package main
 
import (
	"net"
	"fmt"
	"io"
	"time"
	"strings"
)
 
func main() {
	if listener, err := net.Listen("tcp", ":7723"); err == nil {
		for {
			if conn, err := listener.Accept(); err == nil {
				go onConnect(conn)
			}
		}
	}
}
 
func send(conn net.Conn, str string) {
	str = strings.Replace(str, "\r", "\\r", -1)
	str = strings.Replace(str, "\n", "\\n", -1)
	str = strings.Replace(str, "\t", "\\t", -1)
	str = strings.Trim(str, " \r\n\t") + "\r\n"
	conn.Write([]byte(str))
}
 
func onCommand(conn net.Conn, command string) (bool, error) {
	command = strings.Trim(command, " \t\r\n")
	commandLower := strings.ToLower(command)
	if commandLower == "quit" {
		return true, nil
	}
	fmt.Println(command)
	send(conn, command)
	return false, nil
}
 
func onConnect(conn net.Conn) {
	defer conn.Close()
	send(conn, "Goodie Console - Welcome!   v14.0.1b")
	line 	:= ""
	buffer	:= make([]byte, 1024)
	conn.SetReadDeadline(time.Now().Add(60 * time.Second))
	for {
		if bufferlen, err := conn.Read(buffer); err == nil && bufferlen > 0 {
 
  			conn.SetReadDeadline(time.Now().Add(60 * time.Second)) // set input timeout
 
			for i := 0; i<bufferlen; i++ {
				switch buffer[i] {
				case 13:
					break
				case 10:
					if close, err := onCommand(conn, line); close {
						return
					} else if err != nil {
						// log error to log
					}
					line = ""
					break
				case 9:
					if len(line) > 0 {
						line = line[ 0 : len(line)-1 ]
					}
				default:
					line += string(buffer[i])
					break
				}
			}
		} else if err == io.EOF {
			fmt.Println("detected closed LAN connection")
			return
		} else if neterr, ok := err.(net.Error); ok && neterr.Timeout() {
			fmt.Println("detected connection timed out")
			return
		} else {
			// log error
		}
	}	
}