/* File: lab3.c
   Author:  Xiuwen Liu
   Purpose: To implement a virtual file system. 
   Command to complie:
         see makefile
*/


#include <sys/types.h>
#include <strings.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include "type-def.h"
#include "fileSystem.h"

int verbose;
int interrupted;
int Parse_Command(char *buf, char *argv_list[]);
void sig_handler(int); /* A signal handler example */
void help(void);

#define  MAX_LINE   512
#define  MAX_ARG    50

int main(int argc, char *argv[])
{
  int i, j, k, k1;
  char c;
  char   buf[MAX_LINE];
  pid_t  pid;
  int    status;
  int    exit_flag;
  char   *my_argv[MAX_ARG];
  int    my_argc;
  int    fromfileflag;
  char   rwbuf[BLOCK_SIZE*10];
  /* Initialization here */
  printf("**********************************************************\n");
  help();
  printf("**********************************************************\n");
  printf("\n\n");
  verbose = 0; 
  exit_flag = 0;
  fromfileflag = 0;
  while ((c = getopt(argc, argv, "v:f:")) != EOF) {
    switch(c) {
    case 'v':
      verbose = atoi(optarg);
      break;
    case 'f':
      i =  open(optarg, O_RDONLY);
      if (i < 0) {
        fprintf(stderr,"Cannot open file %s.\n", optarg);
      }
      else {
       close(0);
       dup(i);
       close(i);
       fromfileflag = 1;
      }
      break; 
    default:
      printf("%c is not valid option.\n", c);
    }
  }
  
  /* Initiliaze here */
  initDisk();
  initFileSystem();
  if (signal(SIGINT, sig_handler) == SIG_ERR) 
    fprintf(stderr,"%d: Could not catch signal SIGINT.\n", getpid());
  interrupted = 0;
  exit_flag = 0;
  while(exit_flag==0) {
    printf("Next command %% "); /* Display prompt */
    fflush(stdout);
    interrupted = 0;
    buf[0]='\0';
    i = 0;
    buf[0]='\0';
    i = 0;
    do {
      /* k = read((int)0, &(buf[i]), (size_t)1);*/
      buf[i] = getchar();
      if (interrupted)
	break;
      
      if (buf[i] == '\n')
	break;
      i++;
      
    } while(1);
    buf[i] = '\0';
    if (interrupted) { 
      fflush(stdin);
      printf("\n");
      fflush(stdout);
      continue;
    }
    if (fromfileflag) printf("%s\n", buf); 
    if (buf[0] == '\0') continue;
    my_argc = Parse_Command(buf, my_argv);
    if (my_argc == 0) continue;
    
    if (strcmp(my_argv[0],"myexit") ==0) {
      exit_flag = 1;
      continue;
    }
    if (strcmp(my_argv[0],"help")==0) {
      help();
      continue;
    }

    if (strcmp(my_argv[0],"myfat")==0) {
      Print_FAT();
      continue;
    }
    if (strcmp(my_argv[0],"mycd")==0) {
      if (my_argc > 2) {
	fprintf(stderr, "mycd: Too many parameters.\n");
	continue;
      }
      if (my_argc == 1) {
	my_argv[1] = getenv("HOME");
	if (my_argv[1] == 0) {
	  fprintf(stderr, "mycd: could not get home directory. \n");
	  continue;
	}
      }
      if (chdir(my_argv[1]) < 0) {
	perror("mycd");
      }
      continue;
    }
    if (strcmp(my_argv[0],"mycd1")==0) {
      if (my_argc != 2) {
	fprintf(stderr, "mycd1: Too few or many parameters.\n");
	continue;
      }
      
      if (fCd(my_argv[1]) < 0) {
	printf("Cannot change the current working directory.\n");
      }
      continue;
    }
    if (strcmp(my_argv[0],"mycreate")==0) {
      if (my_argc != 2) {
	fprintf(stderr, "mycreate: Too many or too few parameters.\n");
	continue;
      }
      i = fOpen(my_argv[1]);
      fClose(i);
      continue;
    }
    if (strcmp(my_argv[0],"myseek")==0) {
      char tmpbuf[2];
      if (my_argc != 3) {
        fprintf(stderr, "myseek: Too many or too few parameters.\n");
        continue;
      }
      i = fOpen(my_argv[1]);
      if (i < 0) {
        fprintf(stderr,"Cannot open virtual file \"%s\".\n", my_argv[1]);
        continue;
      }
      j = atoi(my_argv[2]);
      k = fSeek(i,j);
      if (k < 0) {
        fprintf(stderr,"Invalid myseek parameters.\n");
        fClose(i);
        continue;
      }
      j=fRead(i, tmpbuf, (int)1);
      if (j < 0) {
        fprintf(stderr,"Reading a byte from virtual file \"%s\" failed.\n",
                my_argv[1]);
        fClose(i);
        continue;
      }
      printf("Character at %d from virtual file \"%s\" is %c (%d).\n",
           (int)atoi(my_argv[2]), my_argv[1], tmpbuf[0], (int)(tmpbuf[0]));
      fClose(i);
      continue;
   } 
    if (strcmp(my_argv[0],"mymkdir")==0) {
      if (my_argc != 2) {
	fprintf(stderr, "mymkdir: Too many or too few parameters.\n");
	continue;
      }
      fMkdir(my_argv[1]);
      continue;
    }
    if (strcmp(my_argv[0],"mypwd1")==0) {
      printf("Current working directory in the virtual file system:\n\t");
      printf("%s\n", Get_Pwd());
      continue;
    }
     
