package cabana

import (
	"context"
	"errors"
	"slices"
	"testing"

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

// TestEnabledLocalesDefaultFirstSmoke pins D-03: the form schema lists the
// default locale first, so every ML control opens on the locale whose values
// live in the host columns, whatever order the writer keeps.
func TestEnabledLocalesDefaultFirstSmoke(t *testing.T) {
	db, _ := openDryRunDB(t)
	app := backpack.New(nil)
	if err := app.Publish(db); err != nil {
		t.Fatal(err)
	}
	if err := app.Publish[TranslationWriter](&recordingWriter{defaultLocale: "pl", enabled: []string{"en", "pl"}}); err != nil {
		t.Fatal(err)
	}
	svc := &service{app: app}
	if got := svc.enabledContentLocales(context.Background()); !slices.Equal(got, []string{"pl", "en"}) {
		t.Fatalf("enabledContentLocales = %v, want [pl en]", got)
	}
}

// failingDefaultWriter answers its enabled locales but fails DefaultLocale.
type failingDefaultWriter struct{ recordingWriter }

func (w *failingDefaultWriter) DefaultLocale(context.Context, *gorm.DB) (string, error) {
	return "", errors.New("default locale unavailable")
}

// failingEnabledWriter fails EnabledLocales.
type failingEnabledWriter struct{ recordingWriter }

func (w *failingEnabledWriter) EnabledLocales(context.Context, *gorm.DB) ([]string, error) {
	return nil, errors.New("enabled locales unavailable")
}

// TestEnabledLocalesDefaultFirst covers every ordering case of
// enabledContentLocales (D-03): the default moves to the front, the other
// codes keep the writer's order, and a missing or failing default leaves
// the writer's order alone.
func TestEnabledLocalesDefaultFirst(t *testing.T) {
	cases := []struct {
		name   string
		writer TranslationWriter
		want   []string
	}{
		{"default not first", &recordingWriter{defaultLocale: "pl", enabled: []string{"en", "pl"}}, []string{"pl", "en"}},
		{"default already first", &recordingWriter{defaultLocale: "pl", enabled: []string{"pl", "en"}}, []string{"pl", "en"}},
		{"default absent from the list", &recordingWriter{defaultLocale: "fr", enabled: []string{"en", "pl"}}, []string{"en", "pl"}},
		{"empty default", &recordingWriter{defaultLocale: "", enabled: []string{"en", "pl"}}, []string{"en", "pl"}},
		{"DefaultLocale error keeps the order", &failingDefaultWriter{recordingWriter{defaultLocale: "pl", enabled: []string{"en", "pl"}}}, []string{"en", "pl"}},
		{"three locales keep their relative order", &recordingWriter{defaultLocale: "pl", enabled: []string{"en", "de", "pl"}}, []string{"pl", "en", "de"}},
		{"default in the middle", &recordingWriter{defaultLocale: "de", enabled: []string{"en", "de", "pl"}}, []string{"de", "en", "pl"}},
		{"single locale", &recordingWriter{defaultLocale: "pl", enabled: []string{"pl"}}, []string{"pl"}},
		{"EnabledLocales error", &failingEnabledWriter{recordingWriter{defaultLocale: "pl"}}, nil},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			db, _ := openDryRunDB(t)
			app := backpack.New(nil)
			if err := app.Publish(db); err != nil {
				t.Fatal(err)
			}
			if err := app.Publish[TranslationWriter](tc.writer); err != nil {
				t.Fatal(err)
			}
			svc := &service{app: app}
			got := svc.enabledContentLocales(context.Background())
			if !slices.Equal(got, tc.want) {
				t.Fatalf("enabledContentLocales = %v, want %v", got, tc.want)
			}
		})
	}

	t.Run("the writer's slice is not reordered in place", func(t *testing.T) {
		db, _ := openDryRunDB(t)
		app := backpack.New(nil)
		if err := app.Publish(db); err != nil {
			t.Fatal(err)
		}
		enabled := []string{"en", "de", "pl"}
		if err := app.Publish[TranslationWriter](&sharedSliceWriter{defaultLocale: "pl", enabled: enabled}); err != nil {
			t.Fatal(err)
		}
		svc := &service{app: app}
		if got := svc.enabledContentLocales(context.Background()); !slices.Equal(got, []string{"pl", "en", "de"}) {
			t.Fatalf("enabledContentLocales = %v", got)
		}
		if !slices.Equal(enabled, []string{"en", "de", "pl"}) {
			t.Fatalf("writer slice changed to %v", enabled)
		}
	})

	t.Run("no published writer", func(t *testing.T) {
		db, _ := openDryRunDB(t)
		app := backpack.New(nil)
		if err := app.Publish(db); err != nil {
			t.Fatal(err)
		}
		svc := &service{app: app}
		if got := svc.enabledContentLocales(context.Background()); got != nil {
			t.Fatalf("enabledContentLocales = %v, want nil", got)
		}
	})

	t.Run("no app", func(t *testing.T) {
		if got := (&service{}).enabledContentLocales(context.Background()); got != nil {
			t.Fatalf("enabledContentLocales = %v, want nil", got)
		}
	})
}

// sharedSliceWriter returns its own enabled slice, not a copy, so a test can
// see whether the caller reorders it in place.
type sharedSliceWriter struct {
	recordingWriter
	defaultLocale string
	enabled       []string
}

func (w *sharedSliceWriter) DefaultLocale(context.Context, *gorm.DB) (string, error) {
	return w.defaultLocale, nil
}

func (w *sharedSliceWriter) EnabledLocales(context.Context, *gorm.DB) ([]string, error) {
	return w.enabled, nil
}