exercise-rot-reader.go

/*
Author: Resul Emre AYGAN
*/

package main

import (
	"io"
	"os"
	"strings"
)

type rot13Reader struct {
	r io.Reader
}

func rot13(x byte) byte {
	capitalLetter := x >= 'A' && x <= 'Z'

	//check is letter
	if !capitalLetter && (x < 'a' || x > 'z') {
		return x
	}

	x += 13
	if capitalLetter && x > 'Z' || !capitalLetter && x > 'z' {
		x -= 26
	}
	return x
}

func (rot *rot13Reader) Read(b []byte) (int, error) {
	n, err := rot.r.Read(b)

	for i := 0; i <= n; i++ {
		b[i] = rot13(b[i])
	}

	return n, err
}

func main() {
	s := strings.NewReader("Lbh penpxrq gur pbqr!")
	r := rot13Reader{s}
	io.Copy(os.Stdout, &r)
}