package engine

import (
	"path/filepath"
	"testing"
	"testing/fstest"
)

type importDestinationConfig struct {
	Mounted     map[string]string            `yaml:"mounted"`
	Collections map[string]map[string]string `yaml:"collections"`
}

func TestLayeredHostImportsInheritInputDestinationTransitively(t *testing.T) {
	t.Parallel()

	directory := t.TempDir()
	mainPath := writeImportFile(t, directory, "main.yml", `configkit:
  imports:
    - path: first.yml
    - path: second.yml
root: main
`)
	firstPath := writeImportFile(t, directory, "first.yml", `configkit:
  imports:
    - path: nested/third.yml
first: one
`)
	thirdPath := writeImportFile(t, directory, "nested/third.yml", "nested: three\n")
	secondPath := writeImportFile(t, directory, "second.yml", "second: two\n")

	loaded, err := LoadLayered(
		Input{Source: File(mainPath), Imports: true, Destination: Keys("mounted")},
		testSecretBinding(),
		LayeredOptions[importDestinationConfig]{},
	)
	if err != nil {
		if loadError, ok := err.(*LoadError); ok {
			t.Fatalf("LoadLayered diagnostics: %#v", loadError.Diagnostics())
		}
		t.Fatalf("LoadLayered: %v", err)
	}
	result := testLoaded(loaded)
	want := map[string]string{"root": "main", "first": "one", "nested": "three", "second": "two"}
	if len(result.Config.Mounted) != len(want) {
		t.Fatalf("mounted values = %#v", result.Config.Mounted)
	}
	for key, value := range want {
		if result.Config.Mounted[key] != value {
			t.Errorf("mounted[%q] = %q, want %q", key, result.Config.Mounted[key], value)
		}
	}
	if _, ok := result.Metadata().Lookup(Keys("mounted", "configkit")); ok {
		t.Fatal("source-root import directive leaked into application content")
	}
	sources := result.Sources()
	wantPaths := []string{canonicalTestPath(t, mainPath), canonicalTestPath(t, firstPath), canonicalTestPath(t, thirdPath), canonicalTestPath(t, secondPath)}
	if len(sources) != len(wantPaths) {
		t.Fatalf("sources = %#v", sources)
	}
	for index, source := range sources {
		if source.Destination.String() != "/mounted" {
			t.Errorf("source %d destination = %q", index, source.Destination.String())
		}
		if source.Path != wantPaths[index] {
			t.Errorf("source %d path = %q, want %q", index, source.Path, wantPaths[index])
		}
		if index > 0 && source.ImportedFrom == nil {
			t.Errorf("imported source %d has no physical import location", index)
		}
	}
}

func TestImportTraversalUsesPerDeclarationDestinations(t *testing.T) {
	t.Parallel()

	directory := t.TempDir()
	mainPath := writeImportFile(t, directory, "main.yml", `configkit:
  imports:
    - path: parent.yml
    - path: sibling.yml
    - glob: fragments/*.yml
`)
	parentPath := writeImportFile(t, directory, "parent.yml", `configkit:
  imports:
    - path: nested/child.yml
parent: true
`)
	childPath := writeImportFile(t, directory, "nested/child.yml", "child: true\n")
	siblingPath := writeImportFile(t, directory, "sibling.yml", "sibling: true\n")
	alphaPath := writeImportFile(t, directory, "fragments/a.yml", "alpha: true\n")
	betaPath := writeImportFile(t, directory, "fragments/b.yml", "beta: true\n")

	main := parseImportMain(t, mainPath)
	_, declarations, diagnostics := splitImportDirectives(main.document)
	if len(diagnostics) != 0 {
		t.Fatalf("main directive diagnostics = %#v", diagnostics)
	}
	declarations[0].destination = Keys("parent")
	declarations[1].destination = Keys("sibling")
	declarations[2].destination = Keys("collection")

