package policy

import (
	"crypto/rand"
	"crypto/rsa"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/golang-jwt/jwt/v5"
)

// generateTestKeyPair generates an RSA key pair for testing
func generateTestKeyPair() (*rsa.PrivateKey, error) {
	return rsa.GenerateKey(rand.Reader, 2048)
}

// createTestJWKS creates a test JWKS server
func createTestJWKS(t *testing.T, privateKey *rsa.PrivateKey) *httptest.Server {
	publicKey := &privateKey.PublicKey

	// Create JWK from public key
	jwk := JWK{
		Kid: "test-key-1",
		Kty: "RSA",
		Alg: "RS256",
		Use: "sig",
		N:   base64URLEncode(publicKey.N.Bytes()),
		E:   base64URLEncode([]byte{1, 0, 1}), // 65537
	}

	jwks := JWKS{
		Keys: []JWK{jwk},
	}

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(jwks)
	}))

	return server
}

// createTestToken creates a test JWT token
func createTestToken(privateKey *rsa.PrivateKey, claims *Claims) (string, error) {
	token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
	token.Header["kid"] = "test-key-1"
	return token.SignedString(privateKey)
}

func TestValidateToken(t *testing.T) {
	// Generate test key pair
	privateKey, err := generateTestKeyPair()
	if err != nil {
		t.Fatalf("generate key pair: %v", err)
	}

	// Create test JWKS server
	jwksServer := createTestJWKS(t, privateKey)
	defer jwksServer.Close()

	// Create validator
	validator := NewValidator(jwksServer.URL, "sequentialthinking.run")

	// Test valid token
	t.Run("valid_token", func(t *testing.T) {
		claims := &Claims{
			Subject: "test-user",
			Scopes:  []string{"sequentialthinking.run"},
			RegisteredClaims: jwt.RegisteredClaims{
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now()),
			},
		}

		tokenString, err := createTestToken(privateKey, claims)
		if err != nil {
			t.Fatalf("create token: %v", err)
		}

		validatedClaims, err := validator.ValidateToken(tokenString)
		if err != nil {
			t.Fatalf("validate token: %v", err)
		}

		if validatedClaims.Subject != "test-user" {
			t.Errorf("wrong subject: got %s, want test-user", validatedClaims.Subject)
		}
	})

	// Test expired token
	t.Run("expired_token", func(t *testing.T) {
		claims := &Claims{
			Subject: "test-user",
			Scopes:  []string{"sequentialthinking.run"},
			RegisteredClaims: jwt.RegisteredClaims{
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(-1 * time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now().Add(-2 * time.Hour)),
			},
		}

		tokenString, err := createTestToken(privateKey, claims)
		if err != nil {
			t.Fatalf("create token: %v", err)
		}

		_, err = validator.ValidateToken(tokenString)
		if err == nil {
			t.Fatal("expected error for expired token")
		}
	})

	// Test missing scope
	t.Run("missing_scope", func(t *testing.T) {
		claims := &Claims{
			Subject: "test-user",
			Scopes:  []string{"other.scope"},
			RegisteredClaims: jwt.RegisteredClaims{
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now()),
			},
		}

		tokenString, err := createTestToken(privateKey, claims)
		if err != nil {
			t.Fatalf("create token: %v", err)
		}

		_, err = validator.ValidateToken(tokenString)
		if err == nil {
			t.Fatal("expected error for missing scope")
		}
	})

	// Test space-separated scopes
	t.Run("space_separated_scopes", func(t *testing.T) {
		claims := &Claims{
			Subject: "test-user",
			Scope:   "read write sequentialthinking.run admin",
			RegisteredClaims: jwt.RegisteredClaims{
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now()),
			},
		}

		tokenString, err := createTestToken(privateKey, claims)
		if err != nil {
			t.Fatalf("create token: %v", err)
		}

		validatedClaims, err := validator.ValidateToken(tokenString)
		if err != nil {
			t.Fatalf("validate token: %v", err)
		}

		if validatedClaims.Subject != "test-user" {
			t.Errorf("wrong subject: got %s, want test-user", validatedClaims.Subject)
		}
	})

	// Test not before
	t.Run("not_yet_valid", func(t *testing.T) {
		claims := &Claims{
			Subject: "test-user",
			Scopes:  []string{"sequentialthinking.run"},
			RegisteredClaims: jwt.RegisteredClaims{
				ExpiresAt: jwt.NewNumericDate(time.Now().Add(2 * time.Hour)),
				NotBefore: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),
				IssuedAt:  jwt.NewNumericDate(time.Now()),
			},
		}

		tokenString, err := createTestToken(privateKey, claims)
		if err != nil {
			t.Fatalf("create token: %v", err)
		}

