package oidc_test

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

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

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

func newUserinfoHandler(t *testing.T, users domain.UserRepository) (*oidc.UserinfoHandler, *rsa.PrivateKey) {
	t.Helper()
	key, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		t.Fatalf("generate RSA key: %v", err)
	}
	capture := &captureEmitter{}
	h := &oidc.UserinfoHandler{
		Users:      users,
		SigningKey:  &key.PublicKey,
		Issuer:     "https://auth.netkingdom.local",
		Emitter:    capture,
	}
	return h, key
}

// buildToken builds and signs a JWT with the given claims using the private key.
func buildToken(t *testing.T, claims map[string]interface{}, key *rsa.PrivateKey) string {
	t.Helper()
	tok, err := oidc.BuildJWT(claims, "key-1", key)
	if err != nil {
		t.Fatalf("buildToken: %v", err)
	}
	return tok
}

func userinfoRequest(token string) *http.Request {
	req := httptest.NewRequest(http.MethodGet, "/userinfo", nil)
	if token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}
	return req
}

func decodeUserinfoClaims(t *testing.T, body string) map[string]interface{} {
	t.Helper()
	var m map[string]interface{}
	if err := json.Unmarshal([]byte(body), &m); err != nil {
		t.Fatalf("decode userinfo response: %v (body: %q)", err, body)
	}
	return m
}

// ---------------------------------------------------------------------------
// T09 — Userinfo Endpoint Tests
// ---------------------------------------------------------------------------

func TestUserinfoHandler_ValidToken_ReturnsClaims(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{
		"user-alice": aliceUser(), // LookupUser by sub (= user.ID)
		"alice":      aliceUser(), // also by username
	}}
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss":   "https://auth.netkingdom.local",
		"sub":   "alice",
		"aud":   "test-client",
		"exp":   now.Add(10 * time.Minute).Unix(),
		"iat":   now.Unix(),
		"scope": "openid profile email groups",
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d (body: %s)", w.Code, w.Body.String())
	}
	ct := w.Header().Get("Content-Type")
	if ct == "" {
		t.Error("Content-Type must be set")
	}

	resp := decodeUserinfoClaims(t, w.Body.String())
	if resp["sub"] != "alice" {
		t.Errorf("sub: expected alice, got %v", resp["sub"])
	}
}

func TestUserinfoHandler_MissingAuthorization_Returns401(t *testing.T) {
	users := &mockUserRepo{}
	h, _ := newUserinfoHandler(t, users)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(""))

	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401, got %d", w.Code)
	}
}

func TestUserinfoHandler_ExpiredToken_Returns401(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss": "https://auth.netkingdom.local",
		"sub": "alice",
		"aud": "test-client",
		"exp": now.Add(-5 * time.Minute).Unix(), // already expired
		"iat": now.Add(-10 * time.Minute).Unix(),
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401 for expired token, got %d", w.Code)
	}
}

func TestUserinfoHandler_InvalidSignature_Returns401(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	h, _ := newUserinfoHandler(t, users) // handler uses key1.Public

	// Sign with a DIFFERENT key
	wrongKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		t.Fatalf("generate wrong key: %v", err)
	}
	now := time.Now()
	claims := map[string]interface{}{
		"iss": "https://auth.netkingdom.local",
		"sub": "alice",
		"exp": now.Add(10 * time.Minute).Unix(),
		"iat": now.Unix(),
	}
	token := buildToken(t, claims, wrongKey)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401 for invalid signature, got %d", w.Code)
	}
}

func TestUserinfoHandler_WithEmailScope_EmailPresent(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss":   "https://auth.netkingdom.local",
		"sub":   "alice",
		"exp":   now.Add(10 * time.Minute).Unix(),
		"iat":   now.Unix(),
		"scope": "openid email",
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d (body: %s)", w.Code, w.Body.String())
	}

	resp := decodeUserinfoClaims(t, w.Body.String())
	if resp["email"] != "alice@example.com" {
		t.Errorf("email: expected alice@example.com, got %v", resp["email"])
	}
}

func TestUserinfoHandler_WithoutEmailScope_EmailAbsent(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss":   "https://auth.netkingdom.local",
		"sub":   "alice",
		"exp":   now.Add(10 * time.Minute).Unix(),
		"iat":   now.Unix(),
		"scope": "openid profile", // no email scope
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d (body: %s)", w.Code, w.Body.String())
	}

	resp := decodeUserinfoClaims(t, w.Body.String())
	if _, ok := resp["email"]; ok {
		t.Error("email must be absent when email scope is not present in token")
	}
}

func TestUserinfoHandler_WithProfileScope_UsernamePresent(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss":   "https://auth.netkingdom.local",
		"sub":   "alice",
		"exp":   now.Add(10 * time.Minute).Unix(),
		"iat":   now.Unix(),
		"scope": "openid profile",
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d (body: %s)", w.Code, w.Body.String())
	}

	resp := decodeUserinfoClaims(t, w.Body.String())
	if resp["preferred_username"] != "alice" {
		t.Errorf("preferred_username: expected alice, got %v", resp["preferred_username"])
	}
}

func TestUserinfoHandler_EmitsTelemetry(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{"alice": aliceUser()}}
	key, _ := rsa.GenerateKey(rand.Reader, 2048)
	capture := &captureEmitter{}
	h := &oidc.UserinfoHandler{
		Users:     users,
		SigningKey: &key.PublicKey,
		Issuer:    "https://auth.netkingdom.local",
		Emitter:   capture,
	}

	now := time.Now()
	claims := map[string]interface{}{
		"iss": "https://auth.netkingdom.local",
		"sub": "alice",
		"exp": now.Add(10 * time.Minute).Unix(),
		"iat": now.Unix(),
	}
	token, _ := oidc.BuildJWT(claims, "key-1", key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", w.Code)
	}

	found := false
	for _, ev := range capture.events {
		if ev.EventType == telemetry.EventAuthSuccess && ev.Endpoint == "/userinfo" {
			found = true
			break
		}
	}
	if !found {
		t.Error("expected auth_success telemetry event for /userinfo")
	}
}

// Ensure mockUserRepo also satisfies the extended interface with ListUsers.
func TestUserinfoHandler_UserNotFound_Returns401(t *testing.T) {
	users := &mockUserRepo{users: map[string]*domain.User{}} // empty — no alice
	h, key := newUserinfoHandler(t, users)

	now := time.Now()
	claims := map[string]interface{}{
		"iss": "https://auth.netkingdom.local",
		"sub": "alice",
		"exp": now.Add(10 * time.Minute).Unix(),
		"iat": now.Unix(),
	}
	token := buildToken(t, claims, key)

	w := httptest.NewRecorder()
	h.ServeHTTP(w, userinfoRequest(token))

	// user not found → treat as 401 (token references unknown user)
	if w.Code != http.StatusUnauthorized {
		t.Errorf("expected 401 when user not found, got %d", w.Code)
	}
}

// Compile-time check: mockUserRepo satisfies domain.UserRepository (including ListUsers).
var _ domain.UserRepository = (*mockUserRepo)(nil)