package auth_test

import (
	"context"
	"crypto/rand"
	"database/sql"
	"errors"
	"net/url"
	"sync"
	"testing"
	"time"

	"galaxy/backend/internal/auth"
	"galaxy/backend/internal/config"
	backendpg "galaxy/backend/internal/postgres"
	"galaxy/backend/internal/user"
	pgshared "galaxy/postgres"

	"github.com/google/uuid"
	testcontainers "github.com/testcontainers/testcontainers-go"
	tcpostgres "github.com/testcontainers/testcontainers-go/modules/postgres"
	"github.com/testcontainers/testcontainers-go/wait"
)

const (
	pgImage    = "postgres:16-alpine"
	pgUser     = "galaxy"
	pgPassword = "galaxy"
	pgDatabase = "galaxy_backend"
	pgSchema   = "backend"
	pgStartup  = 90 * time.Second
	pgOpTO     = 10 * time.Second
)

// startPostgres spins up a Postgres testcontainer with the backend
// migrations applied. The returned *sql.DB is closed and the container
// terminated by t.Cleanup hooks.
func startPostgres(t *testing.T) *sql.DB {
	t.Helper()
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
	t.Cleanup(cancel)

	pgContainer, err := tcpostgres.Run(ctx, pgImage,
		tcpostgres.WithDatabase(pgDatabase),
		tcpostgres.WithUsername(pgUser),
		tcpostgres.WithPassword(pgPassword),
		testcontainers.WithWaitStrategy(
			wait.ForLog("database system is ready to accept connections").
				WithOccurrence(2).
				WithStartupTimeout(pgStartup),
		),
	)
	if err != nil {
		t.Skipf("postgres testcontainer unavailable, skipping: %v", err)
	}
	t.Cleanup(func() {
		if termErr := testcontainers.TerminateContainer(pgContainer); termErr != nil {
			t.Errorf("terminate postgres container: %v", termErr)
		}
	})

	baseDSN, err := pgContainer.ConnectionString(ctx, "sslmode=disable")
	if err != nil {
		t.Fatalf("connection string: %v", err)
	}
	scopedDSN, err := dsnWithSearchPath(baseDSN, pgSchema)
	if err != nil {
		t.Fatalf("scope dsn: %v", err)
	}

	cfg := pgshared.DefaultConfig()
	cfg.PrimaryDSN = scopedDSN
	cfg.OperationTimeout = pgOpTO

	db, err := pgshared.OpenPrimary(ctx, cfg)
	if err != nil {
		t.Fatalf("open primary: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })

	if err := pgshared.Ping(ctx, db, cfg.OperationTimeout); err != nil {
		t.Fatalf("ping: %v", err)
	}
	if err := backendpg.ApplyMigrations(ctx, db); err != nil {
		t.Fatalf("apply migrations: %v", err)
	}
	return db
}

func dsnWithSearchPath(baseDSN, schema string) (string, error) {
	parsed, err := url.Parse(baseDSN)
	if err != nil {
		return "", err
	}
	values := parsed.Query()
	values.Set("search_path", schema)
	if values.Get("sslmode") == "" {
		values.Set("sslmode", "disable")
	}
	parsed.RawQuery = values.Encode()
	return parsed.String(), nil
}

// recordingMailer implements auth.LoginCodeMailer and remembers the most
// recent enqueue.
type recordingMailer struct {
	mu       sync.Mutex
	lastCode string
	lastTo   string
	calls    int
}

func newRecordingMailer() *recordingMailer { return &recordingMailer{} }

func (m *recordingMailer) EnqueueLoginCode(_ context.Context, email, code string, _ time.Duration) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.lastTo = email
	m.lastCode = code
	m.calls++
	return nil
}

func (m *recordingMailer) snapshot() (string, string, int) {
	m.mu.Lock()
	defer m.mu.Unlock()
	return m.lastTo, m.lastCode, m.calls
}

// recordingPush implements auth.SessionInvalidator and counts emissions.
type recordingPush struct {
	mu    sync.Mutex
	calls []recordedPush
}

type recordedPush struct {
	deviceSessionID, userID uuid.UUID
	reason                  string
}

func newRecordingPush() *recordingPush { return &recordingPush{} }

func (p *recordingPush) PublishSessionInvalidation(_ context.Context, dsID, uid uuid.UUID, reason string) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.calls = append(p.calls, recordedPush{deviceSessionID: dsID, userID: uid, reason: reason})
}

func (p *recordingPush) snapshot() []recordedPush {
	p.mu.Lock()
	defer p.mu.Unlock()
	out := make([]recordedPush, len(p.calls))
	copy(out, p.calls)
	return out
}

