package configkit_test

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
	"testing/fstest"

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

func TestFacadeInputDestinationsAcrossSourceKinds(t *testing.T) {
	directory := t.TempDir()
	hostPath := filepath.Join(directory, "host.yml")
	if err := os.WriteFile(hostPath, []byte("value: host\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	native := configkit.NewFilesystem("native", fstest.MapFS{
		"main.yml": &fstest.MapFile{Data: []byte("value: native\n")},
	})
	const literalValuePath = "/collections/weather.reporter/profiles/a~1b/~0/0"
	destination := configkit.Keys("collections", "weather.reporter", "profiles", "a/b", "~", "0")
	for _, test := range []struct {
		name   string
		source configkit.Source
		want   string
		kind   configkit.SourceKind
	}{
		{name: "host file", source: configkit.File(hostPath), want: "host", kind: configkit.SourceKindFile},
		{name: "native filesystem", source: native.File("main.yml"), want: "native", kind: configkit.SourceKindFilesystem},
		{name: "bytes", source: configkit.Bytes("bytes", []byte("value: bytes\n")), want: "bytes", kind: configkit.SourceKindBytes},
		{name: "reader", source: configkit.Reader("reader", strings.NewReader("value: reader\n")), want: "reader", kind: configkit.SourceKindReader},
		{name: "mapping", source: configkit.Mapping("mapping", map[string]any{"value": "mapping"}), want: "mapping", kind: configkit.SourceKindMapping},
	} {
		t.Run(test.name, func(t *testing.T) {
			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: test.source, Destination: destination})
			if err != nil {
				t.Fatalf("LoadLayered: %v", err)
			}
			if got := facadeDestinationValue(t, result.Config, "collections", "weather.reporter", "profiles", "a/b", "~", "0", "value"); got != test.want {
				t.Fatalf("placed value = %#v, want %q", got, test.want)
			}
			sources := result.Sources()
			if len(sources) != 1 || sources[0].Kind != test.kind || sources[0].Destination.String() != destination.String() || destination.String() != literalValuePath {
				t.Fatalf("source placement = %#v, destination = %q", sources, destination.String())
			}
		})
	}
}

func TestFacadeDestinationRootEmptyMappingNoSourceAndInvalidPaths(t *testing.T) {
	for _, test := range []struct {
		name        string
		destination configkit.Path
	}{
		{name: "omitted destination"},
		{name: "explicit empty destination", destination: configkit.Path{}},
	} {
		t.Run(test.name, func(t *testing.T) {
			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Bytes("root", []byte("value: root\n")), Destination: test.destination})
			if err != nil {
				t.Fatalf("root load: %v", err)
			}
			if result.Config["value"] != "root" || len(result.Sources()) != 1 || result.Sources()[0].Destination.String() != "" {
				t.Fatalf("root placement = %#v, sources %#v", result.Config, result.Sources())
			}
		})
	}

	emptyPath := configkit.Keys("collections", "empty")
	empty, err := configkit.LoadLayered[map[string]any](configkit.Input{
		Source: configkit.Mapping("empty", map[string]any{}), Destination: emptyPath,
	})
	if err != nil {
		t.Fatalf("empty mapping load: %v", err)
	}
	if value := facadeDestinationMap(t, empty.Config, "collections")["empty"]; value == nil {
		t.Fatal("empty mapping did not materialize its destination")
	}
	if info, ok := empty.Metadata().Lookup(emptyPath); !ok || !info.Explicit {
		t.Fatalf("empty destination metadata = %#v, %v", info, ok)
	}

	absentPath := configkit.Keys("collections", "absent")
	absent, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource(), Destination: absentPath})
	if err != nil {
		t.Fatalf("NoSource with a destination: %v", err)
	}
	if len(absent.Sources()) != 0 {
		t.Fatalf("NoSource created source records: %#v", absent.Sources())
	}
	if _, ok := absent.Metadata().Lookup(absentPath); ok {
		t.Fatal("NoSource materialized its destination")
	}

	reader := &destinationCountingReader{}
	for _, test := range []struct {
		name        string
		source      configkit.Source
		destination configkit.Path
		wantReads   int
	}{
		{name: "index segment", source: configkit.Reader("unread", reader), destination: configkit.Keys("catalog").Index(0)},
		{name: "reserved configkit key", source: configkit.NoSource(), destination: configkit.Keys("configkit")},
		{name: "reserved extends key", source: configkit.NoSource(), destination: configkit.Keys("catalog", "extends")},
	} {
		t.Run(test.name, func(t *testing.T) {
			_, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: test.source, Destination: test.destination})
			loadError, ok := err.(*configkit.LoadError)
			if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeOptionsInvalid {
				t.Fatalf("invalid destination error = %#v", err)
			}
			if reader.reads != test.wantReads {
				t.Fatalf("reader calls = %d, want %d", reader.reads, test.wantReads)
			}
		})
	}
}

