/*
 * Copyright 2026 gRPC authors.
 *
 * 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 advancedtls

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"math/big"
	"testing"
	"time"
)

func generateCertificates(t *testing.T, extKeyUsages []x509.ExtKeyUsage) (*x509.CertPool, tls.Certificate) {
	t.Helper()
	caKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		t.Fatalf("Failed to generate CA key: %v", err)
	}
	caTemplate := &x509.Certificate{
		SerialNumber:          big.NewInt(1),
		Subject:               pkix.Name{CommonName: "Test CA"},
		NotBefore:             time.Now().Add(-1 * time.Hour),
		NotAfter:              time.Now().Add(1 * time.Hour),
		IsCA:                  true,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
		BasicConstraintsValid: true,
	}
	caDER, err := x509.CreateCertificate(rand.Reader, caTemplate, caTemplate, &caKey.PublicKey, caKey)
	if err != nil {
		t.Fatalf("Failed to create CA cert: %v", err)
	}
	caCert, err := x509.ParseCertificate(caDER)
	if err != nil {
		t.Fatalf("Failed to parse CA cert: %v", err)
	}

	serverKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		t.Fatalf("Failed to generate server key: %v", err)
	}
	serverTemplate := &x509.Certificate{
		SerialNumber: big.NewInt(2),
		Subject:      pkix.Name{CommonName: "localhost"},
		NotBefore:    time.Now().Add(-1 * time.Hour),
		NotAfter:     time.Now().Add(1 * time.Hour),
		ExtKeyUsage:  extKeyUsages,
		DNSNames:     []string{"localhost"},
	}
	serverDER, err := x509.CreateCertificate(rand.Reader, serverTemplate, caCert, &serverKey.PublicKey, caKey)
	if err != nil {
		t.Fatalf("Failed to create server cert: %v", err)
	}

	rootPool := x509.NewCertPool()
	rootPool.AddCert(caCert)

	serverCert := tls.Certificate{
		Certificate: [][]byte{serverDER},
		PrivateKey:  serverKey,
	}

	return rootPool, serverCert
}