package tls

import (
	"crypto/tls"
	"net"

	"github.com/Dreamacro/clash/log"

	"github.com/mroth/weightedrand/v2"
	utls "github.com/sagernet/utls"
)

type UConn struct {
	*utls.UConn
}

type UClientHelloID struct {
	*utls.ClientHelloID
}

var initRandomFingerprint UClientHelloID
var initUtlsClient string

func UClient(c net.Conn, config *tls.Config, fingerprint UClientHelloID) net.Conn {
	utlsConn := utls.UClient(c, copyConfig(config), utls.ClientHelloID{
		Client:  fingerprint.Client,
		Version: fingerprint.Version,
		Seed:    fingerprint.Seed,
	})
	return &UConn{UConn: utlsConn}
}

func GetFingerprint(ClientFingerprint string) (UClientHelloID, bool) {
	if ClientFingerprint == "none" {
		return UClientHelloID{}, false
	}

	if initRandomFingerprint.ClientHelloID == nil {
		initRandomFingerprint, _ = RollFingerprint()
	}

	if ClientFingerprint == "random" {
		log.Debugln("use initial random HelloID:%s", initRandomFingerprint.Client)
		return initRandomFingerprint, true
	}

	fingerprint, ok := Fingerprints[ClientFingerprint]
	if ok {
		log.Debugln("use specified fingerprint:%s", fingerprint.Client)
		return fingerprint, ok
	} else {
		log.Warnln("wrong ClientFingerprint:%s", ClientFingerprint)
		return UClientHelloID{}, false
	}
}

func RollFingerprint() (UClientHelloID, bool) {
	chooser, _ := weightedrand.NewChooser(
		weightedrand.NewChoice("chrome", 6),
		weightedrand.NewChoice("safari", 3),
		weightedrand.NewChoice("ios", 2),
		weightedrand.NewChoice("firefox", 1),
	)
	initClient := chooser.Pick()
	log.Debugln("initial random HelloID:%s", initClient)
	fingerprint, ok := Fingerprints[initClient]
	return fingerprint, ok
}

var Fingerprints = map[string]UClientHelloID{
	"chrome":     {&utls.HelloChrome_Auto},
	"firefox":    {&utls.HelloFirefox_Auto},
	"safari":     {&utls.HelloSafari_Auto},
	"ios":        {&utls.HelloIOS_Auto},
	"android":    {&utls.HelloAndroid_11_OkHttp},
	"edge":       {&utls.HelloEdge_Auto},
	"360":        {&utls.Hello360_Auto},
	"qq":         {&utls.HelloQQ_Auto},
	"random":     {nil},
	"randomized": {nil},
}

func init() {
	weights := utls.DefaultWeights
	weights.TLSVersMax_Set_VersionTLS13 = 1
	weights.FirstKeyShare_Set_CurveP256 = 0
	randomized := utls.HelloRandomized
	randomized.Seed, _ = utls.NewPRNGSeed()
	randomized.Weights = &weights
	Fingerprints["randomized"] = UClientHelloID{&randomized}
}

func copyConfig(c *tls.Config) *utls.Config {
	return &utls.Config{
		RootCAs:               c.RootCAs,
		ServerName:            c.ServerName,
		NextProtos:            c.NextProtos,
		InsecureSkipVerify:    c.InsecureSkipVerify,
		VerifyPeerCertificate: c.VerifyPeerCertificate,
	}
}

// WebsocketHandshake basically calls UConn.Handshake inside it but it will only send
// http/1.1 in its ALPN.
// Copy from https://github.com/XTLS/Xray-core/blob/main/transport/internet/tls/tls.go
func (c *UConn) WebsocketHandshake() error {
	// Build the handshake state. This will apply every variable of the TLS of the
	// fingerprint in the UConn
	if err := c.BuildHandshakeState(); err != nil {
		return err
	}
	// Iterate over extensions and check for utls.ALPNExtension
	hasALPNExtension := false
	for _, extension := range c.Extensions {
		if alpn, ok := extension.(*utls.ALPNExtension); ok {
			hasALPNExtension = true
			alpn.AlpnProtocols = []string{"http/1.1"}
			break
		}
	}
	if !hasALPNExtension { // Append extension if doesn't exists
		c.Extensions = append(c.Extensions, &utls.ALPNExtension{AlpnProtocols: []string{"http/1.1"}})
	}
	// Rebuild the client hello and do the handshake
	if err := c.BuildHandshakeState(); err != nil {
		return err
	}
	return c.Handshake()
}

func SetGlobalUtlsClient(Client string) {
	initUtlsClient = Client
}

func HaveGlobalFingerprint() bool {
	return len(initUtlsClient) != 0 && initUtlsClient != "none"
}

func GetGlobalFingerprint() string {
	return initUtlsClient
}