package oidc_test

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"
	"time"

	"keycape/internal/domain"
	profileerrors "keycape/internal/errors"
	"keycape/internal/server/oidc"
	"keycape/internal/server/telemetry"
)

// ---------------------------------------------------------------------------
// Mock implementations
// ---------------------------------------------------------------------------

// mockAuthProvider implements domain.AuthProvider.
type mockAuthProvider struct {
	authorizeURL string
	authorizeErr error

	callbackResult *domain.AuthResult
	callbackErr    error
}

func (m *mockAuthProvider) AuthorizeURL(_ context.Context, _ domain.AuthRequest) (string, error) {
	if m.authorizeErr != nil {
		return "", m.authorizeErr
	}
	return m.authorizeURL, nil
}

func (m *mockAuthProvider) HandleCallback(_ context.Context, _ domain.CallbackParams) (*domain.AuthResult, error) {
	return m.callbackResult, m.callbackErr
}

// mockMFAProvider implements domain.MFAProvider.
type mockMFAProvider struct {
	required    bool
	requiredErr error

	validateErr error
}

func (m *mockMFAProvider) CheckMFARequired(_ context.Context, _ string) (bool, error) {
	return m.required, m.requiredErr
}

func (m *mockMFAProvider) ValidateMFAToken(_ context.Context, _, _ string) error {
	return m.validateErr
}

// captureEmitter captures the last emitted event.
type captureEmitter struct {
	events []telemetry.Event
}

func (c *captureEmitter) Emit(_ context.Context, ev telemetry.Event) {
	c.events = append(c.events, ev)
}

func (c *captureEmitter) last() telemetry.Event {
	if len(c.events) == 0 {
		return telemetry.Event{}
	}
	return c.events[len(c.events)-1]
}

// ---------------------------------------------------------------------------
// Test helpers
// ---------------------------------------------------------------------------

func testClient() map[string]*domain.Client {
	return map[string]*domain.Client{
		"test-client": {
			ClientID:      "test-client",
			RedirectURIs:  []string{"https://app.example.com/callback"},
			AllowedScopes: []string{"openid", "profile", "email"},
			ClientType:    "public",
		},
	}
}

func newAuthorizeHandler(auth domain.AuthProvider, mfa domain.MFAProvider, emitter telemetry.Emitter) *oidc.AuthorizeHandler {
	return &oidc.AuthorizeHandler{
		ClientConfig: testClient(),
		Auth:         auth,
		MFA:          mfa,
		Sessions:     oidc.NewSessionStore(),
		Emitter:      emitter,
	}
}

func validAuthorizeParams() url.Values {
	return url.Values{
		"client_id":             []string{"test-client"},
		"redirect_uri":          []string{"https://app.example.com/callback"},
		"response_type":         []string{"code"},
		"scope":                 []string{"openid profile"},
		"state":                 []string{"random-state"},
		"code_challenge":        []string{"E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM"},
		"code_challenge_method": []string{"S256"},
	}
}

func authorizeRequest(params url.Values) *http.Request {
	return httptest.NewRequest(http.MethodGet, "/authorize?"+params.Encode(), nil)
}

func decodeProfileError(t *testing.T, body string) profileerrors.ErrorType {
	t.Helper()
	var pe profileerrors.ProfileError
	if err := json.Unmarshal([]byte(body), &pe); err != nil {
		t.Fatalf("could not decode ProfileError: %v (body: %q)", err, body)
	}
	return pe.Error
}

// ---------------------------------------------------------------------------
// T06 Authorization Endpoint Tests
// ---------------------------------------------------------------------------

func TestAuthorizeHandler_ValidRequest_RedirectsToAuthelia(t *testing.T) {
	auth := &mockAuthProvider{authorizeURL: "https://authelia.example.com/auth?state=xyz"}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	req := authorizeRequest(validAuthorizeParams())
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusFound {
		t.Errorf("expected 302 redirect, got %d (body: %s)", w.Code, w.Body.String())
	}
	loc := w.Header().Get("Location")
	if loc != "https://authelia.example.com/auth?state=xyz" {
		t.Errorf("expected redirect to Authelia, got %q", loc)
	}
}

func TestAuthorizeHandler_EmitsAuthStart(t *testing.T) {
	auth := &mockAuthProvider{authorizeURL: "https://authelia.example.com/auth"}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)
	req := authorizeRequest(validAuthorizeParams())
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	found := false
	for _, ev := range emitter.events {
		if ev.EventType == telemetry.EventAuthStart {
			found = true
			break
		}
	}
	if !found {
		t.Error("expected auth_start telemetry event to be emitted")
	}
}

func TestAuthorizeHandler_MissingCodeChallenge_InvalidProfileUsage(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Del("code_challenge")
	params.Del("code_challenge_method")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrInvalidProfileUsage {
		t.Errorf("expected invalid_profile_usage, got %q", errType)
	}
}

