👔 Created basic site use case interface implementation

internal/site/usecase/site_ucase.go

@@ -0,0 +1,40 @@
+package usecase
+
+import (
+	"context"
+	"fmt"
+
+	"golang.org/x/text/language"
+
+	"source.toby3d.me/toby3d/home/internal/domain"
+	"source.toby3d.me/toby3d/home/internal/site"
+)
+
+type siteUseCase struct {
+	sites site.Repository
+}
+
+func NewSiteUseCase(sites site.Repository) site.UseCase {
+	return &siteUseCase{
+		sites: sites,
+	}
+}
+
+func (ucase *siteUseCase) Do(ctx context.Context, lang language.Tag) (*domain.Site, error) {
+	base, err := ucase.sites.Get(ctx, language.Und)
+	if err != nil {
+		return nil, fmt.Errorf("cannot find base site data: %w", err)
+	}
+
+	sub, err := ucase.sites.Get(ctx, lang)
+	if err != nil {
+		return nil, fmt.Errorf("cannot find site data for '%s' language code: %w", lang, err)
+	}
+
+	out := &domain.Site{Language: sub.Language}
+	if sub.Title == "" {
+		out.Title = base.Title
+	}
+
+	return out, nil
+}