	access, err := openHostAccess(directory)
	if err != nil {
		t.Fatal(err)
	}
	defer func() { _ = access.close() }()
	state := importTraversal{
		access: access, accounting: &importAccounting{}, limits: defaultImportLimits(),
		active: make(map[resourceIdentity]int), visited: make(map[resourceIdentity]importRoute),
	}
	if diagnostics := state.walkDeclarations(directory, declarations, 0, Keys("entry")); len(diagnostics) != 0 {
		t.Fatalf("walk diagnostics = %#v", diagnostics)
	}

	wantSources := []struct {
		path        string
		destination string
	}{
		{path: parentPath, destination: "/entry/parent"},
		{path: childPath, destination: "/entry/parent"},
		{path: siblingPath, destination: "/entry/sibling"},
		{path: alphaPath, destination: "/entry/collection"},
		{path: betaPath, destination: "/entry/collection"},
	}
	if len(state.sources) != len(wantSources) {
		t.Fatalf("import sources = %#v, want %d", state.sources, len(wantSources))
	}
	for index, want := range wantSources {
		got := state.sources[index]
		if got.Path != canonicalTestPath(t, want.path) || got.Destination.String() != want.destination {
			t.Errorf("source %d = (%q, %q), want (%q, %q)", index, got.Path, got.Destination.String(), canonicalTestPath(t, want.path), want.destination)
		}
	}

	composed, diagnostics := composeDocuments(state.documents...)
	if len(diagnostics) != 0 {
		t.Fatalf("composition diagnostics = %#v", diagnostics)
	}
	for _, path := range []Path{
		Keys("entry", "parent", "parent"), Keys("entry", "parent", "child"),
		Keys("entry", "sibling", "sibling"), Keys("entry", "collection", "alpha"),
		Keys("entry", "collection", "beta"),
	} {
		if _, present := documentAtPath(composed.root, path); !present {
			t.Errorf("no composed value at %q", path.String())
		}
	}
}

func TestEntryDestinationSurvivesImportSetupAndParseFailures(t *testing.T) {
	t.Parallel()

	t.Run("import context failure", func(t *testing.T) {
		directory := t.TempDir()
		mainPath := writeImportFile(t, directory, "main.yml", "configkit: {imports: [{path: child.yml}]}\n")
		input, diagnostics := assembleBaseInputTracked(
			File(mainPath),
			Options[map[string]any]{Imports: true, Filesystem: &FilesystemContext{Root: t.TempDir()}},
			Keys("mounted"), &importAccounting{}, nil, nil,
		)
		if len(diagnostics) != 1 || diagnostics[0].Code != CodeImportOutsideRoot {
			t.Fatalf("context diagnostics = %#v", diagnostics)
		}
		if len(input.sources) != 1 || input.sources[0].Destination.String() != "/mounted" {
			t.Fatalf("entry source fallback = %#v", input.sources)
		}
	})

	t.Run("imported parse failure", func(t *testing.T) {
		directory := t.TempDir()
		mainPath := writeImportFile(t, directory, "main.yml", "configkit: {imports: [{path: broken.yml}]}\n")
		writeImportFile(t, directory, "broken.yml", "broken: [\n")
		input, diagnostics := assembleBaseInputTracked(
			File(mainPath), Options[map[string]any]{Imports: true},
			Keys("mounted"), &importAccounting{}, nil, nil,
		)
		if len(diagnostics) != 1 || diagnostics[0].Code != CodeYAMLInvalid {
			t.Fatalf("parse diagnostics = %#v", diagnostics)
		}
		if len(input.sources) != 2 {
			t.Fatalf("parse-failure sources = %#v", input.sources)
		}
		for index, source := range input.sources {
			if source.Destination.String() != "/mounted" {
				t.Errorf("source %d destination = %q, want /mounted", index, source.Destination.String())
			}
		}
	})
}

func TestRelativeImportDestinationsKeepStrictCompositionBoundaries(t *testing.T) {
	t.Parallel()