func TestFacadeImportedSourcesRetainInputDestination(t *testing.T) {
	directory := t.TempDir()
	mainPath := filepath.Join(directory, "main.yml")
	fragmentPath := filepath.Join(directory, "fragment.yml")
	if err := os.WriteFile(mainPath, []byte("configkit: {imports: [{path: fragment.yml}]}\nmain: present\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(fragmentPath, []byte("imported: present\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	destination := configkit.Keys("collections", "weatherreporter")
	result, err := configkit.LoadLayered[map[string]any](configkit.Input{
		Source: configkit.File(mainPath), Imports: true, Destination: destination,
	})
	if err != nil {
		t.Fatalf("mounted import load: %v", err)
	}
	collection := facadeDestinationMap(t, result.Config, "collections", "weatherreporter")
	if collection["main"] != "present" || collection["imported"] != "present" {
		t.Fatalf("mounted imported values = %#v", collection)
	}
	sources := result.Sources()
	if len(sources) != 2 || sources[0].Destination.String() != destination.String() || sources[1].Destination.String() != destination.String() {
		t.Fatalf("mounted import source destinations = %#v", sources)
	}
	if sources[1].ImportedFrom == nil {
		t.Fatalf("imported source lacks its authored directive: %#v", sources[1])
	}
}

func TestFacadeSameFragmentMountsAtSeparateCollectionDestinations(t *testing.T) {
	weatherDestination := configkit.Keys("collections", "weather", "prompts")
	homeDestination := configkit.Keys("collections", "homewatch", "prompts")
	result, err := configkit.LoadLayered(
		configkit.Input{Source: configkit.NoSource()},
		configkit.LayeredOptions[map[string]any]{Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
			{Source: configkit.Bytes("weather", []byte("summarize.alerts: {title: weather}\n")), Destination: weatherDestination},
			{Source: configkit.Bytes("homewatch", []byte("summarize.alerts: {title: home}\n")), Destination: homeDestination},
		}}}},
	)
	if err != nil {
		t.Fatalf("LoadLayered: %v", err)
	}
	for _, test := range []struct {
		path []string
		want string
	}{
		{path: []string{"collections", "weather", "prompts", "summarize.alerts", "title"}, want: "weather"},
		{path: []string{"collections", "homewatch", "prompts", "summarize.alerts", "title"}, want: "home"},
	} {
		if got := facadeDestinationValue(t, result.Config, test.path...); got != test.want {
			t.Errorf("value at %v = %#v, want %q", test.path, got, test.want)
		}
	}
	sources := result.Sources()
	if len(sources) != 2 || sources[0].Destination.String() != weatherDestination.String() || sources[1].Destination.String() != homeDestination.String() {
		t.Fatalf("independent collection source placements = %#v", sources)
	}
}

type destinationCountingReader struct{ reads int }

func (reader *destinationCountingReader) Read([]byte) (int, error) {
	reader.reads++
	return 0, io.EOF
}

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

	filesystem := configkit.NewFilesystem("resources", fstest.MapFS{
		"assets/summary.md": &fstest.MapFile{Data: []byte("source-relative summary")},
	})
	context := &configkit.FilesystemContext{Root: ".", BaseDir: "assets", FS: &filesystem}
	destination := configkit.Keys("catalog", "entries")
	tokenPath := configkit.Keys("catalog", "entries", "item", "token")
	titlePath := configkit.Keys("catalog", "entries", "item", "title")
	var callbacks struct{ resolve, validate int }
	load := func(token string) *configkit.Result[map[string]any] {
		t.Helper()
		main := configkit.Input{
			Source:      configkit.Bytes("main", []byte("item:\n  title: main\n  resource: summary.md\n  token: "+token+"\n")),
			Destination: destination, Filesystem: context,
		}
		underlay := configkit.Input{
			Source:      configkit.Bytes("underlay", []byte("item:\n  title: lower\n  retained: lower-value\n  token: LOWER-TOKEN-CANARY\n")),
			Destination: destination,
		}
		result, err := configkit.LoadLayered(main, configkit.LayeredOptions[map[string]any]{
			Underlays: []configkit.Underlay{{Inputs: []configkit.Input{underlay}}},
			Definition: configkit.Definition[map[string]any]{
				Resolve: func(configuration *map[string]any, resolution *configkit.Resolution) error {
					callbacks.resolve++
					resourcePath := configkit.Keys("catalog", "entries", "item", "resource")
					input, ok := resolution.InputInfo(resourcePath)
					if !ok || len(input.Origin.Locations) != 1 {
						return fmt.Errorf("mounted resource input has no single source origin")
					}
					source, ok := resolution.Source(input.Origin.Locations[0].SourceID)
					if !ok || source.Destination.String() != destination.String() {
						return fmt.Errorf("resolution source did not retain its destination")
					}
					resourceContext, ok := resolution.SourceContext(source.ID)
					if !ok {
						return fmt.Errorf("resolution source context is unavailable")
					}
					data, err := fs.ReadFile(resourceContext.FS, path.Join(resourceContext.BaseDir, "summary.md"))
					if err != nil {
						return fmt.Errorf("read source-relative resource: %w", err)
					}
					entry := facadeDestinationMap(t, facadeDestinationMap(t, facadeDestinationMap(t, *configuration, "catalog"), "entries"), "item")
					entry["resource_text"] = string(data)
					resolution.Record(configkit.Keys("catalog", "entries", "item", "resource_text"), configkit.ChangeNormalization, "read source-relative summary", resourcePath)
					return nil
				},
				Validate: func(*map[string]any, *configkit.Validation) { callbacks.validate++ },
				Secret:   func(candidate configkit.Path) bool { return candidate.String() == tokenPath.String() },
			},
		})
		if err != nil {
			t.Fatalf("mounted load: %v", err)
		}
		return result
	}

