pansy/internal/service/revisions_test.go

package service

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"testing"

	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
)

// history returns a garden's change sets newest-first, failing the test on error.
func history(t *testing.T, s *Service, actor, gardenID int64) []domain.ChangeSet {
	t.Helper()
	sets, _, err := s.GardenHistory(context.Background(), actor, gardenID, 0, 0)
	if err != nil {
		t.Fatalf("GardenHistory: %v", err)
	}
	return sets
}

// revisionsOf loads a change set's revisions.
func revisionsOf(t *testing.T, s *Service, id int64) []domain.Revision {
	t.Helper()
	cs, err := s.store.GetChangeSet(context.Background(), id)
	if err != nil {
		t.Fatalf("GetChangeSet: %v", err)
	}
	return cs.Revisions
}

// TestAutoScopeRecordsEveryMutation is the acceptance criterion that keeps this
// feature shallow: a plain REST-shaped mutation, with nobody opening a change
// set, still lands in history.
func TestAutoScopeRecordsEveryMutation(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	bed := seedBed(t, s, owner, g.ID)
	if _, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{Name: strPtr("North Bed")}, bed.Version); err != nil {
		t.Fatalf("UpdateObject: %v", err)
	}

	sets := history(t, s, owner, g.ID)
	if len(sets) != 2 {
		t.Fatalf("got %d change sets, want 2 (create + update)", len(sets))
	}
	// Newest first.
	if sets[0].Summary != "Edited North Bed" {
		t.Errorf("newest summary = %q", sets[0].Summary)
	}
	if sets[0].Source != domain.SourceUI {
		t.Errorf("source = %q, want ui", sets[0].Source)
	}
	if sets[0].ActorID != owner || sets[0].ActorName == "" {
		t.Errorf("actor not resolved: %+v", sets[0])
	}
	if len(sets[0].Counts) != 1 || sets[0].Counts[0].Op != domain.OpUpdate || sets[0].Counts[0].N != 1 {
		t.Errorf("counts = %+v", sets[0].Counts)
	}
}

// TestFillRegionIsOneChangeSet: N plops, one undo. The whole reason the unit of
// undo is the operation and not the row.
func TestFillRegionIsOneChangeSet(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	plant := seedOwnPlant(t, s, owner, 15)
	ctx := context.Background()

	created, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil)
	if err != nil {
		t.Fatalf("FillNamedRegion: %v", err)
	}
	if len(created) < 2 {
		t.Fatalf("expected a multi-plop fill, got %d", len(created))
	}

	sets := history(t, s, owner, g.ID)
	fill := sets[0]
	revs := revisionsOf(t, s, fill.ID)
	if len(revs) != len(created) {
		t.Fatalf("fill produced %d revisions for %d plops", len(revs), len(created))
	}
	for _, r := range revs {
		if r.Op != domain.OpCreate || r.EntityType != domain.EntityPlanting {
			t.Errorf("unexpected revision %+v", r)
		}
		if r.Before != nil || r.After == nil {
			t.Errorf("a create should snapshot only the after state: %+v", r)
		}
	}

	// Reverting removes all N and leaves the bed as it was.
	_, conflicts, err := s.RevertChangeSet(ctx, owner, fill.ID, domain.SourceUI)
	if err != nil {
		t.Fatalf("RevertChangeSet: %v", err)
	}
	if len(conflicts) != 0 {
		t.Fatalf("unexpected conflicts: %+v", conflicts)
	}
	active, err := s.store.ListActivePlantingsForObject(ctx, bed.ID)
	if err != nil {
		t.Fatalf("list: %v", err)
	}
	if len(active) != 0 {
		t.Errorf("%d plops survived the revert", len(active))
	}
}