	for _, test := range []struct {
		name     string
		main     string
		files    map[string]string
		want     map[string]any
		conflict bool
		wantPath string
	}{
		{
			name:  "disjoint peers at one destination",
			main:  "configkit:\n  imports:\n    - path: left.yml\n      destination: [application]\n    - path: right.yml\n      destination: [application]\n",
			files: map[string]string{"left.yml": "left: one\n", "right.yml": "right: two\n"},
			want:  map[string]any{"/application/left": "one", "/application/right": "two"},
		},
		{
			name:  "different destinations",
			main:  "configkit:\n  imports:\n    - path: left.yml\n      destination: [left]\n    - path: right.yml\n      destination: [right]\n",
			files: map[string]string{"left.yml": "value: shared\n", "right.yml": "value: shared\n"},
			want:  map[string]any{"/left/value": "shared", "/right/value": "shared"},
		},
		{
			name:  "ancestor and descendant overlap",
			main:  "configkit:\n  imports:\n    - path: parent.yml\n      destination: [application]\n    - path: child.yml\n      destination: [application, branch]\n",
			files: map[string]string{"parent.yml": "branch: {base: one}\n", "child.yml": "leaf: two\n"},
			want:  map[string]any{"/application/branch/base": "one", "/application/branch/leaf": "two"},
		},
		{
			name:     "collision with explicitly wrapped content",
			main:     "configkit: {imports: [{path: fragment.yml, destination: [application]}]}\napplication: {value: root}\n",
			files:    map[string]string{"fragment.yml": "value: imported\n"},
			conflict: true,
			wantPath: "/application/value",
		},
		{
			name:     "equal peer values conflict",
			main:     "configkit:\n  imports:\n    - path: left.yml\n      destination: [application]\n    - path: right.yml\n      destination: [application]\n",
			files:    map[string]string{"left.yml": "value: same\n", "right.yml": "value: same\n"},
			conflict: true,
			wantPath: "/application/value",
		},
		{
			name:     "unequal peer values conflict",
			main:     "configkit:\n  imports:\n    - path: left.yml\n      destination: [application]\n    - path: right.yml\n      destination: [application]\n",
			files:    map[string]string{"left.yml": "value: left\n", "right.yml": "value: right\n"},
			conflict: true,
			wantPath: "/application/value",
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			directory := t.TempDir()
			mainPath := writeImportFile(t, directory, "main.yml", test.main)
			for name, body := range test.files {
				writeImportFile(t, directory, name, body)
			}
			loaded, err := LoadLayered(
				Input{Source: File(mainPath), Imports: true}, testSecretBinding(),
				LayeredOptions[map[string]any]{},
			)
			if test.conflict {
				if loaded != nil || groupedErrorCode(t, err) != CodeComposeConflict {
					t.Fatalf("relative import composition = %#v, %v", loaded, err)
				}
				loadError := err.(*LoadError)
				if diagnostics := loadError.Diagnostics(); diagnostics[0].Path.String() != test.wantPath {
					t.Fatalf("conflict path = %q, want %q", diagnostics[0].Path.String(), test.wantPath)
				}
				return
			}
			if err != nil {
				t.Fatalf("relative import composition: %v", err)
			}
			configuration := testLoaded(loaded).Config
			for path, want := range test.want {
				parsed, err := ParsePath(path)
				if err != nil {
					t.Fatal(err)
				}
				keys := make([]string, len(parsed.segments))
				for index, segment := range parsed.segments {
					keys[index] = segment.key
				}
				if got := layeredMapValue(t, configuration, keys...); got != want {
					t.Errorf("value at %s = %#v, want %#v", path, got, want)
				}
			}
		})
	}

