package server

import (
	"context"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/x509"
	"encoding/base64"
	"fmt"
	"log/slog"
	"net/http"
	"path/filepath"
	"testing"
	"time"

	"glchat/internal/auth"
	"glchat/internal/config"
	"glchat/internal/database"
	"glchat/internal/gateway"
	"glchat/internal/httpx"
	"glchat/internal/permissions"
	"glchat/internal/source"
	"glchat/internal/store"
)

// newPushTestServer поднимает тестовый сервер с настроенным VAPID-ключом:
// newTestServer из server_test.go о push ничего не знает, а ручки обязаны
// работать и с ключом, и без него.
func newPushTestServer(t *testing.T, withKeys bool) (*Server, *store.Store) {
	t.Helper()
	ctx := context.Background()
	db, err := database.Open(ctx, database.Options{
		Path:     filepath.Join(t.TempDir(), "glchat.db"),
		ReadPool: 2,
		Migrate:  true,
	})
	if err != nil {
		t.Fatalf("open test database: %v", err)
	}
	t.Cleanup(func() {
		if err := db.Close(); err != nil {
			t.Errorf("close test database: %v", err)
		}
	})

	cfg := config.Config{
		DataDir:           t.TempDir(),
		Domain:            "gl.mhspx.su",
		WebRoot:           filepath.Join("testdata", "web"),
		FilesDomain:       "files.gl.mhspx.su",
		InstanceName:      "glchat",
		ListenAddr:        "127.0.0.1:0",
		Version:           "v0.1.0-test",
		Commit:            "deadbee",
		BuildDate:         "2026-09-19T00:00:00Z",
		MaxUploadSize:     26214400,
		TLSEnabled:        true,
		SessionPepper:     "test-pepper",
		MasterKey:         "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
		Argon2MemoryKiB:   1024,
		Argon2Iterations:  1,
		Argon2Parallelism: 1,
		LogLevel:          "error",
		LogFormat:         "json",
		UnfurlEnabled:     true,
		UnfurlTimeout:     5 * time.Second,
	}
	if withKeys {
		cfg.VAPIDPrivateKey = testVAPIDPrivateKey(t)
		cfg.VAPIDSubject = "mailto:admin@gl.mhspx.su"
	}
	logger := slog.New(slog.DiscardHandler)
	st := store.New(db)
	authService, err := auth.New(context.Background(), cfg, st, logger)
	if err != nil {
		t.Fatalf("initialize authentication: %v", err)
	}
	calculator := permissions.NewCalculator(source.New(st))
	gatewayService := gateway.New(st, authService, gateway.NewSnapshot(st, calculator), logger, cfg.AllowedOrigins())
	return New(cfg, db, logger, Deps{
		Store: st, Auth: authService, Gateway: gatewayService, Permissions: calculator,
	}), st
}

func testVAPIDPrivateKey(t *testing.T) string {
	t.Helper()
	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatalf("generate key: %v", err)
	}
	der, err := x509.MarshalPKCS8PrivateKey(key)
	if err != nil {
		t.Fatalf("marshal PKCS#8: %v", err)
	}
	return base64.StdEncoding.EncodeToString(der)
}

// testPushKeys возвращает корректные ключи подписки (65-байтовая точка P-256
// и 16 байт auth) в base64url — как их отдаёт PushSubscription.toJSON().
func testPushKeys(t *testing.T) (string, string) {
	t.Helper()
	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatalf("generate subscription key: %v", err)
	}
	point, err := key.PublicKey.Bytes()
	if err != nil {
		t.Fatalf("public key bytes: %v", err)
	}
	auth := make([]byte, 16)
	if _, err := rand.Read(auth); err != nil {
		t.Fatalf("auth: %v", err)
	}
	return base64.RawURLEncoding.EncodeToString(point), base64.RawURLEncoding.EncodeToString(auth)
}

// testAuthKey — корректный auth-ключ подписки (16 байт).
func testAuthKey(t *testing.T) string {
	t.Helper()
	_, auth := testPushKeys(t)
	return auth
}

func pushSubscribeBody(t *testing.T, endpoint string) string {
	t.Helper()
	p256dh, auth := testPushKeys(t)
	return fmt.Sprintf(`{"endpoint":%q,"keys":{"p256dh":%q,"auth":%q}}`, endpoint, p256dh, auth)
}

func TestPushConfigDisabledWithoutKeys(t *testing.T) {
	srv, _ := newPushTestServer(t, false)
	cookie := registerAndLogin(t, srv, "push_off", "push-off@example.com")

	rec := doJSON(t, srv, http.MethodGet, "/api/v1/push/config", "", cookie)
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /push/config = %d, body = %s", rec.Code, rec.Body.String())
	}
	payload := decodeResponse[struct {
		Enabled   bool   `json:"enabled"`
		PublicKey string `json:"public_key"`
	}](t, rec)
	if payload.Enabled || payload.PublicKey != "" {
		t.Fatalf("без ключей push должен быть выключен: %+v", payload)
	}

