package outbound

import (
	"context"
	"io"
	"net"
	"time"

	"github.com/Dreamacro/clash/common/cache"
	"github.com/Dreamacro/clash/component/dialer"
	C "github.com/Dreamacro/clash/constant"
)

const (
	rejectCountLimit = 50
	rejectDelay      = time.Second * 35
)

var rejectCounter = cache.NewLRUCache[string, int](cache.WithAge[string, int](15), cache.WithStale[string, int](false), cache.WithSize[string, int](512))

type Reject struct {
	*Base
}

// DialContext implements C.ProxyAdapter
func (r *Reject) DialContext(ctx context.Context, metadata *C.Metadata, opts ...dialer.Option) (C.Conn, error) {
	key := metadata.RemoteAddress()

	count, existed := rejectCounter.Get(key)
	if !existed {
		count = 0
	}

	count = count + 1

	rejectCounter.Set(key, count)

	if count > rejectCountLimit {
		c, _ := net.Pipe()

		_ = c.SetDeadline(time.Now().Add(rejectDelay))

		return NewConn(c, r), nil
	}

	return NewConn(&nopConn{}, r), nil
}

// ListenPacketContext implements C.ProxyAdapter
func (r *Reject) ListenPacketContext(ctx context.Context, metadata *C.Metadata, opts ...dialer.Option) (C.PacketConn, error) {
	return newPacketConn(&nopPacketConn{}, r), nil
}

func NewReject() *Reject {
	return &Reject{
		Base: &Base{
			name: "REJECT",
			tp:   C.Reject,
			udp:  true,
		},
	}
}

type nopConn struct{}

func (rw *nopConn) Read(b []byte) (int, error) {
	return 0, io.EOF
}

func (rw *nopConn) Write(b []byte) (int, error) {
	return 0, io.EOF
}

func (rw *nopConn) Close() error                     { return nil }
func (rw *nopConn) LocalAddr() net.Addr              { return nil }
func (rw *nopConn) RemoteAddr() net.Addr             { return nil }
func (rw *nopConn) SetDeadline(time.Time) error      { return nil }
func (rw *nopConn) SetReadDeadline(time.Time) error  { return nil }
func (rw *nopConn) SetWriteDeadline(time.Time) error { return nil }

type nopPacketConn struct{}

func (npc *nopPacketConn) WriteTo(b []byte, addr net.Addr) (n int, err error) { return len(b), nil }
func (npc *nopPacketConn) ReadFrom(b []byte) (int, net.Addr, error)           { return 0, nil, io.EOF }
func (npc *nopPacketConn) Close() error                                       { return nil }
func (npc *nopPacketConn) LocalAddr() net.Addr                                { return &net.UDPAddr{IP: net.IPv4zero, Port: 0} }
func (npc *nopPacketConn) SetDeadline(time.Time) error                        { return nil }
func (npc *nopPacketConn) SetReadDeadline(time.Time) error                    { return nil }
func (npc *nopPacketConn) SetWriteDeadline(time.Time) error                   { return nil }