// Package profile_test contains integration-style tests for the complete OIDC
// profile (Scenario A from the Acceptance Test Matrix, spec §7). All handler
// implementations are real; only the auth backend adapters are mocked.
package profile_test

import (
	"context"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"testing"
	"time"

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

// ---------------------------------------------------------------------------
// Mock adapters
// ---------------------------------------------------------------------------

// mockAuth implements domain.AuthProvider for tests.
type mockAuth struct {
	authorizeURL string
	callbackUser string
	callbackErr  error
}

func (m *mockAuth) AuthorizeURL(_ context.Context, req domain.AuthRequest) (string, error) {
	if m.authorizeURL != "" {
		return m.authorizeURL, nil
	}
	return "https://authelia.example.com/auth?state=" + req.State, nil
}

func (m *mockAuth) HandleCallback(_ context.Context, params domain.CallbackParams) (*domain.AuthResult, error) {
	if m.callbackErr != nil {
		return nil, m.callbackErr
	}
	username := m.callbackUser
	if username == "" {
		username = "testuser"
	}
	return &domain.AuthResult{Username: username}, nil
}

// mockMFA implements domain.MFAProvider for tests.
type mockMFA struct {
	required bool
	checkErr error
	mfaErr   error
}

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

func (m *mockMFA) HasEnrolledFactor(_ context.Context, _ string) (bool, error) {
	return m.required, m.checkErr
}

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

// mockUsers implements domain.UserRepository for tests.
type mockUsers struct {
	users map[string]*domain.User
}

func newMockUsers() *mockUsers {
	return &mockUsers{users: map[string]*domain.User{
		"testuser": {
			ID:          "uid-001",
			Username:    "testuser",
			DisplayName: "Test User",
			Email:       "testuser@example.com",
			Groups:      []string{"developers"},
			Enabled:     true,
		},
	}}
}

func (m *mockUsers) LookupUser(_ context.Context, username string) (*domain.User, error) {
	u, ok := m.users[username]
	if !ok {
		return nil, domain.ErrUserNotFound
	}
	return u, nil
}

func (m *mockUsers) LookupGroups(_ context.Context, _ string) ([]domain.Group, error) {
	return nil, nil
}

func (m *mockUsers) ValidatePassword(_ context.Context, _, _ string) (bool, error) {
	return false, nil
}

func (m *mockUsers) ListUsers(_ context.Context) ([]domain.User, error) {
	return nil, nil
}

// ---------------------------------------------------------------------------
// TestServer
// ---------------------------------------------------------------------------

// TestServer wraps an httptest.Server with all the wired-up handlers.
type TestServer struct {
	Server     *httptest.Server
	PrivateKey *rsa.PrivateKey
	Sessions   *oidc.SessionStore
	AuthMock   *mockAuth
	Clients    map[string]*domain.Client
}

func newTestServer(t *testing.T) *TestServer {
	t.Helper()

	// Generate RSA key pair.
	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		t.Fatalf("generate RSA key: %v", err)
	}

	issuer := "http://localhost" // will be overridden with actual server URL after start

	// Create test client registry.
	clients := map[string]*domain.Client{
		"demo-app": {
			ClientID:      "demo-app",
			DisplayName:   "Demo Application",
			RedirectURIs:  []string{"http://localhost:3000/callback"},
			AllowedScopes: []string{"openid", "profile", "email", "groups"},
			GrantTypes:    []string{"authorization_code"},
			ClientType:    "public",
		},
	}

	// Create mock adapters.
	authMock := &mockAuth{}
	mfaMock := &mockMFA{required: false}
	usersMock := newMockUsers()

	// Session store.
	sessions := oidc.NewSessionStore()

	// Telemetry — noop for tests.
	emitter := telemetry.NoopEmitter{}

	// Key set.
	ks := oidc.NewKeySet()
	ks.AddKey("key-1", &privateKey.PublicKey)

	// Enforcement registry.
	reg := errors.DefaultRegistry()

	mux := http.NewServeMux()

