/* Sliding puzzle
 *
 * This demo demonstrates how to use gestures and paintables to create a
 * small sliding puzzle game.
 *
 */

#include <gtk/gtk.h>

/* Include the header for the puzzle piece */
#include "puzzlepiece.h"
#include "paintable.h"

static GtkWidget *window = NULL;
static GtkWidget *frame = NULL;
static GtkWidget *choices = NULL;
static GtkWidget *size_spin = NULL;
static GdkPaintable *puzzle = NULL;

static gboolean solved = TRUE;
static guint width = 3;
static guint height = 3;
static guint pos_x;
static guint pos_y;

static gboolean
move_puzzle (GtkWidget *grid,
             int        dx,
             int        dy)
{
  GtkWidget *pos, *next;
  GdkPaintable *piece;
  guint next_x, next_y;

  /* We don't move anything if the puzzle is solved */
  if (solved)
    return FALSE;

  /* Return FALSE if we can't move to where the call 
   * wants us to move.
   */
  if ((dx < 0 && pos_x < -dx) ||
      dx + pos_x >= width ||
      (dy < 0 && pos_y < -dy) ||
      dy + pos_y >= height)
    return FALSE;

  /* Compute the new position */
  next_x = pos_x + dx;
  next_y = pos_y + dy;

  /* Get the current and next image */
  pos = gtk_grid_get_child_at (GTK_GRID (grid), pos_x, pos_y);
  next = gtk_grid_get_child_at (GTK_GRID (grid), next_x, next_y);

  /* Move the displayed piece. */
  piece = gtk_picture_get_paintable (GTK_PICTURE (next));
  gtk_picture_set_paintable (GTK_PICTURE (pos), piece);
  gtk_picture_set_paintable (GTK_PICTURE (next), NULL);

  /* Update the current position */
  pos_x = next_x;
  pos_y = next_y;

  /* Return TRUE because we successfully moved the piece */
  return TRUE;
}

static void
shuffle_puzzle (GtkWidget *grid)
{
  guint i, n_steps;

  /* Do this many random moves */
  n_steps = width * height * 50;

  for (i = 0; i < n_steps; i++)
    {
      /* Get a random number for the direction to move in */
      switch (g_random_int_range (0, 4))
        {
        case 0:
          /* left */
          move_puzzle (grid, -1, 0);
          break;

        case 1:
          /* up */
          move_puzzle (grid, 0, -1);
          break;

        case 2:
          /* right */
          move_puzzle (grid, 1, 0);
          break;

        case 3:
          /* down */
          move_puzzle (grid, 0, 1);
          break;

        default:
          g_assert_not_reached ();
          continue;
        }
    }
}

static gboolean
check_solved (GtkWidget *grid)
{
  GtkWidget *picture;
  GdkPaintable *piece;
  guint x, y;

  /* Nothing to check if the puzzle is already solved */
  if (solved)
    return TRUE;

  /* If the empty cell isn't in the bottom right,
   * the puzzle is obviously not solved */
  if (pos_x != width - 1 ||
      pos_y != height - 1)
    return FALSE;

  /* Check that all pieces are in the right position */
  for (y = 0; y < height; y++)
    {
      for (x = 0; x < width; x++)
        {
          picture = gtk_grid_get_child_at (GTK_GRID (grid), x, y);
          piece = gtk_picture_get_paintable (GTK_PICTURE (picture));

          /* empty cell */
          if (piece == NULL)
            continue;

          if (gtk_puzzle_piece_get_x (GTK_PUZZLE_PIECE (piece)) != x ||
              gtk_puzzle_piece_get_y (GTK_PUZZLE_PIECE (piece)) != y)
            return FALSE;
        }
    }

  /* We solved the puzzle!
   */
  solved = TRUE;

  /* Fill the empty cell to show that we're done.
   */
  picture = gtk_grid_get_child_at (GTK_GRID (grid), 0, 0);
  piece = gtk_picture_get_paintable (GTK_PICTURE (picture));

  piece = gtk_puzzle_piece_new (gtk_puzzle_piece_get_puzzle (GTK_PUZZLE_PIECE (piece)),
                                pos_x, pos_y,
                                width, height);
  picture = gtk_grid_get_child_at (GTK_GRID (grid), pos_x, pos_y);
  gtk_picture_set_paintable (GTK_PICTURE (picture), piece);

  return TRUE;
}

static gboolean
puzzle_key_pressed (GtkEventControllerKey *controller,
                    guint                  keyval,
                    guint                  keycode,
                    GdkModifierType        state,
                    GtkWidget             *grid)
{
  int dx, dy;

  dx = 0;
  dy = 0;

  switch (keyval)
    {
    case GDK_KEY_KP_Left:
    case GDK_KEY_Left:
      /* left */
      dx = -1;
      break;

    case GDK_KEY_KP_Up:
    case GDK_KEY_Up:
      /* up */
      dy = -1;
      break;

    case GDK_KEY_KP_Right:
    case GDK_KEY_Right:
      /* right */
      dx = 1;
      break;

