/**************************************************************/
  /*                                                            */
  /*      UNIX 1 / WS 92/93       Gruppe  ux803                 */
  /*      7. Uebung - Aufgabe 5 - builtin.c                     */
  /*                                                            */
  /*      Vorname     Name        Matrikelnr.                   */
  /*     ---------   -------     -------------                  */
  /*      Dietmar     Dierks        125761                      */
  /*      Roman       Czyborra      127221                      */
  /*      Torsten     Buller        117894                      */
  /*      Gerasimos   Paliatsaras   140956                      */
  /*                                                            */
  /**************************************************************/

#include "msh.h"       /* MAXPROC struct kommando */
#include <stdlib.h>    /* getenv */
#include <sys/param.h> /* MAXPATHLEN */
#include <pwd.h>       /* pw_dir */

#define EXIT    1
#define CHDIR   2
#define PWD     3
#define LISTALL 4
#define WAIT    5
#define JOBS	6
#define FG	7
#define BG	8
#define MENU    9

#define DONE  1
#define NONE  0

static struct map 
{
  char * name;
  int function;
}
builtins [] = 
{
  {"exit", EXIT},
  {"quit", EXIT},
  {"cd",   CHDIR},
  {"pwd",  PWD},
  {"la",   LISTALL},
  {"wait", WAIT},
  {"jobs", JOBS},
  {"fg",   FG},
  {"bg",   BG},
  {"help", MENU},
  {"menu", MENU},
  {NONE, NONE}
};

static int jobspecified (struct kommando *kp)
{
  static int i;
  if (kp->num_tok1 == 1) return -1;
  i = atoi (kp->token_1[1]);
  if (i < 0 || i >= SLOTS) {
    printf ("better try job[0..%d]!\n", SLOTS-1);
    return -1;
  }
  return i;
}

int do_builtin (kp)
     struct kommando * kp;

{
  static struct map * mp;
  static char *home, buf [MAXPATHLEN];

  if (!kp-> num_tok1)
    return DONE;

  for (mp = builtins; mp->name && strcmp (mp->name, kp->token_1[0]); ++mp);

  switch (mp -> function)
    {
    case EXIT: exit (0);
    case CHDIR:
      if (kp->num_tok1 > 1)
	chdir (kp->token_1[1]) == -1 ? perror ("chdir") : 0;
      else {
	home = getenv ("HOME");
	if (!home) home = getpwuid (getuid ()) -> pw_dir;
	chdir (home);
      }
      /* flow through */
    case PWD:
      printf ("cwd=%s\n", getwd (buf));
      return DONE;
    case LISTALL: do_ls (kp);                     return DONE;
    case WAIT:    do_wait (jobspecified (kp), 1); return DONE;
    case JOBS:    do_jobs ();                     return DONE;
    case FG:      do_fg (jobspecified (kp));      return DONE;
    case BG:      do_bg (jobspecified (kp));      return DONE;
    case MENU:
      printf ("help menu of msh builtin functions:\n");
      for (mp = builtins; mp->name; ++mp) printf ("%s ", mp->name);
      printf ("\n");
      return DONE;
    case NONE: return NONE;
    default:
      printf ("error in builtin's map!\n");
      return DONE;
    }
}