func TestAuthorizeHandler_WildcardRedirectURI_RejectedForSafety(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	clients := map[string]*domain.Client{
		"wildcard-client": {
			ClientID:     "wildcard-client",
			RedirectURIs: []string{"https://app.example.com/*"},
			ClientType:   "public",
		},
	}
	h := &oidc.AuthorizeHandler{
		ClientConfig: clients,
		Auth:         auth,
		MFA:          mfa,
		Sessions:     oidc.NewSessionStore(),
		Emitter:      emitter,
	}

	params := validAuthorizeParams()
	params.Set("client_id", "wildcard-client")
	params.Set("redirect_uri", "https://app.example.com/anything")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrRejectedForSafety {
		t.Errorf("expected rejected_for_profile_safety, got %q", errType)
	}
}

func TestAuthorizeHandler_UnknownClient_InvalidProfileUsage(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Set("client_id", "no-such-client")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrInvalidProfileUsage {
		t.Errorf("expected invalid_profile_usage, got %q", errType)
	}
}

func TestAuthorizeHandler_WrongResponseType_FeatureNotSupported(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Set("response_type", "token")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrFeatureNotSupported {
		t.Errorf("expected feature_not_supported_by_profile, got %q", errType)
	}
}

func TestAuthorizeHandler_MissingOpenIDScope_InvalidProfileUsage(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Set("scope", "profile email")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrInvalidProfileUsage {
		t.Errorf("expected invalid_profile_usage, got %q", errType)
	}
}

func TestAuthorizeHandler_PlainCodeChallengeMethod_RejectedForSafety(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Set("code_challenge_method", "plain")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrRejectedForSafety {
		t.Errorf("expected rejected_for_profile_safety, got %q", errType)
	}
}

func TestAuthorizeHandler_UnknownRedirectURI_InvalidProfileUsage(t *testing.T) {
	auth := &mockAuthProvider{}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	params := validAuthorizeParams()
	params.Set("redirect_uri", "https://evil.example.com/callback")

	req := authorizeRequest(params)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Errorf("expected 400, got %d", w.Code)
	}
	errType := decodeProfileError(t, w.Body.String())
	if errType != profileerrors.ErrInvalidProfileUsage {
		t.Errorf("expected invalid_profile_usage, got %q", errType)
	}
}

// ---------------------------------------------------------------------------
// Callback tests
// ---------------------------------------------------------------------------

func TestAuthorizeCallback_Success_RedirectsWithCode(t *testing.T) {
	auth := &mockAuthProvider{
		callbackResult: &domain.AuthResult{Username: "alice"},
	}
	mfa := &mockMFAProvider{required: false}
	emitter := &captureEmitter{}

	sessions := oidc.NewSessionStore()
	h := &oidc.AuthorizeHandler{
		ClientConfig: testClient(),
		Auth:         auth,
		MFA:          mfa,
		Sessions:     sessions,
		Emitter:      emitter,
	}

	req := httptest.NewRequest(http.MethodGet,
		"/authorize/callback?code=authelia-code&state=random-state", nil)
	// Simulate that there is an ongoing PKCE flow stored in query param forwarding
	// The callback needs the original client context. We store it via a pre-seeded
	// pending session keyed by state.
	// For the callback handler, we expect it to look up the pending state by the
	// "state" parameter that was originally embedded. We seed the pending state.
	h.PendingStates().Store("random-state", &oidc.PendingState{
		ClientID:            "test-client",
		RedirectURI:         "https://app.example.com/callback",
		PKCEChallenge:       "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM",
		PKCEChallengeMethod: "S256",
		State:               "random-state",
		Scopes:              []string{"openid", "profile"},
		ExpiresAt:           time.Now().Add(5 * time.Minute),
	})

	w := httptest.NewRecorder()
	h.ServeHTTPCallback(w, req)

	if w.Code != http.StatusFound {
		t.Errorf("expected 302 redirect, got %d (body: %s)", w.Code, w.Body.String())
	}
	loc := w.Header().Get("Location")
	parsed, err := url.Parse(loc)
	if err != nil {
		t.Fatalf("invalid Location header: %v", err)
	}
	if parsed.Query().Get("code") == "" {
		t.Error("expected code param in redirect, got empty")
	}
	if parsed.Query().Get("state") != "random-state" {
		t.Errorf("expected state=random-state, got %q", parsed.Query().Get("state"))
	}
}

func TestAuthorizeCallback_MFAFailed_AuthFailure(t *testing.T) {
	auth := &mockAuthProvider{
		callbackResult: &domain.AuthResult{Username: "alice"},
	}
	mfa := &mockMFAProvider{
		required:    true,
		validateErr: domain.ErrMFAFailed,
	}
	emitter := &captureEmitter{}