// TestRevertRestoresObjectGeometry covers the everyday case: move a bed, undo it.
func TestRevertRestoresObjectGeometry(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	moved, err := s.UpdateObject(ctx, owner, bed.ID,
		ObjectPatch{XCM: f64Ptr(300), YCM: f64Ptr(400)}, bed.Version)
	if err != nil {
		t.Fatalf("UpdateObject: %v", err)
	}

	sets := history(t, s, owner, g.ID)
	if _, conflicts, err := s.RevertChangeSet(ctx, owner, sets[0].ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
		t.Fatalf("revert: err=%v conflicts=%+v", err, conflicts)
	}

	back, err := s.store.GetObject(ctx, bed.ID)
	if err != nil {
		t.Fatalf("GetObject: %v", err)
	}
	if back.XCM != bed.XCM || back.YCM != bed.YCM {
		t.Errorf("position = (%v,%v), want the original (%v,%v)", back.XCM, back.YCM, bed.XCM, bed.YCM)
	}
	// The revert is a WRITE, not a rewind: the row's version moves forward.
	if back.Version <= moved.Version {
		t.Errorf("version = %d, want > %d (revert is an append-only change)", back.Version, moved.Version)
	}
}

// TestRevertOfRevertRestoresTheChange — undo is undoable, because a revert is
// itself a change set rather than a rewrite of history.
func TestRevertOfRevertRestoresTheChange(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	if _, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{XCM: f64Ptr(300)}, bed.Version); err != nil {
		t.Fatalf("UpdateObject: %v", err)
	}
	move := history(t, s, owner, g.ID)[0]

	undo, _, err := s.RevertChangeSet(ctx, owner, move.ID, domain.SourceUI)
	if err != nil {
		t.Fatalf("revert: %v", err)
	}
	if undo.RevertsID == nil || *undo.RevertsID != move.ID {
		t.Fatalf("revert doesn't point at its target: %+v", undo)
	}
	if o, _ := s.store.GetObject(ctx, bed.ID); o.XCM != bed.XCM {
		t.Fatalf("undo didn't restore x: %v", o.XCM)
	}

	redo, conflicts, err := s.RevertChangeSet(ctx, owner, undo.ID, domain.SourceUI)
	if err != nil || len(conflicts) != 0 {
		t.Fatalf("revert of revert: err=%v conflicts=%+v", err, conflicts)
	}
	if o, _ := s.store.GetObject(ctx, bed.ID); o.XCM != 300 {
		t.Errorf("redo didn't reapply the move: x = %v", o.XCM)
	}
	if redo.Summary == "" {
		t.Error("a revert should carry a summary")
	}

	// The original is marked as reverted, and every step is still in the list.
	sets := history(t, s, owner, g.ID)
	if len(sets) != 4 { // create bed, move, undo, redo
		t.Fatalf("got %d change sets, want 4", len(sets))
	}
	var moveEntry *domain.ChangeSet
	for i := range sets {
		if sets[i].ID == move.ID {
			moveEntry = &sets[i]
		}
	}
	if moveEntry == nil || moveEntry.RevertedByID == nil || *moveEntry.RevertedByID != undo.ID {
		t.Errorf("the move isn't marked as reverted: %+v", moveEntry)
	}
}

// TestRevertConflictsOnLaterEdit is the guard that stops undo from silently
// discarding someone's newer work — and the promise that the REST of the change
// set still reverts.
func TestRevertConflictsOnLaterEdit(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	bedA := seedBed(t, s, owner, g.ID)
	bedB, err := s.CreateObject(ctx, owner, g.ID, ObjectInput{
		Kind: domain.KindBed, Name: "B", XCM: 200, YCM: 200, WidthCM: 100, HeightCM: 100,
	})
	if err != nil {
		t.Fatalf("CreateObject: %v", err)
	}

