package sync

import (
	"context"
	"path/filepath"
	"testing"
	"time"

	"geniusrun/backend/internal/classify"
	"geniusrun/backend/internal/garmin"
	"geniusrun/backend/internal/garmin/mock"
	"geniusrun/backend/internal/store"
)

func f(v float64) *float64 { return &v }

func openTestDB(t *testing.T) *store.DB {
	t.Helper()
	db, err := store.Open(filepath.Join(t.TempDir(), "geniusrun_test.db"))
	if err != nil {
		t.Fatalf("store.Open: %v", err)
	}
	t.Cleanup(func() { db.Close() })
	return db
}

func fixedNow(t time.Time) func() time.Time {
	return func() time.Time { return t }
}

func provisionTestUser(t *testing.T, db *store.DB) int64 {
	t.Helper()
	userID, err := db.ProvisionUser(context.Background(), "test-sub", "Test")
	if err != nil {
		t.Fatalf("ProvisionUser: %v", err)
	}
	return userID
}

// setBackfillHorizon sets Profile.BackfillHorizonDays, which Backfill reads
// fresh on every call (it's no longer part of Config).
func setBackfillHorizon(t *testing.T, db *store.DB, userID int64, days int) {
	t.Helper()
	ctx := context.Background()
	profile, err := db.GetProfile(ctx, userID)
	if err != nil {
		t.Fatalf("GetProfile: %v", err)
	}
	profile.BackfillHorizonDays = days
	if err := db.UpdateProfile(ctx, userID, profile); err != nil {
		t.Fatalf("UpdateProfile: %v", err)
	}
}

func TestBackfill_StoresActivitiesAndRecordsSyncRun(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityName: "Morning Run", ActivityType: garmin.ActivityType{TypeKey: "running"},
			StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500, AverageSpeed: 3.33, AverageHR: 145},
	}}
	svc := NewService(m, db, userID, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}

	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities: %v", err)
	}
	if len(activities) != 1 {
		t.Fatalf("expected 1 stored activity, got %d", len(activities))
	}
	if activities[0].GarminActivityID != 1 {
		t.Errorf("GarminActivityID = %d, want 1", activities[0].GarminActivityID)
	}

	runs, err := db.ListSyncRuns(ctx, userID, 10)
	if err != nil {
		t.Fatalf("ListSyncRuns: %v", err)
	}
	if len(runs) != 1 || runs[0].Status != store.SyncStatusSuccess {
		t.Fatalf("expected 1 successful sync run, got %+v", runs)
	}
}

func TestAlignWorkoutTargets_MatchesLapsToFlattenedSteps(t *testing.T) {
	laps := []garmin.Lap{{LapIndex: 1}, {LapIndex: 2}}
	workout := garmin.Workout{Segments: []garmin.WorkoutSegment{
		{Steps: []garmin.WorkoutStep{
			{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(3), TargetValueTwo: f(4)},
			{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "no.target"}},
		}},
	}}

	targets := alignWorkoutTargets(laps, workout)
	if len(targets) != 2 {
		t.Fatalf("expected 2 aligned targets, got %d", len(targets))
	}
	if targets[0] == nil || targets[0].TargetType.TypeKey != "pace.zone" {
		t.Errorf("targets[0] = %+v, want pace.zone step", targets[0])
	}
	if targets[1] == nil || targets[1].TargetType.TypeKey != "no.target" {
		t.Errorf("targets[1] = %+v, want no.target step", targets[1])
	}
}

func TestAlignWorkoutTargets_OneExtraTrailingLapKeepsOtherTargets(t *testing.T) {
	// Confirmed via Garmin Connect against a real activity: recording
	// sometimes continues one lap past the workout's last step (e.g. a
	// 5-minute prescribed cool-down followed by another 6:46 the athlete
	// just kept running). The extra lap should have no target, but every
	// other lap's real target must still come through.
	laps := []garmin.Lap{{LapIndex: 1}, {LapIndex: 2}, {LapIndex: 3}}
	workout := garmin.Workout{Segments: []garmin.WorkoutSegment{
		{Steps: []garmin.WorkoutStep{
			{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(3), TargetValueTwo: f(4)},
			{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(2), TargetValueTwo: f(2.5)},
		}},
	}}

