package beachcomber

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"reflect"
	"strings"
	"sync"
	"testing"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/compass"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"gorm.io/gorm"
)

// Doc is a soft-deletable Searchable model whose document reads a related
// row through the handle it is given.
type Doc struct {
	ID        uint           `gorm:"column:id;primaryKey"`
	Title     string         `gorm:"column:title"`
	Hidden    bool           `gorm:"column:hidden"`
	OwnerID   uint           `gorm:"column:owner_id"`
	DeletedAt gorm.DeletedAt `gorm:"column:deleted_at"`
}

func (Doc) TableName() string    { return "acme_docs" }
func (Doc) SearchableAs() string { return "acme_docs" }

func (d *Doc) ShouldBeSearchable() bool { return !d.Hidden }

func (d *Doc) ToSearchableArray(ctx context.Context, db *gorm.DB) (map[string]any, error) {
	switch d.Title {
	case "boom":
		return nil, errors.New("document failed")
	case "panic":
		panic("document panicked")
	case "empty":
		return map[string]any{}, nil
	}
	var owners []string
	if err := db.WithContext(ctx).Table("acme_owners").Where("id = ?", d.OwnerID).Pluck("name", &owners).Error; err != nil {
		return nil, err
	}
	owner := ""
	if len(owners) == 1 {
		owner = owners[0]
	}
	return map[string]any{"title": d.Title, "owner": owner, "collection_id": d.OwnerID}, nil
}

func (Doc) SearchIndexSchema() map[string]any {
	return map[string]any{"fields": []map[string]any{{"name": "title", "type": "string"}}}
}

// Note is a hard-deleted Searchable model with its own document key.
type Note struct {
	ID   uint   `gorm:"column:id;primaryKey"`
	Body string `gorm:"column:body"`
}

func (Note) TableName() string           { return "acme_notes" }
func (Note) SearchableAs() string        { return "acme_notes" }
func (n *Note) ShouldBeSearchable() bool { return true }
func (n Note) SearchKey() string         { return fmt.Sprintf("note-%d", n.ID) }
func (n *Note) ToSearchableArray(context.Context, *gorm.DB) (map[string]any, error) {
	return map[string]any{"body": n.Body}, nil
}

// Plain is not Searchable.
type Plain struct {
	ID   uint   `gorm:"column:id;primaryKey"`
	Name string `gorm:"column:name"`
}

func (Plain) TableName() string { return "acme_plain" }

const syncTables = `
CREATE TABLE acme_owners (id SERIAL PRIMARY KEY, name TEXT NOT NULL);
CREATE TABLE acme_docs (id SERIAL PRIMARY KEY, title TEXT NOT NULL UNIQUE, hidden BOOLEAN NOT NULL DEFAULT FALSE, owner_id INT NOT NULL DEFAULT 0, deleted_at TIMESTAMPTZ NULL);
CREATE TABLE acme_notes (id SERIAL PRIMARY KEY, body TEXT NOT NULL);
CREATE TABLE acme_plain (id SERIAL PRIMARY KEY, name TEXT NOT NULL);
CREATE TABLE acme_settings (id SERIAL PRIMARY KEY, search_enabled BOOLEAN NOT NULL);
INSERT INTO acme_owners (name) VALUES ('Owner One');
INSERT INTO acme_settings (search_enabled) VALUES (true);
`

// engineCall is one recorded engine call.
type engineCall struct {
	op     string
	index  string
	schema map[string]any
	docs   []map[string]any
	ids    []string
	ctxErr error
}

