#ifndef TECTONICS_H
#define TECTONICS_H

#include <stdlib.h>
#include <stdbool.h>
#include <cairo.h>

struct point_t {
   double x, y;
   void *data;
};


struct quad_region_t {
   struct point_t center;
   double half_dim;
};


struct quadtree_node_t {
   struct quad_region_t region;

   int id;
   
   /* children */
   struct quadtree_node_t *nw, *ne, *sw, *se;
};


struct world_t {
   struct point_t *points;
   struct quadtree_node_t tree;
   int n_points;
};

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * quadtree
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

bool contains_point(struct quad_region_t region, struct point_t pt);
struct quadtree_node_t new_node(struct point_t center, double half_dim);
void subdivide(struct quadtree_node_t *node, struct point_t *points);
bool insert(struct quadtree_node_t *node,
	    struct point_t *points, int id);
int get_closest(struct quadtree_node_t *root,
		struct point_t pt);
void draw_quadtree(cairo_t *cr, struct quadtree_node_t *root);

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * util
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

void get_cairo_size(cairo_t *cr, int *width, int *height);
double rand01();
double distance(double x0, double y0, double x1, double y1);


/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 * worlds
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

void create_world(struct world_t *world, int n_points);
void free_world(struct world_t *world);
void render_world(cairo_t *cr, struct world_t *world);
void run_world_step(struct world_t *world);

#endif