	targets := alignWorkoutTargets(laps, workout)
	if len(targets) != 3 {
		t.Fatalf("expected 3 slots (one per lap), got %d", len(targets))
	}
	if targets[0] == nil || targets[0].TargetType.TypeKey != "pace.zone" {
		t.Errorf("targets[0] = %+v, want the first step's pace.zone target", targets[0])
	}
	if targets[1] == nil || targets[1].TargetType.TypeKey != "pace.zone" {
		t.Errorf("targets[1] = %+v, want the second step's pace.zone target", targets[1])
	}
	if targets[2] != nil {
		t.Errorf("targets[2] = %+v, want nil for the trailing unplanned continuation lap", targets[2])
	}
}

func TestAlignWorkoutTargets_MismatchedCountYieldsAllNil(t *testing.T) {
	laps := []garmin.Lap{{LapIndex: 1}, {LapIndex: 2}, {LapIndex: 3}}
	workout := garmin.Workout{Segments: []garmin.WorkoutSegment{
		{Steps: []garmin.WorkoutStep{
			{Type: "ExecutableStepDTO"},
		}},
	}}

	targets := alignWorkoutTargets(laps, workout)
	if len(targets) != 3 {
		t.Fatalf("expected 3 slots (one per lap), got %d", len(targets))
	}
	for i, target := range targets {
		if target != nil {
			t.Errorf("targets[%d] = %+v, want nil on count mismatch", i, target)
		}
	}
}

func TestTargetPaceRange_OnlyForPaceZoneAndOrdersLowHigh(t *testing.T) {
	lo, hi := targetPaceRange(garmin.WorkoutStep{
		TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(4), TargetValueTwo: f(3),
	})
	if lo == nil || hi == nil || *lo != 3 || *hi != 4 {
		t.Errorf("targetPaceRange = (%v, %v), want (3, 4) reordered", lo, hi)
	}

	lo, hi = targetPaceRange(garmin.WorkoutStep{TargetType: garmin.WorkoutTargetType{TypeKey: "heart.rate.zone"}, TargetValueOne: f(3), TargetValueTwo: f(4)})
	if lo != nil || hi != nil {
		t.Errorf("targetPaceRange for a non-pace step = (%v, %v), want (nil, nil)", lo, hi)
	}
}

func TestTargetHRRange_CustomRangeAndZoneNumberViaKarvonen(t *testing.T) {
	lo, hi := targetHRRange(garmin.WorkoutStep{
		TargetType: garmin.WorkoutTargetType{TypeKey: "heart.rate.zone"}, TargetValueOne: f(160), TargetValueTwo: f(150),
	}, store.Profile{})
	if lo == nil || hi == nil || *lo != 150 || *hi != 160 {
		t.Errorf("custom bpm range = (%v, %v), want (150, 160) reordered", lo, hi)
	}

	zone := 3
	profile := store.Profile{
		MaxHeartRate: f(190), RestingHeartRate: f(50),
		HRZone3MinPct: 70, HRZone3MaxPct: 80,
	}
	lo, hi = targetHRRange(garmin.WorkoutStep{TargetType: garmin.WorkoutTargetType{TypeKey: "heart.rate.zone"}, ZoneNumber: &zone}, profile)
	// Karvonen: restHR + pct * (maxHR - restHR) = 50 + 0.70*140 = 148, 50 + 0.80*140 = 162
	if lo == nil || hi == nil || *lo != 148 || *hi != 162 {
		t.Errorf("zone-based bpm range = (%v, %v), want (148, 162)", lo, hi)
	}

	lo, hi = targetHRRange(garmin.WorkoutStep{TargetType: garmin.WorkoutTargetType{TypeKey: "heart.rate.zone"}, ZoneNumber: &zone}, store.Profile{})
	if lo != nil || hi != nil {
		t.Errorf("zone-based range without max/resting HR configured = (%v, %v), want (nil, nil)", lo, hi)
	}
}

func TestBackfill_SkipsNonRunningActivities(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"},
			StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500},
		{ActivityID: 2, ActivityType: garmin.ActivityType{TypeKey: "trail_running"},
			StartTimeGMT: "2026-07-02 06:00:00", Distance: 8000, Duration: 2400},
		{ActivityID: 3, ActivityType: garmin.ActivityType{TypeKey: "paddelball"},
			StartTimeGMT: "2026-07-03 06:00:00", Distance: 0, Duration: 1800},
		{ActivityID: 4, ActivityType: garmin.ActivityType{TypeKey: "indoor_cycling"},
			StartTimeGMT: "2026-07-04 06:00:00", Distance: 0, Duration: 1800},
	}}
	svc := NewService(m, db, userID, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}

