/* File:  ~liux/public_html/courses/cop4610/examples/simple-cd.cc
   Purpose: Demonstrate how to use chdir, getenv and getcwd system calls 
            for COP 4610
   Author:  Xiuwen Liu, based on an example in Advanced Programming
            in the UNIX Environment, by W. Richard Stevens, 
            Addison-Wesley, 1992
   On the web: 
     http://www.cs.fsu.edu/~liux/courses/cop4610/examples/simple-cd.cc
   Complie
     g++ -o simple-cd simple-cd.cc 
*/

#include <sys/types.h>
#include <strings.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <iostream.h>

#define  MAX_LINE   512
#define  MAX_ARG    50

int Parse_Command(char *buf, char *argv_list[]);
void sig_handler(int); /* A signal handler */
int   interrupted;
pid_t my_pid;
int main(void)
{
  char   buf[MAX_LINE];
  pid_t  pid;
  int    status;
  char   *my_argv[MAX_ARG];
  int    my_argc;
  int    i; 
  char   ch;
  my_pid = getpid(); /* Get my process id */
  
  if (signal(SIGINT, sig_handler) == SIG_ERR) 
    cerr << my_pid << " Could not catch signal SIGINT.\n";
  do {
    getcwd(buf,MAX_LINE);
    cout <<"Your current working directory is \n\t" << buf <<"\n";
    cout << "Do you want to change it ? ";
    interrupted = 0;
    cout.flush();
    cin.getline((char *)buf,MAX_LINE);
    cin.clear();
    /*sleep(1);
      cout << "Now buffer is " << buf;*/
    if (interrupted) {
      cin.clear();
      cout << endl;
      /* cin >> ch;
	 cout << ch;*/
      continue;
    }
    if (buf[0] == 'N' || buf[0] == 'n') break;
    cout << "Please enter your desired directory: ";
    
    interrupted = 0;
    buf[0]='\0';
    /* cin >> ch; */
    cin.clear();
    cin.getline((char *)buf,MAX_LINE);
    /* cout << "Enter directory: " << buf; */
    if (interrupted) {
      cin.clear(); 
      cout << endl;
      /* cin >> i; */
      continue;
    }
    if (buf[0] == '\0') {
      my_argc = 0;
    }
    else {
      if (buf[strlen(buf)-1] != '/')
	strcat(buf,"/");
      my_argc = Parse_Command(buf, my_argv);
    }
    if (my_argc > 1) {
      cout <<"cd: Too many parameters.\n";
      continue;
    }
    if (my_argc == 0) {
      my_argv[0] = getenv("HOME");
      if (my_argv[0] != NULL)
	my_argc = 1;
      else {
	cerr<<"cd: could not get home directory.\n";
	continue;
      }
    }
    if (chdir(my_argv[0]) < 0) {
      perror("cd");
    }
  } while(1);
  return 0;
}

int Parse_Command(char *buf, char *argv_list[])
{
  int now_argc = 0;
  char *bufp;
  
  bufp = strtok(buf, " \t");

  argv_list[now_argc] = bufp;

  if (bufp == NULL) return now_argc;

  now_argc++; 

  while (bufp != NULL && now_argc < MAX_ARG) {
    bufp = strtok(NULL," \t");
    argv_list[now_argc++] = bufp;
  }
  now_argc --; /* Because the last one is an empty string */
  if (now_argc >= MAX_ARG) {
    cerr<<"Argument list too long.\n";
  }
  return now_argc;
}

void sig_handler(int signo) /* signo: Signal number defined in <signal.h>*/
{
  signal(signo,sig_handler); /* Refine the signal handler,
                                otherwise, the system resets to the
                                default action */
  switch(signo) {
  case SIGINT:
    interrupted = 1;
    cout << my_pid << ": Receieved signal SIGINT = " << signo << ".\n";
    
    break;

  default:
    cout<<my_pid<<": Received signal " << signo <<" with unknown type.\n";
  }
  return;
}