// recEngine records calls and fails on demand. It is configured when
// search.acme_key is set.
type recEngine struct {
	configured bool

	mu    sync.Mutex
	calls []engineCall
	fail  string // "upsert", "delete", "panic"
}

func (e *recEngine) Name() string     { return "acme-recording" }
func (e *recEngine) Configured() bool { return e.configured }

func (e *recEngine) record(c engineCall) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.calls = append(e.calls, c)
	switch e.fail {
	case "panic":
		panic("engine panicked")
	case c.op:
		return errors.New(c.op + " failed with status 500")
	}
	return nil
}

func (e *recEngine) Upsert(ctx context.Context, index string, schema map[string]any, docs []map[string]any) error {
	return e.record(engineCall{op: "upsert", index: index, schema: schema, docs: docs, ctxErr: ctx.Err()})
}

func (e *recEngine) Delete(ctx context.Context, index string, ids []string) error {
	return e.record(engineCall{op: "delete", index: index, ids: ids, ctxErr: ctx.Err()})
}

func (e *recEngine) Flush(context.Context, string) error { return nil }

func (e *recEngine) SearchIDs(context.Context, string, Query) ([]string, error) { return nil, nil }

func (e *recEngine) take() []engineCall {
	e.mu.Lock()
	defer e.mu.Unlock()
	out := e.calls
	e.calls = nil
	return out
}

func (e *recEngine) setFail(mode string) {
	e.mu.Lock()
	e.fail = mode
	e.mu.Unlock()
}

func init() {
	RegisterEngine("acme-recording", func(app *backpack.App) (Engine, error) {
		return &recEngine{configured: app != nil && app.Config != nil && app.Config.String("search.acme_key") != ""}, nil
	})
	RegisterEngine("acme-broken", func(*backpack.App) (Engine, error) { return nil, errors.New("engine config invalid") })
	RegisterEngine("acme-nil", func(*backpack.App) (Engine, error) { return nil, nil })
}

// logRecorder records log messages with their attributes.
type logRecorder struct {
	mu      sync.Mutex
	records []map[string]string
}

func (h *logRecorder) Enabled(context.Context, slog.Level) bool { return true }
func (h *logRecorder) WithAttrs([]slog.Attr) slog.Handler       { return h }
func (h *logRecorder) WithGroup(string) slog.Handler            { return h }
func (h *logRecorder) Handle(_ context.Context, r slog.Record) error {
	rec := map[string]string{"msg": r.Message, "level": r.Level.String()}
	r.Attrs(func(a slog.Attr) bool {
		rec[a.Key] = a.Value.String()
		return true
	})
	h.mu.Lock()
	h.records = append(h.records, rec)
	h.mu.Unlock()
	return nil
}

func (h *logRecorder) take(msg string) []map[string]string {
	h.mu.Lock()
	defer h.mu.Unlock()
	var out, rest []map[string]string
	for _, r := range h.records {
		if r["msg"] == msg {
			out = append(out, r)
		} else {
			rest = append(rest, r)
		}
	}
	h.records = rest
	return out
}

type syncEnv struct {
	app  *backpack.App
	svc  *Service
	eng  *recEngine
	db   *sql.DB
	gdb  *gorm.DB
	logs *logRecorder
}

// newSyncEnv builds an app in the production boot order: the service
// first, then the database published (which installs the callbacks).
func newSyncEnv(t *testing.T, kv map[string]any, gate bool) syncEnv {
	t.Helper()
	db, _ := migratedDB(t)
	cfg, err := compass.Open(compass.Options{Dir: t.TempDir(), Env: "testing", Environ: []string{}})
	if err != nil {
		t.Fatal(err)
	}
	settings := map[string]any{"search.driver": "acme-recording", "search.acme_key": "test-only-key", "search.prefix": "dev_"}
	for k, v := range kv {
		settings[k] = v
	}
	for k, v := range settings {
		if err := cfg.Set(k, v); err != nil {
			t.Fatal(err)
		}
	}
	app := backpack.New(cfg)
	logs := &logRecorder{}
	if err := app.Publish(slog.New(logs)); err != nil {
		t.Fatal(err)
	}
	svc, err := From(app)
	if err != nil {
		t.Fatal(err)
	}
	if gate {
		svc.SetGate(GateFunc(func(ctx context.Context, db *gorm.DB) bool {
			var on []bool
			if err := db.WithContext(ctx).Table("acme_settings").Order("id").Limit(1).Pluck("search_enabled", &on).Error; err != nil {
				return false
			}
			return len(on) == 1 && on[0]
		}))
	}
	gdb, err := lagoon.Use(t.Context(), db)
	if err != nil {
		t.Fatal(err)
	}
	if err := gdb.Exec(syncTables).Error; err != nil {
		t.Fatal(err)
	}
	if err := lagoon.Publish(app, db, gdb); err != nil {
		t.Fatal(err)
	}
	eng, ok := svc.Engine().(*recEngine)
	if !ok {
		eng = nil
	}
	return syncEnv{app: app, svc: svc, eng: eng, db: db, gdb: gdb, logs: logs}
}