	// One change set touching both beds.
	_, err = s.WithChangeSet(ctx, owner, g.ID, ChangeSetOptions{Source: domain.SourceAgent, Summary: "Rearranged"},
		func(ctx context.Context) error {
			if _, err := s.UpdateObject(ctx, owner, bedA.ID, ObjectPatch{XCM: f64Ptr(600)}, bedA.Version); err != nil {
				return err
			}
			_, err := s.UpdateObject(ctx, owner, bedB.ID, ObjectPatch{XCM: f64Ptr(300)}, bedB.Version)
			return err
		})
	if err != nil {
		t.Fatalf("WithChangeSet: %v", err)
	}
	turn := history(t, s, owner, g.ID)[0]
	if turn.Source != domain.SourceAgent || len(revisionsOf(t, s, turn.ID)) != 2 {
		t.Fatalf("expected one agent change set with 2 revisions: %+v", turn)
	}

	// Someone edits bed A afterwards.
	cur, _ := s.store.GetObject(ctx, bedA.ID)
	if _, err := s.UpdateObject(ctx, owner, bedA.ID, ObjectPatch{Name: strPtr("Touched")}, cur.Version); err != nil {
		t.Fatalf("later edit: %v", err)
	}

	_, conflicts, err := s.RevertChangeSet(ctx, owner, turn.ID, domain.SourceUI)
	if err != nil {
		t.Fatalf("RevertChangeSet: %v", err)
	}
	if len(conflicts) != 1 {
		t.Fatalf("got %d conflicts, want 1: %+v", len(conflicts), conflicts)
	}
	if conflicts[0].EntityID != bedA.ID || conflicts[0].Reason != domain.ConflictChanged {
		t.Errorf("unexpected conflict %+v", conflicts[0])
	}
	if conflicts[0].Name != "Touched" {
		t.Errorf("conflict should name the entity as it stands now, got %q", conflicts[0].Name)
	}

	// A was left alone; B still reverted.
	a, _ := s.store.GetObject(ctx, bedA.ID)
	if a.XCM != 600 || a.Name != "Touched" {
		t.Errorf("conflicted object was modified: %+v", a)
	}
	b, _ := s.store.GetObject(ctx, bedB.ID)
	if b.XCM != bedB.XCM {
		t.Errorf("bed B should have reverted to %v, got %v", bedB.XCM, b.XCM)
	}
}

// TestRevertRestoresDeletedObjectWithItsPlantings covers the cascade: deleting an
// object takes its plops with it at the FK level, where the service never sees
// them. If they aren't snapshotted the delete is listed in history but can't
// actually be undone.
func TestRevertRestoresDeletedObjectWithItsPlantings(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	plant := seedOwnPlant(t, s, owner, 15)
	ctx := context.Background()

	plop, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
		PlantID: plant.ID, XCM: 10, YCM: 10, RadiusCM: 20,
	})
	if err != nil {
		t.Fatalf("CreatePlanting: %v", err)
	}
	if err := s.DeleteObject(ctx, owner, bed.ID); err != nil {
		t.Fatalf("DeleteObject: %v", err)
	}

	del := history(t, s, owner, g.ID)[0]
	revs := revisionsOf(t, s, del.ID)
	if len(revs) != 2 {
		t.Fatalf("delete recorded %d revisions, want 2 (the bed and its plop)", len(revs))
	}

	if _, conflicts, err := s.RevertChangeSet(ctx, owner, del.ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
		t.Fatalf("revert: err=%v conflicts=%+v", err, conflicts)
	}

	back, err := s.store.GetObject(ctx, bed.ID)
	if err != nil {
		t.Fatalf("bed not restored: %v", err)
	}
	if back.ID != bed.ID || back.Name != bed.Name || back.XCM != bed.XCM {
		t.Errorf("restored bed differs: %+v", back)
	}
	restoredPlop, err := s.store.GetPlanting(ctx, plop.ID)
	if err != nil {
		t.Fatalf("plop not restored: %v", err)
	}
	if restoredPlop.ObjectID != bed.ID || restoredPlop.XCM != plop.XCM {
		t.Errorf("restored plop differs: %+v", restoredPlop)
	}
}

