package configkit

import (
	"errors"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"sync/atomic"
	"testing"
)

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

	type config struct {
		Name string `yaml:"name"`
	}
	input := []byte("name: configured\n")
	temporary := t.TempDir()
	filename := filepath.Join(temporary, "config.yml")
	if err := os.WriteFile(filename, input, 0o600); err != nil {
		t.Fatal(err)
	}

	tests := []struct {
		name        string
		source      func() Source
		want        string
		wantSources int
	}{
		{name: "file", source: func() Source { return File(filename) }, want: "configured", wantSources: 1},
		{name: "bytes", source: func() Source { return Bytes("memory.yml", input) }, want: "configured", wantSources: 1},
		{name: "reader", source: func() Source { return Reader("reader.yml", strings.NewReader(string(input))) }, want: "configured", wantSources: 1},
		{name: "no source", source: NoSource, want: "default", wantSources: 0},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			var defaultsCalls atomic.Int32
			result, err := Load(test.source(), Options[config]{Definition: Definition[config]{
				Defaults: func() config {
					defaultsCalls.Add(1)
					return config{Name: "default"}
				},
			}})
			if err != nil {
				t.Fatal(err)
			}
			if result.Config.Name != test.want || defaultsCalls.Load() != 1 || len(result.Sources()) != test.wantSources {
				t.Fatalf("result = %#v, calls = %d, sources = %#v", result.Config, defaultsCalls.Load(), result.Sources())
			}
		})
	}
}

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

	type config struct {
		SchemaVersion *string `yaml:"schema_version"`
	}
	versionPath := Keys("schema_version")
	tests := []struct {
		name       string
		source     Source
		want       Version
		wantLine   int
		wantErr    Code
		returnOnly bool
	}{
		{name: "absent", source: Bytes("absent.yml", []byte("{}\n")), want: Version{}, wantLine: 1},
		{name: "no source absent", source: NoSource(), want: Version{}},
		{name: "null", source: Bytes("null.yml", []byte("schema_version: null\n")), want: Version{Present: true, Null: true}, wantLine: 1},
		{name: "string", source: Bytes("string.yml", []byte("schema_version: app.v1\n")), want: Version{Present: true, Text: "app.v1"}, wantLine: 1},
		{name: "integer", source: Bytes("integer.yml", []byte("schema_version: 1\n")), wantErr: CodeVersionType},
		{name: "returned error", source: Bytes("return.yml", []byte("{}\n")), wantErr: CodeVersionHookFailed, returnOnly: true},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			called := false
			rule := &VersionRule{Path: versionPath, Check: func(version Version, validation *Validation) error {
				called = true
				if test.returnOnly {
					return errors.New("CANARY_VERSION_ERROR")
				}
				if version != test.want {
					t.Errorf("version = %#v, want %#v", version, test.want)
				}
				validation.Warning(versionPath, "review schema compatibility", Keys("missing_related"))
				return nil
			}}
			result, err := Load(test.source, Options[config]{Definition: Definition[config]{Version: rule}})
			if test.wantErr != "" {
				if result != nil || err == nil {
					t.Fatalf("result, err = %#v, %v", result, err)
				}
				var loadError *LoadError
				if !errors.As(err, &loadError) {
					t.Fatalf("error type = %T", err)
				}
				diagnostics := loadError.Diagnostics()
				if len(diagnostics) != 1 || diagnostics[0].Code != test.wantErr || strings.Contains(diagnostics[0].Message, "CANARY") {
					t.Fatalf("diagnostics = %#v", diagnostics)
				}
				if test.wantErr == CodeVersionType && called {
					t.Fatal("checker ran for a non-string version")
				}
				return
			}
			if err != nil {
				t.Fatal(err)
			}
			diagnostics := result.Diagnostics()
			if len(diagnostics) != 1 || diagnostics[0].Code != CodeVersionWarning || diagnostics[0].Severity != SeverityWarning {
				t.Fatalf("diagnostics = %#v", diagnostics)
			}
			if test.wantLine == 0 && (diagnostics[0].Primary != nil || len(diagnostics[0].Related) != 0) {
				t.Fatalf("synthetic diagnostic locations = %#v", diagnostics[0])
			}
			if test.wantLine != 0 && (diagnostics[0].Primary == nil || diagnostics[0].Primary.Line != test.wantLine || len(diagnostics[0].Related) != 1) {
				t.Fatalf("diagnostic locations = %#v", diagnostics[0])
			}
		})
	}
}

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

	type config struct {
		Name string `yaml:"name"`
	}
	var defaultsCalls atomic.Int32
	result, err := Load(Bytes("version.yml", []byte("name: value\n")), Options[config]{Definition: Definition[config]{
		Defaults: func() config {
			defaultsCalls.Add(1)
			return config{Name: "default"}
		},
		Version: &VersionRule{Path: Keys("schema_version"), Check: func(_ Version, validation *Validation) error {
			validation.Error(Keys("schema_version"), "schema_version is required")
			return errors.New("CANARY_RETURNED_ERROR")
		}},
	}})
	if result != nil || err == nil || defaultsCalls.Load() != 0 {
		t.Fatalf("result = %#v, err = %v, calls = %d", result, err, defaultsCalls.Load())
	}
	var loadError *LoadError
	if !errors.As(err, &loadError) {
		t.Fatalf("error type = %T", err)
	}
	diagnostics := loadError.Diagnostics()
	if len(diagnostics) != 1 || diagnostics[0].Code != CodeVersionError || strings.Contains(diagnostics[0].Message, "CANARY") {
		t.Fatalf("diagnostics = %#v", diagnostics)
	}
}