func (e syncEnv) setGate(t *testing.T, on bool) {
	t.Helper()
	if err := e.gdb.Exec(`UPDATE acme_settings SET search_enabled = ?`, on).Error; err != nil {
		t.Fatal(err)
	}
}

// TestSyncGates covers D-20 and T-11-25: with the null engine, an engine
// without a key, no published database or the application gate off,
// nothing is sent.
func TestSyncGates(t *testing.T) {
	ctx := context.Background()

	t.Run("null_engine_by_default", func(t *testing.T) {
		env := newSyncEnv(t, map[string]any{"search.driver": ""}, false)
		if env.svc.Engine().Name() != NullEngine || env.svc.Engine().Configured() {
			t.Fatalf("engine = %s", env.svc.Engine().Name())
		}
		if err := env.gdb.WithContext(ctx).Create(&Doc{Title: "null"}).Error; err != nil {
			t.Fatal(err)
		}
		if err := env.svc.Sync(ctx, nil, &Doc{ID: 1}); err != nil {
			t.Fatal(err)
		}
		ne := env.svc.Engine()
		if ne.Upsert(ctx, "i", nil, nil) != nil || ne.Delete(ctx, "i", nil) != nil || ne.Flush(ctx, "i") != nil {
			t.Fatal("null engine returned an error")
		}
		if ids, err := ne.SearchIDs(ctx, "i", Query{}); err != nil || ids == nil || len(ids) != 0 {
			t.Fatalf("null SearchIDs = %v, %v", ids, err)
		}
	})

	t.Run("empty_key_sends_nothing", func(t *testing.T) {
		env := newSyncEnv(t, map[string]any{"search.acme_key": ""}, false)
		if err := env.gdb.WithContext(ctx).Create(&Doc{Title: "no-key"}).Error; err != nil {
			t.Fatal(err)
		}
		if err := env.svc.Sync(ctx, env.gdb, &Doc{ID: 1}); err != nil {
			t.Fatal(err)
		}
		if n := len(env.eng.take()); n != 0 {
			t.Fatalf("%d engine calls without a key", n)
		}
	})

	t.Run("gate_off_then_on", func(t *testing.T) {
		env := newSyncEnv(t, nil, true)
		env.setGate(t, false)
		if err := env.gdb.WithContext(ctx).Create(&Doc{Title: "gated"}).Error; err != nil {
			t.Fatal(err)
		}
		if n := len(env.eng.take()); n != 0 {
			t.Fatalf("%d engine calls with the gate off", n)
		}
		env.setGate(t, true)
		if err := env.gdb.WithContext(ctx).Create(&Doc{Title: "open"}).Error; err != nil {
			t.Fatal(err)
		}
		if calls := env.eng.take(); len(calls) != 1 || calls[0].op != "upsert" {
			t.Fatalf("calls with the gate on = %+v", calls)
		}
	})

	t.Run("no_published_database", func(t *testing.T) {
		env := newSyncEnv(t, nil, false)
		bare := backpack.New(env.app.Config)
		svc := &Service{app: bare, engine: env.eng}
		if err := svc.Sync(ctx, nil, &Doc{ID: 1}); err != nil {
			t.Fatal(err)
		}
		if err := svc.syncOne(ctx, env.gdb, pending{op: opUpsert}); err != nil {
			t.Fatal(err)
		}
		if n := len(env.eng.take()); n != 0 {
			t.Fatalf("%d engine calls without a published database", n)
		}
	})
}

