refactor: centralize page filtering logic, and allow sort by lastmod (#1250)

* refactor: migrate page visibility control from `Params.hidden` to the new `build.list` parameter.

* refactor: centralize page filtering logic into a new `helper/pages.html` partial

* feat: introduce `SortBy` parameter to enable sorting pages by last modified date

* refactor: extract page sorting logic into a new `pages-sort.html` partial

layouts/_partials/helper/pages-sort.html

@@ -0,0 +1,7 @@
+{{- $pages := .Pages -}}
+
+{{- if eq .Context.Site.Params.SortBy "lastmod" -}}
+    {{- $pages = $pages.ByLastmod.Reverse -}}
+{{- end -}}
+
+{{- return $pages -}}

layouts/_partials/helper/pages.html

@@ -0,0 +1,16 @@
+{{- $pages := .Pages -}}
+
+{{- if .IsHome -}}
+    {{- $pages = where .Site.RegularPages "Type" "in" .Site.Params.mainSections -}}
+{{- else if or (eq .Kind "section") (eq .Kind "taxonomy") (eq .Kind "term") -}}
+    {{- $subsections := .Sections -}}
+    {{- $pages = .Pages | complement $subsections -}}
+
+    {{- if eq (len $pages) 0 -}}
+        {{- $pages = $subsections -}}
+    {{- end -}}
+{{- end -}}
+
+{{- $pages := partial "helper/pages-sort.html" (dict "Pages" $pages "Context" .) -}}
+
+{{- return $pages -}}

layouts/_partials/helper/paginator.html

@@ -1,26 +1,8 @@
-{{- $pages := slice -}}
-{{- $hasPages := false -}}
+{{- $result := slice -}}
 
-{{- if .IsHome -}}
-    {{ $pages = where .Site.RegularPages "Section" "in" .Site.Params.mainSections }}
-    {{- $hasPages = true -}}
-{{- else if eq .Kind "term" -}}
-    {{ $pages = .Pages }}
-    {{- $hasPages = true -}}
-{{- else if or (eq .Kind "section") (eq .Kind "taxonomy") -}}
-    {{ $subsections := .Sections }}
-    {{ $pages = .Pages | complement $subsections }}
-
-    {{- if eq (len $pages) 0 -}}
-        {{/* See complete logic in list.html */}}
-        {{- $pages = $subsections -}}
-    {{- end -}}
-    
-    {{- $hasPages = true -}}
+{{- if or .IsHome (eq .Kind "section") (eq .Kind "taxonomy") (eq .Kind "term") -}}
+    {{- $pages := partial "helper/pages.html" . -}}
+    {{- $result = .Paginate $pages -}}
 {{- end -}}
 
-{{- if $hasPages -}}
-    {{ $pages = .Paginate $pages }}
-{{- end -}}
-
-{{ return $pages }}
+{{- return $result -}}