From e17a095ce26917954b7667614a4d158e82d7508f Mon Sep 17 00:00:00 2001
From: Kaushal Modi <kaushal.modi@gmail.com>
Date: Thu, 1 Mar 2018 12:32:58 -0500
Subject: [PATCH] Add opengraph meta-data to doc site pages

---
 doc/ox-hugo-manual.org                        |  7 +-
 .../layouts/partials/head.html                |  4 +
 .../layouts/partials/opengraph.html           | 92 +++++++++++++++++++
 .../layouts/partials/summary_minus_toc.html   | 20 ++++
 .../layouts/partials/twitter_cards.html       | 40 ++++++++
 5 files changed, 160 insertions(+), 3 deletions(-)
 create mode 100644 doc/themes/hugo-alabaster-theme/layouts/partials/opengraph.html
 create mode 100644 doc/themes/hugo-alabaster-theme/layouts/partials/summary_minus_toc.html
 create mode 100644 doc/themes/hugo-alabaster-theme/layouts/partials/twitter_cards.html

diff --git a/doc/ox-hugo-manual.org b/doc/ox-hugo-manual.org
index e1687e2..2f1af08 100644
--- a/doc/ox-hugo-manual.org
+++ b/doc/ox-hugo-manual.org
@@ -1811,9 +1811,10 @@ for writing your posts in Org, there are examples for both in the
 :PROPERTIES:
 :EXPORT_FILE_NAME: replace-front-matter-keys
 :END:
-This is a =ox-hugo=-unique feature that allows you to
-replace/substitute any front-matter key name to accommodate for your
-favorite Hugo theme.
+This is a =ox-hugo=-unique feature that allows you to replace any
+front-matter key name to accommodate for your favorite Hugo theme.
+
+#+hugo: more
 
 The syntax is:
 
diff --git a/doc/themes/hugo-alabaster-theme/layouts/partials/head.html b/doc/themes/hugo-alabaster-theme/layouts/partials/head.html
index 8806ade..b428b4f 100644
--- a/doc/themes/hugo-alabaster-theme/layouts/partials/head.html
+++ b/doc/themes/hugo-alabaster-theme/layouts/partials/head.html
@@ -38,4 +38,8 @@
     {{ with .Params.mathjax }}
         {{ partial "mathjax.html" }}
     {{ end }}
+
+    <!-- Opengraph and Twitter -->
+    {{ partial "opengraph.html" . }}
+    {{ partial "twitter_cards.html" . }}
 </head>
diff --git a/doc/themes/hugo-alabaster-theme/layouts/partials/opengraph.html b/doc/themes/hugo-alabaster-theme/layouts/partials/opengraph.html
new file mode 100644
index 0000000..881c386
--- /dev/null
+++ b/doc/themes/hugo-alabaster-theme/layouts/partials/opengraph.html
@@ -0,0 +1,92 @@
+{{ $permalink := .Permalink }}
+<meta property="og:title" content="{{ .Title }}" />
+<meta property="og:description"
+      content="{{ with .Description }}{{ . | plainify }}{{ else }}{{ if .IsPage }}{{ partial "summary_minus_toc.html" . | plainify }}{{ else }}{{ with .Site.Params.description }}{{ . | plainify }}{{ end }}{{ end }}{{ end }}" />
+<meta property="og:type" content="{{ if .IsPage }}article{{ else }}website{{ end }}" />
+<meta property="og:url" content="{{ .Permalink }}" />
+{{ with .Params.images }}
+    {{ range first 6 . }}
+        {{ $image := . }}
+        {{ $image_link_absolute := (findRE "^/" $image) }}
+        {{ if $image_link_absolute }}
+            <meta name="og:image" content="{{ $image | absURL }}"/>
+        {{ else }}
+            <meta name="og:image" content="{{ (printf "%s%s" $permalink $image) }}"/>
+        {{ end }}
+    {{ end }}
+{{ end }}
+{{ if .IsPage }}
+    {{ if not .PublishDate.IsZero }}
+        <meta property="article:published_time" content="{{ .PublishDate.Format "2006-01-02T15:04:05-07:00" | safeHTML }}"/>
+    {{ else if not .Date.IsZero }}
