#include <stdbool.h> // bool
#include <stdio.h> // fprintf()
#include <unistd.h> // EXIT_{FAILURE,SUCCESS}
#include <stdlib.h> // exit()
#include <string.h> // memset()
#include <math.h>  // fabsf()

#define STB_IMAGE_WRITE_IMPLEMENTATION
#define STB_ONLY_PNG
#include "stb_image_write.h"

#include "util.h"
#include "km.h"

// maximum number of clusters to test
#define MAX_CLUSTERS 10

// number of tests to run on each cluster size
#define NUM_TESTS 100
#define MAX_BEST 10

// output image size
#define IM_WIDTH 128
#define IM_HEIGHT 128
#define IM_STRIDE (3 * IM_WIDTH)

// static output image data buffer
static uint8_t im_data[3 * IM_WIDTH * IM_HEIGHT];

typedef struct {
  float score;
  km_set_t set;
} best_item_t;

typedef struct {
  // cluster initialization method
  km_init_type_t init_type;

  // random number source
  km_rand_t rs;

  struct {
    float distance,
          silouette,
          cluster_size;
    size_t num_empty;
  } rows[MAX_CLUSTERS - 2];

  // best clusters
  best_item_t best[MAX_BEST];
  size_t num_best;
} ctx_t;

static inline size_t
ctx_get_max_best(
  const ctx_t * const ctx
) {
  return MIN(ctx->num_best, MAX_BEST);
}

static int
best_score_cmp(
  const void * const ap,
  const void * const bp
) {
  const best_item_t * const a = ap;
  const best_item_t * const b = bp;

  return (a->score > b->score) ? 1 : -1;
}

static void
ctx_best_sort(
  ctx_t * const ctx
) {
  // sort best sets by ascending score (worst to best)
  qsort(
    ctx->best,
    ctx_get_max_best(ctx),
    sizeof(best_item_t),
    best_score_cmp
  );
}

static bool
load_on_shape(
  const km_shape_t * const shape,
  void * const cb_data
) {
  km_set_t * const set = cb_data;

  // D("shape: %zu floats, %zu ints", shape->num_floats, shape->num_ints);

  // init set
  if (!km_set_init(set, shape, 100)) {
    die("km_set_init() failed");
  }

  // return success
  return true;
}

static bool
load_on_row(
  const float * const floats,
  const int * const ints,
  void * const cb_data
) {
  km_set_t * const set = cb_data;

  // push row
  if (!km_set_push(set, 1, floats, ints)) {
    die("km_set_push_rows() failed");
  }

  // return success
  return true;
}

static void
load_on_error(
  const char * const err,
  void * const cb_data
) {
  UNUSED(cb_data);
  die("load failed: %s", err);
}

static const km_load_cbs_t
LOAD_CBS = {
  .on_shape = load_on_shape,
  .on_row   = load_on_row,
  .on_error = load_on_error,
};

static bool
find_on_init(
  km_set_t * const cs,
  const size_t num_clusters,
  const km_set_t * const set,
  void *cb_data
) {
  ctx_t * const ctx = cb_data;
  return km_init(cs, ctx->init_type, num_clusters, set, &(ctx->rs));
}

static bool
find_on_fini(
  km_set_t * const cs,
  void *cb_data
) {
  UNUSED(cb_data);
  km_set_fini(cs);
  return true;
}

static void
find_on_data(
  const km_find_data_t * const data,
  void *cb_data
) {
  ctx_t * const ctx = cb_data;
  const size_t ofs = data->num_clusters - 2;

  ctx->rows[ofs].distance += data->distance_sum;
  ctx->rows[ofs].silouette += data->silouette;
  ctx->rows[ofs].cluster_size += data->mean_cluster_size;
  ctx->rows[ofs].num_empty += data->num_empty_clusters;
}

static bool
find_on_best(
  const float score,
  const km_set_t * const cs,
  void *cb_data
) {
  ctx_t * const ctx = cb_data;