    if (strcmp(my_argv[0],"myls")==0) {
      fLs();
      continue;
    }
    if (strcmp(my_argv[0],"mycopyfrom") ==0) {
      int fd, fd1;
      if (my_argc != 3) {
	fprintf(stderr, "mycopyfrom: Too many or too few parameters.\n");
	continue;
      }
      fd = open(my_argv[1],O_RDONLY);
      if (fd < 0) {
	fprintf(stderr,"Cannot open file \"%s\" for reading ",my_argv[1]);
	fprintf(stderr,"in the real system.\n");
	continue;
      }
      fd1 = fOpen(my_argv[2]);
      if (fd1 < 0) {
	fprintf(stderr,"Cannot open file \"%s\" for writing ",my_argv[2]);
	fprintf(stderr,"in the virtual system.\n");
	close(fd);
	continue;
      }
      do {
        k1 = rand() % (10*BLOCK_SIZE-1) + 1;
	k = read(fd, rwbuf, (int)k1);
	if (k>0) {
	  fWrite(fd1, rwbuf, k);
	}
	if (k != k1) break;
      } while (1);
      close(fd);
      fClose(fd1);
      continue;
    }
    if (strcmp(my_argv[0],"mycopyto") ==0) {
      int fd, fd1;
      if (my_argc != 3) {
	fprintf(stderr, "mycopyto: Too many or too few parameters.\n");
	continue;
      }
      fd = open(my_argv[2],O_WRONLY|O_CREAT|O_TRUNC,
		S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
      if (fd < 0) {
	fprintf(stderr,"Cannot open file \"%s\" for writing ",my_argv[2]);
	fprintf(stderr,"in the real system.\n");
	continue;
      }
      /* Make the sure will be 0755 */
      fchmod(fd, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);

      fd1 = fOpen(my_argv[1]);
      if (fd1 < 0) {
	fprintf(stderr,"Cannot open file \"%s\" for reading ",my_argv[1]);
	fprintf(stderr,"in the virtual system.\n");
	close(fd);
	continue;
      }
      do {
        k1 = rand() % (10*BLOCK_SIZE-1) + 1;
	k = fRead(fd1, rwbuf, k1);
	if (k>0) {
	  write(fd, rwbuf, k);
	}
	if (k != k1) break;
      } while (1);
      close(fd);
      fClose(fd1);
      continue;
    }
    
    if (strcmp(my_argv[0],"mycat") ==0) {
      int fd1;
      if (my_argc != 2) {
	fprintf(stderr, "mycat: Too many or too few parameters.\n");
	continue;
      }
      
      fd1 = fOpen(my_argv[1]);
      if (fd1 < 0) {
	fprintf(stderr,"Cannot open file \"%s\" for reading ",my_argv[1]);
	fprintf(stderr,"in the virtual system.\n");
	continue;
      }
      do {
        k1 = rand() % (10*BLOCK_SIZE-1) + 1;
	k = fRead(fd1, rwbuf, k1);
	if (k>0) {
	  for (i=0; i < k; i++)
	    putchar((int)rwbuf[i]);
	}
	if (k != k1) break;
      } while(1);
      printf("\n");
      fClose(fd1);
      continue;
    }
    /* Run an external command */
    if ( (pid = fork()) < 0) {
      fprintf(stderr,"Counld not create new process.");
    }
    else {
      if (pid ==0) { /* Child */
	execvp(my_argv[0],my_argv);
	
	fprintf(stderr,"Could not execute \"%s\".\n", my_argv[0]);
	perror("execvp");
	exit(-1);
      }
      /* Parent */
      
      if((pid = waitpid(pid, &status, 0)) < 0) {
	fprintf(stderr,"System call \"waitpid\" error.\n");
      }
    }
  }
  /* Release memory here */
  freeDisk();
  
  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 (bufp != NULL) {
    fprintf(stderr,"Argument list too long.\n");
  }
  return now_argc;
}


void sig_handler(int signo) /* signo: Signal number defined in <signal.h>*/
{
  /* Reset to the interpret handler */
  signal(signo, sig_handler);
  switch(signo) {
  case SIGINT:
    interrupted = 1;
    break;  
  default:
    printf("%d received signal %d with unknown type.\n",
	   getpid(), signo);
  }
  return;
}

void help(void)
{
  printf("Usage: lab3 -v verbose -f command-file\n");
  printf("   Implemented internal commands:\n");
  printf("\thelp - Show this information.\n");
  printf("\tmyexit - Exit from this program.\n");
  printf("\tmyfat  - Show the FAT table structure (only used blocks).\n");
  printf("\tmycd  [dir] - Change the current working directory on the UNIX system.\n");
  printf("\tmycd1 dir   - Change the current working directory on the ");
  printf("virtual file system.\n");
  printf("\tmycreate file - Create an empty with the specified name.\n");
  printf("\tmyseek virtualfile position - Show the character at the given position\n");
  printf("\t\tof the virtual file.\n");
  printf("\tmymkdir dir - Create a subdirectory under the the current \n");
  printf("\t\tworking directory on the ");
  printf("virtual file system.\n");
  printf("\tmyls - List the files under the current working directory on the \n");
  printf("\t\tvirtual file system.\n");
  printf("\tmycopyfrom realfile vfile - Copy a unix file to the virtual file system.\n");
  printf("\tmycopyto vfile realfile - Copy a virtual file to the unix system.\n");
  printf("\tmycat vfile - Display the content of the virtual file.\n");
  printf("  All other commands will be executed as an external unix command.\n");
  return;
}