/*

 */


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

// mmap(2)
#include <sys/mman.h>

// stat(2)
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

// open(2)
#include <fcntl.h>

// va_arg(3)
#include <stdarg.h>

// terminals
#include "grammar.h"
#include "figure2-15-calc.h"

// forward declarations
void program(void);
void parse(char *file);
void get_nexttoken(void);
char *scanToken(char *ptr, char *lastchar, int *token_type, int *token_value, struct ParseState *ps);
void memorymap_file(char *file, char **start, char **lastchar);
void error_out(int error_code, const char *error_description, ...) 
   __attribute__ ((noreturn))
   __attribute__ ((format (printf, 2, 3)))
;
int usage(void);


int main(int argc, char **argv)
{
  argc--;
  parse(argv[1]);
}


// state variables
int nextToken = 0;
int tokenValue = 0;
char *where = NULL;
char *lastchar = NULL;

void parse(char *file)
{
  // It's a lot easier to treat a file as a sequence of bytes, implying
  // we should use mmap(2)...
  memorymap_file(file,&where,&lastchar);

  get_nexttoken();

  printf("digraph {\n");
  printf("node [shape=none]\n");
  program();          // first production in parser.c
  printf("}\n");
}


void get_nexttoken()
{
  static struct ParseState ParseState = {1,0,0};
  while(where < lastchar)
    {
      where = scanToken(where,lastchar,&nextToken,&tokenValue,&ParseState);
      return;
    }
  nextToken = 0;
  return;
}



// UTILITY

void memorymap_file(char *file, char **start, char **lastchar)
{
  struct stat stat_buff;
  int ret = stat(file,&stat_buff);
  if(ret == -1)
    {
      error_out(1,"Error: stat(2) failed for file '%s'\n",file);
    }
  size_t file_size = (size_t) stat_buff.st_size;

  // mmap(2) the file into memory
  int fd = open(file,O_RDONLY);
  if(fd == -1)
    {
      error_out(1,"Error: open(2) failed for file %s\n",file);
    }

  *start = mmap(NULL,           // Any location in memory is fine
		file_size,      // Length of the file
		PROT_READ,      // Let us read the file
		MAP_PRIVATE,    // We don't need to share this
		fd,             // Our file descriptor
		0);             // Start at the beginning
  *lastchar = *start + file_size;

  close(fd);                    // Apparently this is fine; look at man mmap(2)
  
  return;
}


void error_out(int error_code, const char *error_description, ...)
{
  va_list ap;
  va_start(ap,error_description);
  vfprintf(stderr,(const char *)error_description,ap);
  usage();
  exit(error_code);
}

int usage()
{
  fprintf(stderr,"Usage: ./figure2-15-calc FILENAME\n");
  return(0);
}