package sbproxy

import (
	"io"
)

func ReadVarInt(r io.Reader) (int32, int, error) {
	var val int32
	var size int
	for {
		var b [1]byte
		if _, err := r.Read(b[:]); err != nil {
			return 0, 0, err
		}
		d := b[0]
		val |= int32(d&0x7F) << (7 * size)
		size++
		if size > 5 {
			return 0, 0, io.ErrUnexpectedEOF
		}
		if d&0x80 == 0 {
			break
		}
	}
	return val, size, nil
}

func WriteVarInt(w io.Writer, val int32) int {
	buf := make([]byte, 5)
	size := 0
	for {
		b := byte(val & 0x7F)
		val >>= 7
		if val != 0 {
			b |= 0x80
		}
		buf[size] = b
		size++
		if val == 0 {
			break
		}
	}
	w.Write(buf[:size])
	return size
}

func ReadString(r io.Reader) (string, error) {
	length, _, err := ReadVarInt(r)
	if err != nil {
		return "", err
	}
	buf := make([]byte, length)
	if _, err := io.ReadFull(r, buf); err != nil {
		return "", err
	}
	return string(buf), nil
}

func WriteString(w io.Writer, s string) {
	WriteVarInt(w, int32(len(s)))
	w.Write([]byte(s))
}