	// Discovery handler.
	mux.Handle("/.well-known/openid-configuration", oidc.NewDiscoveryHandler(oidc.DiscoveryConfig{
		Issuer:                issuer,
		AuthorizationEndpoint: issuer + "/authorize",
		TokenEndpoint:         issuer + "/token",
		JWKSUri:               issuer + "/jwks",
		UserinfoEndpoint:      issuer + "/userinfo",
	}))

	// JWKS handler.
	mux.Handle("/jwks", oidc.NewJWKSHandler(ks))

	// Authorize handler (with enforcement middleware).
	authorizeHandler := &oidc.AuthorizeHandler{
		ClientConfig: clients,
		Auth:         authMock,
		MFA:          mfaMock,
		Sessions:     sessions,
		Emitter:      emitter,
	}
	mux.Handle("/authorize", reg.Middleware(authorizeHandler))
	mux.Handle("/authorize/callback", authorizeHandler)

	// Token handler (with enforcement middleware).
	tokenHandler := &oidc.TokenHandler{
		ClientConfig:  clients,
		Sessions:      sessions,
		Users:         usersMock,
		SigningKey:    privateKey,
		Issuer:        issuer,
		TokenLifetime: 15 * time.Minute,
		Emitter:       emitter,
	}
	mux.Handle("/token", reg.Middleware(tokenHandler))

	// Userinfo handler.
	mux.Handle("/userinfo", &oidc.UserinfoHandler{
		Users:      usersMock,
		SigningKey: &privateKey.PublicKey,
		Issuer:     issuer,
		Emitter:    emitter,
	})

	// Healthz handler.
	mux.HandleFunc("/healthz", func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte(`{"status":"ok","version":"0.1.0"}`))
	})

	srv := httptest.NewServer(mux)
	t.Cleanup(srv.Close)

	return &TestServer{
		Server:     srv,
		PrivateKey: privateKey,
		Sessions:   sessions,
		AuthMock:   authMock,
		Clients:    clients,
	}
}

// ---------------------------------------------------------------------------
// PKCE helpers
// ---------------------------------------------------------------------------

func generatePKCE(t *testing.T) (verifier, challenge string) {
	t.Helper()
	b := make([]byte, 32)
	if _, err := rand.Read(b); err != nil {
		t.Fatalf("generate PKCE verifier: %v", err)
	}
	verifier = base64.RawURLEncoding.EncodeToString(b)
	h := sha256.Sum256([]byte(verifier))
	challenge = base64.RawURLEncoding.EncodeToString(h[:])
	return
}

// ---------------------------------------------------------------------------
// Test cases
// ---------------------------------------------------------------------------

// 1. Discovery test.
func TestDiscovery(t *testing.T) {
	ts := newTestServer(t)

	resp, err := http.Get(ts.Server.URL + "/.well-known/openid-configuration")
	if err != nil {
		t.Fatalf("GET /.well-known/openid-configuration: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("status: want 200, got %d", resp.StatusCode)
	}

	ct := resp.Header.Get("Content-Type")
	if !strings.HasPrefix(ct, "application/json") {
		t.Errorf("Content-Type: want application/json, got %q", ct)
	}

	var doc map[string]interface{}
	if err := json.NewDecoder(resp.Body).Decode(&doc); err != nil {
		t.Fatalf("decode discovery doc: %v", err)
	}

	requiredFields := []string{
		"issuer", "authorization_endpoint", "token_endpoint", "jwks_uri",
		"response_types_supported", "grant_types_supported",
		"code_challenge_methods_supported", "id_token_signing_alg_values_supported",
		"scopes_supported",
	}
	for _, f := range requiredFields {
		if _, ok := doc[f]; !ok {
			t.Errorf("discovery doc missing field %q", f)
		}
	}

	// registration_endpoint must be absent.
	if _, ok := doc["registration_endpoint"]; ok {
		t.Error("discovery doc must not contain registration_endpoint")
	}

	// scopes_supported must include openid.
	scopes, ok := doc["scopes_supported"].([]interface{})
	if !ok {
		t.Fatal("scopes_supported is not an array")
	}
	found := false
	for _, s := range scopes {
		if s == "openid" {
			found = true
			break
		}
	}
	if !found {
		t.Error("scopes_supported must include openid")
	}
}