+        <meta property="article:published_time" content="{{ .Date.Format "2006-01-02T15:04:05-07:00" | safeHTML }}"/>
+    {{ end }}
+    {{ if not .Lastmod.IsZero }}
+        <meta property="article:modified_time" content="{{ .Lastmod.Format "2006-01-02T15:04:05-07:00" | safeHTML }}"/>
+    {{ end }}
+{{ else }}
+    {{ if not .Date.IsZero }}
+        <meta property="og:updated_time" content="{{ .Date.Format "2006-01-02T15:04:05-07:00" | safeHTML }}"/>
+    {{ end }}
+{{ end }}
+{{ with .Params.audio }}
+    {{ $audio := . }}
+    {{ $audio_link_absolute := (findRE "^/" $audio) }}
+    {{ if $audio_link_absolute }}
+        <meta name="og:audio" content="{{ $audio | absURL }}"/>
+    {{ else }}
+        <meta name="og:audio" content="{{ (printf "%s%s" $permalink $audio) }}"/>
+    {{ end }}
+{{ end }}
+{{ with .Params.locale }}
+    <meta property="og:locale" content="{{ . }}" />
+{{ end }}
+{{ with .Site.Params.title }}
+    <meta property="og:site_name" content="{{ . }}" />
+{{ end }}
+{{ with .Params.videos }}
+    {{ range . }}
+        {{ $video := . }}
+        {{ $video_link_absolute := (findRE "^/" $video) }}
+        {{ if $video_link_absolute }}
+            <meta name="og:video" content="{{ $video | absURL }}"/>
+        {{ else }}
+            <meta name="og:video" content="{{ (printf "%s%s" $permalink $video) }}"/>
+        {{ end }}
+    {{ end }}
+{{ end }}
+<!-- If it is part of a series, link to related articles -->
+{{ $siteSeries := .Site.Taxonomies.series }}
+{{ if $siteSeries }}
+    {{ with .Params.series }}
+        {{ range $name := . }}
+            {{ $series := index $siteSeries $name }}
+            {{ range $page := first 6 $series.Pages }}
+                {{ if ne $page.Permalink $permalink }}
+                    <meta property="og:see_also" content="{{ $page.Permalink }}" />
+                {{ end }}
+            {{ end }}
+        {{ end }}
+    {{ end }}
+{{ end }}
+
+{{ if .IsPage }}
+    {{ range .Site.Authors }}
+        {{ with .Social.facebook }}
+            <meta property="article:author" content="https://www.facebook.com/{{ . }}" />
+        {{ end }}
+        {{ with .Site.Social.facebook }}
+            <meta property="article:publisher" content="https://www.facebook.com/{{ . }}" />
+        {{ end }}
+        <meta property="article:section" content="{{ .Section }}" />
+        {{ with .Params.tags }}
+            {{ range first 6 . }}
+                <meta property="article:tag" content="{{ . }}" />
+            {{ end }}
+        {{ end }}
+    {{ end }}
+{{ end }}
+<!-- Facebook Page Admin ID for Domain Insights -->
+{{ with .Site.Social.facebook_admin }}
+    <meta property="fb:admins" content="{{ . }}" />
+{{ end }}
diff --git a/doc/themes/hugo-alabaster-theme/layouts/partials/summary_minus_toc.html b/doc/themes/hugo-alabaster-theme/layouts/partials/summary_minus_toc.html
new file mode 100644
index 0000000..6ec6447
--- /dev/null
+++ b/doc/themes/hugo-alabaster-theme/layouts/partials/summary_minus_toc.html
@@ -0,0 +1,20 @@
+{{- $summary_has_org_toc := substr .Content 0 30 | findRE "[\".]ox-hugo-toc" -}}
+{{- if $summary_has_org_toc -}}
+    {{- $content_splits := split .RawContent "<!--endtoc-->" -}} <!-- Need to use .RawContent as we will be parsing for 'more' comment later. -->
+    <!-- If Org TOC is present, the special comment endtoc would also be present.