// stubGeo implements auth.GeoService with no real lookups. The country
// it returns is configurable per call via CountryForIP; LanguageForIP
// returns "" so the auth flow exercises the "en" fallback path.
type stubGeo struct {
	countryByIP map[string]string
}

func newStubGeo() *stubGeo {
	return &stubGeo{countryByIP: map[string]string{}}
}

func (g *stubGeo) LookupCountry(sourceIP string) string {
	return g.countryByIP[sourceIP]
}

func (g *stubGeo) LanguageForIP(_ string) string { return "" }

func (g *stubGeo) SetDeclaredCountryAtRegistration(_ context.Context, _ uuid.UUID, _ string) error {
	return nil
}

// authConfig builds an AuthConfig suitable for tests.
func authConfig() config.AuthConfig {
	return config.AuthConfig{
		ChallengeTTL:         5 * time.Minute,
		ChallengeMaxAttempts: 3,
		ChallengeThrottle: config.AuthChallengeThrottleConfig{
			Window: time.Minute,
			Max:    3,
		},
		UserNameMaxRetries: 10,
	}
}

// buildService wires every dependency around db and returns the service
// plus the recording fakes for assertions.
func buildService(t *testing.T, db *sql.DB) (*auth.Service, *recordingMailer, *recordingPush, *stubGeo) {
	t.Helper()
	store := auth.NewStore(db)
	cache := auth.NewCache()
	if err := cache.Warm(context.Background(), store); err != nil {
		t.Fatalf("warm cache: %v", err)
	}
	mailer := newRecordingMailer()
	pusher := newRecordingPush()
	geo := newStubGeo()
	userStore := user.NewStore(db)
	userSvc := user.NewService(user.Deps{

		Store:              userStore,
		Cache:              user.NewCache(),
		UserNameMaxRetries: 10,
		Now:                time.Now,
	})
	svc := auth.NewService(auth.Deps{
		Store:  store,
		Cache:  cache,
		User:   userSvc,
		Geo:    geo,
		Mail:   mailer,
		Push:   pusher,
		Config: authConfig(),
		Now:    time.Now,
	})
	return svc, mailer, pusher, geo
}

func randomKey(t *testing.T) []byte {
	t.Helper()
	key := make([]byte, 32)
	if _, err := rand.Read(key); err != nil {
		t.Fatalf("rand: %v", err)
	}
	return key
}

func TestAuthEndToEnd(t *testing.T) {
	db := startPostgres(t)
	svc, mailer, pusher, _ := buildService(t, db)
	ctx := context.Background()

	challengeID, err := svc.SendEmailCode(ctx, "Alice@Example.Test", "ru", "", "")
	if err != nil {
		t.Fatalf("SendEmailCode: %v", err)
	}
	if challengeID == uuid.Nil {
		t.Fatalf("SendEmailCode returned nil challenge_id")
	}
	gotEmail, gotCode, calls := mailer.snapshot()
	if gotEmail != "alice@example.test" {
		t.Fatalf("mailer email = %q, want lower-cased", gotEmail)
	}
	if len(gotCode) != auth.CodeLength {
		t.Fatalf("mailer code = %q (len %d), want length %d", gotCode, len(gotCode), auth.CodeLength)
	}
	if calls != 1 {
		t.Fatalf("mailer calls = %d, want 1", calls)
	}

	pubKey := randomKey(t)
	session, err := svc.ConfirmEmailCode(ctx, auth.ConfirmInputs{
		ChallengeID:     challengeID,
		Code:            gotCode,
		ClientPublicKey: pubKey,
		TimeZone:        "Europe/Moscow",
		SourceIP:        "",
	})
	if err != nil {
		t.Fatalf("ConfirmEmailCode: %v", err)
	}
	if session.UserID == uuid.Nil {
		t.Fatalf("session has nil user_id")
	}
	if session.Status != auth.SessionStatusActive {
		t.Fatalf("session.Status = %q, want %q", session.Status, auth.SessionStatusActive)
	}

	got, err := svc.GetSession(ctx, session.DeviceSessionID)
	if err != nil {
		t.Fatalf("GetSession: %v", err)
	}
	if got.UserID != session.UserID {
		t.Fatalf("GetSession user_id = %s, want %s", got.UserID, session.UserID)
	}