// TestSyncAfterCommit covers D-20: a write syncs only after it commits
// (lagoon.Transaction and a single statement's implicit transaction), a
// foreign GORM transaction is refused, a rollback syncs nothing, and the
// document is built from a reload on a clean statement.
func TestSyncAfterCommit(t *testing.T) {
	env := newSyncEnv(t, nil, true)
	ctx := context.Background()

	t.Run("lagoon_transaction_commit", func(t *testing.T) {
		var d Doc
		err := lagoon.Transaction(ctx, env.gdb, func(ctx context.Context, tx *gorm.DB) error {
			d = Doc{Title: "committed", OwnerID: 1}
			if err := tx.WithContext(ctx).Create(&d).Error; err != nil {
				return err
			}
			if n := len(env.eng.take()); n != 0 {
				t.Errorf("%d engine calls before commit", n)
			}
			return nil
		})
		if err != nil {
			t.Fatal(err)
		}
		calls := env.eng.take()
		if len(calls) != 1 {
			t.Fatalf("calls = %+v", calls)
		}
		c := calls[0]
		want := map[string]any{"id": fmt.Sprint(d.ID), "title": "committed", "owner": "Owner One", "collection_id": uint(1)}
		if c.op != "upsert" || c.index != "dev_acme_docs" || !reflect.DeepEqual(c.docs[0], want) || c.schema["fields"] == nil || c.ctxErr != nil {
			t.Fatalf("call = %+v, want doc %v", c, want)
		}
	})

	t.Run("rollback_sends_nothing", func(t *testing.T) {
		err := lagoon.Transaction(ctx, env.gdb, func(ctx context.Context, tx *gorm.DB) error {
			if err := tx.WithContext(ctx).Create(&Doc{Title: "rolled-back"}).Error; err != nil {
				return err
			}
			return errors.New("rollback")
		})
		if err == nil {
			t.Fatal("transaction did not fail")
		}
		if n := len(env.eng.take()); n != 0 {
			t.Fatalf("%d engine calls after a rollback", n)
		}
	})

	t.Run("single_statement_implicit_commit", func(t *testing.T) {
		d := Doc{Title: "implicit", OwnerID: 1}
		if err := env.gdb.WithContext(ctx).Create(&d).Error; err != nil {
			t.Fatal(err)
		}
		calls := env.eng.take()
		if len(calls) != 1 || calls[0].docs[0]["owner"] != "Owner One" {
			t.Fatalf("calls = %+v", calls)
		}
		d.Title = "implicit-updated"
		if err := env.gdb.WithContext(ctx).Save(&d).Error; err != nil {
			t.Fatal(err)
		}
		if calls := env.eng.take(); len(calls) != 1 || calls[0].docs[0]["title"] != "implicit-updated" {
			t.Fatalf("update calls = %+v", calls)
		}
	})

	t.Run("plain_gorm_transaction_rollback_sends_nothing", func(t *testing.T) {
		rollback := errors.New("roll back plain transaction")
		err := env.gdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
			if err := tx.Create(&Doc{Title: "plain-tx", OwnerID: 1}).Error; err != nil {
				return err
			}
			if calls := env.eng.take(); len(calls) != 0 {
				t.Errorf("inside a plain transaction: calls = %+v, want none", calls)
			}
			return rollback
		})
		if !errors.Is(err, rollback) {
			t.Fatalf("err = %v", err)
		}
		if calls := env.eng.take(); len(calls) != 0 {
			t.Fatalf("after rollback: calls = %+v, want none", calls)
		}
	})

	t.Run("zero_key_batch_update_and_plain_model_are_skipped", func(t *testing.T) {
		if err := env.gdb.WithContext(ctx).Model(&Doc{}).Where("owner_id = ?", 1).Update("hidden", false).Error; err != nil {
			t.Fatal(err)
		}
		if err := env.gdb.WithContext(ctx).Create(&Plain{Name: "plain"}).Error; err != nil {
			t.Fatal(err)
		}
		if n := len(env.eng.take()); n != 0 {
			t.Fatalf("%d engine calls for a batch update or a plain model", n)
		}
	})

	t.Run("batch_create_syncs_each_row", func(t *testing.T) {
		docs := []Doc{{Title: "batch-1"}, {Title: "batch-2"}}
		if err := env.gdb.WithContext(ctx).Create(&docs).Error; err != nil {
			t.Fatal(err)
		}
		if n := len(env.eng.take()); n != 2 {
			t.Fatalf("batch create calls = %d, want 2", n)
		}
	})
}

