#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/types.h>
#include <string.h>
#include <math.h>
#include <sqlite3.h>

#ifndef MIN_PTS
#define MIN_PTS 3
#endif

#ifndef MAX_DISTANCE
#define MAX_DISTANCE 0.47L
#endif

typedef struct Face {
  float descriptor[128];
  long int clusterId;
  long faceId;
  long photoId;
  float confidence;
  float *distances;
} Face;

typedef struct FaceLink {
  struct FaceLink *pNext;
  float distance;
  Face *pFace;
} FaceLink;

char fileBuf[5000];
char pathBuf[1028];

Face *readFaceDescriptor(Face *pFace, long id, char *path) {
  FILE *f;
  f = fopen(path, "r");
  if (!f) {
    return NULL;
  }
  size_t s = fread(fileBuf, 1, sizeof(fileBuf), f);
  fclose(f);
  
  char *p = fileBuf;
  fileBuf[s] = 0;
  while (*p && *p != '-' && *p != '+' && (*p < '0' || *p > '9')) {
    p++;
  }
  int i = 0;
  for (i = 0; i < 128; i++) {
    char *start = p;
    while (*p && *p != ',' && *p != ']' && *p != ' ' && *p != '\n') {
      p++;
    }
    if (!*p) {
      break;
    }
    *p++ = 0;
    sscanf(start, "%f", &pFace->descriptor[i]);
  }

  if (i != 128) {
    return NULL;
  }

  pFace->faceId = id;

  return pFace;
}

int insert_descriptors(sqlite3 *db, long int faceId, float descriptor[128]) {
  char sql_buf[1024];
	int rc;

  snprintf(sql_buf, sizeof(sql_buf), "INSERT INTO facedescriptors (faceId,descriptors) VALUES (%ld,?)", faceId);
	
  sqlite3_stmt *insert_stmt;
	rc = sqlite3_prepare_v2(db, sql_buf, -1, &insert_stmt, NULL);
	if(SQLITE_OK != rc) {
		fprintf(stderr, "Can't prepare insert statment %s (%i): %s\n", sql_buf, rc, sqlite3_errmsg(db));
    return rc;
	}

	// Bind a block of zeros the size of the file we're going to insert later
	sqlite3_bind_zeroblob(insert_stmt, 1, sizeof(float) * 128);
	if (SQLITE_DONE != (rc = sqlite3_step(insert_stmt))) {
		fprintf(stderr, "Insert statement didn't work (%i): %s\n", rc, sqlite3_errmsg(db));
    return rc;
	}

	sqlite3_int64 rowid = sqlite3_last_insert_rowid(db);

	// Getting here means we have a valid file handle, f, and a valid db handle, db
	//   Also, a blank row has been inserted with key rowid
	sqlite3_blob *blob;
	rc = sqlite3_blob_open(db, "main", "facedescriptors", "descriptors", rowid, 1, &blob);
	if (SQLITE_OK != rc) {
		fprintf(stderr, "Couldn't get blob handle (%i): %s\n", rc, sqlite3_errmsg(db));
    return rc;
	}

  if(SQLITE_OK != (rc = sqlite3_blob_write(blob, descriptor, 128 * sizeof(float), 0))) {
    fprintf(stderr, "Error writing to blob handle.\n");
    return rc;
  }

	sqlite3_blob_close(blob);

  return SQLITE_OK;
}

/* 
 * 1. Count how many entries there are
 * 2. Allocate storage to hold all entries
 * 3. Read all entries into flat array
 * 4. Allocate MxM matrix and pre-calculate distances
 * 5. Perform DBSCAN across MxM matrix to cluster
 */
int main(int argc, char *argv[]) {
  long maxId = 0;
  long i;
  long entries = 0;
  long int minPts = MIN_PTS;
  float maxDistance = MAX_DISTANCE;
  char sqlBuf[1024];

  if (argc == 1) {
    fprintf(stderr, "usage: scanner PATH MAX_DISTANCE MIN_PTS\n");
    return -1;
  }

  for (i = 0; i < 100; i++) {
    sprintf(pathBuf, "%s/face-data/%ld", argv[1], i);
    DIR *faceDir = opendir(pathBuf);
    if (!faceDir) {
      continue;
    } 

    struct dirent *ent;
    while ((ent = readdir(faceDir)) != NULL) {
      if (strstr(ent->d_name, ".json") == NULL) {
        continue;
      }
      entries++;
    }
    closedir(faceDir);
  }

  fprintf(stderr, "Found %ld entries to load and process.\n", entries);

  /* Allocate storage for all distances */
  sqlite3 *db;

  int rc = sqlite3_open("db/photos.db", &db);
  if (rc != SQLITE_OK) {
    fprintf(stderr, "Cannot open database: %s\n", sqlite3_errmsg(db));
    sqlite3_close(db);
    return 1;
  }

  fprintf(stderr, "DB opened.\n");

  Face **ppFaces = malloc(sizeof(Face *) * entries);
  if (!ppFaces) {
    fprintf(stderr, "Unable to allocate storage face descriptors.");
    return -1;
  }
  for (i = 0; i < entries; i++) {
    ppFaces[i] = malloc(sizeof(Face));
    memset(ppFaces[i], 0, sizeof(Face));
  }

  char *err_msg = NULL;

  char *sql = 
    "DELETE FROM facedescriptors;"
    "BEGIN TRANSACTION;";

  rc = sqlite3_exec(db, sql, 0, 0, &err_msg);
  if (rc != SQLITE_OK ) {
    fprintf(stderr, "SQL error: %s\n", err_msg);
    sqlite3_free(err_msg);        
    sqlite3_close(db);
    return 1;
  } 

  long int processed = 0;
  int last = 0;
  for (i = 0; i < 100; i++) {
    sprintf(pathBuf, "%s/face-data/%ld", argv[1], i);
    DIR *faceDir = opendir(pathBuf);
    if (!faceDir) {
      fprintf(stderr, "Can not open %s\n", pathBuf);
      continue;
    } 

    struct dirent *ent;
    while (processed < entries && (ent = readdir(faceDir)) != NULL) {
      if (strstr(ent->d_name, ".json") == NULL) {
        continue;
      }
      long id = 0;
      char *p = ent->d_name;
      while (*p && *p != '-') {
        id *= 10;
        id += *p - '0';
        p++;
      }
      char path[1028*2];
      sprintf(path, "%s/%s", pathBuf, ent->d_name);
      maxId = maxId > id ? maxId : id;
      if (!readFaceDescriptor(ppFaces[processed], id, path)) {
        fprintf(stderr, "Unable to read %s.\n", path);
        continue;
      }

      rc = insert_descriptors(db, id, ppFaces[processed]->descriptor);
      if (rc != SQLITE_OK ) {
        fprintf(stderr, "SQL error: %s\n", err_msg);
        sqlite3_free(err_msg);        
        sqlite3_close(db);
        return 1;
      } 

      if (processed % 1000 == 0) {
        int perc = 100 * processed / entries;
        if (perc != last) {
          fprintf(stderr, "\rLoading %d%% complete.", perc);
          last = perc;
        }
      }
    }
    closedir(faceDir);
  }

  rc = sqlite3_exec(db, "COMMIT;", 0, 0, &err_msg);
  if (rc != SQLITE_OK ) {
    fprintf(stderr, "SQL error: %s\n", err_msg);
    sqlite3_free(err_msg);        
    sqlite3_close(db);
    return 1;
  } 

  sqlite3_close(db);

  fprintf(stderr, "\nDone.\n");
  return 0;
}