protohackers/pkg/conn/conn.go

package conn

import (
	"bufio"
	"fmt"
	"net"
)

const (
	Port = ":3030"
	Type = "tcp4"
)

func StartSimple(handler func(conn net.Conn)) error {
	l, err := net.Listen(Type, Port)
	if err != nil {
		return err
	}
	defer l.Close()

	fmt.Println(fmt.Sprintf("Listening on port %s", Port))

	for {
		c, err := l.Accept()
		if err != nil {
			return err
		}
		go handler(c)
		if err != nil {
			return err
		}
	}
}

func ReadAndRespond(c net.Conn, process func([]byte) []byte) error {
	defer c.Close()
	sc := bufio.NewScanner(c)
	for sc.Scan() {
		response := process(sc.Bytes())
		_, err := c.Write(response)
		if err != nil {
			return err
		}
	}
	if err := sc.Err(); err != nil {
		return err
	}
	return nil
}