package configkit_test

import (
	"bytes"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
	"testing/fstest"

	configkit "gitea.maximumdirect.net/eric/ConfigKit"
)

func TestFacadeNoSourcePreservesAbsenceWithSequencePolicy(t *testing.T) {
	t.Parallel()
	for _, defaults := range []bool{false, true} {
		for _, registered := range []bool{false, true} {
			definition := configkit.Definition[map[string]any]{}
			if defaults {
				definition.Defaults = func() map[string]any { return map[string]any{"fallback": true} }
			}
			if registered {
				definition.SequenceCompositions = []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}
			}
			ordinary, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{Definition: definition})
			if err != nil {
				t.Fatal(err)
			}
			layered, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{Definition: definition})
			if err != nil {
				t.Fatal(err)
			}
			if !reflect.DeepEqual(ordinary.Config, layered.Config) {
				t.Fatal("NoSource values differ between entry points")
			}
			for _, result := range []*configkit.Result[map[string]any]{ordinary, layered} {
				if len(result.Sources()) != 0 || result.Metadata().IsExplicit(configkit.Keys()) {
					t.Fatal("NoSource contributed an explicit root")
				}
				info, ok := result.Metadata().Lookup(configkit.Keys())
				if !ok || info.Origin.Layer != configkit.LayerDefault {
					t.Fatalf("NoSource root origin = %#v, %t", info, ok)
				}
			}
			empty, err := configkit.Load(configkit.Mapping("empty", map[string]any{}), configkit.Options[map[string]any]{Definition: definition})
			if err != nil || !empty.Metadata().IsExplicit(configkit.Keys()) {
				t.Fatal("real empty mapping lost its presence")
			}
		}
	}
}

func TestFacadeItemHelperHistoryPreservesTraversalOrder(t *testing.T) {
	t.Parallel()
	filesystem := configkit.NewFilesystem("history", fstest.MapFS{
		"main.yml":         {Data: []byte("records: [{id: authored}]\nconfigkit: {imports: [{path: one.yml, destination: [records], placement: sequence-item}, {path: two.yml, destination: [records], placement: sequence-item}]}\n")},
		"one.yml":          {Data: []byte("id: one\nconfigkit: {imports: [{path: helper-one.yml}, {path: child.yml, destination: [children], placement: sequence-item}]}\n")},
		"two.yml":          {Data: []byte("id: two\nconfigkit: {imports: [{path: helper-two.yml}]}\n")},
		"helper-one.yml":   {Data: []byte("text: first helper\n")},
		"helper-two.yml":   {Data: []byte("text: second helper\n")},
		"child.yml":        {Data: []byte("id: child\nconfigkit: {imports: [{path: child-helper.yml}]}\n")},
		"child-helper.yml": {Data: []byte("text: nested helper\n")},
	})
	result, err := configkit.Load(filesystem.File("main.yml"), configkit.Options[map[string]any]{
		Imports: true, Definition: configkit.Definition[map[string]any]{SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}},
	})
	if err != nil {
		t.Fatal(err)
	}
	sourceOrder := make(map[string]int)
	sourceFiles := make(map[string]string)
	for index, source := range result.Sources() {
		sourceOrder[source.ID] = index
		sourceFiles[source.ID] = source.Path
	}
	for _, test := range []struct {
		path       configkit.Path
		file, text string
	}{
		{configkit.Keys("records").Index(1).Key("text"), "helper-one.yml", "first helper\n"},
		{configkit.Keys("records").Index(2).Key("text"), "helper-two.yml", "second helper\n"},
		{configkit.Keys("records").Index(1).Key("children").Index(0).Key("text"), "child-helper.yml", "nested helper\n"},
	} {
		explanation, ok := result.Explain(test.path)
		if !ok || explanation.Effective.YAML != test.text || len(explanation.History) != 1 {
			t.Fatalf("helper history at %s = %#v", test.path.String(), explanation)
		}
		locations := explanation.History[0].Origin.Locations
		if len(locations) != 1 || sourceFiles[locations[0].SourceID] != test.file {
			t.Fatalf("helper origin at %s = %#v", test.path.String(), locations)
		}
		info, ok := result.Metadata().Lookup(test.path)
		if !ok || len(info.Origin.Locations) != 1 || info.Origin.Locations[0].SourceID != locations[0].SourceID {
			t.Fatal("metadata and explanation disagree")
		}
	}
	explanation, ok := result.Explain(configkit.Keys())
	if !ok {
		t.Fatal("root explanation missing")
	}
	previous := -1
	for _, change := range explanation.History {
		for _, location := range change.Origin.Locations {
			current := sourceOrder[location.SourceID]
			if current < previous {
				t.Fatalf("source %s replayed out of traversal order", location.SourceID)
			}
			previous = current
		}
	}
}

