/* 
 * external.c
 * 
 * functions that deals with external commmands
 * such as csound, play, playmidi, lpr...
 *
 * this is part of the GNU Denemo, 
 * Copyright (c) 2000-2006 Adam Tee
 */

#include <denemo/denemo.h>
#include "prefops.h"
#include <signal.h>
#include "external.h"


/* test it a given temp filename points to an 
 * existing file in the dotdenemo directory.
 */
gboolean
exists_temp_filename (const GString * name)
{
  GString *path;

  path = g_string_new (locatedotdenemo ());
  g_string_append (path, "/");
  g_string_append (path, name->str);
  return g_file_test (name->str, G_FILE_TEST_EXISTS);
}

/* parse spaces and tabs as field delimitors, return an argv
 * suitable for use without the need of system()
 * FIXME: let delimitors "as is" if they are inside quotations mark
 */
static gchar **
build_argv (gchar * cmd)
{
  gint i = 0;			/* index in cmd */
  gint argi = 0;		/* arg index in vector */
  gint vlen = 0;		/* vector length in args */
  gchar **argv = NULL;

  argv = (gchar **) g_malloc (sizeof (gchar *));
  argv[0] = 0;			/* vlen = 0 */

  if (!cmd)
    return NULL;

  while (cmd[i] != 0)
    {
      gint ci = 0;		/* char index in current arg */
      gint alen = 0;		/* arg length in chars */

      if (argi >= (vlen - 2))	/* ensure to not overflow */
	argv = (gchar **) realloc (argv, (vlen += 32) * sizeof (gchar *));
      argv[argi] = g_malloc (sizeof (gchar));
      argv[argi] = 0;		/* curently, alen=0 */
      while (cmd[i] == ' ' || cmd[i] == '\t' || cmd[i] == '\n')
	i++;			/* crop */
      while (cmd[i] != ' ' && cmd[i] != '\t' && cmd[i] != '\n' && cmd[i] != 0)
	{
	  if (ci >= (alen - 2))	/* ensure to not overflow */
	    argv[argi] =
	      (gchar *) realloc (argv[argi], (alen += 32) * sizeof (gchar));
	  argv[argi][ci] = cmd[i];
	  ci++, i++;
	}
      argv[argi][ci] = 0;	/* close string */
      argi++;
      if (cmd[i])
	i++;
#ifdef DEBUG
      fprintf (stderr, "argv[%d]=#%s#\n", (argi - 1), argv[argi - 1]);
#endif
    }
  argv[argi] = NULL;		/* close args list */
  return argv;
}

/* free memory that was allocated by build_argv */
static void
free_argv (gchar ** av)
{
  int i = 0;

  if (!av)
    return;
  while (av[i])
    {
      free (av[i++]);
    }
}

/* give a filepath string pointing to the user's
 * Denemo temporary directory.
 * 
 * if constname is NULL, basename is random.
 * else, basename is the given constname.
 *
 * returns: the filepath string
 */

GString *
get_temp_filename (gchar * constname)
{
  GString *path = NULL;

  if (constname)
    {
      path = g_string_new (locatedotdenemo ());
      g_string_append (path, "/");
      g_string_append (path, constname);
    }
  else
    {
      path = g_string_new ("");
      while (exists_temp_filename (path));
      /* GCC warns, but i know what i am doing */
      g_string_append (path, tmpnam (NULL));
    }
#ifdef DEBUG
  fprintf (stderr, "temp filename: %s\n", path->str);
#endif
  return path;
}

/* init pid files */
void
ext_init (void)
{
  GString *pidpath;
  FILE *fp;
  int i, len;

  len = sizeof (ext_pidfiles) / sizeof (gchar *);

  for (i = 0; i < len; i++)
    {
      pidpath = get_temp_filename (ext_pidfiles[i]);
      fp = fopen (pidpath->str, "w+");
      fprintf (fp, "%d", -1);
      fclose (fp);
      g_string_free (pidpath, TRUE);
    }
}

/* invalid pid files */
void
ext_quit (void)
{
  GString *pidpath;
  FILE *fp;
  int i, pid, len;

  len = sizeof (ext_pidfiles) / sizeof (gchar *);

  for (i = 0; i < len; i++)
    {
      pidpath = get_temp_filename (ext_pidfiles[i]);
      fp = fopen (pidpath->str, "r+");
      fscanf (fp, "%d", &pid);
#ifdef DEBUG
      fprintf (stderr, "ext_quit: read pid %d\n", pid);
#endif
      if (pid > 0)
	kill (pid, SIGTERM);
      rewind (fp);
      fprintf (fp, "%d", -1);
      fclose (fp);
      truncate (pidpath->str, 2);	/* '-' '1' EOF */
      g_string_free (pidpath, TRUE);
    }
}

/*
 * spawn an external shell command line with
 * its arguments and returns immediately.
 * 
 * additional options can be put in cmdline, 
 * separated by spaces or tabs.
 *
 * return: PID of spawned process.
 */

GPid
spawn_external (const GString * cmdline)
{
  GError *err = NULL; /* force implicit g_malloc */
  gchar **argv;
  GPid pid = -1;
  gboolean ok;

  if (!cmdline->str)
    return -1;

  argv = build_argv (cmdline->str);
  ok = g_spawn_async (NULL,	/* dir */
		      argv, NULL,	/* env */
		      G_SPAWN_SEARCH_PATH,	/* | G_SPAWN_DO_NOT_REAP_CHILD, */
		      NULL,	/* child setup func */
		      NULL,	/* user data passed to setup */
		      &pid,	/* child pid */
		      &err);

  if (!ok)
    {
      g_warning ("error spawning pid %d: %s", pid, err->message);
      g_error_free (err);
    }
  free_argv (argv);
  return pid;
}