package auth

import (
	"crypto/ed25519"
	"crypto/rand"
	"encoding/base64"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/sessionkey"
	"github.com/netbirdio/netbird/proxy/auth"
)

func generateTestKeyPair(t *testing.T) *sessionkey.KeyPair {
	t.Helper()
	kp, err := sessionkey.GenerateKeyPair()
	require.NoError(t, err)
	return kp
}

// stubScheme is a minimal Scheme implementation for testing.
type stubScheme struct {
	method    auth.Method
	token     string
	promptID  string
	authFn    func(*http.Request) (string, string)
}

func (s *stubScheme) Type() auth.Method { return s.method }

func (s *stubScheme) Authenticate(r *http.Request) (string, string) {
	if s.authFn != nil {
		return s.authFn(r)
	}
	return s.token, s.promptID
}

func newPassthroughHandler() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("backend"))
	})
}

func TestAddDomain_ValidKey(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	err := mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour)
	require.NoError(t, err)

	mw.domainsMux.RLock()
	config, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()

	assert.True(t, exists, "domain should be registered")
	assert.Len(t, config.Schemes, 1)
	assert.Equal(t, ed25519.PublicKeySize, len(config.SessionPublicKey))
	assert.Equal(t, time.Hour, config.SessionExpiration)
}

func TestAddDomain_EmptyKey(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	err := mw.AddDomain("example.com", []Scheme{scheme}, "", time.Hour)
	require.Error(t, err)
	assert.Contains(t, err.Error(), "invalid session public key size")

	mw.domainsMux.RLock()
	_, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()
	assert.False(t, exists, "domain must not be registered with an empty session key")
}

func TestAddDomain_InvalidBase64(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	err := mw.AddDomain("example.com", []Scheme{scheme}, "not-valid-base64!!!", time.Hour)
	require.Error(t, err)
	assert.Contains(t, err.Error(), "decode session public key")

	mw.domainsMux.RLock()
	_, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()
	assert.False(t, exists, "domain must not be registered with invalid base64 key")
}

func TestAddDomain_WrongKeySize(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())

	shortKey := base64.StdEncoding.EncodeToString([]byte("tooshort"))
	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	err := mw.AddDomain("example.com", []Scheme{scheme}, shortKey, time.Hour)
	require.Error(t, err)
	assert.Contains(t, err.Error(), "invalid session public key size")

	mw.domainsMux.RLock()
	_, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()
	assert.False(t, exists, "domain must not be registered with a wrong-size key")
}

func TestAddDomain_NoSchemes_NoKeyRequired(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())

	err := mw.AddDomain("example.com", nil, "", time.Hour)
	require.NoError(t, err, "domains with no auth schemes should not require a key")

	mw.domainsMux.RLock()
	_, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()
	assert.True(t, exists)
}

func TestAddDomain_OverwritesPreviousConfig(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp1 := generateTestKeyPair(t)
	kp2 := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}

	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp1.PublicKey, time.Hour))
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp2.PublicKey, 2*time.Hour))

	mw.domainsMux.RLock()
	config := mw.domains["example.com"]
	mw.domainsMux.RUnlock()

	pubKeyBytes, _ := base64.StdEncoding.DecodeString(kp2.PublicKey)
	assert.Equal(t, ed25519.PublicKey(pubKeyBytes), config.SessionPublicKey, "should use the latest key")
	assert.Equal(t, 2*time.Hour, config.SessionExpiration)
}

func TestRemoveDomain(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	mw.RemoveDomain("example.com")

	mw.domainsMux.RLock()
	_, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()
	assert.False(t, exists)
}

func TestProtect_UnknownDomainPassesThrough(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	handler := mw.Protect(newPassthroughHandler())

	req := httptest.NewRequest(http.MethodGet, "http://unknown.com/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusOK, rec.Code)
	assert.Equal(t, "backend", rec.Body.String())
}

func TestProtect_DomainWithNoSchemesPassesThrough(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	require.NoError(t, mw.AddDomain("example.com", nil, "", time.Hour))

	handler := mw.Protect(newPassthroughHandler())

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusOK, rec.Code)
	assert.Equal(t, "backend", rec.Body.String())
}

func TestProtect_UnauthenticatedRequestIsBlocked(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "unauthenticated request should not reach backend")
}

func TestProtect_HostWithPortIsMatched(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	req := httptest.NewRequest(http.MethodGet, "http://example.com:8443/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "host with port should still match the protected domain")
}

func TestProtect_ValidSessionCookiePassesThrough(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	token, err := sessionkey.SignToken(kp.PrivateKey, "test-user", "example.com", auth.MethodPIN, time.Hour)
	require.NoError(t, err)

	handler := mw.Protect(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		user := UserFromContext(r.Context())
		method := MethodFromContext(r.Context())
		assert.Equal(t, "test-user", user)
		assert.Equal(t, auth.MethodPIN, method)
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("authenticated"))
	}))

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	req.AddCookie(&http.Cookie{Name: auth.SessionCookieName, Value: token})
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusOK, rec.Code)
	assert.Equal(t, "authenticated", rec.Body.String())
}

func TestProtect_ExpiredSessionCookieIsRejected(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	// Sign a token that expired 1 second ago.
	token, err := sessionkey.SignToken(kp.PrivateKey, "test-user", "example.com", auth.MethodPIN, -time.Second)
	require.NoError(t, err)

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	req.AddCookie(&http.Cookie{Name: auth.SessionCookieName, Value: token})
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "expired session should not reach the backend")
}

func TestProtect_WrongDomainCookieIsRejected(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	// Token signed for a different domain audience.
	token, err := sessionkey.SignToken(kp.PrivateKey, "test-user", "other.com", auth.MethodPIN, time.Hour)
	require.NoError(t, err)