	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities: %v", err)
	}
	if len(activities) != 2 {
		t.Fatalf("expected 2 stored (running-only) activities, got %d: %+v", len(activities), activities)
	}
	for _, a := range activities {
		if a.GarminActivityID != 1 && a.GarminActivityID != 2 {
			t.Errorf("unexpected non-running activity stored: %+v", a)
		}
	}
}

func TestFillPendingDetailsAndClassify_EndToEnd(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	const garminActivityID = 42
	m := &mock.Client{
		Activities: []garmin.Activity{
			{ActivityID: garminActivityID, ActivityType: garmin.ActivityType{TypeKey: "running"},
				StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500, AverageSpeed: 3.33, AverageHR: 145},
		},
		Splits: map[int64]garmin.ActivitySplits{
			garminActivityID: {ActivityID: garminActivityID, Laps: []garmin.Lap{
				{LapIndex: 1, Duration: 900, ElapsedDuration: 900, Distance: 3000, AverageHR: 150, AverageSpeed: 3.33, IntensityType: "ACTIVE"},
			}},
		},
		Details: map[int64]garmin.ActivityDetails{
			garminActivityID: {
				ActivityID: garminActivityID,
				MetricDescriptors: []garmin.MetricDescriptor{
					{Key: "directHeartRate", MetricsIndex: 0},
					{Key: "sumElapsedDuration", MetricsIndex: 1},
				},
			},
		},
	}
	svc := NewService(m, db, userID, Config{MinConfidence: 0.5}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}

	// A workout kind that should cleanly match the seeded activity's pace.
	ruleJSON := `{"match":"all","conditions":[{"metric":"avg_pace_sec_per_km","op":"between","value":[280,320]}]}`
	if _, err := db.CreateWorkoutKind(ctx, userID, store.WorkoutKind{Name: "Test Classification Tempo", RuleJSON: ruleJSON, IsActive: true}); err != nil {
		t.Fatalf("CreateWorkoutKind: %v", err)
	}

	if err := svc.FillPendingDetails(ctx, 10); err != nil {
		t.Fatalf("FillPendingDetails: %v", err)
	}

	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil || len(activities) != 1 {
		t.Fatalf("ListActivities: %v, %+v", err, activities)
	}
	activityID := activities[0].ID

	if activities[0].DetailsFetchedAt == nil {
		t.Error("expected DetailsFetchedAt to be set after FillPendingDetails")
	}
	if activities[0].SplitsFetchedAt == nil {
		t.Error("expected SplitsFetchedAt to be set after FillPendingDetails")
	}

	laps, err := db.LapsForActivity(ctx, userID, activityID)
	if err != nil || len(laps) != 1 {
		t.Fatalf("LapsForActivity: %v, %+v", err, laps)
	}

	assignment, ok, err := db.CurrentAssignment(ctx, userID, activityID)
	if err != nil || !ok {
		t.Fatalf("CurrentAssignment: ok=%v err=%v", ok, err)
	}
	if assignment.Status != classify.StatusAssigned {
		t.Fatalf("assignment.Status = %q, want %q (candidates: %s)", assignment.Status, classify.StatusAssigned, assignment.CandidateKindsJSON)
	}
}