	revoked, err := svc.RevokeSession(ctx, session.DeviceSessionID)
	if err != nil {
		t.Fatalf("RevokeSession: %v", err)
	}
	if revoked.Status != auth.SessionStatusRevoked {
		t.Fatalf("revoked.Status = %q, want %q", revoked.Status, auth.SessionStatusRevoked)
	}
	if revoked.RevokedAt == nil {
		t.Fatalf("revoked.RevokedAt nil after revoke")
	}

	if _, err := svc.GetSession(ctx, session.DeviceSessionID); !errors.Is(err, auth.ErrSessionNotFound) {
		t.Fatalf("GetSession after revoke = %v, want ErrSessionNotFound", err)
	}

	again, err := svc.RevokeSession(ctx, session.DeviceSessionID)
	if err != nil {
		t.Fatalf("idempotent RevokeSession: %v", err)
	}
	if again.DeviceSessionID != session.DeviceSessionID || again.Status != auth.SessionStatusRevoked {
		t.Fatalf("idempotent revoke shape mismatch: %+v", again)
	}

	pushes := pusher.snapshot()
	if len(pushes) != 1 {
		t.Fatalf("push emissions = %d, want 1", len(pushes))
	}
	if pushes[0].deviceSessionID != session.DeviceSessionID {
		t.Fatalf("push device_session_id mismatch")
	}
}

func TestSendEmailCodePermanentlyBlocked(t *testing.T) {
	db := startPostgres(t)
	svc, _, _, _ := buildService(t, db)

	// Insert a permanent_block account directly.
	if _, err := db.Exec(`
		INSERT INTO backend.accounts (
			user_id, email, user_name, preferred_language, time_zone, permanent_block
		) VALUES ($1, $2, $3, $4, $5, true)
	`, uuid.New(), "blocked@example.test", "Player-XXBLOCK1", "en", "UTC"); err != nil {
		t.Fatalf("seed account: %v", err)
	}

	_, err := svc.SendEmailCode(context.Background(), "blocked@example.test", "", "", "")
	if !errors.Is(err, auth.ErrEmailPermanentlyBlocked) {
		t.Fatalf("SendEmailCode for blocked email = %v, want ErrEmailPermanentlyBlocked", err)
	}
}

func TestSendEmailCodeThrottleReusesChallenge(t *testing.T) {
	db := startPostgres(t)
	svc, mailer, _, _ := buildService(t, db)
	ctx := context.Background()

	const email = "throttle@example.test"
	cfg := authConfig()
	var firstID uuid.UUID
	for i := range cfg.ChallengeThrottle.Max {
		id, err := svc.SendEmailCode(ctx, email, "", "", "")
		if err != nil {
			t.Fatalf("SendEmailCode #%d: %v", i, err)
		}
		if i == 0 {
			firstID = id
		}
	}
	_, _, callsBefore := mailer.snapshot()

	// One more call — must reuse the latest challenge_id and skip mail.
	id, err := svc.SendEmailCode(ctx, email, "", "", "")
	if err != nil {
		t.Fatalf("SendEmailCode (throttled): %v", err)
	}
	_, _, callsAfter := mailer.snapshot()
	if callsAfter != callsBefore {
		t.Fatalf("mail enqueue should be skipped on throttle: before=%d after=%d", callsBefore, callsAfter)
	}
	if id == uuid.Nil {
		t.Fatalf("throttled call returned nil challenge_id")
	}
	if id == firstID {
		t.Fatalf("throttled call returned the FIRST challenge — expected the latest")
	}
}

func TestConfirmEmailCodeWrongCode(t *testing.T) {
	db := startPostgres(t)
	svc, mailer, _, _ := buildService(t, db)
	ctx := context.Background()

	id, err := svc.SendEmailCode(ctx, "wrong@example.test", "en", "", "")
	if err != nil {
		t.Fatalf("send: %v", err)
	}
	_, code, _ := mailer.snapshot()
	wrong := flipDigit(code)

	_, err = svc.ConfirmEmailCode(ctx, auth.ConfirmInputs{
		ChallengeID:     id,
		Code:            wrong,
		ClientPublicKey: randomKey(t),
		TimeZone:        "UTC",
	})
	if !errors.Is(err, auth.ErrCodeMismatch) {
		t.Fatalf("ConfirmEmailCode wrong code = %v, want ErrCodeMismatch", err)
	}
}

func TestConfirmEmailCodeAttemptsCeiling(t *testing.T) {
	db := startPostgres(t)
	svc, mailer, _, _ := buildService(t, db)
	ctx := context.Background()

	id, err := svc.SendEmailCode(ctx, "ceiling@example.test", "en", "", "")
	if err != nil {
		t.Fatalf("send: %v", err)
	}
	_, code, _ := mailer.snapshot()
	wrong := flipDigit(code)

