package adminstop_test

import (
	"context"
	"errors"
	"sync"
	"testing"
	"time"

	"galaxy/gamemaster/internal/adapters/mocks"
	"galaxy/gamemaster/internal/domain/operation"
	"galaxy/gamemaster/internal/domain/runtime"
	"galaxy/gamemaster/internal/ports"
	"galaxy/gamemaster/internal/service/adminstop"
	"galaxy/gamemaster/internal/telemetry"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.uber.org/mock/gomock"
)

// --- test doubles -----------------------------------------------------

type fakeRuntimeRecords struct {
	mu      sync.Mutex
	stored  map[string]runtime.RuntimeRecord
	getErr  error
	updErr  error
	updates []ports.UpdateStatusInput
}

func newFakeRuntimeRecords() *fakeRuntimeRecords {
	return &fakeRuntimeRecords{stored: map[string]runtime.RuntimeRecord{}}
}

func (s *fakeRuntimeRecords) seed(record runtime.RuntimeRecord) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.stored[record.GameID] = record
}

func (s *fakeRuntimeRecords) Get(_ context.Context, gameID string) (runtime.RuntimeRecord, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.getErr != nil {
		return runtime.RuntimeRecord{}, s.getErr
	}
	record, ok := s.stored[gameID]
	if !ok {
		return runtime.RuntimeRecord{}, runtime.ErrNotFound
	}
	return record, nil
}

func (s *fakeRuntimeRecords) Insert(context.Context, runtime.RuntimeRecord) error {
	return errors.New("not used")
}

func (s *fakeRuntimeRecords) UpdateStatus(_ context.Context, input ports.UpdateStatusInput) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.updErr != nil {
		return s.updErr
	}
	record, ok := s.stored[input.GameID]
	if !ok {
		return runtime.ErrNotFound
	}
	if record.Status != input.ExpectedFrom {
		return runtime.ErrConflict
	}
	record.Status = input.To
	record.UpdatedAt = input.Now
	if input.To == runtime.StatusStopped {
		stopped := input.Now
		record.StoppedAt = &stopped
	}
	s.stored[input.GameID] = record
	s.updates = append(s.updates, input)
	return nil
}

func (s *fakeRuntimeRecords) UpdateScheduling(context.Context, ports.UpdateSchedulingInput) error {
	return errors.New("not used")
}

func (s *fakeRuntimeRecords) UpdateImage(context.Context, ports.UpdateImageInput) error {
	return errors.New("not used")
}

func (s *fakeRuntimeRecords) UpdateEngineHealth(context.Context, ports.UpdateEngineHealthInput) error {
	return errors.New("not used")
}

func (s *fakeRuntimeRecords) Delete(context.Context, string) error {
	return errors.New("not used")
}

func (s *fakeRuntimeRecords) ListDueRunning(context.Context, time.Time) ([]runtime.RuntimeRecord, error) {
	return nil, errors.New("not used")
}

func (s *fakeRuntimeRecords) ListByStatus(context.Context, runtime.Status) ([]runtime.RuntimeRecord, error) {
	return nil, errors.New("not used")
}

func (s *fakeRuntimeRecords) List(context.Context) ([]runtime.RuntimeRecord, error) {
	return nil, errors.New("not used")
}

func (s *fakeRuntimeRecords) updateCount() int {
	s.mu.Lock()
	defer s.mu.Unlock()
	return len(s.updates)
}

type fakeOperationLogs struct {
	mu      sync.Mutex
	entries []operation.OperationEntry
	appErr  error
}

func (s *fakeOperationLogs) Append(_ context.Context, entry operation.OperationEntry) (int64, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.appErr != nil {
		return 0, s.appErr
	}
	if err := entry.Validate(); err != nil {
		return 0, err
	}
	s.entries = append(s.entries, entry)
	return int64(len(s.entries)), nil
}

func (s *fakeOperationLogs) ListByGame(context.Context, string, int) ([]operation.OperationEntry, error) {
	return nil, errors.New("not used")
}

func (s *fakeOperationLogs) lastEntry() (operation.OperationEntry, bool) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if len(s.entries) == 0 {
		return operation.OperationEntry{}, false
	}
	return s.entries[len(s.entries)-1], true
}

func (s *fakeOperationLogs) snapshot() []operation.OperationEntry {
	s.mu.Lock()
	defer s.mu.Unlock()
	out := make([]operation.OperationEntry, len(s.entries))
	copy(out, s.entries)
	return out
}