	t.Run("upper tier cannot repair a lower import conflict", func(t *testing.T) {
		directory := t.TempDir()
		lowerPath := writeImportFile(t, directory, "lower.yml", `configkit:
  imports:
    - path: left.yml
      destination: [application]
    - path: right.yml
      destination: [application]
`)
		writeImportFile(t, directory, "left.yml", "value: left\n")
		writeImportFile(t, directory, "right.yml", "value: right\n")
		loaded, err := LoadLayered(
			Input{Source: Bytes("upper", []byte("application: {value: upper}\n"))},
			testSecretBinding(),
			LayeredOptions[map[string]any]{Underlays: []Underlay{{Inputs: []Input{{Source: File(lowerPath), Imports: true}}}}},
		)
		if loaded != nil || groupedErrorCode(t, err) != CodeComposeConflict {
			t.Fatalf("upper tier repaired a lower conflict: %#v, %v", loaded, err)
		}
	})
}

func TestRelativeImportDestinationsUseEffectiveVersionOwnership(t *testing.T) {
	t.Parallel()

	for _, test := range []struct {
		name     string
		rulePath Path
		fragment string
	}{
		{name: "direct claim", rulePath: Keys("collection", "group", "nested", "version"), fragment: "version: v2\n"},
		{name: "ancestor claim", rulePath: Keys("collection", "group", "nested", "schema", "version"), fragment: "schema: null\n"},
	} {
		t.Run(test.name, func(t *testing.T) {
			directory := t.TempDir()
			mainPath := writeImportFile(t, directory, "main.yml", `configkit:
  imports:
    - path: parent.yml
      destination: [group]
`)
			writeImportFile(t, directory, "parent.yml", `configkit:
  imports:
    - path: fragment.yml
      destination: [nested]
`)
			writeImportFile(t, directory, "fragment.yml", test.fragment)
			_, err := LoadLayered(
				Input{Source: File(mainPath), Imports: true, Destination: Keys("collection")},
				testSecretBinding(),
				LayeredOptions[map[string]any]{Definition: Definition[map[string]any]{Version: &VersionRule{
					Path: test.rulePath, Check: func(Version, *Validation) error { return nil },
				}}},
			)
			if groupedErrorCode(t, err) != CodeImportVersion {
				t.Fatalf("effective imported claim error = %v", err)
			}
			loadError := err.(*LoadError)
			diagnostic := loadError.Diagnostics()[0]
			if diagnostic.Path.String() != test.rulePath.String() || diagnostic.Primary == nil || diagnostic.Primary.SourceID != "source-3" {
				t.Fatalf("effective version diagnostic = %#v", diagnostic)
			}
			sources := loadError.Sources()
			wantDestinations := []string{"/collection", "/collection/group", "/collection/group/nested"}
			if len(sources) != len(wantDestinations) {
				t.Fatalf("version failure sources = %#v", sources)
			}
			for index, source := range sources {
				if source.Destination.String() != wantDestinations[index] {
					t.Errorf("source %d destination = %q, want %q", index, source.Destination.String(), wantDestinations[index])
				}
			}
		})
	}
}

func TestRelativeImportDestinationsKeepMainVersionCheckScoped(t *testing.T) {
	t.Parallel()

	type config struct {
		Collection struct {
			SchemaVersion string         `yaml:"schema_version"`
			Group         map[string]any `yaml:"group"`
		} `yaml:"collection"`
	}
	directory := t.TempDir()
	mainPath := writeImportFile(t, directory, "main.yml", `configkit:
  imports:
    - path: parent.yml
      destination: [group]
schema_version: 6
`)
	writeImportFile(t, directory, "parent.yml", `configkit:
  imports:
    - path: fragment.yml
      destination: [nested]
`)
	writeImportFile(t, directory, "fragment.yml", "version: 7\n")
	checks := 0
	loaded, err := LoadLayered(
		Input{Source: File(mainPath), Imports: true, Destination: Keys("collection")},
		testSecretBinding(),
		LayeredOptions[config]{Definition: Definition[config]{Version: &VersionRule{
			Path: Keys("collection", "schema_version"),
			Check: func(version Version, _ *Validation) error {
				checks++
				if !version.Present || version.Text != "6" {
					t.Errorf("main-owned version = %#v", version)
				}
				return nil
			},
		}}},
	)
	if err != nil {
		t.Fatalf("ordinary nested imported version was rejected: %v", err)
	}
	result := testLoaded(loaded)
	if checks != 1 || result.Config.Collection.SchemaVersion != "6" {
		t.Fatalf("main version callback/value = %d/%q", checks, result.Config.Collection.SchemaVersion)
	}
	nested, ok := result.Config.Collection.Group["nested"].(map[string]any)
	if !ok {
		t.Fatalf("nested imported payload = %#v", result.Config.Collection.Group["nested"])
	}
	if got, ok := nested["version"].(int64); !ok || got != 7 {
		t.Fatalf("ordinary nested version = %#v, want integer payload 7", nested["version"])
	}
}