	first := load("FIRST-TOKEN-CANARY")
	second := load("SECOND-TOKEN-CANARY")
	if callbacks.resolve != 2 || callbacks.validate != 2 {
		t.Fatalf("lifecycle callbacks = %#v", callbacks)
	}
	for _, result := range []*configkit.Result[map[string]any]{first, second} {
		entry := facadeDestinationMap(t, facadeDestinationMap(t, facadeDestinationMap(t, result.Config, "catalog"), "entries"), "item")
		if entry["title"] != "main" || entry["retained"] != "lower-value" || entry["resource_text"] != "source-relative summary" {
			t.Fatalf("mounted main/underlay configuration = %#v", entry)
		}
		sources := result.Sources()
		if len(sources) != 2 || sources[0].Destination.String() != destination.String() || sources[1].Destination.String() != destination.String() {
			t.Fatalf("public source destinations = %#v", sources)
		}
		resource, ok := result.SourceContext(sources[0].ID)
		if !ok || resource.BaseDir != "assets" {
			t.Fatalf("completed source context = %#v, %v", resource, ok)
		}
		data, err := fs.ReadFile(resource.FS, path.Join(resource.BaseDir, "summary.md"))
		if err != nil || string(data) != "source-relative summary" {
			t.Fatalf("completed relative resource = %q, %v", data, err)
		}
		if info, ok := result.Metadata().Lookup(titlePath); !ok || info.Origin.Layer != configkit.LayerBase {
			t.Fatalf("mounted title metadata = %#v, %v", info, ok)
		}
		if history := result.Metadata().History(titlePath); len(history) < 2 {
			t.Fatalf("mounted title history = %#v", history)
		}
		if explanation, ok := result.Explain(tokenPath); !ok || !explanation.Effective.Redacted {
			t.Fatalf("mounted secret explanation = %#v, %v", explanation, ok)
		}
		var effective, explanation bytes.Buffer
		if err := result.WriteEffective(&effective); err != nil {
			t.Fatal(err)
		}
		if err := result.WriteExplanation(&explanation, tokenPath); err != nil {
			t.Fatal(err)
		}
		output := effective.String() + explanation.String()
		for _, canary := range []string{"FIRST-TOKEN-CANARY", "SECOND-TOKEN-CANARY", "LOWER-TOKEN-CANARY"} {
			if strings.Contains(output, canary) {
				t.Fatalf("public inspection leaked %q: %s", canary, output)
			}
		}
	}

	// Mutating published records and query copies must not alter the retained result.
	returnedSources := first.Sources()
	returnedSources[0].Destination = configkit.Keys("mutated")
	if got := first.Sources()[0].Destination.String(); got != destination.String() {
		t.Fatalf("source destination changed after caller mutation: %q", got)
	}
	info, ok := first.Metadata().Lookup(titlePath)
	if !ok {
		t.Fatal("mounted metadata lookup failed")
	}
	info.Origin.Locations[0].SourceID = "mutated"
	if fresh, ok := first.Metadata().Lookup(titlePath); !ok || fresh.Origin.Locations[0].SourceID == "mutated" {
		t.Fatalf("metadata copy mutation escaped: %#v, %v", fresh, ok)
	}
	history := first.Metadata().History(titlePath)
	if len(history) == 0 {
		t.Fatal("mounted history is empty")
	}
	history[0].Path = configkit.Keys("mutated")
	if fresh := first.Metadata().History(titlePath); len(fresh) == 0 || fresh[0].Path.String() != titlePath.String() {
		t.Fatalf("history copy mutation escaped: %#v", fresh)
	}