// TestRevertClearObject: "clear bed" is a bulk soft-remove, and undoing it should
// bring the whole bed back planted.
func TestRevertClearObject(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	plant := seedOwnPlant(t, s, owner, 15)
	ctx := context.Background()

	if _, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil); err != nil {
		t.Fatalf("fill: %v", err)
	}
	before, _ := s.store.ListActivePlantingsForObject(ctx, bed.ID)

	n, err := s.ClearObject(ctx, owner, bed.ID)
	if err != nil {
		t.Fatalf("ClearObject: %v", err)
	}
	if n != len(before) {
		t.Fatalf("cleared %d of %d", n, len(before))
	}
	if active, _ := s.store.ListActivePlantingsForObject(ctx, bed.ID); len(active) != 0 {
		t.Fatalf("%d plops still active after clear", len(active))
	}

	clear := history(t, s, owner, g.ID)[0]
	if _, conflicts, err := s.RevertChangeSet(ctx, owner, clear.ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
		t.Fatalf("revert: err=%v conflicts=%+v", err, conflicts)
	}
	after, _ := s.store.ListActivePlantingsForObject(ctx, bed.ID)
	if len(after) != len(before) {
		t.Errorf("%d plops active after undo, want %d", len(after), len(before))
	}
}

// TestRevertPermissions: a viewer may read history but not undo; a stranger sees
// neither (existence stays masked).
func TestRevertPermissions(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	viewer := seedUser(t, s, "[email protected]")
	stranger := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	if _, err := s.AddShare(ctx, owner, g.ID, "[email protected]", domain.RoleViewer); err != nil {
		t.Fatalf("AddShare: %v", err)
	}
	_ = bed
	cs := history(t, s, owner, g.ID)[0]

	if _, _, err := s.GardenHistory(ctx, viewer, g.ID, 0, 0); err != nil {
		t.Errorf("a viewer should be able to read history: %v", err)
	}
	if _, _, err := s.RevertChangeSet(ctx, viewer, cs.ID, domain.SourceUI); !errors.Is(err, domain.ErrForbidden) {
		t.Errorf("viewer revert err = %v, want ErrForbidden", err)
	}
	if _, _, err := s.GardenHistory(ctx, stranger, g.ID, 0, 0); !errors.Is(err, domain.ErrNotFound) {
		t.Errorf("stranger history err = %v, want ErrNotFound", err)
	}
	if _, _, err := s.RevertChangeSet(ctx, stranger, cs.ID, domain.SourceUI); !errors.Is(err, domain.ErrNotFound) {
		t.Errorf("stranger revert err = %v, want ErrNotFound", err)
	}
}

// TestWithChangeSetRecordsWhatCommittedOnFailure — a turn that fails partway has
// still committed the mutations it got through, because this scope buffers
// HISTORY, not data. Dropping the buffer would leave those changes with no
// history and no way to undo them, which is exactly the situation undo exists
// for. So they're recorded, marked as partial, and the failure is still reported.
func TestWithChangeSetRecordsWhatCommittedOnFailure(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	sentinel := errors.New("boom")
	_, err := s.WithChangeSet(ctx, owner, g.ID, ChangeSetOptions{Source: domain.SourceAgent, Summary: "Half a turn"},
		func(ctx context.Context) error {
			if _, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{XCM: f64Ptr(600)}, bed.Version); err != nil {
				return err
			}
			return sentinel
		})
	if !errors.Is(err, sentinel) {
		t.Fatalf("err = %v, want the sentinel", err)
	}

	// The move really happened, so it must be in history and undoable.
	if o, _ := s.store.GetObject(ctx, bed.ID); o.XCM != 600 {
		t.Fatalf("the committed move was rolled back? x = %v", o.XCM)
	}
	sets := history(t, s, owner, g.ID)
	partial := sets[0]
	if !strings.Contains(partial.Summary, "failed partway") {
		t.Errorf("summary = %q, want it to say the turn failed partway", partial.Summary)
	}
	if len(revisionsOf(t, s, partial.ID)) != 1 {
		t.Errorf("expected the one committed mutation to be recorded")
	}
	if _, conflicts, err := s.RevertChangeSet(ctx, owner, partial.ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
		t.Fatalf("the partial turn should be undoable: err=%v conflicts=%+v", err, conflicts)
	}
	if o, _ := s.store.GetObject(ctx, bed.ID); o.XCM != bed.XCM {
		t.Errorf("undo of the partial turn didn't restore x: %v", o.XCM)
	}
}

