#include <stdbool.h> // bool
#include <string.h> // memset()
#include "util.h"
#include "km.h"

// init a set with num_clusters clusters of shape num_floats by picking
// random initial points from the set
bool
km_init_forgy(
  km_set_t * const cs,
  const size_t num_clusters,
  const km_set_t * const set,
  km_rand_t * const rs
) {
  const size_t num_floats = set->shape.num_floats,
               stride = sizeof(float) * num_floats;

  // init cluster shape
  const km_shape_t shape = {
    .num_floats = num_floats,
    .num_ints = 1,
  };

  // get random row offsets
  size_t rows[num_clusters];
  if (!km_rand_fill_sizes(rs, num_clusters, rows)) {
    // return failure
    return false;
  }

  // generate random cluster centers
  float floats[num_floats * num_clusters];
  for (size_t i = 0; i < num_clusters; i++) {
    const size_t row_num = rows[i] % set->num_rows;
    const float * const row_floats = km_set_get_row(set, row_num);
    memcpy(floats + i * num_floats, row_floats, stride);
  }

  // FIXME: should probably be heap-allocated
  int ints[num_clusters];
  memset(ints, 0, sizeof(ints));

  // init cluster set
  if (!km_set_init(cs, &shape, num_clusters)) {
    // return failure
    return false;
  }

  // add data, return result
  return km_set_push(cs, num_clusters, floats, ints);
}