	// Подписка на инстансе без ключей — честная ошибка, а не молчаливый успех.
	rec = doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions",
		pushSubscribeBody(t, "https://fcm.googleapis.com/fcm/send/disabled"), cookie)
	if rec.Code != http.StatusServiceUnavailable {
		t.Fatalf("подписка без ключей = %d, ожидалось 503", rec.Code)
	}
	if code := errorCodeOf(t, rec); code != "push.disabled" {
		t.Fatalf("код ошибки = %q, ожидался push.disabled", code)
	}
}

func TestPushSubscribeFlow(t *testing.T) {
	srv, st := newPushTestServer(t, true)
	cookie := registerAndLogin(t, srv, "push_on", "push-on@example.com")
	user, err := srv.auth.UserByEmail(t.Context(), "push-on@example.com")
	if err != nil {
		t.Fatalf("UserByEmail: %v", err)
	}

	config := decodeResponse[struct {
		Enabled   bool   `json:"enabled"`
		PublicKey string `json:"public_key"`
	}](t, doJSON(t, srv, http.MethodGet, "/api/v1/push/config", "", cookie))
	if !config.Enabled || config.PublicKey == "" {
		t.Fatalf("push должен быть включён: %+v", config)
	}
	decoded, err := base64.RawURLEncoding.DecodeString(config.PublicKey)
	if err != nil || len(decoded) != 65 {
		t.Fatalf("публичный ключ не годится для applicationServerKey: %v", err)
	}

	endpoint := "https://fcm.googleapis.com/fcm/send/device-one"
	rec := doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions",
		pushSubscribeBody(t, endpoint), cookie)
	if rec.Code != http.StatusOK {
		t.Fatalf("подписка = %d, body = %s", rec.Code, rec.Body.String())
	}

	subscriptions, err := st.ListPushSubscriptions(t.Context(), user.ID)
	if err != nil || len(subscriptions) != 1 {
		t.Fatalf("подписок в базе %d (%v), ожидалась 1", len(subscriptions), err)
	}
	if subscriptions[0].Endpoint != endpoint {
		t.Fatalf("эндпоинт = %q", subscriptions[0].Endpoint)
	}

	// Список для интерфейса отдаёт устройства и лимит.
	list := decodeResponse[struct {
		Subscriptions []struct {
			ID       string `json:"id"`
			Endpoint string `json:"endpoint"`
		} `json:"subscriptions"`
		Limit int `json:"limit"`
	}](t, doJSON(t, srv, http.MethodGet, "/api/v1/push/subscriptions", "", cookie))
	if len(list.Subscriptions) != 1 || list.Limit != maxPushSubscriptionsPerUser {
		t.Fatalf("неожиданный список подписок: %+v", list)
	}

	// Отписка устройства.
	rec = doJSON(t, srv, http.MethodDelete,
		"/api/v1/push/subscriptions?endpoint="+endpoint, "", cookie)
	if rec.Code != http.StatusOK {
		t.Fatalf("отписка = %d, body = %s", rec.Code, rec.Body.String())
	}
	if count, err := st.CountPushSubscriptions(t.Context(), user.ID); err != nil || count != 0 {
		t.Fatalf("после отписки подписок %d (%v)", count, err)
	}
}

func TestPushSubscribeValidation(t *testing.T) {
	srv, _ := newPushTestServer(t, true)
	cookie := registerAndLogin(t, srv, "push_bad", "push-bad@example.com")