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

	type nested struct {
		Kept string `yaml:"kept"`
		Set  string `yaml:"set"`
	}
	type config struct {
		Nested   nested            `yaml:"nested"`
		Nullable map[string]string `yaml:"nullable"`
	}
	result, err := Load(Bytes("metadata.yml", []byte("nested: {set: configured}\nnullable: null\n")), Options[config]{Definition: Definition[config]{
		Defaults: func() config {
			return config{Nested: nested{Kept: "default", Set: "default"}, Nullable: map[string]string{"key": "value"}}
		},
	}})
	if err != nil {
		t.Fatal(err)
	}
	metadata := result.Metadata()
	kept, ok := metadata.Lookup(Keys("nested", "kept"))
	if !ok || kept.Explicit || kept.Origin.Layer != LayerDefault {
		t.Fatalf("kept = %#v, %v", kept, ok)
	}
	set, ok := metadata.Lookup(Keys("nested", "set"))
	if !ok || !set.Explicit || set.Origin.Layer != LayerBase || len(set.Origin.Locations) != 1 {
		t.Fatalf("set = %#v, %v", set, ok)
	}
	nullable, ok := metadata.Lookup(Keys("nullable"))
	if !ok || !nullable.Explicit || !nullable.Null || nullable.Origin.Layer != LayerBase {
		t.Fatalf("nullable = %#v, %v", nullable, ok)
	}
	if metadata.IsExplicit(Keys("nested", "kept")) || !metadata.IsExplicit(Keys("nested", "set")) {
		t.Fatal("explicit presence disagrees with lookup")
	}
	if history := metadata.History(Keys("nested", "set")); len(history) != 2 || history[0].Origin.Layer != LayerDefault || history[1].Origin.Layer != LayerBase || len(history[1].Previous) != 1 {
		t.Fatalf("history = %#v", history)
	}

	set.Origin.Locations[0].Line = 99
	history := metadata.History(Keys("nested", "set"))
	history[1].Origin.Locations[0].Line = 99
	sources := result.Sources()
	sources[0].Label = "changed"
	diagnostics := result.Diagnostics()
	if diagnostics != nil {
		diagnostics[0].Message = "changed"
	}
	fresh, _ := result.Metadata().Lookup(Keys("nested", "set"))
	if fresh.Origin.Locations[0].Line == 99 || result.Sources()[0].Label != "metadata.yml" || result.Diagnostics() != nil {
		t.Fatal("result inspection aliases internal records")
	}
}

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

	type config struct {
		Name string `yaml:"name"`
	}
	validSource := func() Source { return Bytes("options.yml", []byte("name: value\n")) }
	tests := []struct {
		name    string
		source  Source
		options []Options[config]
		code    Code
	}{
		{name: "multiple options", source: validSource(), options: []Options[config]{{}, {}}, code: CodeOptionsInvalid},
		{name: "imports without filesystem context", source: validSource(), options: []Options[config]{{Imports: true}}, code: CodeOptionsInvalid},
		{name: "incomplete filesystem", source: validSource(), options: []Options[config]{{Filesystem: &FilesystemContext{}}}, code: CodeOptionsInvalid},
		{name: "missing version checker", source: validSource(), options: []Options[config]{{Definition: Definition[config]{Version: &VersionRule{Path: Keys("version")}}}}, code: CodeOptionsInvalid},
		{name: "no-source filesystem", source: NoSource(), options: []Options[config]{{Filesystem: &FilesystemContext{}}}, code: CodeOptionsInvalid},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			result, err := Load(test.source, test.options...)
			if result != nil || err == nil {
				t.Fatalf("result, err = %#v, %v", result, err)
			}
			var loadError *LoadError
			if !errors.As(err, &loadError) || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != test.code {
				t.Fatalf("error = %#v", err)
			}
		})
	}

	result, err := Load[config](Bytes("directive.yml", []byte("nested:\n  _configkit: {}\n")))
	if result != nil || err == nil {
		t.Fatalf("result, err = %#v, %v", result, err)
	}
	var loadError *LoadError
	if !errors.As(err, &loadError) {
		t.Fatal(err)
	}
	diagnostic := loadError.Diagnostics()[0]
	if diagnostic.Code != CodeImportDisabled || diagnostic.Path.String() != "/nested/_configkit" || diagnostic.Primary == nil || diagnostic.Primary.Line != 2 {
		t.Fatalf("diagnostic = %#v", diagnostic)
	}
}

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

	type invalidSchema struct {
		Channel chan int `yaml:"channel"`
	}
	type validConfig struct {
		Known int `yaml:"known"`
	}
	tests := []struct {
		name string
		run  func() (any, error)
		code Code
	}{
		{name: "source", run: func() (any, error) { return Load[validConfig](File(filepath.Join(t.TempDir(), "missing.yml"))) }, code: CodeSourceMissing},
		{name: "schema", run: func() (any, error) { return Load[invalidSchema](Bytes("schema.yml", []byte("{}\n"))) }, code: CodeSchemaUnsupportedType},
		{name: "decode", run: func() (any, error) { return Load[validConfig](Bytes("decode.yml", []byte("unknown: 1\n"))) }, code: CodeDecodeUnknownField},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			result, err := test.run()
			if !isNilInterface(result) || err == nil {
				t.Fatalf("result, err = %#v, %v", result, err)
			}
			var loadError *LoadError
			if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != test.code {
				t.Fatalf("error = %#v", err)
			}
		})
	}
}

func isNilInterface(value any) bool {
	if value == nil {
		return true
	}
	reflected := reflect.ValueOf(value)
	return reflected.Kind() == reflect.Pointer && reflected.IsNil()
}