func TestLayeredNativeFilesystemImportsInheritInputDestination(t *testing.T) {
	t.Parallel()

	native := fstest.MapFS{
		"main.yml":   &fstest.MapFile{Data: []byte("configkit:\n  imports:\n    - path: first.yml\nroot: main\n")},
		"first.yml":  &fstest.MapFile{Data: []byte("configkit: {imports: [{path: nested.yml}]}\nfirst: imported\n")},
		"nested.yml": &fstest.MapFile{Data: []byte("nested: imported\n")},
	}
	namespace := newNativeNamespace("bundle", native)
	loaded, err := LoadLayered(
		Input{Source: filesystemFile(namespace, "main.yml"), Imports: true, Destination: Keys("mounted")},
		testSecretBinding(),
		LayeredOptions[importDestinationConfig]{},
	)
	if err != nil {
		if loadError, ok := err.(*LoadError); ok {
			t.Fatalf("LoadLayered diagnostics: %#v", loadError.Diagnostics())
		}
		t.Fatalf("LoadLayered: %v", err)
	}
	result := testLoaded(loaded)
	if result.Config.Mounted["root"] != "main" || result.Config.Mounted["first"] != "imported" || result.Config.Mounted["nested"] != "imported" {
		t.Fatalf("mounted native filesystem values = %#v", result.Config.Mounted)
	}
	sources := result.Sources()
	if len(sources) != 3 || sources[0].Destination.String() != "/mounted" || sources[1].Destination.String() != "/mounted" || sources[2].Destination.String() != "/mounted" {
		t.Fatalf("native source destinations = %#v", sources)
	}
}

func TestLayeredImportOnlyInputMaterializesDestination(t *testing.T) {
	t.Parallel()

	directory := t.TempDir()
	mainPath := writeImportFile(t, directory, "main.yml", `configkit:
  imports:
    - path: optional.yml
      optional: true
`)
	loaded, err := LoadLayered(
		Input{Source: File(mainPath), Imports: true, Destination: Keys("collections", "empty")},
		testSecretBinding(),
		LayeredOptions[importDestinationConfig]{},
	)
	if err != nil {
		t.Fatalf("LoadLayered: %v", err)
	}
	result := testLoaded(loaded)
	info, ok := result.Metadata().Lookup(Keys("collections", "empty"))
	if !ok || !info.Explicit {
		t.Fatalf("import-only body destination = %#v, %v", info, ok)
	}
	sources := result.Sources()
	if len(sources) != 1 || sources[0].Destination.String() != "/collections/empty" {
		t.Fatalf("sources = %#v", sources)
	}
}

func TestLayeredImportedVersionClaimsUseEffectiveDestination(t *testing.T) {
	t.Parallel()

