#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

#define MAXLINE 81
#define MAXARG 10
#define WHITE "\t \n"
#define RED   "\x1B[31m"
#define GRN   "\x1B[32m"
#define RESET "\x1B[0m"

void execCommand(char *input){
	char *args[MAXARG];	//array of tokens
	char *token;
	int tknCtr = 0;

	/*Split string into tokens*/
	//first token
	token = strtok(input, WHITE);
	args[0] = token;
	//all other tokens
	while(token != NULL){
		token = strtok(NULL, WHITE);
		args[++tknCtr] = token;
	}
	
	/*Shell fork*/
	int forkStatus = 0;
	pid_t pexec, waitPexec;

	if ((pexec = fork()) == 0){
		//search current directory, including relative paths
		int status = execv(args[0], args);

		//search /bin directory
		if( status == -1){
			//prepend first token with /bin directory
			char dir1[80] = "/bin";
			char buf[256];

			snprintf(buf, sizeof buf, "%s/%s", dir1, args[0]);
			args[0] = buf;

			status = execv(args[0], args);
			
			//binary not found in /bin directory
			if( status == -1){
				printf(RED"\n\t/!\\ ERROR: command not found/!\\\n\n"RESET);
			}
		}
		exit(0);
	} else if (pexec < 0) {
		printf(RED"\n\t/!\\ ERROR: could not fork executor /!\\\n"RESET);
	} else {
		while ((waitPexec = wait(&forkStatus)) > 0);	//wait on child
	}
}

int main(){
	char input[MAXLINE];
	
	do{
		printf(GRN"What command do you desire: "RESET);
	
		scanf("%80[^\n]", input);		//read until enter pressed		
		while ((getchar()) != '\n');	//flush stdin buffer

		if (strcmp(input, "exit") == 0) break;

		execCommand(input);
	} while (strcmp(input, "exit") != 0);
	
	printf("\n\tGOODBYE !\n");
	exit(EXIT_SUCCESS);
}