func TestFillPendingDetails_ResolvesWorkoutTargetsOntoLaps(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	const garminActivityID = 55
	const workoutID = 999
	workoutIDPtr := int64(workoutID)
	m := &mock.Client{
		Activities: []garmin.Activity{
			{ActivityID: garminActivityID, ActivityType: garmin.ActivityType{TypeKey: "running"}, WorkoutID: &workoutIDPtr,
				StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500},
		},
		Splits: map[int64]garmin.ActivitySplits{
			garminActivityID: {ActivityID: garminActivityID, Laps: []garmin.Lap{
				{LapIndex: 1, Duration: 900, ElapsedDuration: 900, Distance: 3000, IntensityType: "ACTIVE"},
			}},
		},
		Details: map[int64]garmin.ActivityDetails{garminActivityID: {ActivityID: garminActivityID}},
		Workouts: map[int64]garmin.Workout{
			workoutID: {Segments: []garmin.WorkoutSegment{
				{Steps: []garmin.WorkoutStep{
					{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(3.0), TargetValueTwo: f(3.5)},
				}},
			}},
		},
	}
	svc := NewService(m, db, userID, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}
	if err := svc.FillPendingDetails(ctx, 10); err != nil {
		t.Fatalf("FillPendingDetails: %v", err)
	}

	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil || len(activities) != 1 {
		t.Fatalf("ListActivities: %v, %+v", err, activities)
	}
	laps, err := db.LapsForActivity(ctx, userID, activities[0].ID)
	if err != nil || len(laps) != 1 {
		t.Fatalf("LapsForActivity: %v, %+v", err, laps)
	}
	if laps[0].TargetPaceLowMps == nil || *laps[0].TargetPaceLowMps != 3.0 {
		t.Errorf("TargetPaceLowMps = %v, want 3.0", laps[0].TargetPaceLowMps)
	}
	if laps[0].TargetPaceHighMps == nil || *laps[0].TargetPaceHighMps != 3.5 {
		t.Errorf("TargetPaceHighMps = %v, want 3.5", laps[0].TargetPaceHighMps)
	}
}

func TestFillPendingDetails_OneExtraTrailingLapKeepsOtherLapsTargets(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	const garminActivityID = 56
	const workoutID = 1000
	workoutIDPtr := int64(workoutID)
	m := &mock.Client{
		Activities: []garmin.Activity{
			{ActivityID: garminActivityID, ActivityType: garmin.ActivityType{TypeKey: "running"}, WorkoutID: &workoutIDPtr,
				StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500},
		},
		Splits: map[int64]garmin.ActivitySplits{
			garminActivityID: {ActivityID: garminActivityID, Laps: []garmin.Lap{
				{LapIndex: 1, Duration: 900, ElapsedDuration: 900, Distance: 3000, IntensityType: "ACTIVE"},
				{LapIndex: 2, Duration: 600, ElapsedDuration: 600, Distance: 2000, IntensityType: "REST"},
			}},
		},
		Details: map[int64]garmin.ActivityDetails{garminActivityID: {ActivityID: garminActivityID}},
		Workouts: map[int64]garmin.Workout{
			// One step for two recorded laps -- the second lap is an
			// unplanned continuation past the workout's end (confirmed via
			// Garmin Connect against a real activity), not a genuine
			// mismatch, so the first lap should still get a real target.
			workoutID: {Segments: []garmin.WorkoutSegment{
				{Steps: []garmin.WorkoutStep{
					{Type: "ExecutableStepDTO", TargetType: garmin.WorkoutTargetType{TypeKey: "pace.zone"}, TargetValueOne: f(3.0), TargetValueTwo: f(3.5)},
				}},
			}},
		},
	}
	svc := NewService(m, db, userID, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}
	if err := svc.FillPendingDetails(ctx, 10); err != nil {
		t.Fatalf("FillPendingDetails: %v", err)
	}

	activities, _ := db.ListActivities(ctx, userID, store.ActivityFilter{})
	laps, err := db.LapsForActivity(ctx, userID, activities[0].ID)
	if err != nil || len(laps) != 2 {
		t.Fatalf("LapsForActivity: %v, %+v", err, laps)
	}
	if laps[0].TargetPaceLowMps == nil || *laps[0].TargetPaceLowMps != 3.0 {
		t.Errorf("laps[0].TargetPaceLowMps = %v, want 3.0 (the one defined step's target)", laps[0].TargetPaceLowMps)
	}
	if laps[1].TargetPaceLowMps != nil || laps[1].TargetPaceHighMps != nil {
		t.Errorf("laps[1] target should be nil (the trailing unplanned continuation lap), got low=%v high=%v", laps[1].TargetPaceLowMps, laps[1].TargetPaceHighMps)
	}
}