    case GDK_KEY_KP_Down:
    case GDK_KEY_Down:
      /* down */
      dy = 1;
      break;

    default:
      /* We return FALSE here because we didn't handle the key that was pressed */
      return FALSE;
    }

  if (!move_puzzle (grid, dx, dy))
    {
      /* Make the error sound and then return TRUE.
       * We handled this key, even though we didn't
       * do anything to the puzzle.
       */
      gtk_widget_error_bell (grid);
      return TRUE;
    }

  check_solved (grid);

  return TRUE;
}

static void
puzzle_button_pressed (GtkGestureMultiPress *gesture,
                       int                   n_press,
                       double                x,
                       double                y,
                       GtkWidget            *grid)
{
  GtkWidget *child;
  int l, t, i;
  int pos;

  child = gtk_widget_pick (grid, x, y);

  if (!child)
    {
      gtk_widget_error_bell (grid);
      return;
    }

  gtk_container_child_get (GTK_CONTAINER (grid), child,
                           "left-attach", &l,
                           "top-attach", &t,
                           NULL);

  if (l == pos_x && t == pos_y)
    {
      gtk_widget_error_bell (grid);
    }
  else if (l == pos_x)
    {
      pos = pos_y;
      for (i = t; i < pos; i++)
        {
          if (!move_puzzle (grid, 0, -1))
            gtk_widget_error_bell (grid);
        }
      for (i = pos; i < t; i++)
        {
          if (!move_puzzle (grid, 0, 1))
            gtk_widget_error_bell (grid);
        }
    }
  else if (t == pos_y)
    {
      pos = pos_x;
      for (i = l; i < pos; i++)
        {
          if (!move_puzzle (grid, -1, 0))
            gtk_widget_error_bell (grid);
        }
      for (i = pos; i < l; i++)
        {
          if (!move_puzzle (grid, 1, 0))
            gtk_widget_error_bell (grid);
        }
    }
  else
    {
      gtk_widget_error_bell (grid);
    }
}

static void
start_puzzle (GdkPaintable *puzzle)
{
  GtkWidget *picture, *grid;
  GtkEventController *controller;
  guint x, y;

  /* Remove the old grid (if there is one) */
  grid = gtk_bin_get_child (GTK_BIN (frame));
  if (grid)
    gtk_container_remove (GTK_CONTAINER (frame), grid);

  /* Create a new grid */
  grid = gtk_grid_new ();
  gtk_widget_set_can_focus (grid, TRUE);
  gtk_container_add (GTK_CONTAINER (frame), grid);
  gtk_aspect_frame_set (GTK_ASPECT_FRAME (frame), 0.5, 0.5, (float) gdk_paintable_get_intrinsic_aspect_ratio (puzzle), FALSE);

  /* Add a key event controller so people can use the arrow
   * keys to move the puzzle */
  controller = gtk_event_controller_key_new ();
  g_signal_connect (controller, "key-pressed",
                    G_CALLBACK (puzzle_key_pressed),
                    grid);
  gtk_widget_add_controller (GTK_WIDGET (grid), controller);

  controller = GTK_EVENT_CONTROLLER (gtk_gesture_multi_press_new ());
  g_signal_connect (controller, "pressed",
                    G_CALLBACK (puzzle_button_pressed),
                    grid);
  gtk_widget_add_controller (GTK_WIDGET (grid), controller);

  /* Make sure the cells have equal size */
  gtk_grid_set_row_homogeneous (GTK_GRID (grid), TRUE);
  gtk_grid_set_column_homogeneous (GTK_GRID (grid), TRUE);

  /* Reset the variables */
  solved = FALSE;
  pos_x = width - 1;
  pos_y = height - 1;

  /* add a picture for every cell */
  for (y = 0; y < height; y++)
    {
      for (x = 0; x < width; x++)
        {
          GdkPaintable *piece;

          /* Don't paint anything for the lsiding part of the video */
          if (x == pos_x && y == pos_y)
            piece = NULL;
          else
            piece = gtk_puzzle_piece_new (puzzle,
                                          x, y,
                                          width, height);
          picture = gtk_picture_new_for_paintable (piece);
          gtk_picture_set_keep_aspect_ratio (GTK_PICTURE (picture), FALSE);
          gtk_grid_attach (GTK_GRID (grid),
                           picture,
                           x, y,
                           1, 1);
        }
    }

  shuffle_puzzle (grid);
}

static void
reshuffle (void)
{
  GtkWidget *grid;

  grid = gtk_bin_get_child (GTK_BIN (frame));
  if (solved)
    start_puzzle (puzzle);
  else
    shuffle_puzzle (grid);
  gtk_widget_grab_focus (grid);
}

static void
reconfigure (void)
{
  GtkWidget *popover;
  GtkWidget *grid;
  GtkWidget *child;
  GtkWidget *image;
  GList *selected;

  width = height = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (size_spin));

  selected = gtk_flow_box_get_selected_children (GTK_FLOW_BOX (choices));
  if (selected == NULL)
    child = gtk_widget_get_first_child (choices);
  else
    {
      child = selected->data;
      g_list_free (selected);
    }
  image = gtk_bin_get_child (GTK_BIN (child));
  puzzle = gtk_image_get_paintable (GTK_IMAGE (image));