// 2. JWKS test.
func TestJWKS(t *testing.T) {
	ts := newTestServer(t)

	resp, err := http.Get(ts.Server.URL + "/jwks")
	if err != nil {
		t.Fatalf("GET /jwks: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("status: want 200, got %d", resp.StatusCode)
	}

	var jwks struct {
		Keys []struct {
			Kty string `json:"kty"`
			Alg string `json:"alg"`
			Use string `json:"use"`
			Kid string `json:"kid"`
			N   string `json:"n"`
			E   string `json:"e"`
		} `json:"keys"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&jwks); err != nil {
		t.Fatalf("decode JWKS: %v", err)
	}

	if len(jwks.Keys) == 0 {
		t.Fatal("JWKS must contain at least one key")
	}

	key := jwks.Keys[0]
	if key.Kty != "RSA" {
		t.Errorf("kty: want RSA, got %q", key.Kty)
	}
	if key.Alg != "RS256" {
		t.Errorf("alg: want RS256, got %q", key.Alg)
	}
	if key.N == "" {
		t.Error("n (modulus) must not be empty")
	}
	if key.E == "" {
		t.Error("e (exponent) must not be empty")
	}
}

// 3. Authorization redirect test — valid PKCE params → 302 redirect.
func TestAuthorize_Redirect(t *testing.T) {
	ts := newTestServer(t)

	_, challenge := generatePKCE(t)

	q := url.Values{}
	q.Set("client_id", "demo-app")
	q.Set("redirect_uri", "http://localhost:3000/callback")
	q.Set("response_type", "code")
	q.Set("scope", "openid profile")
	q.Set("state", "test-state-123")
	q.Set("code_challenge", challenge)
	q.Set("code_challenge_method", "S256")

	client := &http.Client{CheckRedirect: func(_ *http.Request, _ []*http.Request) error {
		return http.ErrUseLastResponse // don't follow redirect
	}}
	resp, err := client.Get(ts.Server.URL + "/authorize?" + q.Encode())
	if err != nil {
		t.Fatalf("GET /authorize: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusFound {
		t.Errorf("status: want 302, got %d", resp.StatusCode)
	}
	location := resp.Header.Get("Location")
	if location == "" {
		t.Error("Location header must be set on redirect")
	}
}

// 4. Invalid client test — unknown client_id → invalid_profile_usage.
func TestAuthorize_InvalidClient(t *testing.T) {
	ts := newTestServer(t)

	_, challenge := generatePKCE(t)

	q := url.Values{}
	q.Set("client_id", "unknown-client")
	q.Set("redirect_uri", "http://localhost:3000/callback")
	q.Set("response_type", "code")
	q.Set("scope", "openid")
	q.Set("state", "s")
	q.Set("code_challenge", challenge)
	q.Set("code_challenge_method", "S256")

	resp, err := http.Get(ts.Server.URL + "/authorize?" + q.Encode())
	if err != nil {
		t.Fatalf("GET /authorize: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusBadRequest {
		t.Errorf("status: want 400, got %d", resp.StatusCode)
	}

	var pe map[string]interface{}
	if err := json.NewDecoder(resp.Body).Decode(&pe); err != nil {
		t.Fatalf("decode error response: %v", err)
	}
	errType, _ := pe["error"].(string)
	if errType != "invalid_profile_usage" {
		t.Errorf("error: want invalid_profile_usage, got %q", errType)
	}
}

// 5. Wildcard redirect URI → rejected_for_profile_safety (caught by enforcement middleware).
func TestAuthorize_WildcardRedirectURI(t *testing.T) {
	ts := newTestServer(t)

	q := url.Values{}
	q.Set("client_id", "demo-app")
	q.Set("redirect_uri", "https://evil.com/*")
	q.Set("response_type", "code")
	q.Set("scope", "openid")
	q.Set("state", "s")
	q.Set("code_challenge", "abc")
	q.Set("code_challenge_method", "S256")

	resp, err := http.Get(ts.Server.URL + "/authorize?" + q.Encode())
	if err != nil {
		t.Fatalf("GET /authorize: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusForbidden {
		t.Errorf("status: want 403, got %d", resp.StatusCode)
	}

	var pe map[string]interface{}
	_ = json.NewDecoder(resp.Body).Decode(&pe)
	errType, _ := pe["error"].(string)
	if errType != "rejected_for_profile_safety" {
		t.Errorf("error: want rejected_for_profile_safety, got %q", errType)
	}
}