func TestFacadeRegisteredReplacementExplainsRemovedDescendants(t *testing.T) {
	t.Parallel()
	for _, test := range []struct {
		name  string
		upper []any
		path  configkit.Path
	}{
		{"shorter", []any{map[string]any{"id": "main"}}, configkit.Keys("records").Index(1).Key("id")},
		{"empty", []any{}, configkit.Keys("records").Index(0).Key("id")},
		{"removed field", []any{map[string]any{"id": "main"}}, configkit.Keys("records").Index(0).Key("text")},
	} {
		t.Run(test.name, func(t *testing.T) {
			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Mapping("main", map[string]any{"records": test.upper})}, configkit.LayeredOptions[map[string]any]{
				Definition: configkit.Definition[map[string]any]{SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}},
				Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"records": []any{map[string]any{"id": "one", "text": "old"}, map[string]any{"id": "two"}}})}}}},
			})
			if err != nil {
				t.Fatal(err)
			}
			explanation, ok := result.Explain(test.path)
			if !ok || explanation.Effective.Present || len(explanation.History) < 2 {
				t.Fatalf("removal not explained: %#v", explanation)
			}
			last := explanation.History[len(explanation.History)-1]
			if !last.Before.Present || last.After.Present || last.Origin.Layer != configkit.LayerBase || len(last.Origin.Locations) != 1 || last.Origin.Locations[0].SourceID != result.Sources()[0].ID {
				t.Fatalf("wrong removal transition/origin: %#v", last)
			}
		})
	}
}

func TestFacadeSequencePlacementControlsAcrossLoadEntryPoints(t *testing.T) {
	definition := configkit.Definition[map[string]any]{
		SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("entries"), IdentityField: "id"}},
	}
	ordinary, err := configkit.Load(configkit.Mapping("ordinary", map[string]any{"id": "one"}), configkit.Options[map[string]any]{
		Definition: definition, Destination: configkit.Keys("entries"), PlacementMode: configkit.PlacementModeSequenceItem,
	})
	if err != nil {
		t.Fatalf("ordinary item load: %v", err)
	}
	if got := ordinary.Config["entries"].([]any); len(got) != 1 || got[0].(map[string]any)["id"] != "one" {
		t.Fatalf("ordinary item placement = %#v", ordinary.Config)
	}
	if sources := ordinary.Sources(); len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeSequenceItem || sources[0].Destination.String() != "/entries" || sources[0].DestinationUnresolved {
		t.Fatalf("ordinary item source = %#v", sources)
	}

	layered, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{
		Definition: definition,
		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
			{Source: configkit.Mapping("first", map[string]any{"id": "first"}), Destination: configkit.Keys("entries"), PlacementMode: configkit.PlacementModeSequenceItem},
			{Source: configkit.Mapping("second", map[string]any{"id": "second"}), Destination: configkit.Keys("entries"), PlacementMode: configkit.PlacementModeSequenceItem},
		}}},
	})
	if err != nil {
		t.Fatalf("layered item load: %v", err)
	}
	items := layered.Config["entries"].([]any)
	if len(items) != 2 || items[0].(map[string]any)["id"] != "first" || items[1].(map[string]any)["id"] != "second" {
		t.Fatalf("layered item placement = %#v", layered.Config)
	}
	for _, source := range layered.Sources() {
		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationUnresolved {
			t.Errorf("layered item source = %#v", source)
		}
	}

	precedence, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Mapping("main", map[string]any{
		"entries": []any{map[string]any{"id": "main"}},
	})}, configkit.LayeredOptions[map[string]any]{
		Definition: definition,
		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
			Source: configkit.Mapping("lower", map[string]any{"id": "lower"}), Destination: configkit.Keys("entries"), PlacementMode: configkit.PlacementModeSequenceItem,
		}}}},
	})
	if err != nil {
		t.Fatalf("registered sequence precedence load: %v", err)
	}
	if got := precedence.Config["entries"].([]any); len(got) != 1 || got[0].(map[string]any)["id"] != "main" {
		t.Fatalf("higher-priority list did not replace the lower sequence: %#v", precedence.Config)
	}