	// Burn `max` attempts with the wrong code.
	for i := range authConfig().ChallengeMaxAttempts {
		_, err := svc.ConfirmEmailCode(ctx, auth.ConfirmInputs{
			ChallengeID:     id,
			Code:            wrong,
			ClientPublicKey: randomKey(t),
			TimeZone:        "UTC",
		})
		if !errors.Is(err, auth.ErrCodeMismatch) {
			t.Fatalf("attempt %d: %v, want ErrCodeMismatch", i, err)
		}
	}
	// One past the ceiling — even with the right code, ErrTooManyAttempts.
	_, err = svc.ConfirmEmailCode(ctx, auth.ConfirmInputs{
		ChallengeID:     id,
		Code:            code,
		ClientPublicKey: randomKey(t),
		TimeZone:        "UTC",
	})
	if !errors.Is(err, auth.ErrTooManyAttempts) {
		t.Fatalf("post-ceiling = %v, want ErrTooManyAttempts", err)
	}
}

func TestConfirmEmailCodeChallengeNotFound(t *testing.T) {
	db := startPostgres(t)
	svc, _, _, _ := buildService(t, db)

	_, err := svc.ConfirmEmailCode(context.Background(), auth.ConfirmInputs{
		ChallengeID:     uuid.New(),
		Code:            "000000",
		ClientPublicKey: randomKey(t),
		TimeZone:        "UTC",
	})
	if !errors.Is(err, auth.ErrChallengeNotFound) {
		t.Fatalf("unknown challenge = %v, want ErrChallengeNotFound", err)
	}
}

func TestRevokeAllForUser(t *testing.T) {
	db := startPostgres(t)
	svc, mailer, pusher, _ := buildService(t, db)
	ctx := context.Background()

	const email = "many@example.test"
	const sessionsToCreate = 3
	var userID uuid.UUID
	deviceSessionIDs := make([]uuid.UUID, 0, sessionsToCreate)
	for range sessionsToCreate {
		id, err := svc.SendEmailCode(ctx, email, "en", "", "")
		if err != nil {
			t.Fatalf("send: %v", err)
		}
		_, code, _ := mailer.snapshot()
		sess, err := svc.ConfirmEmailCode(ctx, auth.ConfirmInputs{
			ChallengeID:     id,
			Code:            code,
			ClientPublicKey: randomKey(t),
			TimeZone:        "UTC",
		})
		if err != nil {
			t.Fatalf("confirm: %v", err)
		}
		userID = sess.UserID
		deviceSessionIDs = append(deviceSessionIDs, sess.DeviceSessionID)
	}

	revoked, err := svc.RevokeAllForUser(ctx, userID)
	if err != nil {
		t.Fatalf("RevokeAllForUser: %v", err)
	}
	if len(revoked) != sessionsToCreate {
		t.Fatalf("revoked count = %d, want %d", len(revoked), sessionsToCreate)
	}
	for _, dsID := range deviceSessionIDs {
		if _, err := svc.GetSession(ctx, dsID); !errors.Is(err, auth.ErrSessionNotFound) {
			t.Fatalf("session %s still in cache: %v", dsID, err)
		}
	}
	if got := len(pusher.snapshot()); got != sessionsToCreate {
		t.Fatalf("push emissions = %d, want %d", got, sessionsToCreate)
	}

	// Idempotent: revoking again returns an empty slice.
	again, err := svc.RevokeAllForUser(ctx, userID)
	if err != nil {
		t.Fatalf("idempotent RevokeAllForUser: %v", err)
	}
	if len(again) != 0 {
		t.Fatalf("idempotent RevokeAllForUser = %d sessions, want 0", len(again))
	}
}

// flipDigit returns code with its first digit replaced by ((digit+1) % 10)
// so the resulting string is still a valid CodeLength-digit code but
// guaranteed to differ.
func flipDigit(code string) string {
	if code == "" {
		return "0"
	}
	bytes := []byte(code)
	if bytes[0] >= '0' && bytes[0] <= '9' {
		bytes[0] = '0' + ((bytes[0]-'0')+1)%10
	} else {
		bytes[0] = '0'
	}
	return string(bytes)
}