// Copyright 2020 lesismal. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

//go:build windows
// +build windows

package nbio

import (
	"bytes"
	"errors"
	"io"
	"net"
	"sync"
	"time"
)

// Conn wraps net.Conn
type Conn struct {
	g *Gopher

	hash int

	mux sync.Mutex

	conn net.Conn

	closed   bool
	closeErr error

	ReadBuffer []byte

	// user session
	session interface{}

	execList []func()

	cache *bytes.Buffer

	DataHandler func(c *Conn, data []byte)
}

// Hash returns a hashcode
func (c *Conn) Hash() int {
	return c.hash
}

// Read wraps net.Conn.Read
func (c *Conn) Read(b []byte) (int, error) {
	if c.closeErr != nil {
		return 0, c.closeErr
	}

	var reader io.Reader = c.conn
	if c.cache != nil {
		reader = c.cache
	}
	nread, err := reader.Read(b)
	if c.closeErr == nil {
		c.closeErr = err
	}
	return nread, err
}

func (c *Conn) read(b []byte) (int, error) {
	c.g.beforeRead(c)
	nread, err := c.conn.Read(b)
	if c.closeErr == nil {
		c.closeErr = err
	}
	if c.g.onRead != nil {
		if nread > 0 {
			if c.cache == nil {
				c.cache = bytes.NewBuffer(nil)
			}
			c.cache.Write(b[:nread])
		}
		c.g.onRead(c)
		return nread, nil
	} else if nread > 0 {
		c.g.onData(c, b[:nread])
	}
	return nread, err
}

// Write wraps net.Conn.Write
func (c *Conn) Write(b []byte) (int, error) {
	c.g.beforeWrite(c)

	nwrite, err := c.conn.Write(b)
	if err != nil {
		if c.closeErr == nil {
			c.closeErr = err
		}
		c.Close()
	}
	c.g.onWriteBufferFree(c, b)

	return nwrite, err
}

// Writev wraps buffers.WriteTo/syscall.Writev
func (c *Conn) Writev(in [][]byte) (int, error) {
	buffers := net.Buffers(in)
	nwrite, err := buffers.WriteTo(c.conn)
	if err != nil {
		if c.closeErr == nil {
			c.closeErr = err
		}
		c.Close()
	}
	for _, v := range in {
		c.g.onWriteBufferFree(c, v)
	}
	return int(nwrite), err
}

// Close wraps net.Conn.Close
func (c *Conn) Close() error {
	c.mux.Lock()
	if !c.closed {
		c.closed = true
		err := c.conn.Close()
		c.mux.Unlock()
		if c.g != nil {
			c.g.pollers[c.Hash()%len(c.g.pollers)].deleteConn(c)
		}
		return err
	}
	c.mux.Unlock()
	return nil
}

// CloseWithError .
func (c *Conn) CloseWithError(err error) error {
	if c.closeErr == nil {
		c.closeErr = err
	}
	return c.Close()
}

// LocalAddr wraps net.Conn.LocalAddr
func (c *Conn) LocalAddr() net.Addr {
	return c.conn.LocalAddr()
}

// RemoteAddr wraps net.Conn.RemoteAddr
func (c *Conn) RemoteAddr() net.Addr {
	return c.conn.RemoteAddr()
}

// SetDeadline wraps net.Conn.SetDeadline
func (c *Conn) SetDeadline(t time.Time) error {
	if t.IsZero() {
		t = time.Now().Add(timeForever)
	}
	return c.conn.SetDeadline(t)
}

// SetReadDeadline wraps net.Conn.SetReadDeadline
func (c *Conn) SetReadDeadline(t time.Time) error {
	if t.IsZero() {
		t = time.Now().Add(timeForever)
	}
	return c.conn.SetReadDeadline(t)
}

// SetWriteDeadline wraps net.Conn.SetWriteDeadline
func (c *Conn) SetWriteDeadline(t time.Time) error {
	if t.IsZero() {
		t = time.Now().Add(timeForever)
	}
	return c.conn.SetWriteDeadline(t)
}

// SetNoDelay wraps net.Conn.SetNoDelay
func (c *Conn) SetNoDelay(nodelay bool) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetNoDelay(nodelay)
	}
	return nil
}

// SetReadBuffer wraps net.Conn.SetReadBuffer
func (c *Conn) SetReadBuffer(bytes int) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetReadBuffer(bytes)
	}
	return nil
}

// SetWriteBuffer wraps net.Conn.SetWriteBuffer
func (c *Conn) SetWriteBuffer(bytes int) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetWriteBuffer(bytes)
	}
	return nil
}

// SetKeepAlive wraps net.Conn.SetKeepAlive
func (c *Conn) SetKeepAlive(keepalive bool) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetKeepAlive(keepalive)
	}
	return nil
}

// SetKeepAlivePeriod wraps net.Conn.SetKeepAlivePeriod
func (c *Conn) SetKeepAlivePeriod(d time.Duration) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetKeepAlivePeriod(d)
	}
	return nil
}

// SetLinger wraps net.Conn.SetLinger
func (c *Conn) SetLinger(onoff int32, linger int32) error {
	conn, ok := c.conn.(*net.TCPConn)
	if ok {
		return conn.SetLinger(int(linger))
	}
	return nil
}

// Session returns user session
func (c *Conn) Session() interface{} {
	return c.session
}

// SetSession sets user session
func (c *Conn) SetSession(session interface{}) {
	c.session = session
}

func newConn(conn net.Conn, fromClient ...interface{}) *Conn {
	c := &Conn{
		conn: conn,
	}

	addr := conn.RemoteAddr().String()
	if len(fromClient) > 0 {
		addr = conn.LocalAddr().String()
	}
	for _, ch := range addr {
		c.hash = 31*c.hash + int(ch)
	}
	if c.hash < 0 {
		c.hash = -c.hash
	}

	return c
}

// NBConn converts net.Conn to *Conn
func NBConn(conn net.Conn) (*Conn, error) {
	if conn == nil {
		return nil, errors.New("invalid conn: nil")
	}
	c, ok := conn.(*Conn)
	if !ok {
		c = newConn(conn, true)
	}
	return c, nil
}