// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////

package signature_test

import (
	"bytes"
	"crypto/ed25519"
	"encoding/hex"
	"fmt"
	"testing"

	"github.com/google/go-cmp/cmp"
	"google.golang.org/protobuf/proto"
	"github.com/google/tink/go/core/registry"
	"github.com/google/tink/go/internal/internalregistry"
	"github.com/google/tink/go/signature/subtle"
	"github.com/google/tink/go/subtle/random"
	"github.com/google/tink/go/testutil"
	ed25519pb "github.com/google/tink/go/proto/ed25519_go_proto"
	tinkpb "github.com/google/tink/go/proto/tink_go_proto"
)

func TestED25519SignerGetPrimitiveBasic(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}
	pvtKey := testutil.NewED25519PrivateKey()
	serializedKey, _ := proto.Marshal(pvtKey)
	tmp, err := km.Primitive(serializedKey)
	if err != nil {
		t.Errorf("unexpect error in test case: %s ", err)
	}
	var s = tmp.(*subtle.ED25519Signer)

	kmPub, err := registry.GetKeyManager(testutil.ED25519VerifierTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}
	pubKey := pvtKey.PublicKey
	serializedKey, _ = proto.Marshal(pubKey)
	tmp, err = kmPub.Primitive(serializedKey)
	if err != nil {
		t.Errorf("unexpect error in test case: %s ", err)
	}
	var v = tmp.(*subtle.ED25519Verifier)

	data := random.GetRandomBytes(1281)
	signature, err := s.Sign(data)
	if err != nil {
		t.Errorf("unexpected error when signing: %s", err)
	}

	if err := v.Verify(signature, data); err != nil {
		t.Errorf("unexpected error when verifying signature: %s", err)
	}

}

func TestED25519SignGetPrimitiveWithInvalidInput(t *testing.T) {
	// invalid params
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}

	// invalid version
	key := testutil.NewED25519PrivateKey()
	key.Version = testutil.ED25519SignerKeyVersion + 1
	serializedKey, _ := proto.Marshal(key)
	if _, err := km.Primitive(serializedKey); err == nil {
		t.Errorf("expect an error when version is invalid")
	}
	// nil input
	if _, err := km.Primitive(nil); err == nil {
		t.Errorf("expect an error when input is nil")
	}
	if _, err := km.Primitive([]byte{}); err == nil {
		t.Errorf("expect an error when input is empty slice")
	}
}

func TestED25519SignNewKeyBasic(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}
	serializedFormat, _ := proto.Marshal(testutil.NewED25519PrivateKey())
	tmp, err := km.NewKey(serializedFormat)
	if err != nil {
		t.Errorf("unexpected error: %s", err)
	}
	key := tmp.(*ed25519pb.Ed25519PrivateKey)
	if err := validateED25519PrivateKey(key); err != nil {
		t.Errorf("invalid private key in test case: %s", err)
	}
}

func TestED25519PublicKeyDataBasic(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}
	pkm, ok := km.(registry.PrivateKeyManager)
	if !ok {
		t.Errorf("cannot obtain private key manager")
	}

	key := testutil.NewED25519PrivateKey()
	serializedKey, _ := proto.Marshal(key)

	pubKeyData, err := pkm.PublicKeyData(serializedKey)
	if err != nil {
		t.Errorf("unexpect error in test case: %s ", err)
	}
	if pubKeyData.TypeUrl != testutil.ED25519VerifierTypeURL {
		t.Errorf("incorrect type url: %s", pubKeyData.TypeUrl)
	}
	if pubKeyData.KeyMaterialType != tinkpb.KeyData_ASYMMETRIC_PUBLIC {
		t.Errorf("incorrect key material type: %d", pubKeyData.KeyMaterialType)
	}
	pubKey := new(ed25519pb.Ed25519PublicKey)
	if err = proto.Unmarshal(pubKeyData.Value, pubKey); err != nil {
		t.Errorf("invalid public key: %s", err)
	}
}

func TestED25519PublicKeyDataWithInvalidInput(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Errorf("cannot obtain ED25519Signer key manager: %s", err)
	}
	pkm, ok := km.(registry.PrivateKeyManager)
	if !ok {
		t.Errorf("cannot obtain private key manager")
	}
	// modified key
	key := testutil.NewED25519PrivateKey()
	serializedKey, _ := proto.Marshal(key)
	serializedKey[0] = 0
	if _, err := pkm.PublicKeyData(serializedKey); err == nil {
		t.Errorf("expect an error when input is a modified serialized key")
	}
	// invalid with a single byte
	if _, err := pkm.PublicKeyData([]byte{42}); err == nil {
		t.Errorf("expect an error when input is an empty slice")
	}
}

func TestED25519KeyMaterialType(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.ED25519SignerTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	if got, want := keyManager.KeyMaterialType(), tinkpb.KeyData_ASYMMETRIC_PRIVATE; got != want {
		t.Errorf("KeyMaterialType() = %v, want %v", got, want)
	}
}