  start_puzzle (puzzle); 
  popover = gtk_widget_get_ancestor (size_spin, GTK_TYPE_POPOVER);
  gtk_popover_popdown (GTK_POPOVER (popover));
  grid = gtk_bin_get_child (GTK_BIN (frame));
  gtk_widget_grab_focus (grid);
}

static void
add_choice (GtkWidget    *choices,
            GdkPaintable *paintable)
{
  GtkWidget *icon;

  icon = gtk_image_new_from_paintable (paintable);
  gtk_image_set_icon_size (GTK_IMAGE (icon), GTK_ICON_SIZE_LARGE);

  gtk_container_add (GTK_CONTAINER (choices), icon);
}

GtkWidget *
do_sliding_puzzle (GtkWidget *do_widget)
{
  if (!window)
    {
      GtkWidget *header;
      GtkWidget *restart;
      GtkWidget *tweak;
      GtkWidget *popover;
      GtkWidget *tweaks;
      GtkWidget *apply;
      GtkWidget *label;
      GtkWidget *sw;
      GtkMediaStream *media;

      puzzle = GDK_PAINTABLE (gdk_texture_new_from_resource ("/sliding_puzzle/portland-rose.jpg"));

      tweaks = gtk_grid_new ();
      gtk_grid_set_row_spacing (GTK_GRID (tweaks), 10);
      gtk_grid_set_column_spacing (GTK_GRID (tweaks), 10);
      g_object_set (tweaks, "margin", 10, NULL);

      choices = gtk_flow_box_new ();
      gtk_style_context_add_class (gtk_widget_get_style_context (choices), GTK_STYLE_CLASS_VIEW);
      add_choice (choices, puzzle);
      add_choice (choices, gtk_nuclear_animation_new ());
      media = gtk_media_file_new_for_resource ("/images/gtk-logo.webm");
      gtk_media_stream_set_loop (media, TRUE);
      gtk_media_stream_set_muted (media, TRUE);
      gtk_media_stream_play (media);
      add_choice (choices, GDK_PAINTABLE (media));
      sw = gtk_scrolled_window_new (NULL, NULL);
      gtk_container_add (GTK_CONTAINER (sw), choices);
      gtk_grid_attach (GTK_GRID (tweaks), sw, 0, 0, 2, 1);

      label = gtk_label_new ("Size");
      gtk_label_set_xalign (GTK_LABEL (label), 0.0);
      gtk_grid_attach (GTK_GRID (tweaks), label, 0, 1, 1, 1);
      size_spin = gtk_spin_button_new_with_range (2, 10, 1);
      gtk_spin_button_set_value (GTK_SPIN_BUTTON (size_spin), width);
      gtk_grid_attach (GTK_GRID (tweaks), size_spin, 1, 1, 1, 1);

      apply = gtk_button_new_with_label ("Apply");
      gtk_widget_set_halign (apply, GTK_ALIGN_END);
      gtk_grid_attach (GTK_GRID (tweaks), apply, 1, 2, 1, 1);
      g_signal_connect (apply, "clicked", G_CALLBACK (reconfigure), NULL);

      popover = gtk_popover_new (NULL);
      gtk_popover_set_modal (GTK_POPOVER (popover), TRUE);
      gtk_container_add (GTK_CONTAINER (popover), tweaks);

      tweak = gtk_menu_button_new ();
      gtk_menu_button_set_popover (GTK_MENU_BUTTON (tweak), popover);
      gtk_button_set_icon_name (GTK_BUTTON (tweak), "emblem-system-symbolic");

      restart = gtk_button_new_from_icon_name ("view-refresh-symbolic");
      g_signal_connect (restart, "clicked", G_CALLBACK (reshuffle), NULL);

      header = gtk_header_bar_new ();
      gtk_header_bar_set_show_title_buttons (GTK_HEADER_BAR (header), TRUE);
      gtk_header_bar_pack_start (GTK_HEADER_BAR (header), restart);
      gtk_header_bar_pack_end (GTK_HEADER_BAR (header), tweak);
      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
      gtk_window_set_display (GTK_WINDOW (window),
                              gtk_widget_get_display (do_widget));
      gtk_window_set_title (GTK_WINDOW (window), "Sliding Puzzle");
      gtk_window_set_titlebar (GTK_WINDOW (window), header);
      gtk_window_set_default_size (GTK_WINDOW (window), 400, 300);
      g_signal_connect (window, "destroy",
                        G_CALLBACK (gtk_widget_destroyed), &window);

      frame = gtk_aspect_frame_new (NULL, 0.5, 0.5, (float) gdk_paintable_get_intrinsic_aspect_ratio (puzzle), FALSE);
      gtk_container_add (GTK_CONTAINER (window), frame);

      start_puzzle (puzzle);
    }

  if (!gtk_widget_get_visible (window))
    gtk_widget_show (window);
  else
    gtk_widget_destroy (window);

  return window;
}