		_, err = validator.ValidateToken(tokenString)
		if err == nil {
			t.Fatal("expected error for not-yet-valid token")
		}
	})
}

func TestJWKSCaching(t *testing.T) {
	privateKey, err := generateTestKeyPair()
	if err != nil {
		t.Fatalf("generate key pair: %v", err)
	}

	fetchCount := 0
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fetchCount++
		publicKey := &privateKey.PublicKey

		jwk := JWK{
			Kid: "test-key-1",
			Kty: "RSA",
			Alg: "RS256",
			Use: "sig",
			N:   base64URLEncode(publicKey.N.Bytes()),
			E:   base64URLEncode([]byte{1, 0, 1}),
		}

		jwks := JWKS{Keys: []JWK{jwk}}
		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(jwks)
	}))
	defer server.Close()

	validator := NewValidator(server.URL, "sequentialthinking.run")
	validator.cacheDuration = 100 * time.Millisecond // Short cache for testing

	claims := &Claims{
		Subject: "test-user",
		Scopes:  []string{"sequentialthinking.run"},
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(1 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

	tokenString, err := createTestToken(privateKey, claims)
	if err != nil {
		t.Fatalf("create token: %v", err)
	}

	// First validation - should fetch JWKS
	_, err = validator.ValidateToken(tokenString)
	if err != nil {
		t.Fatalf("validate token: %v", err)
	}

	if fetchCount != 1 {
		t.Errorf("expected 1 fetch, got %d", fetchCount)
	}

	// Second validation - should use cache
	_, err = validator.ValidateToken(tokenString)
	if err != nil {
		t.Fatalf("validate token: %v", err)
	}

	if fetchCount != 1 {
		t.Errorf("expected 1 fetch (cached), got %d", fetchCount)
	}

	// Wait for cache to expire
	time.Sleep(150 * time.Millisecond)

	// Third validation - should fetch again
	_, err = validator.ValidateToken(tokenString)
	if err != nil {
		t.Fatalf("validate token: %v", err)
	}

	if fetchCount != 2 {
		t.Errorf("expected 2 fetches (cache expired), got %d", fetchCount)
	}
}

func TestParseScopes(t *testing.T) {
	tests := []struct {
		name     string
		input    string
		expected []string
	}{
		{
			name:     "single_scope",
			input:    "read",
			expected: []string{"read"},
		},
		{
			name:     "multiple_scopes",
			input:    "read write admin",
			expected: []string{"read", "write", "admin"},
		},
		{
			name:     "extra_spaces",
			input:    "read  write   admin",
			expected: []string{"read", "write", "admin"},
		},
		{
			name:     "empty_string",
			input:    "",
			expected: nil,
		},
		{
			name:     "spaces_only",
			input:    "   ",
			expected: nil,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := parseScopes(tt.input)

			if len(result) != len(tt.expected) {
				t.Errorf("wrong length: got %d, want %d", len(result), len(tt.expected))
				return
			}

			for i, expected := range tt.expected {
				if result[i] != expected {
					t.Errorf("scope %d: got %s, want %s", i, result[i], expected)
				}
			}
		})
	}
}

func TestInvalidJWKS(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
	}))
	defer server.Close()

	validator := NewValidator(server.URL, "sequentialthinking.run")

	err := validator.RefreshJWKS()
	if err == nil {
		t.Fatal("expected error for invalid JWKS server")
	}
}

func TestGetCachedKeyCount(t *testing.T) {
	privateKey, err := generateTestKeyPair()
	if err != nil {
		t.Fatalf("generate key pair: %v", err)
	}

	jwksServer := createTestJWKS(t, privateKey)
	defer jwksServer.Close()

	validator := NewValidator(jwksServer.URL, "sequentialthinking.run")

	// Initially no keys
	if count := validator.GetCachedKeyCount(); count != 0 {
		t.Errorf("expected 0 cached keys initially, got %d", count)
	}

	// Refresh JWKS
	if err := validator.RefreshJWKS(); err != nil {
		t.Fatalf("refresh JWKS: %v", err)
	}

	// Should have 1 key
	if count := validator.GetCachedKeyCount(); count != 1 {
		t.Errorf("expected 1 cached key after refresh, got %d", count)
	}
}