	for _, test := range []struct {
		name        string
		rulePath    Path
		destination Path
		wantCode    Code
	}{
		{name: "protected effective path", rulePath: Keys("mounted", "version"), destination: Keys("mounted"), wantCode: CodeImportVersion},
		{name: "ordinary nested domain version", rulePath: Keys("version"), destination: Keys("collections", "entry")},
	} {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()
			directory := t.TempDir()
			writeImportFile(t, directory, "main.yml", "configkit: {imports: [{path: fragment.yml}]}\n")
			writeImportFile(t, directory, "fragment.yml", "version: v2\n")
			rule := &VersionRule{Path: test.rulePath, Check: func(Version, *Validation) error { return nil }}
			loaded, err := LoadLayered(
				Input{Source: NoSource()},
				testSecretBinding(),
				LayeredOptions[importDestinationConfig]{
					Definition: Definition[importDestinationConfig]{Version: rule},
					Underlays: []Underlay{{Inputs: []Input{{
						Source: File(filepath.Join(directory, "main.yml")), Imports: true, Destination: test.destination,
					}}}},
				},
			)
			if test.wantCode != "" {
				if err == nil {
					t.Fatal("protected imported version claim was accepted")
				}
				loadError, ok := err.(*LoadError)
				if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != test.wantCode {
					t.Fatalf("load error = %#v", err)
				}
				if test.name == "protected effective path" {
					sources := loadError.Sources()
					if len(sources) != 2 || sources[0].Destination.String() != "/mounted" || sources[1].Destination.String() != "/mounted" {
						t.Fatalf("error source destinations = %#v", sources)
					}
				}
				return
			}
			if err != nil {
				t.Fatalf("ordinary nested version was rejected: %v", err)
			}
			result := testLoaded(loaded)
			if got := result.Config.Collections["entry"]["version"]; got != "v2" {
				t.Fatalf("nested version = %q", got)
			}
		})
	}
}

func TestLayeredDestinationsDoNotChangeRepeatedSourceIdentity(t *testing.T) {
	t.Parallel()

	directory := t.TempDir()
	writeImportFile(t, directory, "shared.yml", "value: shared\n")
	importerPath := writeImportFile(t, directory, "importer.yml", "configkit: {imports: [{path: shared.yml, destination: [nested]}]}\n")
	_, err := LoadLayered(
		Input{Source: NoSource()},
		testSecretBinding(),
		LayeredOptions[importDestinationConfig]{Underlays: []Underlay{{Inputs: []Input{
			{Source: File(importerPath), Imports: true, Destination: Keys("imported")},
			{Source: File(filepath.Join(directory, "shared.yml")), Destination: Keys("direct")},
		}}}},
	)
	if err == nil {
		t.Fatal("the same physical source was accepted at two destinations in one group")
	}
	loadError, ok := err.(*LoadError)
	if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != CodeImportRepeated {
		t.Fatalf("load error = %#v", err)
	}
	sources := loadError.Sources()
	if len(sources) != 3 || sources[1].Destination.String() != "/imported/nested" || sources[2].Destination.String() != "/direct" {
		t.Fatalf("repeated import sources = %#v", sources)
	}

	t.Run("placement does not break a physical cycle", func(t *testing.T) {
		t.Parallel()
		directory := t.TempDir()
		mainPath := writeImportFile(t, directory, "main.yml", "configkit: {imports: [{path: parent.yml, destination: [one]}]}\n")
		writeImportFile(t, directory, "parent.yml", "configkit: {imports: [{path: main.yml, destination: [two]}]}\n")
		_, err := LoadLayered(Input{Source: File(mainPath), Imports: true}, testSecretBinding(), LayeredOptions[map[string]any]{})
		loadError, ok := err.(*LoadError)
		if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != CodeImportCycle {
			t.Fatalf("cycle load error = %#v", err)
		}
		diagnostic := loadError.Diagnostics()[0]
		if diagnostic.Primary == nil || diagnostic.Primary.SourceID != "source-2" {
			t.Fatalf("cycle primary location = %#v", diagnostic.Primary)
		}
		if sources := loadError.Sources(); len(sources) != 2 || sources[1].Destination.String() != "/one" {
			t.Fatalf("cycle sources = %#v", sources)
		}
	})
}