#include<stdio.h>
#include<stdlib.h>
#include<sys/wait.h>
#include<unistd.h>
#include<string.h>
#include<readline/readline.h>
#include<readline/history.h>
int handleBuiltins(char **args) {
  if(strcmp(args[0], "cd") == 0) {
    chdir(args[1] == NULL ? getenv("HOME") : args[1]);
    return 1;
  }
  else if(strcmp(args[0], "exit") == 0) {
    exit(0);
  } else { return 0;}
}
char **parse(char *line) {
  char **args= malloc(64 * sizeof(char *));
  int i = 0;
  char *token = strtok(line, " \t\n");
  while(token !=NULL) {
    args[i] = token;
    i++;
    token = strtok(NULL, " \t\n");
  }
  args[i] = NULL;
  return args;
}
int main() {
	while(1) {
		char *user = getenv("USER");
		char dir[1024];
		getcwd(dir, sizeof(dir));
		char host[1024];
		gethostname(host, sizeof(host));
		char prompt[2048];
		snprintf(prompt, sizeof(prompt), "%s@%s %s$ ", user, host, dir);
		char *line = readline(prompt);
		if(line == NULL) return 0;
		if(line && *line) add_history(line);
		char **parsed = parse(line);
		if(parsed[0] == NULL) { free(parsed); free(line); continue; }
		if(handleBuiltins(parsed)) { free(line); free(parsed); continue; }
		pid_t pid = fork();
		if(pid == 0) {
		  if(execvp(parsed[0], parsed) == -1 ) {
		    perror("tinysh");
		    exit(1);
		  }
		} else if(pid > 0) {
		  wait(NULL);
		}
		free(parsed);
		free(line);
	}
}