// Deadlined socket read/write. https://github.com/golang/go/issues/16100

package godlighty

import (
	"net"
	"time"
)

type DeadlinedConn struct {
	net.Conn
	ReadTimeout              time.Duration
	WriteTimeout             time.Duration
	ReadThreshold            int64
	WriteThreshold           int64
	BytesReadFromDeadline    int64
	BytesWrittenFromDeadline int64
}

func (c *DeadlinedConn) Read(b []byte) (n int, err error) {
	if c.BytesReadFromDeadline > c.ReadThreshold {
		c.BytesReadFromDeadline = 0
		err = c.Conn.SetDeadline(time.Now().Add(c.ReadTimeout))
		if err != nil {
			return
		}
	}
	n, err = c.Conn.Read(b)
	c.BytesReadFromDeadline += int64(n)
	return
}

func (c *DeadlinedConn) Write(b []byte) (n int, err error) {
	if c.BytesWrittenFromDeadline > c.WriteThreshold {
		c.BytesWrittenFromDeadline = 0
		err = c.Conn.SetWriteDeadline(time.Now().Add(c.WriteTimeout))
		if err != nil {
			return
		}
	}
	n, err = c.Conn.Write(b)
	c.BytesWrittenFromDeadline += int64(n)
	return
}

type DeadlinedListener struct {
	net.Listener
	ReadTimeout  time.Duration
	WriteTimeout time.Duration
}

func (l *DeadlinedListener) Accept() (net.Conn, error) {
	c, err := l.Listener.Accept()
	if err != nil {
		return nil, err
	}
	return &DeadlinedConn{
		Conn:           c,
		ReadTimeout:    l.ReadTimeout,
		WriteTimeout:   l.WriteTimeout,
		ReadThreshold:  int64((l.ReadTimeout * 1024) / time.Second),
		WriteThreshold: int64((l.WriteTimeout * 1024) / time.Second),
	}, nil
}

func DeadlinedListen(
	network, addr string,
	readTimeout, writeTimeout time.Duration,
) (net.Listener, error) {
	l, err := net.Listen(network, addr)
	if err != nil {
		return nil, err
	}
	return &DeadlinedListener{
		Listener:     l,
		ReadTimeout:  readTimeout,
		WriteTimeout: writeTimeout,
	}, nil
}