// TestChangeSetSkippedWhenNothingChanged — a scope that mutates nothing writes no
// change set, so history isn't padded with empty entries.
func TestChangeSetSkippedWhenNothingChanged(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	before := len(history(t, s, owner, g.ID))
	cs, err := s.WithChangeSet(ctx, owner, g.ID, ChangeSetOptions{Source: domain.SourceAgent, Summary: "Looked around"},
		func(context.Context) error { return nil })
	if err != nil {
		t.Fatalf("WithChangeSet: %v", err)
	}
	if cs != nil {
		t.Errorf("expected no change set, got %+v", cs)
	}
	if got := len(history(t, s, owner, g.ID)); got != before {
		t.Errorf("history grew by %d", got-before)
	}
}

// TestGardenMetadataRevert covers the third entity type.
func TestGardenMetadataRevert(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	if _, err := s.UpdateGarden(ctx, owner, g.ID, GardenInput{
		Name: "Renamed", WidthCM: 1200, HeightCM: 1000, UnitPref: domain.UnitImperial,
	}, g.Version); err != nil {
		t.Fatalf("UpdateGarden: %v", err)
	}
	cs := history(t, s, owner, g.ID)[0]
	if _, conflicts, err := s.RevertChangeSet(ctx, owner, cs.ID, domain.SourceUI); err != nil || len(conflicts) != 0 {
		t.Fatalf("revert: err=%v conflicts=%+v", err, conflicts)
	}
	back, _ := s.store.GetGarden(ctx, g.ID)
	if back.Name != g.Name || back.WidthCM != g.WidthCM {
		t.Errorf("garden not restored: %+v", back)
	}
	// MyRole is computed, never stored — the snapshot must not have carried it
	// back into the row.
	if back.MyRole != "" {
		t.Errorf("MyRole leaked into the stored row: %q", back.MyRole)
	}
}

// TestPlanRevertOrdersRestoresParentFirst pins the ordering the FKs depend on,
// rather than trusting reverse-seq to get it right by luck.
func TestPlanRevertOrdersRestoresParentFirst(t *testing.T) {
	revs := []domain.Revision{
		{Seq: 1, EntityType: domain.EntityPlanting, EntityID: 10, Op: domain.OpDelete},
		{Seq: 2, EntityType: domain.EntityObject, EntityID: 1, Op: domain.OpDelete},
		{Seq: 3, EntityType: domain.EntityObject, EntityID: 2, Op: domain.OpCreate},
		{Seq: 4, EntityType: domain.EntityPlanting, EntityID: 11, Op: domain.OpCreate},
		{Seq: 5, EntityType: domain.EntityObject, EntityID: 3, Op: domain.OpUpdate},
	}
	got := planRevert(revs)
	want := []struct {
		entity string
		id     int64
	}{
		{domain.EntityObject, 1},    // restore parents first
		{domain.EntityPlanting, 10}, // then children
		{domain.EntityObject, 3},    // then updates
		{domain.EntityPlanting, 11}, // then delete created children
		{domain.EntityObject, 2},    // and only then their parents
	}
	if len(got) != len(want) {
		t.Fatalf("planned %d revisions, want %d", len(got), len(want))
	}
	for i, w := range want {
		if got[i].EntityType != w.entity || got[i].EntityID != w.id {
			t.Errorf("step %d = %s/%d, want %s/%d", i, got[i].EntityType, got[i].EntityID, w.entity, w.id)
		}
	}
}

