// Copyright 2022 PingCAP, Inc.
//
// 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 sessionstates

import (
	"crypto/x509"
	"encoding/json"
	"fmt"
	"path/filepath"
	"testing"
	"time"

	"github.com/pingcap/failpoint"
	"github.com/pingcap/tidb/util"
	"github.com/stretchr/testify/require"
)

var (
	mockNowOffset = "github.com/pingcap/tidb/sessionctx/sessionstates/mockNowOffset"
)

func TestSetCertAndKey(t *testing.T) {
	tempDir := t.TempDir()
	certPath := filepath.Join(tempDir, "test1_cert.pem")
	keyPath := filepath.Join(tempDir, "test1_key.pem")
	createRSACert(t, certPath, keyPath)

	// no cert and no key
	_, err := CreateSessionToken("test_user")
	require.ErrorContains(t, err, "no certificate or key file")
	// no cert
	SetKeyPath(keyPath)
	_, err = CreateSessionToken("test_user")
	require.ErrorContains(t, err, "no certificate or key file")
	// no key
	SetKeyPath("")
	SetCertPath(certPath)
	_, err = CreateSessionToken("test_user")
	require.ErrorContains(t, err, "no certificate or key file")
	// both configured
	SetKeyPath(keyPath)
	_, err = CreateSessionToken("test_user")
	require.NoError(t, err)
	// When the key and cert don't match, it will still use the old pair.
	certPath2 := filepath.Join(tempDir, "test2_cert.pem")
	keyPath2 := filepath.Join(tempDir, "test2_key.pem")
	err = util.CreateCertificates(certPath2, keyPath2, 4096, x509.RSA, x509.UnknownSignatureAlgorithm)
	require.NoError(t, err)
	SetKeyPath(keyPath2)
	_, err = CreateSessionToken("test_user")
	require.NoError(t, err)
}

func TestSignAlgo(t *testing.T) {
	tests := []struct {
		pubKeyAlgo x509.PublicKeyAlgorithm
		signAlgos  []x509.SignatureAlgorithm
		keySizes   []int
	}{
		{
			pubKeyAlgo: x509.RSA,
			signAlgos: []x509.SignatureAlgorithm{
				x509.SHA256WithRSA,
				x509.SHA384WithRSA,
				x509.SHA512WithRSA,
				x509.SHA256WithRSAPSS,
				x509.SHA384WithRSAPSS,
				x509.SHA512WithRSAPSS,
			},
			keySizes: []int{
				2048,
				4096,
			},
		},
		{
			pubKeyAlgo: x509.ECDSA,
			signAlgos: []x509.SignatureAlgorithm{
				x509.ECDSAWithSHA256,
				x509.ECDSAWithSHA384,
				x509.ECDSAWithSHA512,
			},
			keySizes: []int{
				4096,
			},
		},
		{
			pubKeyAlgo: x509.Ed25519,
			signAlgos: []x509.SignatureAlgorithm{
				x509.PureEd25519,
			},
			keySizes: []int{
				4096,
			},
		},
	}

	tempDir := t.TempDir()
	certPath := filepath.Join(tempDir, "test1_cert.pem")
	keyPath := filepath.Join(tempDir, "test1_key.pem")
	SetKeyPath(keyPath)
	SetCertPath(certPath)
	for _, test := range tests {
		for _, signAlgo := range test.signAlgos {
			for _, keySize := range test.keySizes {
				msg := fmt.Sprintf("pubKeyAlgo: %s, signAlgo: %s, keySize: %d", test.pubKeyAlgo.String(),
					signAlgo.String(), keySize)
				err := util.CreateCertificates(certPath, keyPath, keySize, test.pubKeyAlgo, signAlgo)
				require.NoError(t, err, msg)
				ReloadSigningCert()
				_, tokenBytes := createNewToken(t, "test_user")
				err = ValidateSessionToken(tokenBytes, "test_user")
				require.NoError(t, err, msg)
			}
		}
	}
}

func TestVerifyToken(t *testing.T) {
	tempDir := t.TempDir()
	certPath := filepath.Join(tempDir, "test1_cert.pem")
	keyPath := filepath.Join(tempDir, "test1_key.pem")
	createRSACert(t, certPath, keyPath)
	SetKeyPath(keyPath)
	SetCertPath(certPath)