// 6. Missing PKCE test — no code_challenge → invalid_profile_usage (enforcement middleware).
func TestAuthorize_MissingPKCE(t *testing.T) {
	ts := newTestServer(t)

	q := url.Values{}
	q.Set("client_id", "demo-app")
	q.Set("redirect_uri", "http://localhost:3000/callback")
	q.Set("response_type", "code")
	q.Set("scope", "openid")
	q.Set("state", "s")
	// No code_challenge

	resp, err := http.Get(ts.Server.URL + "/authorize?" + q.Encode())
	if err != nil {
		t.Fatalf("GET /authorize: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusBadRequest {
		t.Errorf("status: want 400, got %d", resp.StatusCode)
	}

	var pe map[string]interface{}
	_ = json.NewDecoder(resp.Body).Decode(&pe)
	errType, _ := pe["error"].(string)
	if errType != "invalid_profile_usage" {
		t.Errorf("error: want invalid_profile_usage, got %q", errType)
	}
}

// 7. Healthz test.
func TestHealthz(t *testing.T) {
	ts := newTestServer(t)

	resp, err := http.Get(ts.Server.URL + "/healthz")
	if err != nil {
		t.Fatalf("GET /healthz: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("status: want 200, got %d", resp.StatusCode)
	}

	var body map[string]interface{}
	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
		t.Fatalf("decode /healthz response: %v", err)
	}
	if body["status"] != "ok" {
		t.Errorf("status field: want ok, got %v", body["status"])
	}
}

// 8. Complete token flow test — auth callback + token exchange → valid JWT.
func TestCompleteTokenFlow(t *testing.T) {
	ts := newTestServer(t)

	verifier, challenge := generatePKCE(t)

	// Step 1: Simulate the callback by seeding a pending state and triggering callback.
	// We do this by first calling /authorize to create the pending state, then calling
	// /authorize/callback with state and a mock code.

	q := url.Values{}
	q.Set("client_id", "demo-app")
	q.Set("redirect_uri", "http://localhost:3000/callback")
	q.Set("response_type", "code")
	q.Set("scope", "openid profile email groups")
	q.Set("state", "flow-state-xyz")
	q.Set("code_challenge", challenge)
	q.Set("code_challenge_method", "S256")

	noRedirectClient := &http.Client{
		CheckRedirect: func(_ *http.Request, _ []*http.Request) error {
			return http.ErrUseLastResponse
		},
	}

	// /authorize → 302 to upstream auth.
	authResp, err := noRedirectClient.Get(ts.Server.URL + "/authorize?" + q.Encode())
	if err != nil {
		t.Fatalf("GET /authorize: %v", err)
	}
	authResp.Body.Close()
	if authResp.StatusCode != http.StatusFound {
		t.Fatalf("authorize: want 302, got %d", authResp.StatusCode)
	}

	// Step 2: Simulate the upstream callback returning code + state.
	cbQ := url.Values{}
	cbQ.Set("code", "upstream-auth-code")
	cbQ.Set("state", "flow-state-xyz")

	cbResp, err := noRedirectClient.Get(ts.Server.URL + "/authorize/callback?" + cbQ.Encode())
	if err != nil {
		t.Fatalf("GET /authorize/callback: %v", err)
	}
	cbResp.Body.Close()
	if cbResp.StatusCode != http.StatusFound {
		t.Fatalf("callback: want 302, got %d", cbResp.StatusCode)
	}

	// Extract the auth code from the Location redirect to our client.
	location := cbResp.Header.Get("Location")
	if location == "" {
		t.Fatal("callback: no Location header")
	}
	locURL, err := url.Parse(location)
	if err != nil {
		t.Fatalf("parse Location URL: %v", err)
	}
	authCode := locURL.Query().Get("code")
	if authCode == "" {
		t.Fatalf("no code in callback redirect: %q", location)
	}

