package i18nx

import (
	"context"
	"errors"
	"testing"
	"time"
)

func TestWithLocalePreservesContext(t *testing.T) {
	type testKey struct{}
	deadline := time.Now().Add(time.Minute)
	parent, cancel := context.WithDeadline(context.WithValue(context.Background(), testKey{}, "request-value"), deadline)
	defer cancel()
	localized := WithLocale(parent, "ru")
	if got := LocaleFromContext(localized); got != LocaleRuRU {
		t.Fatalf("locale = %q", got)
	}
	if got := localized.Value(testKey{}); got != "request-value" {
		t.Fatalf("parent value lost: %v", got)
	}
	if got, ok := localized.Deadline(); !ok || !got.Equal(deadline) {
		t.Fatalf("deadline lost: %v, %v", got, ok)
	}
	cancel()
	if !errors.Is(localized.Err(), context.Canceled) {
		t.Fatalf("cancellation lost: %v", localized.Err())
	}
}

func TestLocaleFromContextDefaultsAndIsolation(t *testing.T) {
	for _, ctx := range []context.Context{nil, context.Background(), context.WithValue(context.Background(), "i18nx.locale", LocaleZhCN)} {
		if got := LocaleFromContext(ctx); got != DefaultLocale {
			t.Fatalf("missing explicit locale = %q, want default %q", got, DefaultLocale)
		}
	}
	english := WithLocale(context.Background(), LocaleEnUS)
	russian := WithLocale(english, LocaleRuRU)
	if LocaleFromContext(english) != LocaleEnUS || LocaleFromContext(russian) != LocaleRuRU {
		t.Fatal("child locale changed parent locale")
	}
	if got := LocaleFromContext(WithLocale(nil, "unsupported")); got != DefaultLocale {
		t.Fatalf("invalid locale = %q", got)
	}
}