	// check succeeds
	token, tokenBytes := createNewToken(t, "test_user")
	err := ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, err)
	// the token expires
	timeOffset := uint64(tokenLifetime + time.Minute)
	require.NoError(t, failpoint.Enable(mockNowOffset, fmt.Sprintf(`return(%d)`, timeOffset)))
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, failpoint.Disable(mockNowOffset))
	require.ErrorContains(t, err, "token expired")
	// the current user is different with the token
	err = ValidateSessionToken(tokenBytes, "another_user")
	require.ErrorContains(t, err, "username does not match")
	// forge the user name
	token.Username = "another_user"
	tokenBytes2, err := json.Marshal(token)
	require.NoError(t, err)
	err = ValidateSessionToken(tokenBytes2, "another_user")
	require.ErrorContains(t, err, "verification error")
	// forge the expire time
	token.Username = "test_user"
	token.ExpireTime = time.Now().Add(-time.Minute)
	tokenBytes2, err = json.Marshal(token)
	require.NoError(t, err)
	err = ValidateSessionToken(tokenBytes2, "test_user")
	require.ErrorContains(t, err, "verification error")
}

func TestCertExpire(t *testing.T) {
	tempDir := t.TempDir()
	certPath := filepath.Join(tempDir, "test1_cert.pem")
	keyPath := filepath.Join(tempDir, "test1_key.pem")
	createRSACert(t, certPath, keyPath)
	SetKeyPath(keyPath)
	SetCertPath(certPath)

	_, tokenBytes := createNewToken(t, "test_user")
	err := ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, err)
	// replace the cert, but the old cert is still valid for a while
	certPath2 := filepath.Join(tempDir, "test2_cert.pem")
	keyPath2 := filepath.Join(tempDir, "test2_key.pem")
	createRSACert(t, certPath2, keyPath2)
	SetKeyPath(keyPath2)
	SetCertPath(certPath2)
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, err)
	// the old cert expires and the original token is invalid
	timeOffset := uint64(LoadCertInterval)
	require.NoError(t, failpoint.Enable(mockNowOffset, fmt.Sprintf(`return(%d)`, timeOffset)))
	ReloadSigningCert()
	timeOffset += uint64(oldCertValidTime + time.Minute)
	require.NoError(t, failpoint.Enable(mockNowOffset, fmt.Sprintf(`return(%d)`, timeOffset)))
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.ErrorContains(t, err, "verification error")
	// the new cert is not rotated but is reloaded
	_, tokenBytes = createNewToken(t, "test_user")
	ReloadSigningCert()
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, err)
	// the cert is rotated but is still valid
	createRSACert(t, certPath2, keyPath2)
	timeOffset += uint64(LoadCertInterval)
	require.NoError(t, failpoint.Enable(mockNowOffset, fmt.Sprintf(`return(%d)`, timeOffset)))
	ReloadSigningCert()
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.ErrorContains(t, err, "token expired")
	// after some time, it's not valid
	timeOffset += uint64(oldCertValidTime + time.Minute)
	require.NoError(t, failpoint.Enable(mockNowOffset, fmt.Sprintf(`return(%d)`, timeOffset)))
	err = ValidateSessionToken(tokenBytes, "test_user")
	require.NoError(t, failpoint.Disable(mockNowOffset))
	require.ErrorContains(t, err, "verification error")
}

func TestLoadAndReadConcurrently(t *testing.T) {
	tempDir := t.TempDir()
	certPath := filepath.Join(tempDir, "test1_cert.pem")
	keyPath := filepath.Join(tempDir, "test1_key.pem")
	createRSACert(t, certPath, keyPath)
	SetKeyPath(keyPath)
	SetCertPath(certPath)

	deadline := time.Now().Add(5 * time.Second)
	var wg util.WaitGroupWrapper
	// the writer
	wg.Run(func() {
		for time.Now().Before(deadline) {
			createRSACert(t, certPath, keyPath)
			time.Sleep(time.Second)
		}
	})
	// the loader
	for i := 0; i < 2; i++ {
		wg.Run(func() {
			for time.Now().Before(deadline) {
				ReloadSigningCert()
				time.Sleep(500 * time.Millisecond)
			}
		})
	}
	// the reader
	for i := 0; i < 3; i++ {
		id := i
		wg.Run(func() {
			username := fmt.Sprintf("test_user_%d", id)
			for time.Now().Before(deadline) {
				_, tokenBytes := createNewToken(t, username)
				time.Sleep(10 * time.Millisecond)
				err := ValidateSessionToken(tokenBytes, username)
				require.NoError(t, err)
				time.Sleep(10 * time.Millisecond)
			}
		})
	}
	wg.Wait()
}

func createNewToken(t *testing.T, username string) (*SessionToken, []byte) {
	token, err := CreateSessionToken(username)
	require.NoError(t, err)
	tokenBytes, err := json.Marshal(token)
	require.NoError(t, err)
	return token, tokenBytes
}

func createRSACert(t *testing.T, certPath, keyPath string) {
	err := util.CreateCertificates(certPath, keyPath, 4096, x509.RSA, x509.UnknownSignatureAlgorithm)
	require.NoError(t, err)
}