#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/types.h>
#include <string.h>
#include <math.h>

typedef struct Face {
  long double descriptor[128];
  int faceId;
  long double *distances;
  struct Face *next;
  struct Face *prev;
} Face;

Face *readFaceDescriptor(int id, char *path) {
  FILE *f;
  char buf[5000];
  Face *pFace = (Face *)malloc(sizeof(Face));
  memset(pFace, 0, sizeof(Face));
  f = fopen(path, "r");
  if (!f) {
    free(pFace);
    return NULL;
  }
  size_t s = fread(buf, 1, sizeof(buf), f);

  char *p = buf;
  buf[s] = 0;
  while (*p && *p != '-' && *p != '+' && (*p < '0' || *p > '9')) {
    p++;
  }
  for (int i = 0; i < 128; i++) {
    char *start = p;
    while (*p && *p != ',' && *p != ']' && *p != ' ' && *p != '\n') {
      p++;
    }
    if (!*p) {
      break;
    }
    *p++ = 0;
    sscanf(start, "%Lf", &pFace->descriptor[i]);
  }

  pFace->faceId = id;
  pFace->next = pFace->prev = NULL;

  return pFace;
}

long double euclideanDistance(long double *a, long double *b) {
  long double sum = 0.0;
  for (int i = 0; i < 128; i++) {
    long double delta = a[i] - b[i];
    sum += delta * delta;
  }
  return sqrtl(sum);
}

int main(int argc, char *argv[]) {
  int i;
  Face *pChain = NULL;
  for (i = 0; i < 100; i++) {
    char buf[1028];
    sprintf(buf, "%s/face-data/%d", argv[1], i);
    DIR *faceDir = opendir(buf);

    if (!faceDir) {
      printf("Can not open %s\n", buf);
    } else {
      struct dirent *ent;
      while ((ent = readdir(faceDir)) != NULL) {
        if (strstr(ent->d_name, ".json") == NULL) {
          continue;
        }
        int id = 0;
        char *p = ent->d_name;
        while (*p && *p != '-') {
          id *= 10;
          id += *p - '0';
          p++;
        }
        char path[1028*2];
        sprintf(path, "%s/%s", buf, ent->d_name);
        Face *pFace = readFaceDescriptor(id, path);
        if (!pFace) {
          continue;
        }
        if (pChain) {
          pFace->next = pChain;
        }
        pChain = pFace;
      }
      closedir(faceDir);
    }
  }
  Face *pLink = pChain;
  int len = 0;
  while (pLink) {
    Face *tmp = pLink;
    len++;
    pLink = pLink->next;
  }
  pLink = pChain;
  while (pLink) {
    pLink->distances = (long double *)malloc(sizeof(long double) * len);
    int index = 0;
    Face *pTarget = pChain;
    while (pTarget) {
      if (pTarget == pLink) {
        pLink->distances[index] = 0.0;
      } else {
        pLink->distances[index] = euclideanDistance(pLink->descriptor, pTarget->descriptor);
        if (pLink->distances[index] < 0.4) {
          printf("%Lf: %5d -> %5d\n", pLink->distances[index], pLink->faceId, pTarget->faceId);
        }
      }
      pTarget = pTarget->next;
    }
    pLink = pLink->next;
  }
  printf("%d faces.\n", len);
  return 0;
}