#include <gtk/gtk.h>
#include <gdk/gdk.h>
#include <gdk/gdkwin32.h>
#include <string.h>

// drag-and-drop callback function
static void drag_data_received(GtkWidget *widget, GdkDragContext *context,
                               gint x, gint y, GtkSelectionData *selection_data,
                               guint info, guint time, gpointer user_data)
{
    GtkWidget *label = GTK_WIDGET(user_data);
    gchar **uris = NULL;
    gchar *data_str = NULL;
    GString *display_text = g_string_new("");
    gint i;
    
    // Security check
    if (!selection_data || selection_data->length <= 0) {
        gtk_label_set_text(GTK_LABEL(label), "Error: no data received.");
        gtk_drag_finish(context, FALSE, FALSE, time);
        g_string_free(display_text, TRUE);
        return;
    }
    
    // Check the data format
    GdkAtom target_type = gtk_selection_data_get_data_type(selection_data);
    gchar *type_name = gdk_atom_name(target_type);
    
    if (type_name == NULL || strcmp(type_name, "text/uri-list") != 0) {
        gtk_label_set_text(GTK_LABEL(label), "Error: Data format not supported");
        if (type_name) g_free(type_name);
        gtk_drag_finish(context, FALSE, FALSE, time);
        g_string_free(display_text, TRUE);
        return;
    }
    if (type_name) {
        g_free(type_name);
    }
    
    // Copy data
    data_str = g_strndup((gchar *)selection_data->data, selection_data->length);
    
    if (!data_str || strlen(data_str) == 0) {
        gtk_label_set_text(GTK_LABEL(label), "Error: Data is empty");
        if (data_str) {
            g_free(data_str);
        }
        gtk_drag_finish(context, FALSE, FALSE, time);
        g_string_free(display_text, TRUE);
        return;
    }
    
    // Extract URI
    uris = g_uri_list_extract_uris(data_str);
    
    if (uris != NULL && uris[0] != NULL) {
        gint file_count = 0;
        for (i = 0; uris[i] != NULL; i++) {
            gchar *filename = g_filename_from_uri(uris[i], NULL, NULL);
            if (filename != NULL) {
                if (file_count > 0){
                    g_string_append(display_text, "\n");
                }
                g_string_append_printf(display_text, "[%d] %s", file_count + 1, filename);
                g_free(filename);
                file_count++;
            }
        }
        
        if (file_count > 0) {
            gtk_label_set_text(GTK_LABEL(label), display_text->str);
            gtk_drag_finish(context, TRUE, FALSE, time);
        } else {
            gtk_label_set_text(GTK_LABEL(label), "No valid documents");
            gtk_drag_finish(context, FALSE, FALSE, time);
        }
        
        g_strfreev(uris);
    } else {
        gtk_label_set_text(GTK_LABEL(label), "Can't parse the file list");
        gtk_drag_finish(context, FALSE, FALSE, time);
    }
    
    // Clean
    if (data_str) {
        g_free(data_str);
    }
    g_string_free(display_text, TRUE);
}

static void drag_leave(GtkWidget *widget, GdkDragContext *context, guint time, gpointer user_data)
{
    
}

int main(int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *vbox;
    GtkWidget *label;
    GtkWidget *frame;
    GtkWidget *scrolled_window;
    
    gtk_init(&argc, &argv);
    
    // Create main window
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "GTK2 Program");
    gtk_window_set_default_size(GTK_WINDOW(window), 550, 350);
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
    
    // vbox
    vbox = gtk_vbox_new(FALSE, 10);
    gtk_container_set_border_width(GTK_CONTAINER(vbox), 20);
    gtk_container_add(GTK_CONTAINER(window), vbox);
    
    // Prompt Label
    GtkWidget *hint = gtk_label_new("Drag and drop files from the file manager into the area below");
    gtk_box_pack_start(GTK_BOX(vbox), hint, FALSE, FALSE, 0);
    
    // Create a scroll window
    scrolled_window = gtk_scrolled_window_new(NULL, NULL);
    gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(scrolled_window),
                                   GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC);
    gtk_box_pack_start(GTK_BOX(vbox), scrolled_window, TRUE, TRUE, 0);
    
    // Frame as a drag-and-drop target
    frame = gtk_frame_new("Drag and drop area");
    gtk_frame_set_shadow_type(GTK_FRAME(frame), GTK_SHADOW_IN);
    gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(scrolled_window), frame);
    
    // label used to display the path
    label = gtk_label_new("Waiting for the file to be dragged in...");
    gtk_label_set_line_wrap(GTK_LABEL(label), TRUE);
    gtk_label_set_justify(GTK_LABEL(label), GTK_JUSTIFY_LEFT);
    gtk_label_set_selectable(GTK_LABEL(label), TRUE);
    gtk_container_add(GTK_CONTAINER(frame), label);
    
    // Set drag-and-drop target
    GtkTargetEntry targets[] = {
        { (gchar *)"text/uri-list", 0, 0 },
        { (gchar *)"text/plain", 0, 1 },
    };
    
    // Use GTK_DEST_DEFAULT_ALL or individual values
    gtk_drag_dest_set(frame, 
                      GTK_DEST_DEFAULT_ALL,
                      targets, G_N_ELEMENTS(targets),
                      GDK_ACTION_COPY);
    
    // Connection signal
    g_signal_connect(frame, "drag-data-received",
                     G_CALLBACK(drag_data_received), label);
    g_signal_connect(frame, "drag-leave",
                     G_CALLBACK(drag_leave), NULL);
    
    // Show all controls
    gtk_widget_show_all(window);
    
    gtk_main();
    return 0;
}