// TestSnapshotsCaptureVersion — the revert guard compares against the version in
// the after-snapshot, so it has to actually be there.
func TestSnapshotsCaptureVersion(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)

	revs := revisionsOf(t, s, history(t, s, owner, g.ID)[0].ID)
	if len(revs) != 1 || revs[0].After == nil {
		t.Fatalf("unexpected revisions %+v", revs)
	}
	var snap domain.GardenObject
	if err := json.Unmarshal([]byte(*revs[0].After), &snap); err != nil {
		t.Fatalf("snapshot isn't a garden object: %v", err)
	}
	if snap.Version != bed.Version || snap.ID != bed.ID {
		t.Errorf("snapshot = %+v, want version %d id %d", snap, bed.Version, bed.ID)
	}
}

func f64Ptr(v float64) *float64 { return &v }

// TestRevertChangeSetTouchingOneEntityTwice — an agent turn that moves a bed and
// then renames it holds two revisions for the same object. Each inverse bumps
// that row's version, so from the second one on the snapshot's version no longer
// matches the live row. Without tracking what the revert itself just wrote, the
// guard flags our own work as somebody else's edit and the undo half-fails.
func TestRevertChangeSetTouchingOneEntityTwice(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	_, err := s.WithChangeSet(ctx, owner, g.ID, ChangeSetOptions{Source: domain.SourceAgent, Summary: "Two edits"},
		func(ctx context.Context) error {
			moved, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{XCM: f64Ptr(600)}, bed.Version)
			if err != nil {
				return err
			}
			_, err = s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{Name: strPtr("Renamed")}, moved.Version)
			return err
		})
	if err != nil {
		t.Fatalf("WithChangeSet: %v", err)
	}
	turn := history(t, s, owner, g.ID)[0]
	if len(revisionsOf(t, s, turn.ID)) != 2 {
		t.Fatalf("expected 2 revisions for the same object")
	}

	_, conflicts, err := s.RevertChangeSet(ctx, owner, turn.ID, domain.SourceUI)
	if err != nil {
		t.Fatalf("RevertChangeSet: %v", err)
	}
	if len(conflicts) != 0 {
		t.Fatalf("the revert conflicted with its own work: %+v", conflicts)
	}
	back, _ := s.store.GetObject(ctx, bed.ID)
	if back.XCM != bed.XCM || back.Name != bed.Name {
		t.Errorf("both edits should have been undone, got x=%v name=%q", back.XCM, back.Name)
	}
}

// TestRevertOfObjectCreateRefusesWhenPlanted — undoing "added a bed" would
// cascade away anything planted in it since. Those plops would be snapshotted and
// so recoverable, but deleting someone's plants as a side effect of an unrelated
// undo should be reported, not performed quietly.
func TestRevertOfObjectCreateRefusesWhenPlanted(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	bed := seedBed(t, s, owner, g.ID)
	create := history(t, s, owner, g.ID)[0]

	plant := seedOwnPlant(t, s, owner, 15)
	if _, err := s.CreatePlanting(ctx, owner, bed.ID, PlantingInput{
		PlantID: plant.ID, XCM: 0, YCM: 0, RadiusCM: 20,
	}); err != nil {
		t.Fatalf("CreatePlanting: %v", err)
	}

	cs, conflicts, err := s.RevertChangeSet(ctx, owner, create.ID, domain.SourceUI)
	if err != nil {
		t.Fatalf("RevertChangeSet: %v", err)
	}
	if len(conflicts) != 1 || conflicts[0].EntityID != bed.ID {
		t.Fatalf("expected one conflict naming the bed, got %+v", conflicts)
	}
	if cs != nil {
		t.Errorf("nothing should have been reverted, got change set %+v", cs)
	}
	if _, err := s.store.GetObject(ctx, bed.ID); err != nil {
		t.Errorf("the planted bed was deleted anyway: %v", err)
	}
}

