package ws

import (
	"context"
	tls "github.com/refraction-networking/utls"
	"net"
	"net/url"
	"time"

	"github.com/go-gost/core/dialer"
	md "github.com/go-gost/core/metadata"
	ws_util "github.com/go-gost/x/internal/util/ws"
	"github.com/go-gost/x/registry"
	"github.com/gorilla/websocket"
)

func init() {
	registry.DialerRegistry().Register("ws", NewDialer)
	registry.DialerRegistry().Register("wss", NewTLSDialer)
}

type wsDialer struct {
	tlsEnabled bool
	md         metadata
	options    dialer.Options
}

func NewDialer(opts ...dialer.Option) dialer.Dialer {
	options := dialer.Options{}
	for _, opt := range opts {
		opt(&options)
	}

	return &wsDialer{
		options: options,
	}
}

func NewTLSDialer(opts ...dialer.Option) dialer.Dialer {
	options := dialer.Options{}
	for _, opt := range opts {
		opt(&options)
	}

	return &wsDialer{
		tlsEnabled: true,
		options:    options,
	}
}

func (d *wsDialer) Init(md md.Metadata) (err error) {
	return d.parseMetadata(md)
}

func (d *wsDialer) Dial(ctx context.Context, addr string, opts ...dialer.DialOption) (net.Conn, error) {
	var options dialer.DialOptions
	for _, opt := range opts {
		opt(&options)
	}

	conn, err := options.NetDialer.Dial(ctx, "tcp", addr)
	if err != nil {
		d.options.Logger.Error(err)
	}
	return conn, err
}

// Handshake implements dialer.Handshaker
func (d *wsDialer) Handshake(ctx context.Context, conn net.Conn, options ...dialer.HandshakeOption) (net.Conn, error) {
	opts := &dialer.HandshakeOptions{}
	for _, option := range options {
		option(opts)
	}

	if d.md.handshakeTimeout > 0 {
		conn.SetReadDeadline(time.Now().Add(d.md.handshakeTimeout))
		defer conn.SetReadDeadline(time.Time{})
	}

	host := d.md.host
	if host == "" {
		host = opts.Addr
	}

	dialer := websocket.Dialer{
		HandshakeTimeout:  d.md.handshakeTimeout,
		ReadBufferSize:    d.md.readBufferSize,
		WriteBufferSize:   d.md.writeBufferSize,
		EnableCompression: d.md.enableCompression,
		NetDial: func(net, addr string) (net.Conn, error) {
			return conn, nil
		},
	}

	urlObj := url.URL{Scheme: "ws", Host: host, Path: d.md.path}
	if d.tlsEnabled {
		urlObj.Scheme = "wss"
		dialer.TLSClientConfig = d.options.TLSConfig
		tlsConfig := d.options.TLSConfig
		dialer.NetDialTLSContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
			utlsConf := &tls.Config{InsecureSkipVerify: tlsConfig.InsecureSkipVerify, ServerName: tlsConfig.ServerName, ClientAuth: tls.ClientAuthType(tlsConfig.ClientAuth), ClientCAs: tlsConfig.ClientCAs, RootCAs: tlsConfig.RootCAs}
			if len(tlsConfig.Certificates) > 0 {
				for _, certificate := range tlsConfig.Certificates {
					utlsConf.Certificates = append(utlsConf.Certificates, tls.Certificate{
						Certificate:                 certificate.Certificate,
						PrivateKey:                  certificate.PrivateKey,
						OCSPStaple:                  certificate.OCSPStaple,
						SignedCertificateTimestamps: certificate.SignedCertificateTimestamps,
						Leaf:                        certificate.Leaf,
					})
				}
			}
			client := tls.UClient(conn, utlsConf, tls.HelloCustom)
			client.ApplyPreset(newWsSpec())
			err := client.Handshake()
			if err != nil {
				return nil, err
			}
			return client, nil
		}
	}
	urlStr, errUnescape := url.QueryUnescape(urlObj.String())
	if errUnescape != nil {
		d.options.Logger.Debugf("[ws] URL QueryUnescape Error URL.String() -> %s", urlObj.String())
	}
	c, resp, err := dialer.DialContext(ctx, urlStr, d.md.header)
	if err != nil {
		return nil, err
	}
	resp.Body.Close()

