/*
**  Alibek Manabayev
**  This program is a very simple shell that only handles
**  single word commands (no arguments).
**  Type "quit" to quit.
*/
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#define CMDLEN 80
#define ARGCNT 10
#define BUFFLEN 2048
#define SEPARATOR " "
#define bool _Bool
#define true 1
#define false 0

int parseArguments(char *buff, char **args);
void tee(int in, int out1, int out2);
void child_proc(char *arguments[ARGCNT], int fd);
void d_log(char * str);
int b_fd = -1;

int main(int argc, char ** argv) {
    if (argc > 1) {
        b_fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0644);
        if (b_fd < 0) {
            puts("Error opening backup file");
            exit(1);
        }
        printf("Backing up to file: %s\n", argv[1]);
    }

  int   childpid;
  int   status;
  int   i, fd;
  char  buff[CMDLEN];
  char  command[CMDLEN];
  char *arguments[ARGCNT];
  bool  background = false;

  d_log("Program begins.\n");

  for (;;) {
    d_log("Please enter a command:   ");
    fgets(buff, CMDLEN, stdin);
        d_log(buff);
    buff[strlen(buff) - 1] = '\0';

    // printf("|%s|%d\n", buff, strcmp(buff, "quit"));

    if (strcmp(buff, "quit") == 0) break;

    int n = parseArguments(buff, arguments);

    // for (int i = 0; arguments[i] != NULL; i++) {
    //   printf("\\%s/\n", arguments[i]);
    // }

    background = n > 0 && !strcmp(arguments[n - 1], "&");

    if (background) {
      arguments[n - 1] = NULL;
    }

        int fds[2];
        pipe(fds);

    childpid = fork();

    if (childpid < 0) {
      d_log("Error in fork.\n");
      exit(-1);
    }

    if (childpid != 0) {
      /* Parent process closes up output side of pipe */
      close(fds[1]);

      /* Read in a string from the pipe (fds[0])*/
            tee(fds[0], 1, b_fd);
      if (!background) {
        waitpid(childpid, &status, 0);
      }
    } else {
      /* Child process closes up input side of pipe */
      close(fds[0]);

            child_proc(arguments, fds[1]);
            exit(0);
    }
  }
}

int parseArguments(char *buff, char **args) {
  int i = 0;

  args[i] = strtok(buff, SEPARATOR);

  while (args[i] != NULL) {
    // printf("%s\n", args[i]);
    args[++i] = strtok(NULL, SEPARATOR);
  }

  // printf("%d\n", i);
  return i;
}

void tee(int in, int out1, int out2) {
    char BUFF[BUFFLEN];
    int n = 0;
    // puts("-- take a cop of tee --");
    while ((n = read(in, BUFF, BUFFLEN)) > 0) {
        // printf("|%s(%d)|", BUFF, n);
        write(out1, BUFF, n);
        write(out2, BUFF, n);
    }
    // puts("-- enough --");
}

void child_proc(char *arguments[ARGCNT], int fd) {
    dup2(fd, 1);
    execvp(arguments[0], arguments);
}

void d_log(char * str) {
    printf("%s", str);
    if ()
}