/* Generate .po file from doc-string file.

   Scan specified doc-string file, creating .po format messages for processing
   with msgfmt.  The results go to standard output or to a file specified
   with -a or -o (-a to append, -o to start from nothing).

   Kludge to make up for shortcoming in make-docfile and Snarf-documentation:
   If arg before input filename is -p, we are scanning an add-on
   package, which requires slightly different processing.
*/

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

#ifndef EXIT_SUCCESS
#define EXIT_SUCCESS 0
#define EXIT_FAILURE 1
#endif

/* #define BUFSIZE    8192 */
/* #define BUFSIZE    16384 */
#define BUFSIZE    32768
#define NEWSTRING  31      /* Character signalling start of new doc string */
#define LINEEND    "\\n"
#define ENDSTRING  "\"\n"
#define LINEBEGIN  "       \""
#define LINEBREAK  ENDSTRING LINEBEGIN

/* some brain-dead headers define this ... */
#undef FALSE
#undef TRUE
enum boolean { FALSE, TRUE };


/***********************/
/* buffer pseudo-class */
/***********************/

typedef struct _buffer
{
  size_t index;  /* current position in buf[] */
  size_t size;   /* size of buf */
  char *buf;
} buffer_struct;

#define BUF_NULL  {0, 0, NULL}

int  buf_init  (buffer_struct *buffer, size_t size);
void buf_free  (buffer_struct *buffer);
void buf_clear (buffer_struct *buffer);
int  buf_putc  (buffer_struct *buffer, int c);
int  buf_print (buffer_struct *buffer, const char *s);


/********************/
/* global variables */
/********************/

FILE *infile  = NULL;
FILE *outfile = NULL;
buffer_struct buf = BUF_NULL;


void scan_file (enum boolean package);
void initialize (void);
void clean_exit (int status);
void buf_putc_safe (int c);
void buf_print_safe (const char *s);
void terminate_string (void);

main (int argc, char *argv[])
{
  register int i;
  enum boolean package = FALSE;  /* TRUE if scanning add-on package */

  initialize ();

  outfile = stdout;

  /* If first two args are -o FILE, output to FILE. */
  i = 1;
  if (argc > i + 1 && strcmp (argv[i], "-o") == 0) {
    outfile = fopen (argv[++i], "w");
    ++i;
  }
  /* ...Or if args are -a FILE, append to FILE. */
  if (argc > i + 1 && strcmp (argv[i], "-a") == 0) {
    outfile = fopen (argv[++i], "a");
    ++i;
  }
  if (!outfile) {
    fprintf (stderr, "Unable to open output file %s\n", argv[--i]);
    return 1;
  }

  if (argc > i && !strcmp (argv[i], "-p")) {
    package = TRUE;
    ++i;
  }

  infile = fopen (argv[i], "r");
  if (!infile) {
    fprintf (stderr, "Unable to open input file %s\n", argv[i]);
    return 1;
  }

  scan_file (package);
  clean_exit (EXIT_SUCCESS);
}


void scan_file (enum boolean package)
{
  register int c;   /* Character read in */

  fprintf (outfile, "###############\n");
  fprintf (outfile, "# DOC strings #\n");
  fprintf (outfile, "###############\n");

  while (c = getc (infile), !feof (infile)) {
    if (c == NEWSTRING) {
      /* If a string was being processed, terminate it. */
      if (buf.index > 0)
	terminate_string ();

      /* Skip function or variable name. */
      while (c != '\n')
	c = getc (infile);
      c = getc (infile);

      /* Begin a new string. */
      fprintf (outfile, "msgid  \"");
      buf_print_safe ("msgstr \"");
    }

    if (c == '\n') {
      /* Peek at next character. */
      c = getc (infile);
      ungetc (c, infile);

      /* For add-on (i.e., non-preloaded) documentation, ignore the last
	 carriage return of a string. */
      if (!(package && c == NEWSTRING)) {
	fprintf (outfile, LINEEND);
	buf_print_safe (LINEEND);
      }

      /* If not end of string, continue it on the next line. */
      if (c != NEWSTRING) {
	fprintf (outfile, LINEBREAK);
	buf_print_safe (LINEBREAK);
      }
    }
    else {

      /* If character is \ or ", precede it by a backslash. */
      if (c == '\\' || c == '\"') {
	putc ('\\', outfile);
	buf_putc_safe ('\\');
      }

      putc (c, outfile);
      buf_putc_safe (c);
    }
  }
  terminate_string ();
}


/* initialize sets up the global variables.
*/
void initialize (void)
{
  if (buf_init (&buf, BUFSIZE) != 0)
    clean_exit (EXIT_FAILURE);
}


/* clean_exit returns any resources and terminates the program.
   An error message is printed if status is EXIT_FAILURE.
*/
void clean_exit (int status)
{
  if (buf.size > 0)
    buf_free (&buf);
  if (outfile)
    fclose (outfile);
  if (infile)
    fclose (infile);

  if (status == EXIT_FAILURE)
    fprintf (stderr, "make-po abnormally terminated\n");
  exit (status);
}


/* buf_putc_safe writes the character c on the global buffer buf,
   checking to make sure that the operation was successful.
*/
void buf_putc_safe (int c)
{
  register int status;
  
  status = buf_putc (&buf, c);
  if (status == EOF)
    clean_exit (EXIT_FAILURE);
}


/* buf_putc_safe writes the string s on the global buffer buf,
   checking to make sure that the operation was successful.
*/
void buf_print_safe (const char *s)
{
  register int status;

  status = buf_print (&buf, s);
  if (status < 0)
    clean_exit (EXIT_FAILURE);
}


/* terminate_string terminates the current doc string and outputs the buffer.
*/
void terminate_string (void)
  {
    fprintf (outfile, ENDSTRING);

    /* Make the "translation" different from the original string. */
    buf_print_safe ("_X");

    buf_print_safe (ENDSTRING);
    fprintf (outfile, "%s", buf.buf);
    buf_clear (&buf);
  }


/*********************************/
/* buffer pseudo-class functions */
/*********************************/

/* buf_init initializes a buffer to the specified size.
   It returns non-zero if the attempt fails.
*/
int buf_init (buffer_struct *buffer, size_t size)
{
  buffer->buf = malloc (size);
  if (buffer->buf == NULL)
    return 1;

  buffer->size = size;
  buf_clear (buffer);
  return 0;
}


/* buf_free releases the memory allocated for the buffer.
*/
void buf_free (buffer_struct *buffer)
{
  free (buffer->buf);
  buffer->size = 0;
}


/* buf_clear resets a buffer to an empty string.
*/
void buf_clear (buffer_struct *buffer)
{
  buffer->index = 0;
  buffer->buf[0] = '\0';
}


/* buf_putc writes the character c on the buffer.
   It returns the character written, or EOF for error.
*/
int buf_putc (buffer_struct *buffer, int c)
{
  if (buffer->index >= buffer->size)
    return EOF;

  buffer->buf[buffer->index++] = c;
  return c;
}


/* buf_print writes the string s on the buffer.
   It returns the number of characters written, or negative if an error occurred.
*/
int buf_print (buffer_struct *buffer, const char *s)
{
  register int len;

  len = strlen (s);
  if (buffer->index + len >= buffer->size)
    return -1;

  sprintf (&(buffer->buf[buffer->index]), s);
  buffer->index += len;
  return len;
}