package p2p

import (
	"bytes"
	"crypto/ecdsa"
	"fmt"
	"net"
	"testing"
	"time"

	"github.com/ethereum/go-ethereum/crypto"
	"github.com/obscuren/ecies"
)

func TestPublicKeyEncoding(t *testing.T) {
	prv0, _ := crypto.GenerateKey() // = ecdsa.GenerateKey(crypto.S256(), rand.Reader)
	pub0 := &prv0.PublicKey
	pub0s := crypto.FromECDSAPub(pub0)
	pub1, err := ImportPublicKey(pub0s)
	if err != nil {
		t.Errorf("%v", err)
	}
	eciesPub1 := ecies.ImportECDSAPublic(pub1)
	if eciesPub1 == nil {
		t.Errorf("invalid ecdsa public key")
	}
	pub1s, err := ExportPublicKey(pub1)
	if err != nil {
		t.Errorf("%v", err)
	}
	if len(pub1s) != 64 {
		t.Errorf("wrong length expect 64, got", len(pub1s))
	}
	pub2, err := ImportPublicKey(pub1s)
	if err != nil {
		t.Errorf("%v", err)
	}
	pub2s, err := ExportPublicKey(pub2)
	if err != nil {
		t.Errorf("%v", err)
	}
	if !bytes.Equal(pub1s, pub2s) {
		t.Errorf("exports dont match")
	}
	pub2sEC := crypto.FromECDSAPub(pub2)
	if !bytes.Equal(pub0s, pub2sEC) {
		t.Errorf("exports dont match")
	}
}

func TestSharedSecret(t *testing.T) {
	prv0, _ := crypto.GenerateKey() // = ecdsa.GenerateKey(crypto.S256(), rand.Reader)
	pub0 := &prv0.PublicKey
	prv1, _ := crypto.GenerateKey()
	pub1 := &prv1.PublicKey

	ss0, err := ecies.ImportECDSA(prv0).GenerateShared(ecies.ImportECDSAPublic(pub1), sskLen, sskLen)
	if err != nil {
		return
	}
	ss1, err := ecies.ImportECDSA(prv1).GenerateShared(ecies.ImportECDSAPublic(pub0), sskLen, sskLen)
	if err != nil {
		return
	}
	t.Logf("Secret:\n%v %x\n%v %x", len(ss0), ss0, len(ss0), ss1)
	if !bytes.Equal(ss0, ss1) {
		t.Errorf("dont match :(")
	}
}

func TestCryptoHandshake(t *testing.T) {
	testCryptoHandshakeWithGen(false, t)
}

func TestTokenCryptoHandshake(t *testing.T) {
	testCryptoHandshakeWithGen(true, t)
}

func TestDetCryptoHandshake(t *testing.T) {
	defer testlog(t).detach()
	tmpkeyF := keyF
	keyF = detkeyF
	tmpnonceF := nonceF
	nonceF = detnonceF
	testCryptoHandshakeWithGen(false, t)
	keyF = tmpkeyF
	nonceF = tmpnonceF
}

func TestDetTokenCryptoHandshake(t *testing.T) {
	defer testlog(t).detach()
	tmpkeyF := keyF
	keyF = detkeyF
	tmpnonceF := nonceF
	nonceF = detnonceF
	testCryptoHandshakeWithGen(true, t)
	keyF = tmpkeyF
	nonceF = tmpnonceF
}

func testCryptoHandshakeWithGen(token bool, t *testing.T) {
	fmt.Printf("init-private-key: ")
	prv0, err := keyF()
	if err != nil {
		t.Errorf("%v", err)
		return
	}
	fmt.Printf("rec-private-key: ")
	prv1, err := keyF()
	if err != nil {
		t.Errorf("%v", err)
		return
	}
	var nonce []byte
	if token {
		fmt.Printf("session-token: ")
		nonce = make([]byte, shaLen)
		nonceF(nonce)
	}
	testCryptoHandshake(prv0, prv1, nonce, t)
}

func testCryptoHandshake(prv0, prv1 *ecdsa.PrivateKey, sessionToken []byte, t *testing.T) {
	var err error
	pub0 := &prv0.PublicKey
	pub1 := &prv1.PublicKey

	pub0s := crypto.FromECDSAPub(pub0)
	pub1s := crypto.FromECDSAPub(pub1)

	// simulate handshake by feeding output to input
	// initiator sends handshake 'auth'
	auth, initNonce, randomPrivKey, _, err := startHandshake(prv0, pub1s, sessionToken)
	if err != nil {
		t.Errorf("%v", err)
	}
	fmt.Printf("-> %v\n", hexkey(auth))