func TestBuildMetricContext_DerivesExpectedMetrics(t *testing.T) {
	activity := store.Activity{
		DurationSeconds:       1800,
		DistanceMeters:        6000,
		AvgSpeedMps:           f(3.33),
		AvgHR:                 f(152),
		AerobicTrainingEffect: f(3.2),
	}
	laps := []store.Lap{
		{IntensityType: "ACTIVE", AvgSpeedMps: f(3.33), HRDriftBpmPerMin: f(2.5)},
		{IntensityType: "REST", AvgSpeedMps: f(1.5), HRRecoveryBpmPerMin: f(4.0)},
	}

	ctx := buildMetricContext(activity, laps, 190)

	if got := ctx["avg_pace_sec_per_km"]; got < 300 || got > 301 {
		t.Errorf("avg_pace_sec_per_km = %v, want ~300.3 (1000/3.33)", got)
	}
	if got, want := ctx["avg_hr_pct_max"], 152.0/190.0; got != want {
		t.Errorf("avg_hr_pct_max = %v, want %v", got, want)
	}
	if got := ctx["lap_hr_drift_bpm_per_min"]; got != 2.5 {
		t.Errorf("lap_hr_drift_bpm_per_min = %v, want 2.5", got)
	}
	if got := ctx["lap_hr_recovery_bpm_per_min"]; got != 4.0 {
		t.Errorf("lap_hr_recovery_bpm_per_min = %v, want 4.0", got)
	}
	// Only one ACTIVE + one REST lap, not repeated -- should not look like a
	// structured interval workout.
	if got := ctx["lap_interval_pattern"]; got != 0 {
		t.Errorf("lap_interval_pattern = %v, want 0", got)
	}
	if got := ctx["is_race"]; got != 0 {
		t.Errorf("is_race = %v, want 0 (EventTypeKey not set)", got)
	}
}

func TestBuildMetricContext_DerivesIsRace(t *testing.T) {
	ctx := buildMetricContext(store.Activity{EventTypeKey: "race"}, nil, 0)
	if got := ctx["is_race"]; got != 1 {
		t.Errorf("is_race = %v, want 1 when EventTypeKey is \"race\"", got)
	}

	ctx = buildMetricContext(store.Activity{EventTypeKey: "training"}, nil, 0)
	if got := ctx["is_race"]; got != 0 {
		t.Errorf("is_race = %v, want 0 when EventTypeKey is not \"race\"", got)
	}
}

func TestBackfill_SecondRunIsANoOpOnceHorizonFullyCovered(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-05 06:00:00", Distance: 5000, Duration: 1500},
	}}
	svc := NewService(m, db, userID, Config{BackfillWindowDays: 10},
		fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))
	setBackfillHorizon(t, db, userID, 10)

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("first Backfill: %v", err)
	}
	firstCallCount := m.GetActivitiesCalls
	if firstCallCount == 0 {
		t.Fatal("expected first backfill to call GetActivities at least once")
	}

	state, err := db.GetSyncState(ctx, userID)
	if err != nil {
		t.Fatalf("GetSyncState: %v", err)
	}
	if !state.BackfillComplete {
		t.Fatalf("expected backfill_complete=true after covering the full horizon, got %+v", state)
	}

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("second Backfill: %v", err)
	}
	if m.GetActivitiesCalls != firstCallCount {
		t.Errorf("second Backfill made %d more GetActivities call(s); want 0 (should be a no-op once horizon is covered)",
			m.GetActivitiesCalls-firstCallCount)
	}
}

func TestResetAll_AllowsFreshBackfillAfterwards(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-05 06:00:00", Distance: 5000, Duration: 1500},
	}}
	svc := NewService(m, db, userID, Config{BackfillWindowDays: 10},
		fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))
	setBackfillHorizon(t, db, userID, 10)