+         In that case, output only the part *after* that comment as Summary. -->
+    {{- $summary_raw := index $content_splits 1 -}}
+    {{- $summary_splits := split $summary_raw "<!--more-->" -}}
+    {{- if eq (len $summary_splits) 2 -}}
+        {{- index $summary_splits 0 | markdownify -}}
+    {{- else -}}
+        {{- $summary_raw | markdownify | truncate 300 -}}
+    {{- end -}}
+    <!-- Print the whole Description/Summary if endtoc special comment is not found. -->
+{{- else -}}
+    {{- with .Description -}}
+        {{- . | markdownify | printf "<p>%s</p>" | safeHTML -}}
+    {{- else -}}
+        {{- .Summary |  printf "<p>%s</p>" | safeHTML -}}
+    {{- end -}}
+{{- end -}}
diff --git a/doc/themes/hugo-alabaster-theme/layouts/partials/twitter_cards.html b/doc/themes/hugo-alabaster-theme/layouts/partials/twitter_cards.html
new file mode 100644
index 0000000..ca3127e
--- /dev/null
+++ b/doc/themes/hugo-alabaster-theme/layouts/partials/twitter_cards.html
@@ -0,0 +1,40 @@
+{{ $permalink := .Permalink }}
+{{- with $.Params.images -}}
+    <meta name="twitter:card" content="summary_large_image"/>
+    <!-- As per https://developer.twitter.com/en/docs/tweets/optimize-with-cards/overview/summary-card-with-large-image,
+         the required card property is "twitter:image", not "twitter:image:src". -->
+    {{- $image := (index . 0) -}}
+    {{- $image_link_absolute := (findRE "^/" $image) -}}
+    {{- if $image_link_absolute -}}
+        <meta name="twitter:image" content="{{- $image | absURL -}}"/>
+    {{- else -}}
+        <meta name="twitter:image" content="{{- (printf "%s%s" $permalink $image) -}}"/>
+    {{- end -}}
+{{ else -}}
+    {{- $images := $.Resources.ByType "image" -}}
+    {{- $featured := $images.GetMatch "*feature*" -}}
+    {{- $featured := cond (ne $featured nil) $featured ($images.GetMatch "{*cover*,*thumbnail*}") -}}
+    {{- with $featured -}}
+        <meta name="twitter:card" content="summary_large_image"/>
+        <meta name="twitter:image" content="{{ $featured.Permalink }}"/>
+    {{- else -}}
+        {{- with $.Site.Params.images -}}
+            <meta name="twitter:card" content="summary_large_image"/>
+            {{- $image := (index . 0) -}}
+            {{- $image_link_absolute := (findRE "^/" $image) -}}
+            {{- if $image_link_absolute -}}
+                <meta name="twitter:image" content="{{- $image | absURL -}}"/>
+            {{- else -}}
+                <meta name="twitter:image" content="{{- (printf "%s%s" $permalink $image) -}}"/>
+            {{- end -}}
+        {{ else -}}
+            <meta name="twitter:card" content="summary"/>
+        {{- end -}}
+    {{- end -}}
+{{- end }}
+<meta name="twitter:title" content="{{ .Title }}"/>
+<meta name="twitter:description" content="{{ with .Description }}{{ . | plainify }}{{ else }}{{ if .IsPage }}{{ partial "summary_minus_toc.html" . | plainify }}{{ else }}{{ with .Site.Params.description }}{{ . | plainify }}{{ end }}{{ end }}{{ end -}}"/>
+{{ with .Site.Social.twitter -}}
+    <meta name="twitter:site" content="@{{ . }}"/>
+    <meta name="twitter:creator" content="@{{ . }}"/>
+{{ end -}}