Add pagination routes on lang post filter

Ref T805

collections.go

@@ -1027,6 +1027,20 @@ func handleViewCollectionLang(app *App, w http.ResponseWriter, r *http.Request)
 	coll := newDisplayCollection(c, cr, page)
 	coll.Language = lang
 
+	ttlPosts, err := app.db.GetCollLangTotalPosts(coll.ID, lang)
+	if err != nil {
+		log.Error("Unable to getCollLangTotalPosts: %s", err)
+	}
+	pagePosts := coll.Format.PostsPerPage()
+	coll.TotalPages = int(math.Ceil(float64(ttlPosts) / float64(pagePosts)))
+	if coll.TotalPages > 0 && page > coll.TotalPages {
+		redirURL := fmt.Sprintf("/lang:%s/page/%d", lang, coll.TotalPages)
+		if !app.cfg.App.SingleUser {
+			redirURL = fmt.Sprintf("/%s%s%s", cr.prefix, coll.Alias, redirURL)
+		}
+		return impart.HTTPError{http.StatusFound, redirURL}
+	}
+
 	coll.Posts, _ = app.db.GetLangPosts(app.cfg, c, lang, page, cr.isCollOwner)
 	if err != nil {
 		return ErrCollectionPageNotFound

database.go

@@ -1260,6 +1260,16 @@ func (db *datastore) GetPostsTagged(cfg *config.Config, c *Collection, tag strin
 	return &posts, nil
 }
 
+func (db *datastore) GetCollLangTotalPosts(collID int64, lang string) (uint64, error) {
+	var articles uint64
+	err := db.QueryRow("SELECT COUNT(*) FROM posts WHERE collection_id = ? AND language = ?", collID, lang).Scan(&articles)
+	if err != nil && err != sql.ErrNoRows {
+		log.Error("Couldn't get total lang posts count for collection %d: %v", collID, err)
+		return 0, err
+	}
+	return articles, nil
+}
+
 func (db *datastore) GetLangPosts(cfg *config.Config, c *Collection, lang string, page int, includeFuture bool) (*[]PublicPost, error) {
 	collID := c.ID
 
@@ -1285,7 +1295,10 @@ func (db *datastore) GetLangPosts(cfg *config.Config, c *Collection, lang string
 		timeCondition = "AND created <= " + db.now()
 	}
 
-	rows, err := db.Query("SELECT "+postCols+" FROM posts WHERE collection_id = ? AND language = ? "+timeCondition+" ORDER BY created "+order+limitStr, collID, lang)
+	rows, err := db.Query(`SELECT `+postCols+`
+FROM posts
+WHERE collection_id = ? AND language = ? `+timeCondition+`
+ORDER BY created `+order+limitStr, collID, lang)
 	if err != nil {
 		log.Error("Failed selecting from posts: %v", err)
 		return nil, impart.HTTPError{http.StatusInternalServerError, "Couldn't retrieve collection posts."}

routes.go

@@ -217,6 +217,7 @@ func RouteCollections(handler *Handler, r *mux.Router) {
 	r.HandleFunc("/logout", handler.Web(handleLogOutCollection, UserLevelOptional))
 	r.HandleFunc("/page/{page:[0-9]+}", handler.Web(handleViewCollection, UserLevelReader))
 	r.HandleFunc("/lang:{lang:[a-z]{2}}", handler.Web(handleViewCollectionLang, UserLevelOptional))
+	r.HandleFunc("/lang:{lang:[a-z]{2}}/page/{page:[0-9]+}", handler.Web(handleViewCollectionLang, UserLevelOptional))
 	r.HandleFunc("/tag:{tag}", handler.Web(handleViewCollectionTag, UserLevelReader))
 	r.HandleFunc("/tag:{tag}/feed/", handler.Web(ViewFeed, UserLevelReader))
 	r.HandleFunc("/sitemap.xml", handler.AllReader(handleViewSitemap))