// --- harness ----------------------------------------------------------

type harness struct {
	t         *testing.T
	ctrl      *gomock.Controller
	runtime   *fakeRuntimeRecords
	logs      *fakeOperationLogs
	rtm       *mocks.MockRTMClient
	lobby     *mocks.MockLobbyEventsPublisher
	telemetry *telemetry.Runtime
	now       time.Time
	service   *adminstop.Service
}

func newHarness(t *testing.T) *harness {
	t.Helper()
	ctrl := gomock.NewController(t)
	telemetryRuntime, err := telemetry.NewWithProviders(nil, nil)
	require.NoError(t, err)
	h := &harness{
		t:         t,
		ctrl:      ctrl,
		runtime:   newFakeRuntimeRecords(),
		logs:      &fakeOperationLogs{},
		rtm:       mocks.NewMockRTMClient(ctrl),
		lobby:     mocks.NewMockLobbyEventsPublisher(ctrl),
		telemetry: telemetryRuntime,
		now:       time.Date(2026, time.May, 1, 12, 0, 0, 0, time.UTC),
	}
	service, err := adminstop.NewService(adminstop.Dependencies{
		RuntimeRecords: h.runtime,
		OperationLogs:  h.logs,
		RTM:            h.rtm,
		LobbyEvents:    h.lobby,
		Telemetry:      h.telemetry,
		Clock:          func() time.Time { return h.now },
	})
	require.NoError(t, err)
	h.service = service
	return h
}

func (h *harness) seedRecord(status runtime.Status) runtime.RuntimeRecord {
	created := h.now.Add(-time.Hour)
	started := h.now.Add(-30 * time.Minute)
	next := h.now.Add(30 * time.Minute)
	record := runtime.RuntimeRecord{
		GameID:               "game-001",
		Status:               status,
		EngineEndpoint:       "http://galaxy-game-game-001:8080",
		CurrentImageRef:      "ghcr.io/galaxy/game:v1.2.3",
		CurrentEngineVersion: "v1.2.3",
		TurnSchedule:         "0 18 * * *",
		CurrentTurn:          7,
		NextGenerationAt:     &next,
		EngineHealth:         "healthy",
		CreatedAt:            created,
		UpdatedAt:            started,
		StartedAt:            &started,
	}
	h.runtime.seed(record)
	return record
}

func baseInput() adminstop.Input {
	return adminstop.Input{
		GameID:    "game-001",
		Reason:    adminstop.ReasonAdminRequest,
		OpSource:  operation.OpSourceAdminRest,
		SourceRef: "req-stop-001",
	}
}

// --- tests ------------------------------------------------------------

func TestNewServiceRejectsMissingDeps(t *testing.T) {
	telemetryRuntime, err := telemetry.NewWithProviders(nil, nil)
	require.NoError(t, err)
	cases := []struct {
		name string
		mut  func(*adminstop.Dependencies)
	}{
		{"runtime records", func(d *adminstop.Dependencies) { d.RuntimeRecords = nil }},
		{"operation logs", func(d *adminstop.Dependencies) { d.OperationLogs = nil }},
		{"rtm", func(d *adminstop.Dependencies) { d.RTM = nil }},
		{"lobby events", func(d *adminstop.Dependencies) { d.LobbyEvents = nil }},
		{"telemetry", func(d *adminstop.Dependencies) { d.Telemetry = nil }},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			ctrl := gomock.NewController(t)
			deps := adminstop.Dependencies{
				RuntimeRecords: newFakeRuntimeRecords(),
				OperationLogs:  &fakeOperationLogs{},
				RTM:            mocks.NewMockRTMClient(ctrl),
				LobbyEvents:    mocks.NewMockLobbyEventsPublisher(ctrl),
				Telemetry:      telemetryRuntime,
			}
			tc.mut(&deps)
			service, err := adminstop.NewService(deps)
			require.Error(t, err)
			require.Nil(t, service)
		})
	}
}