	differences, err := configkit.Diff(first, second)
	if err != nil {
		t.Fatal(err)
	}
	if len(differences) != 1 || differences[0].Path.String() != tokenPath.String() ||
		!differences[0].Left.Redacted || !differences[0].Right.Redacted ||
		strings.Contains(differences[0].Left.YAML+differences[0].Right.YAML, "TOKEN-CANARY") {
		t.Fatalf("public mounted secret diff = %#v", differences)
	}
	if callbacks.resolve != 2 || callbacks.validate != 2 {
		t.Fatalf("inspection reran lifecycle callbacks: %#v", callbacks)
	}
}

func TestFacadeFailedLoadExposesDetachedSourceDestination(t *testing.T) {
	type configuration struct {
		Tenant struct {
			Count int `yaml:"count"`
		} `yaml:"tenant"`
	}
	destination := configkit.Keys("tenant")
	_, err := configkit.LoadLayered[configuration](configkit.Input{
		Source: configkit.Bytes("invalid", []byte("count: not-an-integer\n")), Destination: destination,
	})
	loadError, ok := err.(*configkit.LoadError)
	if !ok {
		t.Fatalf("failed load error = %T %v", err, err)
	}
	sources := loadError.Sources()
	if len(sources) != 1 || sources[0].Destination.String() != destination.String() {
		t.Fatalf("failed source destinations = %#v", sources)
	}
	sources[0].Destination = configkit.Keys("caller-change")
	if fresh := loadError.Sources(); len(fresh) != 1 || fresh[0].Destination.String() != destination.String() {
		t.Fatalf("failed source destination was not detached: %#v", fresh)
	}
}

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

	cycle := map[string]any{}
	cycle["self"] = cycle
	for _, fixture := range []struct {
		name   string
		values map[string]any
		path   func(configkit.Path) configkit.Path
	}{
		{
			name:   "unsupported nested sequence value",
			values: map[string]any{"a/b": []any{map[string]any{"~": func() {}}}},
			path:   func(base configkit.Path) configkit.Path { return base.Key("a/b").Index(0).Key("~") },
		},
		{
			name:   "cyclic value",
			values: map[string]any{"item": cycle},
			path:   func(base configkit.Path) configkit.Path { return base.Key("item").Key("self") },
		},
		{
			name: "constructor failure keeps source coordinates",
			path: func(configkit.Path) configkit.Path { return configkit.Path{} },
		},
	} {
		t.Run(fixture.name, func(t *testing.T) {
			for _, role := range []string{"root", "mounted main", "mounted underlay"} {
				t.Run(role, func(t *testing.T) {
					var destination configkit.Path
					if role != "root" {
						destination = configkit.Keys("catalog", "entries")
					}
					wantPath := fixture.path(destination)
					input := configkit.Input{Source: configkit.Mapping("invalid mapping", fixture.values), Destination: destination}
					var result *configkit.Result[map[string]any]
					var err error
					if role == "mounted underlay" {
						result, err = configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{
							Underlays: []configkit.Underlay{{Inputs: []configkit.Input{input}}},
						})
					} else {
						result, err = configkit.LoadLayered[map[string]any](input)
					}
					var loadError *configkit.LoadError
					if result != nil || !errors.As(err, &loadError) {
						t.Fatalf("failed load = %#v, %v", result, err)
					}
					diagnostics := loadError.Diagnostics()
					if len(diagnostics) != 1 {
						t.Fatalf("diagnostics = %#v", diagnostics)
					}
					diagnostic := diagnostics[0]
					if diagnostic.Code != configkit.CodeSourceInvalid || !reflect.DeepEqual(diagnostic.Path, wantPath) {
						t.Fatalf("diagnostic = %#v; want source.invalid at %q", diagnostic, wantPath.String())
					}
					if diagnostic.Primary == nil || *diagnostic.Primary != (configkit.Location{SourceID: "source-1"}) || len(diagnostic.Related) != 0 {
						t.Fatalf("mapping source locations = %#v, %#v", diagnostic.Primary, diagnostic.Related)
					}
					sources := loadError.Sources()
					if len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Destination.String() != destination.String() {
						t.Fatalf("error sources = %#v", sources)
					}
				})
			}
		})
	}
}

func facadeDestinationMap(t *testing.T, value map[string]any, keys ...string) map[string]any {
	t.Helper()
	for _, key := range keys {
		child, ok := value[key].(map[string]any)
		if !ok {
			t.Fatalf("%q = %#v, want mapping", key, value[key])
		}
		value = child
	}
	return value
}

func facadeDestinationValue(t *testing.T, value map[string]any, keys ...string) any {
	t.Helper()
	return facadeDestinationMap(t, value, keys[:len(keys)-1]...)[keys[len(keys)-1]]
}