// TestSyncDeleteAndSoftDelete covers deletes: a hard delete removes the
// document under its SearchKey, a soft delete or a row that should not be
// searchable removes it, a restore re-indexes it, and Sync/Remove follow
// the same gated path.
func TestSyncDeleteAndSoftDelete(t *testing.T) {
	env := newSyncEnv(t, nil, true)
	ctx := context.Background()

	n := Note{Body: "note"}
	if err := env.gdb.WithContext(ctx).Create(&n).Error; err != nil {
		t.Fatal(err)
	}
	if calls := env.eng.take(); len(calls) != 1 || calls[0].docs[0]["id"] != fmt.Sprintf("note-%d", n.ID) || calls[0].schema != nil {
		t.Fatalf("note upsert = %+v", calls)
	}
	if err := env.gdb.WithContext(ctx).Delete(&Note{ID: n.ID}).Error; err != nil {
		t.Fatal(err)
	}
	if calls := env.eng.take(); len(calls) != 1 || calls[0].op != "delete" || calls[0].ids[0] != fmt.Sprintf("note-%d", n.ID) || calls[0].index != "dev_acme_notes" {
		t.Fatalf("note delete = %+v", calls)
	}

	d := Doc{Title: "soft", OwnerID: 1}
	if err := env.gdb.WithContext(ctx).Create(&d).Error; err != nil {
		t.Fatal(err)
	}
	env.eng.take()
	if err := env.gdb.WithContext(ctx).Delete(&d).Error; err != nil {
		t.Fatal(err)
	}
	if calls := env.eng.take(); len(calls) != 1 || calls[0].op != "delete" || calls[0].ids[0] != fmt.Sprint(d.ID) {
		t.Fatalf("soft delete = %+v", calls)
	}
	if err := env.gdb.WithContext(ctx).Unscoped().Model(&d).Update("deleted_at", nil).Error; err != nil {
		t.Fatal(err)
	}
	if calls := env.eng.take(); len(calls) != 1 || calls[0].op != "upsert" {
		t.Fatalf("restore = %+v", calls)
	}
	if err := env.gdb.WithContext(ctx).Model(&d).Update("hidden", true).Error; err != nil {
		t.Fatal(err)
	}
	if calls := env.eng.take(); len(calls) != 1 || calls[0].op != "delete" {
		t.Fatalf("hidden row = %+v, want a delete", calls)
	}

	t.Run("explicit_sync_and_remove", func(t *testing.T) {
		if err := env.gdb.Exec(`UPDATE acme_docs SET hidden = false WHERE id = ?`, d.ID).Error; err != nil {
			t.Fatal(err)
		}
		if err := env.svc.Sync(ctx, nil, &Doc{ID: d.ID}); err != nil {
			t.Fatal(err)
		}
		if err := env.svc.Remove(ctx, env.gdb, &Doc{ID: d.ID}); err != nil {
			t.Fatal(err)
		}
		if err := env.svc.Sync(nil, env.gdb, &Doc{ID: 999999}); err != nil {
			t.Fatal(err)
		}
		calls := env.eng.take()
		if len(calls) != 3 || calls[0].op != "upsert" || calls[1].op != "delete" || calls[2].op != "delete" || calls[2].ids[0] != "999999" {
			t.Fatalf("explicit calls = %+v", calls)
		}
		for _, bad := range []any{Doc{ID: 1}, &Doc{}, &Plain{ID: 1}, (*Doc)(nil), 42} {
			if err := env.svc.Sync(ctx, env.gdb, bad); err == nil {
				t.Errorf("Sync(%T %v) accepted", bad, bad)
			}
		}
		var nilSvc *Service
		if err := nilSvc.Sync(ctx, env.gdb, &Doc{ID: 1}); err == nil {
			t.Fatal("nil service accepted")
		}
	})
}