func TestHandleHappyPath(t *testing.T) {
	h := newHarness(t)
	original := h.seedRecord(runtime.StatusRunning)

	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).Return(nil)
	h.lobby.EXPECT().PublishSnapshotUpdate(gomock.Any(), gomock.AssignableToTypeOf(ports.RuntimeSnapshotUpdate{})).
		DoAndReturn(func(_ context.Context, msg ports.RuntimeSnapshotUpdate) error {
			assert.Equal(t, "game-001", msg.GameID)
			assert.Equal(t, runtime.StatusStopped, msg.RuntimeStatus)
			assert.Equal(t, original.CurrentTurn, msg.CurrentTurn)
			assert.Equal(t, original.EngineHealth, msg.EngineHealthSummary)
			assert.Empty(t, msg.PlayerTurnStats)
			assert.True(t, msg.OccurredAt.Equal(h.now))
			return nil
		})

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	require.True(t, result.IsSuccess(), "want success, got %+v", result)
	assert.Equal(t, runtime.StatusStopped, result.Record.Status)
	assert.Equal(t, 1, h.runtime.updateCount(), "exactly one CAS call expected")

	entry, ok := h.logs.lastEntry()
	require.True(t, ok, "operation log entry must be appended")
	assert.Equal(t, operation.OpKindStop, entry.OpKind)
	assert.Equal(t, operation.OpSourceAdminRest, entry.OpSource)
	assert.Equal(t, operation.OutcomeSuccess, entry.Outcome)
	assert.Empty(t, entry.ErrorCode)
}

func TestHandleHappyPathFromGenerationFailed(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusGenerationFailed)

	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).Return(nil)
	h.lobby.EXPECT().PublishSnapshotUpdate(gomock.Any(), gomock.Any()).Return(nil)

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	require.True(t, result.IsSuccess())
	assert.Equal(t, runtime.StatusStopped, result.Record.Status)
	require.Len(t, h.runtime.updates, 1)
	assert.Equal(t, runtime.StatusGenerationFailed, h.runtime.updates[0].ExpectedFrom)
}

func TestHandleEmptyReasonDefaultsToAdminRequest(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusRunning)

	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).Return(nil)
	h.lobby.EXPECT().PublishSnapshotUpdate(gomock.Any(), gomock.Any()).Return(nil)

	input := baseInput()
	input.Reason = ""
	result, err := h.service.Handle(context.Background(), input)
	require.NoError(t, err)
	require.True(t, result.IsSuccess())
}

func TestHandleIdempotentOnAlreadyStopped(t *testing.T) {
	h := newHarness(t)
	original := h.seedRecord(runtime.StatusStopped)

	// No RTM call, no snapshot publication expected.
	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	require.True(t, result.IsSuccess())
	assert.Equal(t, runtime.StatusStopped, result.Record.Status)
	assert.Equal(t, original.UpdatedAt, result.Record.UpdatedAt, "no mutation expected")
	assert.Zero(t, h.runtime.updateCount(), "no CAS expected on idempotent path")

	entry, ok := h.logs.lastEntry()
	require.True(t, ok)
	assert.Equal(t, operation.OutcomeSuccess, entry.Outcome)
}

func TestHandleIdempotentOnFinished(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusFinished)

