#include <stdio.h>
#include <stdlib.h>
#include <libpq-fe.h>

void do_exit(PGconn *conn) {
  PQfinish(conn);
  exit(1);
}

int main(int argc, char *argv[]) {
  /*declaration*/
  const char *conninfo;
  const int LEN = 10;
  const char *paramValues[1];

  printf("main() Started...\n");
  if (argc != 3) {
    fprintf(stderr, "Usage: ./main <row id> <connection info>\n");
    exit(1);
  }

  printf("main() argv[1]: %s\n", argv[1]);
  int rowId;

  /*store command line argument in int variable*/
  /*validate user input*/
  /*omit SQL injection*/
  /*stream:argv*/
  int ret = sscanf(argv[1], "%d", &rowId);

  /*valid user input:1 successfully filled item*/
  if (ret != 1) {
    fprintf(stderr, "The argument must be an integer\n");
    exit(1);
  }

  if (rowId < 0) {
    fprintf(stderr, "Error passing a negative rowId\n");
    exit(1);
  }

  printf("main() LEN: %d\n", LEN);
  char str[LEN];
  printf("main() str.length: %ld\n", sizeof(str));
  snprintf(str, LEN, "%d", rowId);
  printf("main() str: %s\n", str);
  paramValues[0] = str;  
    
  /*read command line*/
  printf("main() argv[2]: %s\n", argv[2]);
  conninfo = argv[2];

  /*connect to database*/
  PGconn *conn = PQconnectdb(conninfo);
  if (PQstatus(conn) == CONNECTION_BAD) {
    fprintf(stderr, "Connection to database failed: %s\n",
            PQerrorMessage(conn));
    PQfinish(conn);
    exit(1);
  }else if(PQstatus(conn)==CONNECTION_OK){
    printf("main() connected to database\n");
  }else{
    printf("main() connection status NOT known\n");
  }

  char *stm = "SELECT * FROM cars_cleanup WHERE Id=$1";

  /*create prepared statement*/
  /*conn:connection*/
  /*stm:statement*/
  /*1:number of passed parameters*/
  /*NULL: server figures out parameter type*/
  /*paramValues:pointer of an array of strings containing parameters*/
  /*NULL:relevant for binary parameters*/
  /*NULL:relevant for binary parameters*/
  /*0:obtain result in text format*/
  PGresult *res = PQexecParams(conn, stm, 1, NULL, paramValues, 
        NULL, NULL, 0);

  if (PQresultStatus(res) != PGRES_TUPLES_OK) {
    printf("No data retrieved\n");
    PQclear(res);
    do_exit(conn);
  }

  printf("%s %s %s\n", PQgetvalue(res, 0, 0),
	 PQgetvalue(res, 0, 1), PQgetvalue(res, 0, 2));
  PQclear(res);

  PQfinish(conn);
  return 0;
}