#include <stdlib.h>

#include <time.h>

#include <gtk/gtk.h>

#define COLS 10

#define ROWS 20

const int size = 30;

const int colors_count = 3;

const double colors[][3] = {

  { 1, 1, 1 },

  { 1, 1, 0 },

  { 1, 0, 0 },

  { 0, 0, 1 },

  { 0.66, 0.66, 0.66 },

  { 0.33, 0.33, 0.33 } };

int board[COLS][ROWS];

void new_game() {

  srand(time(NULL));

  for(int x = 0; x < COLS; ++x)

    for(int y = 0; y < ROWS; ++y)

      board[x][y] = 1 + rand()%colors_count;

}

int get_block(int x, int y) {

  if (x < 0 || y < 0 || x >= COLS || y >= ROWS)

    return -1;

  return board[x][y];

}

void check(int x, int y) {

  int color = get_block(x, y);

  if (color > 0) {

    if (get_block(x-1, y) == color) {

      board[x][y] = 0;

      check(x-1, y);

      board[x-1][y] = 0;

    }

    if (get_block(x+1, y) == color) {

      board[x][y] = 0;

      check(x+1, y);

      board[x+1][y] = 0;

    }

    if (get_block(x, y-1) == color) {

      board[x][y] = 0;

      check(x, y-1);

      board[x][y-1] = 0;

    }

    if (get_block(x, y+1) == color) {

      board[x][y] = 0;

      check(x, y+1);

      board[x][y+1] = 0;

    }

  }

}

void fall() {

  int dx = 0;

  for(int x = 0; x < COLS; ++x) {

    int dy = 0;

    for(int y = 0; y < ROWS; ++y) {

      if (board[x][y] != 0) {

        if (dx > 0 || dy > 0) {

          board[x-dx][y-dy] = board[x][y];

          board[x][y] = 0;

        }

      } else {

        ++dy;

      }

    }

    if (dy == ROWS) ++dx;

  }

}

gboolean button_press(GtkWidget *widget, GdkEventButton *event, gpointer data) {

  if (event->button == 1) {

    check((int)(event->x)/size, ROWS - 1 - (int)(event->y)/size);

    fall();

  } else

  if (event->button == 3) {

    new_game();

  }

  gtk_widget_queue_draw(widget);

  return TRUE;

}

gboolean draw(GtkWidget *widget, cairo_t *cr, gpointer data) {

  for(int x = 0; x < COLS; ++x) {

    for(int y = 0; y < ROWS; ++y) {

      int c = board[x][ROWS - 1 - y];

      cairo_rectangle(cr, x*size, y*size, size, size);

      cairo_set_source_rgb(cr, colors[c][0], colors[c][1], colors[c][2]);

      cairo_fill(cr);

    }

  }

  return TRUE;

}

void activate(GtkApplication* app, gpointer data) {

  GtkWidget *window = gtk_application_window_new (app);

  g_signal_connect(window, "draw", G_CALLBACK(draw), NULL);

  g_signal_connect(window, "button-press-event", G_CALLBACK(button_press), NULL);

  gtk_window_set_default_size(GTK_WINDOW(window), size*COLS, size*ROWS);

  gtk_widget_add_events(window, GDK_BUTTON_PRESS_MASK);

  gtk_widget_show_all(window);

  new_game();

}

int main(int argc, char **argv) {

  GtkApplication *application = gtk_application_new(NULL, 0);

  g_signal_connect(application, "activate", G_CALLBACK(activate), NULL);

  int status = g_application_run(G_APPLICATION(application), argc, argv);

  g_object_unref(application);

  return status;

}