  D("new best: score = %0.3f, num_clusters = %zu", score, cs->num_rows);

  // get pointer to destination set
  // (note: data->best is a ring buffer)
  const size_t ofs = ctx->num_best % MAX_BEST;
  ctx->best[ofs].score = score;
  km_set_t * const dst = &(ctx->best[ofs].set);

  if (ctx->num_best >= MAX_BEST) {
    // finalize old best data set
    km_set_fini(dst);
  }

  // copy data set to best ring buffer
  if (!km_set_copy(dst, cs)) {
    die("km_set_copy()");
  }

  // increment best count
  ctx->num_best++;

  // return success
  return true;
}

// init find config
static const km_find_cbs_t
FIND_CBS = {
  .max_clusters = MAX_CLUSTERS,
  .num_tests    = NUM_TESTS,

  .on_init      = find_on_init,
  .on_fini      = find_on_fini,
  .on_data      = find_on_data,
  .on_best      = find_on_best,
};

static void
ctx_save_png(
  const ctx_t * const ctx,
  const char * const png_path,
  const km_set_t * const set
) {
  // clear image data to white
  memset(im_data, 0xff, sizeof(im_data));

  // draw data points
  km_set_draw(set, im_data, IM_WIDTH, IM_HEIGHT, 1, 0x000000);
  if (!stbi_write_png(png_path, IM_WIDTH, IM_HEIGHT, 3, im_data, IM_STRIDE)) {
    die("stbi_write_png(\"%s\")", png_path);
  }

  // draw best centroids in green
  const km_set_t * const best_set = &(ctx->best[ctx_get_max_best(ctx) - 1].set);
  km_set_draw(best_set, im_data, IM_WIDTH, IM_HEIGHT, 3, 0x00ff00);

  // save png
  if (!stbi_write_png(png_path, IM_WIDTH, IM_HEIGHT, 3, im_data, IM_STRIDE)) {
    die("stbi_write_png(\"%s\")", png_path);
  }
}

static void
ctx_best_print(
  const ctx_t * const ctx,
  FILE * const fh
) {
  if (!km_set_print(&(ctx->best[ctx_get_max_best(ctx) - 1].set), fh)) {
    die("km_set_print()");
  }
}

static const char USAGE_FORMAT[] =
  "Usage: %s [init] [data_path] <png_path>\n"
  "\n"
  "Arguments:\n"
  "* init:      Cluster init method (one of \"rand\" or \"set\").\n"
  "* data_path: Path to input data file.\n"
  "* png_path:  Path to output PNG (optional).\n"
  "";

int main(int argc, char *argv[]) {
  // check command-line arguments
  if (argc < 3) {
    fprintf(stderr, USAGE_FORMAT, argv[0]);
    return EXIT_FAILURE;
  }

  // get command-line arguments
  const char * const init_type_name = argv[1];
  const char * const data_path = argv[2];
  const char * const png_path = (argc > 3) ? argv[3] : NULL;

  // init rng
  srand(getpid());
  const int rand_seed = rand();

  // init context
  ctx_t ctx;
  memset(&ctx, 0, sizeof(ctx_t));
  ctx.init_type = km_init_get_type(init_type_name);

  // init ctx rng
  km_rand_init_erand48(&(ctx.rs), rand_seed);

  // init data set
  km_set_t set;
  if (!km_load_path(data_path, &LOAD_CBS, &set)) {
    die("km_load_path(\"%s\") failed", data_path);
  }

  // normalize data set
  if (!km_set_normalize(&set)) {
    die("km_set_normalize() failed");
  }

  // find best solutions
  if (!km_find(&set, &FIND_CBS, &ctx)) {
    die("km_find()");
  }

  // sort best results from lowest to highest
  ctx_best_sort(&ctx);

  // print best
  ctx_best_print(&ctx, stdout);

  if (png_path) {
    // save png of normalized data set and best clusters
    ctx_save_png(&ctx, png_path, &set);
  }

  // finalize data set
  km_set_fini(&set);

  // return success
  return 0;
}