package tlsservice

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"errors"
	"math/big"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func testPEMPair(t *testing.T, dnsNames []string) (certPEM, keyPEM string, otherKeyPEM string) {
	t.Helper()
	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	other, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	serial, err := rand.Int(rand.Reader, big.NewInt(1<<62))
	if err != nil {
		t.Fatal(err)
	}
	tmpl := &x509.Certificate{
		SerialNumber: serial,
		Subject:      pkix.Name{CommonName: dnsNames[0], Organization: []string{"opsx-vpn-test"}},
		NotBefore:    time.Now().Add(-time.Hour),
		NotAfter:     time.Now().Add(24 * time.Hour),
		KeyUsage:     x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
		ExtKeyUsage:  []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		DNSNames:     dnsNames,
	}
	der, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
	if err != nil {
		t.Fatal(err)
	}
	certPEMBytes := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
	keyDER, err := x509.MarshalECPrivateKey(key)
	if err != nil {
		t.Fatal(err)
	}
	otherDER, err := x509.MarshalECPrivateKey(other)
	if err != nil {
		t.Fatal(err)
	}
	return string(certPEMBytes),
		string(pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: keyDER})),
		string(pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: otherDER}))
}

func TestInstallUploadedCertificateSuccess(t *testing.T) {
	t.Setenv("VPN_TLS_DOMAIN", "")
	t.Setenv("VPN_TLS_SCHEME", "")
	t.Setenv("VPN_TLS_PORT", "")
	t.Setenv("VPN_TLS_MODE", "")
	dir := t.TempDir()
	certPEM, keyPEM, _ := testPEMPair(t, []string{"vpn.example.com"})
	if err := ConfigureMode(dir, "nginx"); err != nil {
		t.Fatal(err)
	}
	if err := ConfigurePublicEntry(dir, "https", "vpn.example.com", 0); err != nil {
		t.Fatal(err)
	}
	if err := InstallUploadedCertificate(dir, "vpn.example.com", certPEM, keyPEM); err != nil {
		t.Fatal(err)
	}
	fullchain, privkey := UploadedCertificatePaths(dir, "vpn.example.com")
	if st, err := os.Stat(fullchain); err != nil || st.Mode().Perm() != 0o600 {
		t.Fatalf("fullchain perms: %v %v", st, err)
	}
	if st, err := os.Stat(privkey); err != nil || st.Mode().Perm() != 0o600 {
		t.Fatalf("privkey perms: %v %v", st, err)
	}
	if got := readCertSource(dir); got != CertSourceUpload {
		t.Fatalf("cert_source=%q", got)
	}
	t.Setenv("VPN_TLS_HTTP_ADDR", "127.0.0.1:0")
	t.Setenv("VPN_TLS_HTTPS_ADDR", "127.0.0.1:0")
	if err := Start(http.NotFoundHandler(), dir); err != nil {
		t.Fatal(err)
	}
	status := Status()
	if !status.Valid || status.CertSource != CertSourceUpload || status.Domain != "vpn.example.com" {
		t.Fatalf("status after upload: %+v", status)
	}
	if status.Issuer == "" || status.NotAfter.IsZero() {
		t.Fatalf("missing issuer/expiry: %+v", status)
	}
	if status.PublicBase != "https://vpn.example.com" {
		t.Fatalf("public_base=%q", status.PublicBase)
	}
	fc, pk, source := CertificateFiles("vpn.example.com")
	if source != CertSourceUpload || fc != fullchain || pk != privkey {
		t.Fatalf("CertificateFiles = %q %q %q", fc, pk, source)
	}
}

func TestInstallUploadedCertificateKeyMismatch(t *testing.T) {
	dir := t.TempDir()
	certPEM, _, otherKey := testPEMPair(t, []string{"vpn.example.com"})
	err := InstallUploadedCertificate(dir, "vpn.example.com", certPEM, otherKey)
	if err == nil {
		t.Fatal("expected mismatch error")
	}
	if _, statErr := os.Stat(filepath.Join(dir, "tls", "certs", "vpn.example.com", "fullchain.pem")); !os.IsNotExist(statErr) {
		t.Fatal("mismatch must not write certificate files")
	}
	if readCertSource(dir) != "" {
		t.Fatal("mismatch must not mark cert_source")
	}
}

func TestInstallUploadedCertificateDomainMismatch(t *testing.T) {
	dir := t.TempDir()
	certPEM, keyPEM, _ := testPEMPair(t, []string{"other.example.com"})
	if err := InstallUploadedCertificate(dir, "vpn.example.com", certPEM, keyPEM); err == nil {
		t.Fatal("expected hostname mismatch")
	}
}

func TestUploadRollbackPreservesPreviousCertificate(t *testing.T) {
	dir := t.TempDir()
	firstCert, firstKey, _ := testPEMPair(t, []string{"vpn.example.com"})
	secondCert, secondKey, _ := testPEMPair(t, []string{"vpn.example.com"})
	if err := InstallUploadedCertificate(dir, "vpn.example.com", firstCert, firstKey); err != nil {
		t.Fatal(err)
	}
	fullchain, privkey := UploadedCertificatePaths(dir, "vpn.example.com")
	if err := InstallUploadedCertificateWithApply(dir, "vpn.example.com", secondCert, secondKey, func() error {
		return errors.New("nginx reload failed")
	}); err == nil {
		t.Fatal("expected reload error")
	}
	gotCert, err := os.ReadFile(fullchain)
	if err != nil || strings.TrimSpace(string(gotCert)) != strings.TrimSpace(firstCert) {
		t.Fatalf("old certificate not restored: %v", err)
	}
	gotKey, err := os.ReadFile(privkey)
	if err != nil || strings.TrimSpace(string(gotKey)) != strings.TrimSpace(firstKey) {
		t.Fatalf("old key not restored: %v", err)
	}
	if readCertSource(dir) != CertSourceUpload {
		t.Fatal("certificate source not restored")
	}
}