// TestHistoryDoesNotDuplicateMultiplyRevertedEntries — more than one change set
// can point at the same target (undo, redo, undo again). Looking that up with a
// LEFT JOIN would emit one duplicate row per revert and silently corrupt the
// page, so it is a scalar subquery instead. Written against the store because
// getting a target legitimately reverted twice through the service is hard: the
// second attempt conflicts, which is itself the correct behaviour.
func TestHistoryDoesNotDuplicateMultiplyRevertedEntries(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	ctx := context.Background()

	target := history(t, s, owner, g.ID) // garden create isn't recorded; start empty
	if len(target) != 0 {
		t.Fatalf("expected an empty history, got %+v", target)
	}
	base, err := s.store.WriteChangeSet(ctx, &domain.ChangeSet{
		GardenID: g.ID, ActorID: owner, Source: domain.SourceUI, Summary: "Base",
	}, []domain.Revision{{EntityType: domain.EntityGarden, EntityID: g.ID, Op: domain.OpUpdate}})
	if err != nil {
		t.Fatalf("WriteChangeSet: %v", err)
	}
	for i := 0; i < 2; i++ {
		if _, err := s.store.WriteChangeSet(ctx, &domain.ChangeSet{
			GardenID: g.ID, ActorID: owner, Source: domain.SourceUI, Summary: "Undo", RevertsID: &base.ID,
		}, []domain.Revision{{EntityType: domain.EntityGarden, EntityID: g.ID, Op: domain.OpUpdate}}); err != nil {
			t.Fatalf("WriteChangeSet revert %d: %v", i, err)
		}
	}

	sets := history(t, s, owner, g.ID)
	if len(sets) != 3 {
		t.Fatalf("got %d change sets, want 3 — a join would have duplicated the base row: %+v", len(sets), sets)
	}
	seen := map[int64]int{}
	for _, cs := range sets {
		seen[cs.ID]++
	}
	for id, n := range seen {
		if n != 1 {
			t.Errorf("change set %d appears %d times", id, n)
		}
	}
	for _, cs := range sets {
		if cs.ID == base.ID && (cs.RevertedByID == nil || *cs.RevertedByID == 0) {
			t.Error("the base change set should be marked as reverted")
		}
	}
}

// TestRevertSourceIsRecorded — an agent undoing its own work must be
// distinguishable from a person clicking undo, or the history badge lies.
func TestRevertSourceIsRecorded(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	ctx := context.Background()

	if _, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{XCM: f64Ptr(300)}, bed.Version); err != nil {
		t.Fatalf("UpdateObject: %v", err)
	}
	move := history(t, s, owner, g.ID)[0]

	undo, _, err := s.RevertChangeSet(ctx, owner, move.ID, domain.SourceAgent)
	if err != nil {
		t.Fatalf("revert: %v", err)
	}
	if undo.Source != domain.SourceAgent {
		t.Errorf("source = %q, want agent", undo.Source)
	}
	if _, _, err := s.RevertChangeSet(ctx, owner, move.ID, "nonsense"); !errors.Is(err, domain.ErrInvalidInput) {
		t.Errorf("an unknown source should be rejected, got %v", err)
	}
}

// TestClearObjectOnlyClearsWhatItSnapshotted — the clear targets the exact ids it
// read, so a plop created between the read and the UPDATE can't be removed
// without a revision to undo it by.
func TestClearObjectOnlyClearsWhatItSnapshotted(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	plant := seedOwnPlant(t, s, owner, 15)
	ctx := context.Background()

	if _, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil); err != nil {
		t.Fatalf("fill: %v", err)
	}
	before, _ := s.store.ListActivePlantingsForObject(ctx, bed.ID)

	n, err := s.ClearObject(ctx, owner, bed.ID)
	if err != nil {
		t.Fatalf("ClearObject: %v", err)
	}
	clear := history(t, s, owner, g.ID)[0]
	revs := revisionsOf(t, s, clear.ID)
	// Every row the clear touched has a revision; the count and the revisions agree.
	if n != len(before) || len(revs) != n {
		t.Errorf("cleared %d of %d with %d revisions — all three should match", n, len(before), len(revs))
	}
}

