package tlsreload

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

func TestResolveSPIFFEIdentityUsesExactRoleSpecificURI(t *testing.T) {
	certificatePath, keyPath := writeWorkloadCertificate(t, "gateway-a", "spiffe://proxy-pool.local/production/worker/gateway-a")
	identity, err := ResolveSPIFFEIdentity(certificatePath, keyPath, "proxy-pool.local", "production", "worker")
	if err != nil || identity != "gateway-a" {
		t.Fatalf("ResolveSPIFFEIdentity() = (%q, %v), want (gateway-a, nil)", identity, err)
	}
	if _, err := ResolveSPIFFEIdentity(certificatePath, keyPath, "proxy-pool.local", "production", "checker"); err == nil {
		t.Fatal("ResolveSPIFFEIdentity(checker) error = nil")
	}
}

func TestResolveSPIFFEIdentityRejectsMultipleMatchingURIs(t *testing.T) {
	certificatePath, keyPath := writeWorkloadCertificate(t, "gateway-a",
		"spiffe://proxy-pool.local/production/worker/gateway-a",
		"spiffe://proxy-pool.local/production/worker/gateway-b",
	)
	if _, err := ResolveSPIFFEIdentity(certificatePath, keyPath, "proxy-pool.local", "production", "worker"); err == nil {
		t.Fatal("ResolveSPIFFEIdentity(multiple identities) error = nil")
	}
}

func TestResolveSPIFFEIdentityRejectsMultipleURISANsAcrossRoles(t *testing.T) {
	certificatePath, keyPath := writeWorkloadCertificate(t, "gateway-a",
		"spiffe://proxy-pool.local/production/worker/gateway-a",
		"spiffe://proxy-pool.local/production/checker/checker-a",
	)
	if _, err := ResolveSPIFFEIdentity(certificatePath, keyPath, "proxy-pool.local", "production", "worker"); err == nil {
		t.Fatal("ResolveSPIFFEIdentity(multiple URI SANs) error = nil")
	}
}

func writeWorkloadCertificate(t *testing.T, commonName string, identityURIs ...string) (string, string) {
	t.Helper()
	directory := t.TempDir()
	certificatePath := filepath.Join(directory, "tls.crt")
	keyPath := filepath.Join(directory, "tls.key")
	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatalf("generate workload key: %v", err)
	}
	identities := make([]*url.URL, 0, len(identityURIs))
	for _, raw := range identityURIs {
		identity, parseErr := url.Parse(raw)
		if parseErr != nil {
			t.Fatalf("parse workload identity: %v", parseErr)
		}
		identities = append(identities, identity)
	}
	now := time.Now()
	template := &x509.Certificate{
		SerialNumber: big.NewInt(now.UnixNano()), Subject: pkix.Name{CommonName: commonName},
		URIs: identities, NotBefore: now.Add(-time.Minute), NotAfter: now.Add(time.Hour),
		KeyUsage:    x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment,
		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
	}
	der, err := x509.CreateCertificate(rand.Reader, template, template, &privateKey.PublicKey, privateKey)
	if err != nil {
		t.Fatalf("create workload certificate: %v", err)
	}
	certificate := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
	privateDER, err := x509.MarshalPKCS8PrivateKey(privateKey)
	if err != nil {
		t.Fatalf("marshal workload key: %v", err)
	}
	key := pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: privateDER})
	if err := os.WriteFile(certificatePath, certificate, 0o600); err != nil {
		t.Fatalf("write workload certificate: %v", err)
	}
	if err := os.WriteFile(keyPath, key, 0o600); err != nil {
		t.Fatalf("write workload key: %v", err)
	}
	return certificatePath, keyPath
}