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	req.AddCookie(&http.Cookie{Name: auth.SessionCookieName, Value: token})
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "cookie for wrong domain should be rejected")
}

func TestProtect_WrongKeyCookieIsRejected(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp1 := generateTestKeyPair(t)
	kp2 := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp1.PublicKey, time.Hour))

	// Token signed with a different private key.
	token, err := sessionkey.SignToken(kp2.PrivateKey, "test-user", "example.com", auth.MethodPIN, time.Hour)
	require.NoError(t, err)

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	req.AddCookie(&http.Cookie{Name: auth.SessionCookieName, Value: token})
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "cookie signed by wrong key should be rejected")
}

func TestProtect_SchemeAuthRedirectsWithCookie(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	token, err := sessionkey.SignToken(kp.PrivateKey, "pin-user", "example.com", auth.MethodPIN, time.Hour)
	require.NoError(t, err)

	scheme := &stubScheme{
		method: auth.MethodPIN,
		authFn: func(r *http.Request) (string, string) {
			if r.FormValue("pin") == "111111" {
				return token, ""
			}
			return "", "pin"
		},
	}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	// Submit the PIN via form POST.
	form := url.Values{"pin": {"111111"}}
	req := httptest.NewRequest(http.MethodPost, "http://example.com/somepath", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "backend should not be called during auth, only a redirect should be returned")
	assert.Equal(t, http.StatusSeeOther, rec.Code)
	assert.Equal(t, "/somepath", rec.Header().Get("Location"), "redirect should point to the original request URI")

	cookies := rec.Result().Cookies()
	var sessionCookie *http.Cookie
	for _, c := range cookies {
		if c.Name == auth.SessionCookieName {
			sessionCookie = c
			break
		}
	}
	require.NotNil(t, sessionCookie, "session cookie should be set after successful auth")
	assert.True(t, sessionCookie.HttpOnly)
	assert.True(t, sessionCookie.Secure)
	assert.Equal(t, http.SameSiteLaxMode, sessionCookie.SameSite)
}

func TestProtect_FailedAuthDoesNotSetCookie(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{
		method: auth.MethodPIN,
		authFn: func(_ *http.Request) (string, string) {
			return "", "pin"
		},
	}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	handler := mw.Protect(newPassthroughHandler())

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	for _, c := range rec.Result().Cookies() {
		assert.NotEqual(t, auth.SessionCookieName, c.Name, "no session cookie should be set on failed auth")
	}
}

func TestProtect_MultipleSchemes(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	token, err := sessionkey.SignToken(kp.PrivateKey, "password-user", "example.com", auth.MethodPassword, time.Hour)
	require.NoError(t, err)

	// First scheme (PIN) always fails, second scheme (password) succeeds.
	pinScheme := &stubScheme{
		method: auth.MethodPIN,
		authFn: func(_ *http.Request) (string, string) {
			return "", "pin"
		},
	}
	passwordScheme := &stubScheme{
		method: auth.MethodPassword,
		authFn: func(r *http.Request) (string, string) {
			if r.FormValue("password") == "secret" {
				return token, ""
			}
			return "", "password"
		},
	}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{pinScheme, passwordScheme}, kp.PublicKey, time.Hour))

	var backendCalled bool
	backend := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		backendCalled = true
		w.WriteHeader(http.StatusOK)
	})
	handler := mw.Protect(backend)

	form := url.Values{"password": {"secret"}}
	req := httptest.NewRequest(http.MethodPost, "http://example.com/", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.False(t, backendCalled, "backend should not be called during auth")
	assert.Equal(t, http.StatusSeeOther, rec.Code)
}

func TestProtect_InvalidTokenFromSchemeReturns400(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	// Return a garbage token that won't validate.
	scheme := &stubScheme{
		method: auth.MethodPIN,
		authFn: func(_ *http.Request) (string, string) {
			return "invalid-jwt-token", ""
		},
	}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	handler := mw.Protect(newPassthroughHandler())

	req := httptest.NewRequest(http.MethodGet, "http://example.com/", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusBadRequest, rec.Code)
}

func TestAddDomain_RandomBytes32NotEd25519(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())

	// 32 random bytes that happen to be valid base64 and correct size
	// but are actually a valid ed25519 public key length-wise.
	// This should succeed because ed25519 public keys are just 32 bytes.
	randomBytes := make([]byte, ed25519.PublicKeySize)
	_, err := rand.Read(randomBytes)
	require.NoError(t, err)

	key := base64.StdEncoding.EncodeToString(randomBytes)
	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}

	err = mw.AddDomain("example.com", []Scheme{scheme}, key, time.Hour)
	require.NoError(t, err, "any 32-byte key should be accepted at registration time")
}

func TestAddDomain_InvalidKeyDoesNotCorruptExistingConfig(t *testing.T) {
	mw := NewMiddleware(log.StandardLogger())
	kp := generateTestKeyPair(t)

	scheme := &stubScheme{method: auth.MethodPIN, promptID: "pin"}
	require.NoError(t, mw.AddDomain("example.com", []Scheme{scheme}, kp.PublicKey, time.Hour))

	// Attempt to overwrite with an invalid key.
	err := mw.AddDomain("example.com", []Scheme{scheme}, "bad", time.Hour)
	require.Error(t, err)

	// The original valid config should still be intact.
	mw.domainsMux.RLock()
	config, exists := mw.domains["example.com"]
	mw.domainsMux.RUnlock()

	assert.True(t, exists, "original config should still exist")
	assert.Len(t, config.Schemes, 1)
	assert.Equal(t, time.Hour, config.SessionExpiration)
}