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	require.True(t, result.IsSuccess())
	assert.Equal(t, runtime.StatusFinished, result.Record.Status)
}

func TestHandleConflictOnStarting(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusStarting)

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	assert.Equal(t, operation.OutcomeFailure, result.Outcome)
	assert.Equal(t, adminstop.ErrorCodeConflict, result.ErrorCode)
	assert.Zero(t, h.runtime.updateCount())

	entry, ok := h.logs.lastEntry()
	require.True(t, ok)
	assert.Equal(t, operation.OutcomeFailure, entry.Outcome)
	assert.Equal(t, adminstop.ErrorCodeConflict, entry.ErrorCode)
}

func TestHandleRuntimeNotFound(t *testing.T) {
	h := newHarness(t)

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	assert.Equal(t, operation.OutcomeFailure, result.Outcome)
	assert.Equal(t, adminstop.ErrorCodeRuntimeNotFound, result.ErrorCode)
}

func TestHandleRTMUnavailable(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusRunning)

	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).
		Return(ports.ErrRTMUnavailable)

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	assert.Equal(t, operation.OutcomeFailure, result.Outcome)
	assert.Equal(t, adminstop.ErrorCodeServiceUnavailable, result.ErrorCode)
	assert.Zero(t, h.runtime.updateCount(), "CAS must not run after RTM failure")
}

func TestHandleCASLostRace(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusRunning)

	// RTM stop succeeds, but a concurrent mutation flipped the row out
	// of `running` before our CAS lands.
	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).Return(nil)
	h.runtime.updErr = runtime.ErrConflict

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	assert.Equal(t, operation.OutcomeFailure, result.Outcome)
	assert.Equal(t, adminstop.ErrorCodeConflict, result.ErrorCode)
}

func TestHandleStoreReadFailure(t *testing.T) {
	h := newHarness(t)
	h.runtime.getErr = errors.New("connection refused")

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	assert.Equal(t, operation.OutcomeFailure, result.Outcome)
	assert.Equal(t, adminstop.ErrorCodeServiceUnavailable, result.ErrorCode)
}

func TestHandleInvalidRequest(t *testing.T) {
	cases := []struct {
		name string
		mut  func(*adminstop.Input)
	}{
		{"empty game id", func(in *adminstop.Input) { in.GameID = "" }},
		{"unknown reason", func(in *adminstop.Input) { in.Reason = "panic" }},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			h := newHarness(t)
			input := baseInput()
			tc.mut(&input)
			result, err := h.service.Handle(context.Background(), input)
			require.NoError(t, err)
			assert.Equal(t, operation.OutcomeFailure, result.Outcome)
			assert.Equal(t, adminstop.ErrorCodeInvalidRequest, result.ErrorCode)
			// Audit log uses the validated game id; for the empty-id
			// case it would fail entry validation, so we only assert
			// when game id is present.
			if input.GameID != "" {
				_, ok := h.logs.lastEntry()
				assert.True(t, ok)
			}
		})
	}
}

func TestHandleNilContextReturnsError(t *testing.T) {
	h := newHarness(t)
	_, err := h.service.Handle(nil, baseInput()) //nolint:staticcheck // intentional nil for guard test
	require.Error(t, err)
}

func TestHandleSnapshotPublishFailureSurfacesSuccess(t *testing.T) {
	h := newHarness(t)
	h.seedRecord(runtime.StatusRunning)

	h.rtm.EXPECT().Stop(gomock.Any(), "game-001", adminstop.ReasonAdminRequest).Return(nil)
	h.lobby.EXPECT().PublishSnapshotUpdate(gomock.Any(), gomock.Any()).
		Return(errors.New("redis down"))

	result, err := h.service.Handle(context.Background(), baseInput())
	require.NoError(t, err)
	require.True(t, result.IsSuccess(), "snapshot publication is best-effort")
	assert.Equal(t, runtime.StatusStopped, result.Record.Status)
}