feat: SEO backend output (2/4)

internal/infrastructure/useCases/ResolveArticleSEO.go

@@ -0,0 +1,185 @@
+package useCases
+
+import (
+	"RenewCMS/internal/domain/article"
+	"RenewCMS/internal/domain/image"
+	"RenewCMS/internal/domain/site"
+	"errors"
+	"strings"
+	"time"
+)
+
+const (
+	openGraphArticleType = "article"
+	twitterCardLarge     = "summary_large_image"
+	twitterCardSmall     = "summary"
+	robotsIndexed        = "index, follow"
+	robotsNotIndexed     = "noindex, nofollow"
+	jsonLDContext        = "https://schema.org"
+	jsonLDArticle        = "Article"
+	jsonLDPerson         = "Person"
+	jsonLDWebPage        = "WebPage"
+	sitePlaceholder      = "%site%"
+)
+
+type ResolveArticleSEOUseCase struct {
+	articleRepository article.Repository
+	sites             site.Repository
+	images            image.Repository
+}
+
+func NewResolveArticleSEOUseCase(articleRepository article.Repository, sites site.Repository, images image.Repository) *ResolveArticleSEOUseCase {
+	return &ResolveArticleSEOUseCase{articleRepository: articleRepository, sites: sites, images: images}
+}
+
+func (u *ResolveArticleSEOUseCase) Resolve(id uint32, verified bool) (article.ResolvedSEO, error) {
+	art, err := u.articleRepository.Get(id)
+	if err != nil {
+		return article.ResolvedSEO{}, err
+	}
+	if !art.IsOnline && !verified {
+		return article.ResolvedSEO{}, article.ErrArticleNotFound
+	}
+	owner, err := u.sites.Get(art.SiteID)
+	if err != nil {
+		return article.ResolvedSEO{}, err
+	}
+	picked, err := u.resolveImage(art, owner)
+	if err != nil {
+		return article.ResolvedSEO{}, err
+	}
+	return buildResolvedSEO(art, owner, picked), nil
+}
+
+func (u *ResolveArticleSEOUseCase) resolveImage(art article.Article, owner site.Site) (article.SEOImage, error) {
+	candidates := []struct {
+		id     *uint32
+		alt    string
+		source string
+	}{
+		{art.SocialImageID, "", article.SEOSourceSocial},
+		{art.CoverImageID, art.CoverImageAlt, article.SEOSourceCover},
+		{owner.DefaultSocialImageID, "", article.SEOSourceSite},
+	}
+	for _, candidate := range candidates {
+		if candidate.id == nil {
+			continue
+		}
+		found, err := u.images.Get(*candidate.id)
+		if errors.Is(err, image.ErrImageNotFound) {
+			continue
+		}
+		if err != nil {
+			return article.SEOImage{}, err
+		}
+		return article.SEOImage{URL: owner.BaseURL + found.Path, Alt: candidate.alt, Source: candidate.source}, nil
+	}
+	return article.SEOImage{Source: article.SEOSourceNone}, nil
+}
+
+func applyTitleTemplate(template string, title string, siteName string) string {
+	if template == "" {
+		template = site.DefaultTitleTemplate
+	}
+	replacer := strings.NewReplacer(site.TitlePlaceholder, title, sitePlaceholder, siteName)
+	return strings.TrimSpace(replacer.Replace(template))
+}
+
+func resolveRobots(art article.Article, owner site.Site) string {
+	if art.Noindex || owner.DefaultRobots == site.RobotsNoIndex {
+		return robotsNotIndexed
+	}
+	return robotsIndexed
+}
+
+func resolveCanonical(art article.Article, owner site.Site) (string, string) {
+	if art.CanonicalURL != "" {
+		return art.CanonicalURL, article.SEOSourceCanonicalURL
+	}
+	return articleURL(owner, art.Slug), article.SEOSourceSite
+}
+
+func articleURL(owner site.Site, slug string) string {
+	return owner.BaseURL + "/" + slug
+}
+
+func resolveAuthors(art article.Article) []article.SEOAuthor {
+	authors := make([]article.SEOAuthor, 0, len(art.Authors))
+	for _, byline := range art.Authors {
+		profile := ""
+		if byline.Website != nil {
+			profile = *byline.Website
+		}
+		sameAs := make([]string, 0, len(byline.SocialLinks))
+		for _, link := range byline.SocialLinks {
+			sameAs = append(sameAs, link.URL)
+		}
+		authors = append(authors, article.SEOAuthor{Name: byline.Name, URL: profile, SameAs: sameAs})
+	}
+	return authors
+}
+
+func formatSEOTime(moment time.Time) string {
+	return moment.UTC().Format(time.RFC3339)
+}
+
+func buildJSONLD(headline string, description string, picked article.SEOImage, authors []article.SEOAuthor, art article.Article, canonical string) article.SEOJSONLD {
+	ld := article.SEOJSONLD{
+		Context:          jsonLDContext,
+		Type:             jsonLDArticle,
+		Headline:         headline,
+		Description:      description,
+		DateModified:     formatSEOTime(art.UpdatedAt),
+		MainEntityOfPage: article.SEOJSONLDPage{Type: jsonLDWebPage, ID: canonical},
+	}
+	if picked.URL != "" {
+		ld.Image = []string{picked.URL}
+	}
+	for _, person := range authors {
+		ld.Author = append(ld.Author, article.SEOJSONLDPerson{Type: jsonLDPerson, Name: person.Name, URL: person.URL, SameAs: person.SameAs})
+	}
+	if art.IsOnline {
+		ld.DatePublished = formatSEOTime(art.CreatedAt)
+	}
+	return ld
+}
+
+func buildResolvedSEO(art article.Article, owner site.Site, picked article.SEOImage) article.ResolvedSEO {
+	meta, titleSource := metaTitle(art)
+	title := applyTitleTemplate(owner.TitleTemplate, meta, owner.SiteName)
+	description, descriptionSource := resolveDescription(art, owner, analyzeBody(art.Body))
+	canonical, canonicalSource := resolveCanonical(art, owner)
+	authors := resolveAuthors(art)
+	shareTitle := firstNonEmpty(art.SocialTitle, title)
+	shareDescription := firstNonEmpty(art.SocialDescription, description)
+	card := twitterCardSmall
+	if picked.URL != "" {
+		card = twitterCardLarge
+	}
+	locale := ""
+	if owner.Locale != nil {
+		locale = *owner.Locale
+	}
+	var published *string
+	if art.IsOnline {
+		formatted := formatSEOTime(art.CreatedAt)
+		published = &formatted
+	}
+	return article.ResolvedSEO{
+		Title:        title,
+		Description:  description,
+		CanonicalURL: canonical,
+		Robots:       resolveRobots(art, owner),
+		OG: article.SEOOpenGraph{
+			Type: openGraphArticleType, Title: shareTitle, Description: shareDescription, Image: picked.URL, ImageAlt: picked.Alt,
+			URL: canonical, SiteName: owner.SiteName, Locale: locale,
+		},
+		Twitter:     article.SEOTwitter{Card: card, Title: shareTitle, Description: shareDescription, Image: picked.URL, ImageAlt: picked.Alt},
+		Image:       picked,
+		Authors:     authors,
+		PublishedAt: published,
+		ModifiedAt:  formatSEOTime(art.UpdatedAt),
+		Fallbacks:   article.SEOFallbacks{Title: titleSource, Description: descriptionSource, Image: picked.Source, Canonical: canonicalSource},
+		JSONLD:      buildJSONLD(meta, description, picked, authors, art, canonical),
+	}
+}