package shadowaead

import (
	"crypto/rand"
	"io"
	"net"
)

type streamConn struct {
	net.Conn
	Cipher
	r *reader
	w *writer
}

// NewConn wraps a stream-oriented net.Conn with cipher.
func NewConn(c net.Conn, ciph Cipher) net.Conn { return &streamConn{Conn: c, Cipher: ciph} }

func (c *streamConn) initReader() error {
	salt := make([]byte, c.SaltSize())
	if _, err := io.ReadFull(c.Conn, salt); err != nil {
		return err
	}

	aead, err := c.Decrypter(salt)
	if err != nil {
		return err
	}

	c.r = newReader(c.Conn, aead)
	return nil
}

func (c *streamConn) Read(b []byte) (int, error) {
	if c.r == nil {
		if err := c.initReader(); err != nil {
			return 0, err
		}
	}
	return c.r.Read(b)
}

func (c *streamConn) initWriter() error {
	salt := make([]byte, c.SaltSize())
	if _, err := io.ReadFull(rand.Reader, salt); err != nil {
		return err
	}
	aead, err := c.Encrypter(salt)
	if err != nil {
		return err
	}
	_, err = c.Conn.Write(salt)
	if err != nil {
		return err
	}
	c.w = newWriter(c.Conn, aead)
	return nil
}

func (c *streamConn) Write(b []byte) (int, error) {
	if c.w == nil {
		if err := c.initWriter(); err != nil {
			return 0, err
		}
	}
	return c.w.Write(b)
}