	for _, test := range []struct {
		name string
		load func(configkit.Source) error
	}{
		{name: "ordinary", load: func(source configkit.Source) error {
			_, loadErr := configkit.Load(source, configkit.Options[map[string]any]{PlacementMode: configkit.PlacementMode(9)})
			return loadErr
		}},
		{name: "layered", load: func(source configkit.Source) error {
			_, loadErr := configkit.LoadLayered[map[string]any](configkit.Input{Source: source, PlacementMode: configkit.PlacementMode(9)})
			return loadErr
		}},
	} {
		t.Run(test.name, func(t *testing.T) {
			reader := &destinationCountingReader{}
			err := test.load(configkit.Reader("unread", reader))
			loadError, ok := err.(*configkit.LoadError)
			if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeOptionsInvalid || reader.reads != 0 {
				t.Fatalf("invalid placement result = %v, reads = %d", err, reader.reads)
			}
		})
	}
}

func TestFacadeItemImportGlobComposesWithAuthoredSequence(t *testing.T) {
	directory := t.TempDir()
	mainPath := filepath.Join(directory, "main.yml")
	if err := os.WriteFile(mainPath, []byte(`configkit:
  imports:
    - glob: records/*.yml
      destination: [items]
      placement: sequence-item
items:
  - id: authored
    name: authored item
`), 0o600); err != nil {
		t.Fatal(err)
	}
	for name, id := range map[string]string{"b.yml": "imported-b", "a.yml": "imported-a"} {
		if err := os.MkdirAll(filepath.Join(directory, "records"), 0o755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filepath.Join(directory, "records", name), []byte("id: "+id+"\n"), 0o600); err != nil {
			t.Fatal(err)
		}
	}
	var callbackSources []configkit.SourceInfo
	var callbackContexts []configkit.ResourceContext
	result, err := configkit.Load(configkit.File(mainPath), configkit.Options[map[string]any]{
		Imports: true,
		Definition: configkit.Definition[map[string]any]{
			SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("items"), IdentityField: "id"}},
			Resolve: func(_ *map[string]any, resolution *configkit.Resolution) error {
				for _, id := range []string{"source-2", "source-3"} {
					source, ok := resolution.Source(id)
					if !ok {
						t.Errorf("resolver could not query %s", id)
						continue
					}
					context, found := resolution.SourceContext(id)
					if !found || context.FS == nil || context.BaseDir != "records" {
						t.Errorf("resolver context for %s = %#v, %v", id, context, found)
					}
					callbackSources = append(callbackSources, source)
					callbackContexts = append(callbackContexts, context)
				}
				return nil
			},
		},
	})
	if err != nil {
		t.Fatalf("load item glob: %v", err)
	}
	items := result.Config["items"].([]any)
	wantIDs := []string{"authored", "imported-a", "imported-b"}
	for index, item := range items {
		if got := item.(map[string]any)["id"]; got != wantIDs[index] {
			t.Errorf("item %d ID = %#v, want %q", index, got, wantIDs[index])
		}
	}
	if len(callbackSources) != 2 || len(callbackContexts) != 2 {
		t.Fatalf("callback snapshots = %#v, contexts %#v", callbackSources, callbackContexts)
	}
	for index, source := range callbackSources {
		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/items" || source.DestinationUnresolved {
			t.Errorf("callback source = %#v", source)
		}
		if callbackContexts[index].FS == nil || callbackContexts[index].BaseDir != "records" {
			t.Errorf("callback context = %#v", callbackContexts[index])
		}
	}
	metadata := result.Metadata()
	for index := 1; index < len(wantIDs); index++ {
		path := configkit.Keys("items").Index(index).Key("id")
		info, ok := metadata.Lookup(path)
		if !ok || !info.Explicit || len(info.Origin.Locations) != 1 || info.Origin.Locations[0].SourceID != []string{"source-2", "source-3"}[index-1] {
			t.Errorf("shifted item origin at %s = %#v, %v", path.String(), info, ok)
		}
	}
	if got := result.Sources(); len(got) != 3 || got[1].Destination.String() != "/items" || got[1].DestinationUnresolved {
		t.Fatalf("final item sources = %#v", got)
	}
}