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("first Backfill: %v", err)
	}
	firstCallCount := m.GetActivitiesCalls

	if err := svc.ResetAll(ctx); err != nil {
		t.Fatalf("ResetAll: %v", err)
	}
	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities: %v", err)
	}
	if len(activities) != 0 {
		t.Fatalf("expected 0 activities after ResetAll, got %d", len(activities))
	}

	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill after reset: %v", err)
	}
	if m.GetActivitiesCalls <= firstCallCount {
		t.Errorf("expected Backfill after ResetAll to call GetActivities again (fresh pull), call count stayed at %d", m.GetActivitiesCalls)
	}
	activities, err = db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities after re-backfill: %v", err)
	}
	if len(activities) != 1 {
		t.Fatalf("expected 1 activity re-fetched after reset+backfill, got %d", len(activities))
	}
}

func TestBackfill_ResumesFromWatermarkWhenHorizonGrows(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-05 06:00:00", Distance: 5000, Duration: 1500},
	}}
	now := fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC))

	svc := NewService(m, db, userID, Config{BackfillWindowDays: 10}, now)
	setBackfillHorizon(t, db, userID, 10)
	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("first Backfill: %v", err)
	}
	firstCallCount := m.GetActivitiesCalls

	// Simulate the user widening the horizon later -- should resume from the
	// watermark (not re-fetch the already-covered recent window) but still
	// make progress toward the new, deeper horizon.
	setBackfillHorizon(t, db, userID, 30)
	svc2 := NewService(m, db, userID, Config{BackfillWindowDays: 10}, now)
	if err := svc2.Backfill(ctx); err != nil {
		t.Fatalf("second Backfill: %v", err)
	}
	if m.GetActivitiesCalls <= firstCallCount {
		t.Errorf("expected additional GetActivities calls when horizon grows, got %d total (was %d)", m.GetActivitiesCalls, firstCallCount)
	}

	state, err := db.GetSyncState(ctx, userID)
	if err != nil {
		t.Fatalf("GetSyncState: %v", err)
	}
	if !state.BackfillComplete {
		t.Fatalf("expected backfill_complete=true after covering the new horizon, got %+v", state)
	}
}

func TestFullSync_RecordsOneCombinedSyncRun(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{
		Activities: []garmin.Activity{
			{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-05 06:00:00", Distance: 5000, Duration: 1500},
			{ActivityID: 2, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-08 06:00:00", Distance: 5000, Duration: 1500},
		},
		Splits: map[int64]garmin.ActivitySplits{
			1: {ActivityID: 1}, 2: {ActivityID: 2},
		},
		Details: map[int64]garmin.ActivityDetails{
			1: {ActivityID: 1}, 2: {ActivityID: 2},
		},
	}
	svc := NewService(m, db, userID, Config{BackfillWindowDays: 10},
		fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))
	setBackfillHorizon(t, db, userID, 10)

	if err := svc.FullSync(ctx, 10); err != nil {
		t.Fatalf("FullSync: %v", err)
	}

	runs, err := db.ListSyncRuns(ctx, userID, 10)
	if err != nil {
		t.Fatalf("ListSyncRuns: %v", err)
	}
	if len(runs) != 1 {
		t.Fatalf("expected exactly 1 sync run recorded by FullSync (not one per stage), got %d: %+v", len(runs), runs)
	}
	run := runs[0]
	if run.Kind != store.SyncKindFull {
		t.Errorf("Kind = %q, want %q", run.Kind, store.SyncKindFull)
	}
	if run.Status != store.SyncStatusSuccess {
		t.Errorf("Status = %q, want success", run.Status)
	}
	// Backfill (one window covering the whole horizon) stores both of the
	// mock's activities as genuinely new (2). IncrementalSync then runs its
	// own separate fetch and -- since the fake client ignores the date range
	// it's called with -- sees the exact same 2 activities again, but they're
	// already stored by then, so it contributes 0 new ones. The combined
	// run's count (2) must reflect that dedup, not naively sum each stage's
	// raw fetch count (which would double-count to 4) or report only
	// whichever stage happened to run last (which would silently drop
	// Backfill's count) -- both are bugs this test guards against.
	if run.ActivitiesFetched != 2 {
		t.Errorf("ActivitiesFetched = %d, want 2 (genuinely new activities, deduped across stages)", run.ActivitiesFetched)
	}