// TestSyncFailuresNonFatal covers T-11-26: engine errors and panics, a
// failing or panicking document builder, and a failed read inside a
// caller's transaction are each one Warn log with index, key and
// operation, and never touch the write.
func TestSyncFailuresNonFatal(t *testing.T) {
	env := newSyncEnv(t, nil, true)
	ctx := context.Background()
	warnings := func() []map[string]string { return env.logs.take("search: sync failed") }

	for _, mode := range []string{"upsert", "panic"} {
		t.Run("engine_"+mode, func(t *testing.T) {
			env.eng.setFail(mode)
			defer env.eng.setFail("")
			d := Doc{Title: "engine-" + mode, OwnerID: 1}
			if err := env.gdb.WithContext(ctx).Create(&d).Error; err != nil {
				t.Fatalf("an engine failure failed the write: %v", err)
			}
			ws := warnings()
			if len(ws) != 1 || ws[0]["index"] != "dev_acme_docs" || ws[0]["key"] != fmt.Sprint(d.ID) || ws[0]["operation"] != "upsert" || ws[0]["level"] != "WARN" {
				t.Fatalf("warnings = %v", ws)
			}
			if strings.Contains(ws[0]["error"], "test-only-key") {
				t.Fatal("the key reached the log")
			}
		})
	}

	t.Run("delete_error", func(t *testing.T) {
		d := Doc{Title: "delete-error"}
		if err := env.gdb.WithContext(ctx).Create(&d).Error; err != nil {
			t.Fatal(err)
		}
		env.eng.setFail("delete")
		defer env.eng.setFail("")
		if err := env.gdb.WithContext(ctx).Delete(&d).Error; err != nil {
			t.Fatal(err)
		}
		if ws := warnings(); len(ws) != 1 || ws[0]["operation"] != "delete" {
			t.Fatalf("warnings = %v", ws)
		}
	})

	for _, title := range []string{"boom", "panic"} {
		t.Run("document_"+title, func(t *testing.T) {
			env.eng.take()
			if err := env.gdb.WithContext(ctx).Create(&Doc{Title: title}).Error; err != nil {
				t.Fatal(err)
			}
			if ws := warnings(); len(ws) != 1 {
				t.Fatalf("warnings = %v", ws)
			}
			if calls := env.eng.take(); len(calls) != 0 {
				t.Fatalf("a failed document was sent: %+v", calls)
			}
		})
	}

	t.Run("empty_document_is_skipped", func(t *testing.T) {
		if err := env.gdb.WithContext(ctx).Create(&Doc{Title: "empty"}).Error; err != nil {
			t.Fatal(err)
		}
		if ws, calls := warnings(), env.eng.take(); len(ws) != 0 || len(calls) != 0 {
			t.Fatalf("empty document: warnings %v calls %v", ws, calls)
		}
	})

	t.Run("failed_gate_read_keeps_the_callers_transaction", func(t *testing.T) {
		env.svc.SetGate(GateFunc(func(ctx context.Context, db *gorm.DB) bool {
			var n int
			return db.WithContext(ctx).Raw(`SELECT count(*) FROM acme_missing_settings`).Scan(&n).Error == nil
		}))
		defer env.svc.SetGate(nil)
		err := env.gdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
			if err := tx.Create(&Doc{Title: "gate-read-fails"}).Error; err != nil {
				return err
			}
			return tx.Create(&Plain{Name: "still-usable"}).Error
		})
		if err != nil {
			t.Fatalf("a failed gate read aborted the caller's transaction: %v", err)
		}
		if calls := env.eng.take(); len(calls) != 0 {
			t.Fatalf("gate off still sent %+v", calls)
		}
	})