// TestRevertResultCarriesItsCounts — found by using the thing.
//
// commitScope returns the freshly inserted row, which carries no tally. A caller
// receiving a change set with empty Counts cannot tell "nothing was reverted"
// from "the tally wasn't loaded", and the chat panel read that ambiguity the
// wrong way: a successful undo reported "nothing left to undo", which is the
// worst possible thing to say about an action that just worked.
//
// It also pins the cross-layer contract that fix created. countRevisions tallies
// in Go what ListChangeSets tallies in SQL, and nothing but this test stops the
// two drifting — so it compares the FULL per-(entity, op) breakdown, not just
// the totals, which would agree even if the groupings had diverged.
func TestRevertResultCarriesItsCounts(t *testing.T) {
	s := newTestService(t, openConfig())
	owner := seedUser(t, s, "[email protected]")
	g := seedGarden(t, s, owner)
	bed := seedBed(t, s, owner, g.ID)
	plant := seedOwnPlant(t, s, owner, 15)
	ctx := context.Background()

	if _, err := s.FillNamedRegion(ctx, owner, bed.ID, "all", plant.ID, nil); err != nil {
		t.Fatalf("fill: %v", err)
	}
	// A second, different kind of change, so the breakdown has more than one row
	// to get wrong.
	if _, err := s.UpdateObject(ctx, owner, bed.ID, ObjectPatch{Name: strPtr("North Bed")}, bed.Version); err != nil {
		t.Fatalf("rename: %v", err)
	}
	sets := history(t, s, owner, g.ID)
	rename, fill := sets[0], sets[1]

	undoRename, conflicts, err := s.RevertChangeSet(ctx, owner, rename.ID, domain.SourceUI)
	if err != nil || len(conflicts) != 0 {
		t.Fatalf("revert rename: err=%v conflicts=%+v", err, conflicts)
	}
	undoFill, conflicts, err := s.RevertChangeSet(ctx, owner, fill.ID, domain.SourceUI)
	if err != nil || len(conflicts) != 0 {
		t.Fatalf("revert fill: err=%v conflicts=%+v", err, conflicts)
	}

	for _, undo := range []*domain.ChangeSet{undoRename, undoFill} {
		if undo == nil {
			t.Fatal("a revert that did work returned no change set")
		}
		if len(undo.Counts) == 0 {
			t.Fatalf("change set %d came back with no tally — an empty tally reads as 'nothing happened'", undo.ID)
		}
	}
	// Undoing a fill deletes every plop it created, so the tallies must match.
	if got, want := countsTotal(undoFill.Counts), countsTotal(fill.Counts); got != want {
		t.Errorf("undo of the fill reports %d changes, want %d", got, want)
	}

	// The SQL tally and the Go tally must agree, row for row.
	listed := history(t, s, owner, g.ID)
	byID := map[int64][]domain.ChangeCount{}
	for _, cs := range listed {
		byID[cs.ID] = cs.Counts
	}
	for _, undo := range []*domain.ChangeSet{undoRename, undoFill} {
		fromSQL, ok := byID[undo.ID]
		if !ok {
			t.Fatalf("revert %d is missing from the history list", undo.ID)
		}
		if !sameCounts(undo.Counts, fromSQL) {
			t.Errorf("change set %d: revert returned %+v, the list read says %+v — countRevisions and the SQL grouping have drifted",
				undo.ID, undo.Counts, fromSQL)
		}
	}
}

// sameCounts compares two tallies regardless of order.
func sameCounts(a, b []domain.ChangeCount) bool {
	if len(a) != len(b) {
		return false
	}
	index := func(cs []domain.ChangeCount) map[string]int {
		m := map[string]int{}
		for _, c := range cs {
			m[c.EntityType+"/"+c.Op] = c.N
		}
		return m
	}
	ia, ib := index(a), index(b)
	for k, v := range ia {
		if ib[k] != v {
			return false
		}
	}
	return true
}

// countsTotal sums a tally — the server-side twin of the client's totalChanges.
func countsTotal(counts []domain.ChangeCount) int {
	n := 0
	for _, c := range counts {
		n += c.N
	}
	return n
}