAX(1, height);
		width = DRAG_ICON_SIZE;
	} else {
		width = width * DRAG_ICON_SIZE / height;
		width = MAX(1, width);
		height = DRAG_ICON_SIZE;
	}
	icon = gdk_pixbuf_scale_simple(image, (int)width, (int)height, GDK_INTERP_BILINEAR);
	if (!icon)
		return;
	gtk_drag_set_icon_pixbuf(context, icon, 0, 0);
	g_object_unref(icon);
}

static void
drag_data_get(GtkWidget *widget, GdkDragContext *context, GtkSelectionData *data,
              unsigned int info, unsigned int time, void *user)
{
	struct file *file = get_file();
	GError *error = NULL;
	char *uri;

	(void) widget;
	(void) context;
	(void) info;
	(void) time;
	(void) user;

	if (!file || !file->path)
		return;

	uri = g_filename_to_uri(file->path, NULL, &error);
	if (!uri) {
		weprintf("g_filename_to_uri: %s", error->message);
		g_error_free(error);
		return;
	}
	gtk_selection_data_set_uris(data, (char *[]){uri, NULL});
	g_free(uri);
}

void
set_up_dragging(void)
{
	set_file_drag_source(display_area);

	g_signal_connect(display_area, "button-press-event", G_CALLBACK(&button_pressed), NULL);
	g_signal_connect(display_area, "button-release-event", G_CALLBACK(&button_released), NULL);
	g_signal_connect(display_area, "motion-notify-event", G_CALLBACK(&pointer_moved), NULL);

	g_signal_connect(display_area, "drag-begin", G_CALLBACK(&drag_begin), NULL);
	g_signal_connect(display_area, "drag-data-get", G_CALLBACK(&drag_data_get), NULL);
}