generate opengraph images

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

themes/minimal/layouts/partials/head.html

@@ -30,6 +30,6 @@
         <meta name="robots" content="all,follow">
         <meta name="googlebot" content="index,follow,snippet,archive">
     {{ end }}
-    {{ template "_internal/opengraph.html" . }}
+    {{ template "partials/opengraph.html" . }}
     {{ template "_internal/twitter_cards.html" . }}
 </head>

themes/minimal/layouts/partials/opengraph.html

@@ -0,0 +1,44 @@
+<meta property="og:title" content="{{ .Title }}" />
+<meta property="og:description" content="{{ with .Description }}{{ . }}{{ else }}{{if .IsPage}}{{ .Summary }}{{ else }}{{ with .Site.Params.description }}{{ . }}{{ 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 . }}<meta property="og:image" content="{{ . | absURL }}" />{{ end -}}
+{{- else -}}
+{{- $featured := partial "get-opengraph-image.html" . }}
+{{- with $featured -}}
+<meta property="og:image" content="{{ $featured.Permalink }}"/>
+{{- else -}}
+{{- with $.Site.Params.images }}<meta property="og:image" content="{{ index . 0 | absURL }}"/>{{ end -}}
+{{- end -}}
+{{- end -}}
+
+{{- if .IsPage }}
+{{- $iso8601 := "2006-01-02T15:04:05-07:00" -}}
+<meta property="article:section" content="{{ .Section }}" />
+{{ with .PublishDate }}<meta property="article:published_time" {{ .Format $iso8601 | printf "content=%q" | safeHTMLAttr }} />{{ end }}
+{{ with .Lastmod }}<meta property="article:modified_time" {{ .Format $iso8601 | printf "content=%q" | safeHTMLAttr }} />{{ end }}
+{{- end -}}
+
+{{- with .Params.audio }}<meta property="og:audio" content="{{ . }}" />{{ 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 . }}
+<meta property="og:video" content="{{ . | absURL }}" />
+{{ end }}{{ end }}
+
+{{- /* If it is part of a series, link to related articles */}}
+{{- $permalink := .Permalink }}
+{{- $siteSeries := .Site.Taxonomies.series }}
+{{- if $siteSeries }}
+{{ with .Params.series }}{{- range $name := . }}
+  {{- $series := index $siteSeries ($name | urlize) }}
+  {{- range $page := first 6 $series.Pages }}
+    {{- if ne $page.Permalink $permalink }}<meta property="og:see_also" content="{{ $page.Permalink }}" />{{ end }}
+  {{- end }}
+{{ end }}{{ end }}
+{{- end }}
+
+{{- /* Facebook Page Admin ID for Domain Insights */}}
+{{- with .Site.Social.facebook_admin }}<meta property="fb:admins" content="{{ . }}" />{{ end }}