	// receiver reads auth and responds with response
	response, remoteRecNonce, remoteInitNonce, remoteRandomPrivKey, remoteInitRandomPubKey, err := respondToHandshake(auth, prv1, pub0s, sessionToken)
	if err != nil {
		t.Errorf("%v", err)
	}
	fmt.Printf("<- %v\n", hexkey(response))

	// initiator reads receiver's response and the key exchange completes
	recNonce, remoteRandomPubKey, _, err := completeHandshake(response, prv0)
	if err != nil {
		t.Errorf("%v", err)
	}

	// now both parties should have the same session parameters
	initSessionToken, initSecretRW, err := newSession(true, initNonce, recNonce, auth, randomPrivKey, remoteRandomPubKey)
	if err != nil {
		t.Errorf("%v", err)
	}

	recSessionToken, recSecretRW, err := newSession(false, remoteInitNonce, remoteRecNonce, auth, remoteRandomPrivKey, remoteInitRandomPubKey)
	if err != nil {
		t.Errorf("%v", err)
	}

	// fmt.Printf("\nauth (%v) %x\n\nresp (%v) %x\n\n", len(auth), auth, len(response), response)

	// fmt.Printf("\nauth %x\ninitNonce %x\nresponse%x\nremoteRecNonce %x\nremoteInitNonce %x\nremoteRandomPubKey %x\nrecNonce %x\nremoteInitRandomPubKey %x\ninitSessionToken %x\n\n", auth, initNonce, response, remoteRecNonce, remoteInitNonce, remoteRandomPubKey, recNonce, remoteInitRandomPubKey, initSessionToken)

	if !bytes.Equal(initNonce, remoteInitNonce) {
		t.Errorf("nonces do not match")
	}
	if !bytes.Equal(recNonce, remoteRecNonce) {
		t.Errorf("receiver nonces do not match")
	}
	if !bytes.Equal(initSessionToken, recSessionToken) {
		t.Errorf("session tokens do not match")
	}
	// aesSecret, macSecret, egressMac, ingressMac
	if !bytes.Equal(initSecretRW.aesSecret, recSecretRW.aesSecret) {
		t.Errorf("AES secrets do not match")
	}
	if !bytes.Equal(initSecretRW.macSecret, recSecretRW.macSecret) {
		t.Errorf("macSecrets do not match")
	}
	if !bytes.Equal(initSecretRW.egressMac, recSecretRW.ingressMac) {
		t.Errorf("initiator's egressMac do not match receiver's ingressMac")
	}
	if !bytes.Equal(initSecretRW.ingressMac, recSecretRW.egressMac) {
		t.Errorf("initiator's inressMac do not match receiver's egressMac")
	}

}

func TestPeersHandshake(t *testing.T) {
	defer testlog(t).detach()
	var err error
	// var sessionToken []byte
	prv0, _ := crypto.GenerateKey() // = ecdsa.GenerateKey(crypto.S256(), rand.Reader)
	pub0 := &prv0.PublicKey
	prv1, _ := crypto.GenerateKey()
	pub1 := &prv1.PublicKey

	prv0s := crypto.FromECDSA(prv0)
	pub0s := crypto.FromECDSAPub(pub0)
	prv1s := crypto.FromECDSA(prv1)
	pub1s := crypto.FromECDSAPub(pub1)

	conn1, conn2 := net.Pipe()
	initiator := newPeer(conn1, []Protocol{}, nil)
	receiver := newPeer(conn2, []Protocol{}, nil)
	initiator.dialAddr = &peerAddr{IP: net.ParseIP("1.2.3.4"), Port: 2222, Pubkey: pub1s[1:]}
	initiator.privateKey = prv0s

	// this is cheating. identity of initiator/dialler not available to listener/receiver
	// its public key should be looked up based on IP address
	receiver.identity = &peerId{nil, pub0s}
	receiver.privateKey = prv1s

	initiator.pubkeyHook = func(*peerAddr) error { return nil }
	receiver.pubkeyHook = func(*peerAddr) error { return nil }

	initiator.cryptoHandshake = true
	receiver.cryptoHandshake = true
	errc0 := make(chan error, 1)
	errc1 := make(chan error, 1)
	go func() {
		_, err := initiator.loop()
		errc0 <- err
	}()
	go func() {
		_, err := receiver.loop()
		errc1 <- err
	}()
	ready := make(chan bool)
	go func() {
		<-initiator.cryptoReady
		<-receiver.cryptoReady
		close(ready)
	}()
	timeout := time.After(10 * time.Second)
	select {
	case <-ready:
	case <-timeout:
		t.Errorf("crypto handshake hanging for too long")
	case err = <-errc0:
		t.Errorf("peer 0 quit with error: %v", err)
	case err = <-errc1:
		t.Errorf("peer 1 quit with error: %v", err)
	}
}