// Copyright (c) 2022 Alibaba Group Holding Ltd.
//
// 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 kubernetes

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"crypto/x509/pkix"
	"fmt"
	"io"
	"math/big"
	"net"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	// ensure auth plugins are loaded
	_ "k8s.io/client-go/plugin/pkg/client/auth"

	"github.com/alibaba/higress/test/ingress/conformance/utils/cert"
)

// MustCreateSelfSignedCertSecret creates a self-signed SSL certificate and stores it in a secret
func MustCreateSelfSignedCertSecret(t *testing.T, namespace, secretName string, hosts []string) *corev1.Secret {
	require.Greater(t, len(hosts), 0, "require a non-empty hosts for Subject Alternate Name values")

	var serverKey, serverCert bytes.Buffer
	host := strings.Join(hosts, ",")
	require.NoError(t, generateRSACert(host, &serverKey, &serverCert), "failed to generate RSA certificate")

	return ConstructTLSSecret(namespace, secretName, serverCert.Bytes(), serverKey.Bytes())
}

// ConstructTLSSecret constructs a secret of type "kubernetes.io/tls"
func ConstructTLSSecret(namespace, secretName string, cert, key []byte) *corev1.Secret {
	return &corev1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: namespace,
			Name:      secretName,
		},
		Type: corev1.SecretTypeTLS,
		Data: map[string][]byte{
			corev1.TLSCertKey:       cert,
			corev1.TLSPrivateKeyKey: key,
		},
	}
}

// ConstructCASecret construct a CA secret of type "Opaque"
func ConstructCASecret(namespace, secretName string, cert []byte) *corev1.Secret {
	return &corev1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Namespace: namespace,
			Name:      secretName,
		},
		Type: corev1.SecretTypeOpaque,
		Data: map[string][]byte{
			corev1.ServiceAccountRootCAKey: cert,
		},
	}
}

// generateRSACert generates a basic self signed certificate valid for a year
func generateRSACert(host string, keyOut, certOut io.Writer) error {
	notBefore := time.Now()
	notAfter := notBefore.Add(cert.ValidFor)
	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
	if err != nil {
		return fmt.Errorf("failed to generate serial number: %w", err)
	}

	template := &x509.Certificate{
		SerialNumber: serialNumber,
		Subject: pkix.Name{
			CommonName:   "default",
			Organization: []string{"Higress E2E Test"},
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
	}

	hosts := strings.Split(host, ",")
	for _, h := range hosts {
		if ip := net.ParseIP(h); ip != nil {
			template.IPAddresses = append(template.IPAddresses, ip)
		} else {
			template.DNSNames = append(template.DNSNames, h)
		}
	}

	priv, err := rsa.GenerateKey(rand.Reader, cert.RSABits)
	if err != nil {
		return fmt.Errorf("failed to generate key: %w", err)
	}
	certOut, keyOut, err = cert.GenerateCert(template, priv, template, nil)
	if err != nil {
		return fmt.Errorf("failed to generate rsa certificate: %w", err)
	}

	return nil
}