package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	stdin := bufio.NewReader(os.Stdin)
	for {
		fmt.Fprint(os.Stdout, "$ ")

		in, err := stdin.ReadString('\n')
		if err != nil {
			fmt.Println(err.Error())
		}

		trim := strings.TrimSpace(in)

		command := strings.Split(trim, " ")

		switch command[0] {
		case "exit":
			code, err := strconv.Atoi(command[1])
			if err != nil {
				fmt.Println(err.Error())
			}
			os.Exit(code)
		case "echo":
			fmt.Println(strings.Join(command[1:], " "))
		case "type":
			switch command[1] {
			case "exit", "echo", "type":
				fmt.Printf("%s is a shell builtin\n", command[1])
			default:
				fmt.Printf("%s not found\n", command[1])
			}
		default:
			fmt.Printf("%s: command not found\n", command[0])
		}
	}
}