#include <stdio.h>
#include <math.h>

#include "tectonics.h"

struct centroid_t {
   double x, y;
   int updates;
};

static int closest_point(struct world_t *world, double x, double y)
{
   double dist = 1e9;
   int closest = -1;
   for (int i=0; i<world->n_points; i++) {
      struct point_t *pt = world->points + i;
      double d = distance(x, y, pt->x, pt->y);
      if (d <= dist) {
	 dist = d;
	 closest = i;
      }
   }
   return closest;
}

static void relax_points(struct world_t *world, int iterations)
{
   struct centroid_t *centroid =
      malloc(sizeof(struct centroid_t) * world->n_points);
   
   for (int i=0; i<world->n_points; i++) {
      struct point_t *pt = world->points + i;
      struct centroid_t *c = centroid + i;
      c->x = pt->x;
      c->y = pt->y;
      c->updates = 1;
   }

   for (int i=0; i<iterations; i++) {
      printf("%02f%%\n", 100*((double)i+1)/iterations);
      double x = rand01();
      double y = rand01();
      int closest = closest_point(world, x, y);

      int t = centroid[closest].updates;
      centroid[closest].x = (t*centroid[closest].x + x)/(t+1);
      centroid[closest].y = (t*centroid[closest].y + y)/(t+1);
      centroid[closest].updates += 1;
   }

   for (int i=0; i<world->n_points; i++) {
      struct point_t *pt = world->points + i;
      struct centroid_t *c = centroid + i;
      pt->x = c->x;
      pt->y = c->y;
   }
}

void create_world(struct world_t *world, int n_points)
{
   world->n_points = n_points;
   world->points = malloc(sizeof(struct point_t) * n_points);
   if (world->points == NULL) {
      fprintf(stderr,
	      "ERROR: failed to allocate %d points\n",
	      n_points);
      return;
   }

   struct point_t center = { 0.5, 0.5 };
   world->tree = new_node(center, 0.5);

   for (int i=0; i<n_points; i++) {
      struct point_t *pt = world->points + i;
      pt->x = rand01();
      pt->y = rand01();

      insert(&(world->tree), world->points, i);
   }
}


void free_world(struct world_t *world)
{
   free(world->points);
}


void render_world(cairo_t *cr, struct world_t *world)
{
   int width, height;
   get_cairo_size(cr, &width, &height);
   double r = ((double)width) / (100*sqrt(world->n_points));
   cairo_set_source_rgba(cr, 1, 0, 0, 1);

   for (int i=0; i<world->n_points; i++) {
      struct point_t *pt = world->points + i;
      double xc = pt->x * width;
      double yc = pt->y * height;
      cairo_arc(cr, xc, yc, r, 0, 2*M_PI);
      cairo_stroke(cr);
   }

   draw_quadtree(cr, &(world->tree));
}