	cc := ws_util.Conn(c)

	if d.md.keepaliveInterval > 0 {
		d.options.Logger.Debugf("keepalive is enabled, ttl: %v", d.md.keepaliveInterval)
		c.SetReadDeadline(time.Now().Add(d.md.keepaliveInterval * 2))
		c.SetPongHandler(func(string) error {
			c.SetReadDeadline(time.Now().Add(d.md.keepaliveInterval * 2))
			d.options.Logger.Debugf("pong: set read deadline: %v", d.md.keepaliveInterval*2)
			return nil
		})
		go d.keepalive(cc)
	}

	return cc, nil
}

func (d *wsDialer) keepalive(conn ws_util.WebsocketConn) {
	ticker := time.NewTicker(d.md.keepaliveInterval)
	defer ticker.Stop()

	for range ticker.C {
		d.options.Logger.Debug("send ping")
		conn.SetWriteDeadline(time.Now().Add(10 * time.Second))
		if err := conn.WriteMessage(websocket.PingMessage, nil); err != nil {
			// d.options.Logger.Error(err)
			return
		}
		conn.SetWriteDeadline(time.Time{})
	}
}

func newWsSpec() *tls.ClientHelloSpec {
	return &tls.ClientHelloSpec{
		CipherSuites: []uint16{
			tls.GREASE_PLACEHOLDER,
			tls.TLS_AES_128_GCM_SHA256,
			tls.TLS_AES_256_GCM_SHA384,
			tls.TLS_CHACHA20_POLY1305_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
			tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
			tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
			tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
			tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
			tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
			tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
			tls.TLS_RSA_WITH_AES_128_CBC_SHA,
			tls.TLS_RSA_WITH_AES_256_CBC_SHA,
		},
		CompressionMethods: []byte{
			0x00, // compressionNone
		},
		Extensions: []tls.TLSExtension{
			&tls.UtlsGREASEExtension{},
			&tls.SNIExtension{},
			&tls.ExtendedMasterSecretExtension{},
			&tls.RenegotiationInfoExtension{Renegotiation: tls.RenegotiateOnceAsClient},
			&tls.SupportedCurvesExtension{[]tls.CurveID{
				tls.GREASE_PLACEHOLDER,
				tls.X25519,
				tls.CurveP256,
				tls.CurveP384,
			}},
			&tls.SupportedPointsExtension{SupportedPoints: []byte{
				0x00, // pointFormatUncompressed
			}},
			&tls.SessionTicketExtension{},
			&tls.ALPNExtension{AlpnProtocols: []string{"http/1.1"}},
			&tls.StatusRequestExtension{},
			&tls.SignatureAlgorithmsExtension{SupportedSignatureAlgorithms: []tls.SignatureScheme{
				tls.ECDSAWithP256AndSHA256,
				tls.PSSWithSHA256,
				tls.PKCS1WithSHA256,
				tls.ECDSAWithP384AndSHA384,
				tls.PSSWithSHA384,
				tls.PKCS1WithSHA384,
				tls.PSSWithSHA512,
				tls.PKCS1WithSHA512,
			}},
			&tls.SCTExtension{},
			&tls.KeyShareExtension{[]tls.KeyShare{
				{Group: tls.CurveID(tls.GREASE_PLACEHOLDER), Data: []byte{0}},
				{Group: tls.X25519},
			}},
			&tls.PSKKeyExchangeModesExtension{[]uint8{
				tls.PskModeDHE,
			}},
			&tls.SupportedVersionsExtension{[]uint16{
				tls.GREASE_PLACEHOLDER,
				tls.VersionTLS13,
				tls.VersionTLS12,
			}},
			&tls.UtlsCompressCertExtension{[]tls.CertCompressionAlgo{
				tls.CertCompressionBrotli,
			}},
			&tls.ApplicationSettingsExtension{SupportedProtocols: []string{"h2"}},
			&tls.UtlsGREASEExtension{},
			&tls.UtlsPaddingExtension{GetPaddingLen: tls.BoringPaddingStyle},
		},
	}
}