	cases := []struct {
		name string
		body string
		code string
	}{
		{
			name: "http вместо https",
			body: pushSubscribeBody(t, "http://fcm.googleapis.com/fcm/send/x"),
			code: "push.invalid_endpoint",
		},
		{
			name: "внутренний адрес",
			body: pushSubscribeBody(t, "https://10.0.0.5/push"),
			code: "push.invalid_endpoint",
		},
		{
			name: "метаданные облака",
			body: pushSubscribeBody(t, "https://169.254.169.254/latest/meta-data"),
			code: "push.invalid_endpoint",
		},
		{
			name: "loopback",
			body: pushSubscribeBody(t, "https://127.0.0.1:8443/push"),
			code: "push.invalid_endpoint",
		},
		{
			name: "p256dh не точка кривой",
			body: fmt.Sprintf(`{"endpoint":"https://fcm.googleapis.com/fcm/send/x","keys":{"p256dh":%q,"auth":%q}}`,
				base64.RawURLEncoding.EncodeToString(make([]byte, 65)), testAuthKey(t)),
			code: "push.invalid_keys",
		},
		{
			name: "битый ключ шифрования",
			body: `{"endpoint":"https://fcm.googleapis.com/fcm/send/x","keys":{"p256dh":"AAAA","auth":"AAAA"}}`,
			code: "push.invalid_keys",
		},
		{
			name: "пустой ключ",
			body: `{"endpoint":"https://fcm.googleapis.com/fcm/send/x","keys":{"p256dh":"","auth":""}}`,
			code: "push.invalid_keys",
		},
	}
	for _, testCase := range cases {
		t.Run(testCase.name, func(t *testing.T) {
			rec := doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions", testCase.body, cookie)
			if rec.Code != http.StatusUnprocessableEntity {
				t.Fatalf("код ответа = %d, ожидался 422 (body = %s)", rec.Code, rec.Body.String())
			}
			if code := errorCodeOf(t, rec); code != testCase.code {
				t.Fatalf("код ошибки = %q, ожидался %q", code, testCase.code)
			}
		})
	}
}

func TestPushSubscribeLimit(t *testing.T) {
	srv, _ := newPushTestServer(t, true)
	cookie := registerAndLogin(t, srv, "push_limit", "push-limit@example.com")
	// Лимит частоты проверяется отдельно: здесь важно дойти до предела
	// устройств на пользователя.
	srv.pushLimiter = httpx.NewRateLimiterWindow(100, time.Minute, 100)

	for i := 0; i < maxPushSubscriptionsPerUser; i++ {
		endpoint := fmt.Sprintf("https://fcm.googleapis.com/fcm/send/device-%d", i)
		rec := doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions",
			pushSubscribeBody(t, endpoint), cookie)
		if rec.Code != http.StatusOK {
			t.Fatalf("подписка %d = %d, body = %s", i, rec.Code, rec.Body.String())
		}
	}
	rec := doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions",
		pushSubscribeBody(t, "https://fcm.googleapis.com/fcm/send/device-over-limit"), cookie)
	if rec.Code != http.StatusConflict {
		t.Fatalf("подписка сверх лимита = %d, ожидалось 409 (body = %s)", rec.Code, rec.Body.String())
	}
	if code := errorCodeOf(t, rec); code != "push.too_many_subscriptions" {
		t.Fatalf("код ошибки = %q", code)
	}
}

// Подписки ограничены и по частоте: перебор устройств не должен превращаться
// в поток запросов (AGENT.md 8.6).
func TestPushSubscribeRateLimited(t *testing.T) {
	srv, _ := newPushTestServer(t, true)
	cookie := registerAndLogin(t, srv, "push_flood", "push-flood@example.com")

	var limited bool
	for i := 0; i < 40; i++ {
		endpoint := fmt.Sprintf("https://fcm.googleapis.com/fcm/send/flood-%d", i)
		rec := doJSON(t, srv, http.MethodPost, "/api/v1/push/subscriptions",
			pushSubscribeBody(t, endpoint), cookie)
		if rec.Code == http.StatusTooManyRequests {
			limited = true
			break
		}
	}
	if !limited {
		t.Fatal("лимит частоты подписок не сработал")
	}
}

func TestPushRoutesRequireSession(t *testing.T) {
	srv, _ := newPushTestServer(t, true)
	body := pushSubscribeBody(t, "https://fcm.googleapis.com/fcm/send/no-session")
	for _, request := range []struct {
		method string
		path   string
		body   string
	}{
		{http.MethodGet, "/api/v1/push/config", ""},
		{http.MethodGet, "/api/v1/push/subscriptions", ""},
		{http.MethodPost, "/api/v1/push/subscriptions", body},
		{http.MethodDelete, "/api/v1/push/subscriptions", ""},
	} {
		rec := doJSON(t, srv, request.method, request.path, request.body)
		if rec.Code != http.StatusUnauthorized {
			t.Errorf("%s %s без сессии = %d, ожидалось 401", request.method, request.path, rec.Code)
		}
	}
}

// Публичный ключ в /meta виден до входа: клиент решает, показывать ли раздел.
func TestMetaExposesWebPushFlag(t *testing.T) {
	srv, _ := newPushTestServer(t, true)
	rec := doJSON(t, srv, http.MethodGet, "/api/v1/meta", "")
	if rec.Code != http.StatusOK {
		t.Fatalf("GET /meta = %d", rec.Code)
	}
	payload := decodeResponse[struct {
		Features struct {
			WebPushEnabled bool `json:"web_push_enabled"`
		} `json:"features"`
	}](t, rec)
	if !payload.Features.WebPushEnabled {
		t.Fatal("meta не сообщает о включённом Web Push")
	}
}