	t.Run("failed_document_read_inside_a_transaction", func(t *testing.T) {
		if err := env.gdb.Exec(`ALTER TABLE acme_owners RENAME TO acme_owners_gone`).Error; err != nil {
			t.Fatal(err)
		}
		defer env.gdb.Exec(`ALTER TABLE acme_owners_gone RENAME TO acme_owners`)
		err := env.gdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
			if err := tx.Create(&Doc{Title: "owner-read-fails"}).Error; err != nil {
				return err
			}
			return tx.Create(&Plain{Name: "still-usable-2"}).Error
		})
		if err != nil {
			t.Fatalf("a failed document read aborted the caller's transaction: %v", err)
		}
		if ws := warnings(); len(ws) != 1 || !strings.Contains(ws[0]["error"], "build document") {
			t.Fatalf("warnings = %v", ws)
		}
	})
}

// TestServiceSetup covers From, the engine registry and the accessors.
func TestServiceSetup(t *testing.T) {
	cfg := func(t *testing.T, kv map[string]any) *backpack.App {
		t.Helper()
		c, err := compass.Open(compass.Options{Dir: t.TempDir(), Env: "testing", Environ: []string{}})
		if err != nil {
			t.Fatal(err)
		}
		for k, v := range kv {
			if err := c.Set(k, v); err != nil {
				t.Fatal(err)
			}
		}
		return backpack.New(c)
	}
	if _, err := From(nil); err == nil {
		t.Fatal("From(nil) succeeded")
	}
	_, err := From(cfg(t, map[string]any{"search.driver": "nope"}))
	if err == nil || !strings.Contains(err.Error(), `unknown search.driver "nope"`) || !strings.Contains(err.Error(), "acme-broken, acme-nil, acme-recording, null") {
		t.Fatalf("unknown driver: %v", err)
	}
	if _, err := From(cfg(t, map[string]any{"search.driver": "acme-broken"})); err == nil || !strings.Contains(err.Error(), "engine config invalid") {
		t.Fatalf("broken engine: %v", err)
	}
	if _, err := From(cfg(t, map[string]any{"search.driver": "acme-nil"})); err == nil || !strings.Contains(err.Error(), "returned nil") {
		t.Fatalf("nil engine: %v", err)
	}
	app := cfg(t, map[string]any{"search.driver": " ACME-Recording ", "search.prefix": " p_ "})
	svc, err := From(app)
	if err != nil {
		t.Fatal(err)
	}
	if again, err := From(app); err != nil || again != svc {
		t.Fatal("From is not idempotent")
	}
	if svc.Prefix() != "p_" || svc.IndexName(&Doc{}) != "p_acme_docs" || svc.IndexName(nil) != "p_" || svc.Logger() == nil {
		t.Fatalf("prefix %q index %q", svc.Prefix(), svc.IndexName(&Doc{}))
	}
	var nilSvc *Service
	nilSvc.SetGate(nil)
	if nilSvc.Engine() != nil || nilSvc.Prefix() != "" || nilSvc.Logger() == nil {
		t.Fatal("nil service accessors")
	}
	if GateFunc(nil).Enabled(context.Background(), nil) {
		t.Fatal("a nil GateFunc is enabled")
	}
	for name, fn := range map[string]func(){
		"empty":     func() { RegisterEngine("", func(*backpack.App) (Engine, error) { return nullEngine{}, nil }) },
		"nil":       func() { RegisterEngine("acme-x", nil) },
		"duplicate": func() { RegisterEngine(NullEngine, func(*backpack.App) (Engine, error) { return nullEngine{}, nil }) },
	} {
		func() {
			defer func() {
				if recover() == nil {
					t.Errorf("RegisterEngine %s did not panic", name)
				}
			}()
			fn()
		}()
	}
	for pk, want := range map[any]string{uint(1): "1", uint32(2): "2", uint64(3): "3", 4: "4", int32(5): "5", int64(6): "6", "k": "k"} {
		if got := searchKey(reflect.ValueOf(Plain{}), pk); got != want {
			t.Errorf("searchKey(%T) = %q", pk, got)
		}
	}
	if got := searchKey(reflect.ValueOf(Note{ID: 7}), uint(7)); got != "note-7" {
		t.Errorf("searchKey of an unaddressable SearchKeyer = %q", got)
	}
}