	activities, err := db.ListActivities(ctx, userID, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities: %v", err)
	}
	if len(activities) != 2 {
		t.Fatalf("expected 2 stored activities (upserted, not duplicated), got %d", len(activities))
	}
}

func TestFillPendingDetails_ReportsLiveProgress(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userID := provisionTestUser(t, db)

	m := &mock.Client{
		Activities: []garmin.Activity{},
		Splits:     map[int64]garmin.ActivitySplits{},
		Details:    map[int64]garmin.ActivityDetails{},
	}
	const n = 3
	for i := int64(1); i <= n; i++ {
		m.Activities = append(m.Activities, garmin.Activity{
			ActivityID: i, ActivityType: garmin.ActivityType{TypeKey: "running"},
			StartTimeGMT: "2026-07-0" + string(rune('0'+i)) + " 06:00:00", Distance: 5000, Duration: 1500,
		})
		m.Splits[i] = garmin.ActivitySplits{ActivityID: i}
		m.Details[i] = garmin.ActivityDetails{ActivityID: i}
	}

	svc := NewService(m, db, userID, Config{InterCallDelay: 150 * time.Millisecond},
		fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))
	if err := svc.Backfill(ctx); err != nil {
		t.Fatalf("Backfill: %v", err)
	}

	if p := svc.Progress(); p.Total != 0 {
		t.Fatalf("Progress before FillPendingDetails = %+v, want zero value", p)
	}

	done := make(chan error, 1)
	go func() { done <- svc.FillPendingDetails(ctx, n) }()

	time.Sleep(200 * time.Millisecond) // into the delay before the 2nd or 3rd item
	mid := svc.Progress()
	if mid.Total != n {
		t.Errorf("mid-flight Progress().Total = %d, want %d", mid.Total, n)
	}
	if mid.Done <= 0 || mid.Done >= n {
		t.Errorf("mid-flight Progress().Done = %d, want strictly between 0 and %d (i.e. actually in progress)", mid.Done, n)
	}

	if err := <-done; err != nil {
		t.Fatalf("FillPendingDetails: %v", err)
	}
	if final := svc.Progress(); final.Total != 0 || final.Done != 0 {
		t.Errorf("Progress after completion = %+v, want zero value (idle)", final)
	}
}

func TestService_TwoUsersSyncIndependently(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()
	userA, err := db.ProvisionUser(ctx, "sub-a", "A")
	if err != nil {
		t.Fatalf("ProvisionUser(a): %v", err)
	}
	userB, err := db.ProvisionUser(ctx, "sub-b", "B")
	if err != nil {
		t.Fatalf("ProvisionUser(b): %v", err)
	}

	mA := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 1, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-01 06:00:00", Distance: 5000, Duration: 1500},
	}}
	mB := &mock.Client{Activities: []garmin.Activity{
		{ActivityID: 2, ActivityType: garmin.ActivityType{TypeKey: "running"}, StartTimeGMT: "2026-07-01 06:00:00", Distance: 8000, Duration: 2400},
	}}
	svcA := NewService(mA, db, userA, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))
	svcB := NewService(mB, db, userB, Config{}, fixedNow(time.Date(2026, 7, 11, 0, 0, 0, 0, time.UTC)))

	if err := svcA.Backfill(ctx); err != nil {
		t.Fatalf("Backfill(a): %v", err)
	}
	if err := svcB.Backfill(ctx); err != nil {
		t.Fatalf("Backfill(b): %v", err)
	}

	activitiesA, err := db.ListActivities(ctx, userA, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities(a): %v", err)
	}
	activitiesB, err := db.ListActivities(ctx, userB, store.ActivityFilter{})
	if err != nil {
		t.Fatalf("ListActivities(b): %v", err)
	}
	if len(activitiesA) != 1 || activitiesA[0].GarminActivityID != 1 {
		t.Fatalf("userA's activities = %+v, want exactly garmin id 1", activitiesA)
	}
	if len(activitiesB) != 1 || activitiesB[0].GarminActivityID != 2 {
		t.Fatalf("userB's activities = %+v, want exactly garmin id 2", activitiesB)
	}
}