func TestFacadeItemDestinationFallbackEvidenceSurvivesFailures(t *testing.T) {
	directory := t.TempDir()
	mainPath := filepath.Join(directory, "main.yml")
	helperPath := filepath.Join(directory, "helper.yml")
	if err := os.WriteFile(mainPath, []byte("configkit: {imports: [{path: helper.yml, destination: [metadata]}]}\nid: main\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(helperPath, []byte("value: [unterminated\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	_, err := configkit.Load(configkit.File(mainPath), configkit.Options[map[string]any]{
		Imports: true, Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem,
	})
	loadError, ok := err.(*configkit.LoadError)
	if !ok {
		t.Fatalf("early failure = %v", err)
	}
	sources := loadError.Sources()
	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationUnresolved ||
		sources[0].PlacementMode != configkit.PlacementModeSequenceItem ||
		sources[1].Destination.String() != "/items" || !sources[1].DestinationUnresolved ||
		sources[1].PlacementMode != configkit.PlacementModeMapping {
		t.Fatalf("early source snapshots = %#v", sources)
	}

	if err := os.WriteFile(helperPath, []byte("value: invalid-for-typed-schema\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	type item struct {
		ID       string `yaml:"id"`
		Metadata struct {
			Value int `yaml:"value"`
		} `yaml:"metadata"`
	}
	type configuration struct {
		Items []item `yaml:"items"`
	}
	_, err = configkit.Load(configkit.File(mainPath), configkit.Options[configuration]{
		Imports: true, Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem,
	})
	loadError, ok = err.(*configkit.LoadError)
	if !ok {
		t.Fatalf("post-placement failure = %v", err)
	}
	sources = loadError.Sources()
	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationUnresolved ||
		sources[1].Destination.String() != "/items/0/metadata" || sources[1].DestinationUnresolved {
		t.Fatalf("post-placement source snapshots = %#v", sources)
	}
	firstSnapshot := sources[1]
	sources[1].Destination = configkit.Keys("mutated")
	if again := loadError.Sources(); len(again) != 2 || again[1].Destination.String() != firstSnapshot.Destination.String() || again[1].DestinationUnresolved {
		t.Fatalf("failure source snapshots were aliased: %#v", again)
	}

	var callback configkit.SourceInfo
	_, err = configkit.Load(configkit.File(mainPath), configkit.Options[map[string]any]{
		Imports: true, Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem,
		Definition: configkit.Definition[map[string]any]{Resolve: func(_ *map[string]any, resolution *configkit.Resolution) error {
			callback, _ = resolution.Source("source-2")
			return nil
		}},
	})
	if err != nil {
		t.Fatalf("successful item load: %v", err)
	}
	if callback.Destination.String() != "/items/0/metadata" || callback.DestinationUnresolved || callback.PlacementMode != configkit.PlacementModeMapping {
		t.Fatalf("callback source snapshot = %#v", callback)
	}
}

func TestFacadeNestedItemFallbackUsesNearestResolvedContainer(t *testing.T) {
	directory := t.TempDir()
	mainPath := filepath.Join(directory, "main.yml")
	childPath := filepath.Join(directory, "child.yml")
	helperPath := filepath.Join(directory, "helper.yml")
	if err := os.WriteFile(mainPath, []byte("configkit: {imports: [{path: child.yml, destination: [children], placement: sequence-item}]}\nid: parent\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(childPath, []byte("configkit: {imports: [{path: helper.yml, destination: [metadata]}]}\nid: child\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(helperPath, []byte("value: [unterminated\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	_, err := configkit.Load(configkit.File(mainPath), configkit.Options[map[string]any]{
		Imports: true, Destination: configkit.Keys("groups"), PlacementMode: configkit.PlacementModeSequenceItem,
	})
	loadError, ok := err.(*configkit.LoadError)
	if !ok {
		t.Fatalf("nested acquisition failure = %v", err)
	}
	sources := loadError.Sources()
	if len(sources) != 3 {
		t.Fatalf("nested source snapshots = %#v", sources)
	}
	if got := sources[0]; got.Destination.String() != "/groups" || got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeSequenceItem {
		t.Errorf("outer item snapshot = %#v", got)
	}
	if got := sources[1]; got.Destination.String() != "/groups" || !got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeSequenceItem {
		t.Errorf("nested item fallback = %#v", got)
	}
	if got := sources[2]; got.Destination.String() != "/groups" || !got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeMapping {
		t.Errorf("nested helper fallback = %#v", got)
	}
}

