#include <stdio.h>
#include <stdlib.h>

/*
 * this code is easiest to design as a state machine, see linecount-fsm.jpg
 */

typedef enum { EL, PC, EOLC, LNGC, ENDC, CL, CPC, CLNGC, CENDC } statelist;
unsigned int line=0;

statelist empty_line(char c)
{
  if (c == '/')
    return PC;
  if (c == '\n')
    return EL;
  if (c == '\t')
    return EL;
  if (c == ' ')
    return EL;
  return CL;
}

statelist potential_comment(char c)
{
  if (c == '/')
    return EOLC;
  if (c == '*')
    return LNGC;
  return EL;
}

statelist eol_comment(char c)
{
  if (c == '\n')
    return EL;
  return EOLC;
}

statelist long_comment(char c)
{
  if (c == '*')
    return ENDC;
  return LNGC;
}

statelist end_comment(char c)
{
  if (c == '/')
    return EL;
  return LNGC;
}

statelist code_line(char c)
{
  if (c == '\n')
  {
    ++line;
    return EL;
  }
  if (c == '/')
    return CPC;
  return CL;
}

statelist cpotential_comment(char c)
{
  if (c == '/')
  {
    ++line;
    return EOLC;
  }
  if (c == '*')
    return CLNGC;
  return CL;
}

statelist clong_comment(char c)
{
  if (c == '\n')
  {
    ++line;
    return LNGC;
  }
  if (c == '*')
    return CENDC;
  return CLNGC;
}

statelist cend_comment(char c)
{
  if (c == '/')
    return CL;
  return CLNGC;
}

int main(int argc, char *argv[])
{
  FILE *fp;
  char c;
  statelist state = EL;
  line = 0;

  if (argc!=2)
  {
    printf("Usage '%s <c source file>'\n",argv[0]);
    exit(1);
  }

  fp=fopen(argv[1],"r");       //read data from opened file
  if (fp == NULL)
  {
    printf("File '%s' could not be opened\n",argv[1]);
    exit(3);
  }

  while( (c=getc(fp)) != EOF )     //
    switch (state)
    {
      case EL:
        state = empty_line(c);
        break;
      case PC:
        state = potential_comment(c);
        break;
      case EOLC:
        state = eol_comment(c);
        break;
      case LNGC:
        state = long_comment(c);
        break;
      case ENDC:
        state = end_comment(c);
        break;
      case CL:
        state = code_line(c);
        break;
      case CPC:
        state = cpotential_comment(c);
        break;
      case CLNGC:
        state = clong_comment(c);
        break;
      case CENDC:
        state = cend_comment(c);
        break;
      default:
        printf("State machine is screwed\n");
        exit(2);
    }
  /*
   * missed EOF transitions on state graph
   */
  switch (state)
  {
    case CL:
    case CPC:
    case CLNGC:
    case CENDC:
      ++line;
      break;
    default:
      break;
  }

  fclose(fp);
  printf("LOC: %d\n",line);
  return 0;
}