Add Pagination to Tags Collection

Mostly copied the logic for pagination from non tag collection

collections.go

@@ -901,6 +901,15 @@ func handleViewCollectionTag(app *App, w http.ResponseWriter, r *http.Request) e
 
 	coll := newDisplayCollection(c, cr, page)
 
+	coll.TotalPages = int(math.Ceil(float64(coll.TotalPosts) / float64(coll.Format.PostsPerPage())))
+	if coll.TotalPages > 0 && page > coll.TotalPages {
+		redirURL := fmt.Sprintf("/page/%d", 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.GetPostsTagged(app.cfg, c, tag, page, cr.isCollOwner)
 	if coll.Posts != nil && len(*coll.Posts) == 0 {
 		return ErrCollectionPageNotFound

routes.go

@@ -206,6 +206,7 @@ func InitRoutes(apper Apper, r *mux.Router) *mux.Router {
 func RouteCollections(handler *Handler, r *mux.Router) {
 	r.HandleFunc("/page/{page:[0-9]+}", handler.Web(handleViewCollection, UserLevelReader))
 	r.HandleFunc("/tag:{tag}", handler.Web(handleViewCollectionTag, UserLevelReader))
+	r.HandleFunc("/tag:{tag}/page/{page:[0-9]+}", handler.Web(handleViewCollectionTag, UserLevelReader))
 	r.HandleFunc("/tag:{tag}/feed/", handler.Web(ViewFeed, UserLevelReader))
 	r.HandleFunc("/sitemap.xml", handler.AllReader(handleViewSitemap))
 	r.HandleFunc("/feed/", handler.AllReader(ViewFeed))

templates/collection-tags.tmpl

@@ -60,6 +60,17 @@
 		{{if .Posts}}<section id="wrapper" itemscope itemtype="http://schema.org/Blog">{{else}}<div id="wrapper">{{end}}
 			<h1>{{.Tag}}</h1>
 			{{template "posts" .}}
+
+		{{if gt .TotalPages 1}}<nav id="paging" class="content-container clearfix">
+			{{if or (and .Format.Ascending (le .CurrentPage .TotalPages)) (isRTL .Direction)}}
+				{{if gt .CurrentPage 1}}<a href="{{.PrevPageURL .Prefix .CurrentPage .IsTopLevel}}">&#8672; {{if and .Format.Ascending (le .CurrentPage .TotalPages)}}Previous{{else}}Newer{{end}}</a>{{end}}
+				{{if lt .CurrentPage .TotalPages}}<a style="float:right;" href="{{.NextPageURL .Prefix .CurrentPage .IsTopLevel}}">{{if and .Format.Ascending (lt .CurrentPage .TotalPages)}}Next{{else}}Older{{end}} &#8674;</a>{{end}}
+			{{else}}
+				{{if lt .CurrentPage .TotalPages}}<a href="{{.NextPageURL .Prefix .CurrentPage .IsTopLevel}}">&#8672; Older</a>{{end}}
+				{{if gt .CurrentPage 1}}<a style="float:right;" href="{{.PrevPageURL .Prefix .CurrentPage .IsTopLevel}}">Newer &#8674;</a>{{end}}
+			{{end}}
+		</nav>{{end}}
+
 		{{if .Posts}}</section>{{else}}</div>{{end}}
 
 		{{ if .Collection.ShowFooterBranding }}