	sessions := oidc.NewSessionStore()
	h := &oidc.AuthorizeHandler{
		ClientConfig: testClient(),
		Auth:         auth,
		MFA:          mfa,
		Sessions:     sessions,
		Emitter:      emitter,
	}

	h.PendingStates().Store("random-state", &oidc.PendingState{
		ClientID:            "test-client",
		RedirectURI:         "https://app.example.com/callback",
		PKCEChallenge:       "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM",
		PKCEChallengeMethod: "S256",
		State:               "random-state",
		Scopes:              []string{"openid"},
		ExpiresAt:           time.Now().Add(5 * time.Minute),
	})

	req := httptest.NewRequest(http.MethodGet,
		"/authorize/callback?code=authelia-code&state=random-state&mfa_token=wrong", nil)
	w := httptest.NewRecorder()
	h.ServeHTTPCallback(w, req)

	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401, got %d", w.Code)
	}
	found := false
	for _, ev := range emitter.events {
		if ev.EventType == telemetry.EventAuthFailure {
			found = true
			break
		}
	}
	if !found {
		t.Error("expected auth_failure telemetry event")
	}
}

func TestAuthorizeCallback_AuthProviderFailed_AuthFailure(t *testing.T) {
	auth := &mockAuthProvider{
		callbackErr: domain.ErrAuthFailed,
	}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	sessions := oidc.NewSessionStore()
	h := &oidc.AuthorizeHandler{
		ClientConfig: testClient(),
		Auth:         auth,
		MFA:          mfa,
		Sessions:     sessions,
		Emitter:      emitter,
	}

	h.PendingStates().Store("random-state", &oidc.PendingState{
		ClientID:    "test-client",
		RedirectURI: "https://app.example.com/callback",
		State:       "random-state",
		ExpiresAt:   time.Now().Add(5 * time.Minute),
	})

	req := httptest.NewRequest(http.MethodGet,
		"/authorize/callback?code=bad&state=random-state", nil)
	w := httptest.NewRecorder()
	h.ServeHTTPCallback(w, req)

	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401, got %d", w.Code)
	}
	found := false
	for _, ev := range emitter.events {
		if ev.EventType == telemetry.EventAuthFailure {
			found = true
			break
		}
	}
	if !found {
		t.Error("expected auth_failure telemetry event")
	}
}

func TestAuthorizeCallback_EmitsAuthSuccess(t *testing.T) {
	auth := &mockAuthProvider{
		callbackResult: &domain.AuthResult{Username: "bob"},
	}
	mfa := &mockMFAProvider{required: false}
	emitter := &captureEmitter{}

	sessions := oidc.NewSessionStore()
	h := &oidc.AuthorizeHandler{
		ClientConfig: testClient(),
		Auth:         auth,
		MFA:          mfa,
		Sessions:     sessions,
		Emitter:      emitter,
	}

	h.PendingStates().Store("s1", &oidc.PendingState{
		ClientID:            "test-client",
		RedirectURI:         "https://app.example.com/callback",
		PKCEChallenge:       "abc",
		PKCEChallengeMethod: "S256",
		State:               "s1",
		Scopes:              []string{"openid"},
		ExpiresAt:           time.Now().Add(5 * time.Minute),
	})

	req := httptest.NewRequest(http.MethodGet,
		"/authorize/callback?code=c&state=s1", nil)
	w := httptest.NewRecorder()
	h.ServeHTTPCallback(w, req)

	found := false
	for _, ev := range emitter.events {
		if ev.EventType == telemetry.EventAuthSuccess {
			found = true
			break
		}
	}
	if !found {
		t.Errorf("expected auth_success telemetry event, got events: %v", emitter.events)
	}
}

// ---------------------------------------------------------------------------
// ServeHTTP dispatch
// ---------------------------------------------------------------------------

func TestAuthorizeHandler_ServeHTTP_DispatchesToCallback(t *testing.T) {
	auth := &mockAuthProvider{
		callbackResult: &domain.AuthResult{Username: "alice"},
	}
	mfa := &mockMFAProvider{}
	emitter := &captureEmitter{}

	h := newAuthorizeHandler(auth, mfa, emitter)

	// A request to /authorize/callback should not be treated as the initial
	// authorize request and must not require PKCE params.
	req := httptest.NewRequest(http.MethodGet, "/authorize/callback?code=x&state=y", nil)
	w := httptest.NewRecorder()
	h.ServeHTTP(w, req)

	// Without a seeded pending state for "y", the callback returns an error.
	// The important thing is that it is NOT a redirect to Authelia.
	if w.Code == http.StatusFound {
		loc := w.Header().Get("Location")
		if strings.Contains(loc, "authelia") {
			t.Error("callback path must not redirect to Authelia")
		}
	}
}