func TestFacadeSequenceCompositionRegistrationPathIsDetached(t *testing.T) {
	registrations := []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}
	definition := configkit.Definition[map[string]any]{
		SequenceCompositions: registrations,
		Version: &configkit.VersionRule{
			Path: configkit.Keys("version"),
			Check: func(configkit.Version, *configkit.Validation) error {
				registrations[0].Path = configkit.Keys("other")
				registrations[0].IdentityField = "changed"
				return nil
			},
		},
	}
	_, err := configkit.Load(configkit.Mapping("registration", map[string]any{
		"version": "1",
		"records": []any{map[string]any{"id": "same"}, map[string]any{"id": "same"}},
	}), configkit.Options[map[string]any]{
		Definition: definition, SourceVersionMode: configkit.SourceVersionModeIfPresent,
	})
	loadError, ok := err.(*configkit.LoadError)
	if !ok {
		t.Fatalf("duplicate registered identity = %v", err)
	}
	for _, diagnostic := range loadError.Diagnostics() {
		if diagnostic.Code == configkit.CodeComposeConflict {
			return
		}
	}
	t.Fatalf("registration mutation changed the in-flight policy: %#v", loadError.Diagnostics())
}

func TestFacadeSourceInfoPlacementCopiesAndZeroValues(t *testing.T) {
	zero := configkit.SourceInfo{}
	if zero.PlacementMode != configkit.PlacementModeMapping || zero.DestinationUnresolved {
		t.Fatalf("zero source info = %#v", zero)
	}
	loaded, err := configkit.Load[map[string]any](configkit.Mapping("mapping", map[string]any{"value": true}))
	if err != nil {
		t.Fatal(err)
	}
	sources := loaded.Sources()
	if len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeMapping || sources[0].DestinationUnresolved {
		t.Fatalf("mapping source evidence = %#v", sources)
	}
	first := sources[0]
	first.Destination = configkit.Keys("caller")
	if again := loaded.Sources(); len(again) != 1 || again[0].Destination.String() != "" || again[0].DestinationUnresolved {
		t.Fatalf("source evidence changed after caller mutation: %#v", again)
	}
}

func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *testing.T) {
	type record struct {
		ID       string  `yaml:"id"`
		Count    int     `yaml:"count"`
		Enabled  bool    `yaml:"enabled"`
		Empty    string  `yaml:"empty"`
		Nullable *string `yaml:"nullable"`
		Token    string  `yaml:"token"`
		Omitted  string  `yaml:"omitted"`
	}
	type configuration struct {
		Entries []record `yaml:"entries"`
	}

	directory := t.TempDir()
	mainPath := filepath.Join(directory, "main.yml")
	underlayPath := filepath.Join(directory, "underlay.yml")
	if err := os.WriteFile(mainPath, []byte(`entries:
  - id: current
    count: 0
    enabled: false
    empty: ""
    nullable: null
    token: CURRENT-SECRET-CANARY
`), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(underlayPath, []byte(`configkit:
  imports:
    - glob: records/*.yml
      destination: [entries]
      placement: sequence-item
`), 0o600); err != nil {
		t.Fatal(err)
	}
	recordsDir := filepath.Join(directory, "records")
	if err := os.MkdirAll(recordsDir, 0o700); err != nil {
		t.Fatal(err)
	}
	for name, body := range map[string]string{
		"a.yml": "id: old-a\ntoken: OLD-SECRET-CANARY-A\n",
		"b.yml": "id: old-b\ntoken: OLD-SECRET-CANARY-B\n",
	} {
		if err := os.WriteFile(filepath.Join(recordsDir, name), []byte(body), 0o600); err != nil {
			t.Fatal(err)
		}
	}