func TestED25519DeriveKey(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.ED25519SignerTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	keyFormat, err := proto.Marshal(&ed25519pb.Ed25519KeyFormat{Version: testutil.ED25519SignerKeyVersion})
	if err != nil {
		t.Fatalf("proto.Marshal() err = %v, want nil", err)
	}
	for _, test := range []struct {
		name      string
		keyFormat []byte
	}{
		{
			// nil unmarshals to an empty proto, which implies version = 0.
			name:      "nil",
			keyFormat: nil,
		},
		{
			// An empty proto implies version = 0.
			name:      "empty",
			keyFormat: []byte{},
		},
		{
			name:      "specified",
			keyFormat: keyFormat,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			rand := random.GetRandomBytes(ed25519.SeedSize)
			buf := &bytes.Buffer{}
			buf.Write(rand) // never returns a non-nil error
			k, err := keyManager.DeriveKey(test.keyFormat, buf)
			if err != nil {
				t.Fatalf("keyManager.DeriveKey() err = %v, want nil", err)
			}
			key := k.(*ed25519pb.Ed25519PrivateKey)
			if got, want := len(key.KeyValue), ed25519.SeedSize; got != want {
				t.Errorf("private key length = %d, want %d", got, want)
			}
			if diff := cmp.Diff(key.KeyValue, rand[:ed25519.SeedSize]); diff != "" {
				t.Errorf("incorrect derived private key: diff = %v", diff)
			}
			if got, want := len(key.PublicKey.KeyValue), ed25519.PublicKeySize; got != want {
				t.Errorf("public key length = %d, want %d", got, want)
			}
			if diff := cmp.Diff(key.PublicKey.KeyValue, []byte(ed25519.NewKeyFromSeed(rand))[32:]); diff != "" {
				t.Errorf("incorrect derived public key: diff = %v", diff)
			}
		})
	}
}

func TestED25519DeriveKeyFailsWithInvalidKeyFormats(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.ED25519SignerTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	invalidVersion, err := proto.Marshal(&ed25519pb.Ed25519KeyFormat{Version: 10})
	if err != nil {
		t.Fatalf("proto.Marshal() err = %v, want nil", err)
	}
	// Proto messages start with a VarInt, which always ends with a byte with the
	// MSB unset, so 0x80 is invalid.
	invalidSerialization, err := hex.DecodeString("80")
	if err != nil {
		t.Errorf("hex.DecodeString() err = %v, want nil", err)
	}
	for _, test := range []struct {
		name      string
		keyFormat []byte
	}{
		{
			name:      "invalid version",
			keyFormat: invalidVersion,
		},
		{
			name:      "invalid serialization",
			keyFormat: invalidSerialization,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			buf := bytes.NewBuffer(random.GetRandomBytes(ed25519.SeedSize))
			if _, err := keyManager.DeriveKey(test.keyFormat, buf); err == nil {
				t.Errorf("keyManager.DeriveKey() err = nil, want non-nil")
			}
		})
	}
}

func TestED25519DeriveKeyFailsWithInsufficientRandomness(t *testing.T) {
	km, err := registry.GetKeyManager(testutil.ED25519SignerTypeURL)
	if err != nil {
		t.Fatalf("registry.GetKeyManager(%q) err = %v, want nil", testutil.ED25519SignerTypeURL, err)
	}
	keyManager, ok := km.(internalregistry.DerivableKeyManager)
	if !ok {
		t.Fatalf("key manager is not DerivableKeyManager")
	}
	keyFormat, err := proto.Marshal(&ed25519pb.Ed25519KeyFormat{Version: 0})
	if err != nil {
		t.Fatalf("proto.Marshal() err = %v, want nil", err)
	}
	{
		buf := bytes.NewBuffer(random.GetRandomBytes(ed25519.SeedSize))
		if _, err := keyManager.DeriveKey(keyFormat, buf); err != nil {
			t.Errorf("keyManager.DeriveKey() err = %v, want nil", err)
		}
	}
	{
		insufficientBuf := bytes.NewBuffer(random.GetRandomBytes(ed25519.SeedSize - 1))
		if _, err := keyManager.DeriveKey(keyFormat, insufficientBuf); err == nil {
			t.Errorf("keyManager.DeriveKey() err = nil, want non-nil")
		}
	}
}

func validateED25519PrivateKey(key *ed25519pb.Ed25519PrivateKey) error {
	if key.Version != testutil.ED25519SignerKeyVersion {
		return fmt.Errorf("incorrect private key's version: expect %d, got %d",
			testutil.ED25519SignerKeyVersion, key.Version)
	}
	publicKey := key.PublicKey
	if publicKey.Version != testutil.ED25519SignerKeyVersion {
		return fmt.Errorf("incorrect public key's version: expect %d, got %d",
			testutil.ED25519SignerKeyVersion, key.Version)
	}

	signer, err := subtle.NewED25519Signer(key.KeyValue)
	if err != nil {
		return fmt.Errorf("unexpected error when creating ED25519Sign: %s", err)
	}

	verifier, err := subtle.NewED25519Verifier(publicKey.KeyValue)
	if err != nil {
		return fmt.Errorf("unexpected error when creating ED25519Verify: %s", err)
	}
	for i := 0; i < 100; i++ {
		data := random.GetRandomBytes(1281)
		signature, err := signer.Sign(data)
		if err != nil {
			return fmt.Errorf("unexpected error when signing: %s", err)
		}

		if err := verifier.Verify(signature, data); err != nil {
			return fmt.Errorf("unexpected error when verifying signature: %s", err)
		}
	}
	return nil
}