	// Step 3: Exchange the auth code for a token.
	tokenForm := url.Values{}
	tokenForm.Set("grant_type", "authorization_code")
	tokenForm.Set("client_id", "demo-app")
	tokenForm.Set("code", authCode)
	tokenForm.Set("code_verifier", verifier)
	// The exchange must repeat the redirect URI the code was issued for.
	tokenForm.Set("redirect_uri", "http://localhost:3000/callback")

	tokenResp, err := http.Post(
		ts.Server.URL+"/token",
		"application/x-www-form-urlencoded",
		strings.NewReader(tokenForm.Encode()),
	)
	if err != nil {
		t.Fatalf("POST /token: %v", err)
	}
	defer tokenResp.Body.Close()

	if tokenResp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(tokenResp.Body)
		t.Fatalf("token: want 200, got %d; body: %s", tokenResp.StatusCode, body)
	}

	var tr struct {
		AccessToken string `json:"access_token"`
		TokenType   string `json:"token_type"`
		ExpiresIn   int    `json:"expires_in"`
		IDToken     string `json:"id_token"`
	}
	if err := json.NewDecoder(tokenResp.Body).Decode(&tr); err != nil {
		t.Fatalf("decode token response: %v", err)
	}

	if tr.AccessToken == "" {
		t.Error("access_token must not be empty")
	}
	if tr.TokenType != "Bearer" {
		t.Errorf("token_type: want Bearer, got %q", tr.TokenType)
	}
	if tr.IDToken == "" {
		t.Error("id_token must not be empty")
	}

	// Verify JWT has 3 parts (header.payload.signature).
	parts := strings.Split(tr.IDToken, ".")
	if len(parts) != 3 {
		t.Errorf("id_token: expected 3 JWT parts, got %d", len(parts))
	}

	// Decode payload and check required claims.
	payloadJSON, err := base64.RawURLEncoding.DecodeString(parts[1])
	if err != nil {
		t.Fatalf("decode JWT payload: %v", err)
	}
	var claims map[string]interface{}
	if err := json.Unmarshal(payloadJSON, &claims); err != nil {
		t.Fatalf("parse JWT claims: %v", err)
	}

	requiredClaims := []string{
		"iss", "sub", "aud", "exp", "iat",
		// IAM Profile v0.3 core claims (KEY-WP-0005-T01) -- required on
		// every production token, not scope-gated.
		"tenant", "principal_type", "groups", "roles", "assurance",
	}
	for _, c := range requiredClaims {
		if _, ok := claims[c]; !ok {
			t.Errorf("JWT missing claim %q", c)
		}
	}

	if claims["aud"] != "demo-app" {
		t.Errorf("aud: want demo-app, got %v", claims["aud"])
	}

	// testuser has no explicit Tenant assignment -- falls back to the
	// platform default (this workstation's single tenant, ADR-0006).
	if claims["tenant"] != "tenant:coulomb" {
		t.Errorf("tenant: want tenant:coulomb, got %v", claims["tenant"])
	}
	if claims["principal_type"] != "human" {
		t.Errorf("principal_type: want human, got %v", claims["principal_type"])
	}
	groups, ok := claims["groups"].([]interface{})
	if !ok || len(groups) != 1 || groups[0] != "developers" {
		t.Errorf("groups: want [developers], got %v", claims["groups"])
	}
	roles, ok := claims["roles"].([]interface{})
	if !ok || len(roles) != 0 {
		t.Errorf("roles: want [] (testuser has none), got %v", claims["roles"])
	}
	assurance, ok := claims["assurance"].(map[string]interface{})
	if !ok {
		t.Fatalf("assurance: want an object, got %v", claims["assurance"])
	}
	// This flow's mockMFA has required: false -- MFA was never performed,
	// so assurance must reflect aal1, not aal2, regardless of the user's
	// static MFA enrollment state.
	if assurance["level"] != "aal1" {
		t.Errorf("assurance.level: want aal1 (MFA not required in this flow), got %v", assurance["level"])
	}
	if assurance["mfa"] != false {
		t.Errorf("assurance.mfa: want false, got %v", assurance["mfa"])
	}
	if assurance["source"] != "key-cape" {
		t.Errorf("assurance.source: want key-cape, got %v", assurance["source"])
	}
}