	var callbackItems []configkit.SourceInfo
	var callbackContexts []configkit.ResourceContext
	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.File(mainPath)}, configkit.LayeredOptions[configuration]{
		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.File(underlayPath), Imports: true}}}},
		Definition: configkit.Definition[configuration]{
			SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("entries"), IdentityField: "id"}},
			Secret: func(path configkit.Path) bool {
				return path.String() == "/entries/0/token" || path.String() == "/entries/1/token"
			},
			Resolve: func(value *configuration, resolution *configkit.Resolution) error {
				for _, field := range []string{"count", "enabled", "empty", "nullable"} {
					path := configkit.Keys("entries").Index(0).Key(field)
					if !resolution.IsExplicit(path) {
						t.Errorf("resolver did not see explicit %s", path.String())
					}
				}
				if resolution.IsExplicit(configkit.Keys("entries").Index(0).Key("omitted")) {
					t.Error("resolver treated an omitted field as explicit")
				}
				info, found := resolution.InputInfo(configkit.Keys("entries").Index(0).Key("count"))
				if !found || info.Origin.Layer != configkit.LayerBase {
					t.Errorf("resolver current-record input info = %#v, %v", info, found)
				}
				for _, id := range []string{"source-3", "source-4"} {
					source, ok := resolution.Source(id)
					if !ok {
						t.Errorf("resolver could not query %s", id)
						continue
					}
					context, contextOK := resolution.SourceContext(id)
					if !contextOK || context.FS == nil || context.BaseDir != "records" {
						t.Errorf("resolver context for %s = %#v, %v", id, context, contextOK)
					}
					callbackItems = append(callbackItems, source)
					callbackContexts = append(callbackContexts, context)
				}
				return nil
			},
		},
	})
	if err != nil {
		if loadError, ok := err.(*configkit.LoadError); ok {
			t.Fatalf("layered item replacement: %#v", loadError.Diagnostics())
		}
		t.Fatalf("layered item replacement: %v", err)
	}
	if len(result.Config.Entries) != 1 || result.Config.Entries[0].ID != "current" || result.Config.Entries[0].Count != 0 ||
		result.Config.Entries[0].Enabled || result.Config.Entries[0].Empty != "" || result.Config.Entries[0].Nullable != nil {
		t.Fatalf("typed replacement result = %#v", result.Config)
	}
	if len(callbackItems) != 2 || len(callbackContexts) != 2 {
		t.Fatalf("callback sources = %#v; contexts = %#v", callbackItems, callbackContexts)
	}
	for _, source := range callbackItems {
		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationUnresolved {
			t.Errorf("callback item source = %#v", source)
		}
	}
	metadata := result.Metadata()
	for _, field := range []string{"count", "enabled", "empty", "nullable"} {
		path := configkit.Keys("entries").Index(0).Key(field)
		if info, ok := metadata.Lookup(path); !ok || !info.Explicit || (field == "nullable") != info.Null {
			t.Errorf("explicit metadata at %s = %#v, %v", path.String(), info, ok)
		}
	}
	if info, ok := metadata.Lookup(configkit.Keys("entries").Index(0).Key("omitted")); ok && info.Explicit {
		t.Errorf("metadata marked an omitted zero-valued field explicit: %#v", info)
	}
	mainID := ""
	for _, source := range result.Sources() {
		if source.Path == mainPath {
			mainID = source.ID
		}
	}
	currentOrigin, ok := metadata.Lookup(configkit.Keys("entries").Index(0).Key("id"))
	if !ok || len(currentOrigin.Origin.Locations) != 1 || currentOrigin.Origin.Locations[0].SourceID != mainID || mainID == "" {
		t.Fatalf("replacement origin = %#v, main source %q", currentOrigin, mainID)
	}
	oldRecord, ok := result.Explain(configkit.Keys("entries").Index(1).Key("token"))
	if !ok || oldRecord.Effective.Present {
		t.Fatalf("removed appended item explanation = %#v, %v", oldRecord, ok)
	}
	maskedHistory := false
	for _, change := range oldRecord.History {
		maskedHistory = maskedHistory || change.Before.Redacted || change.After.Redacted
	}
	if !maskedHistory {
		t.Fatal("removed appended item lost historical sensitivity")
	}
	var effective bytes.Buffer
	if err := result.WriteEffective(&effective); err != nil {
		t.Fatal(err)
	}
	var explanation bytes.Buffer
	if err := result.WriteExplanation(&explanation, configkit.Keys("entries").Index(1).Key("token")); err != nil {
		t.Fatal(err)
	}
	for _, output := range []string{effective.String(), explanation.String()} {
		for _, canary := range []string{"CURRENT-SECRET-CANARY", "OLD-SECRET-CANARY-A", "OLD-SECRET-CANARY-B"} {
			if strings.Contains(output, canary) {
				t.Fatalf("sensitive sequence value leaked: %s", output)
			}
		}
	}
}