fix twitter card images for pngs and absolute urls

themes/brainbaking-minimal/layouts/partials/head-meta.html

@@ -1,11 +1,12 @@
 {{ $perm := .Permalink }}
+{{ $base := .Site.BaseURL }}
 {{ $logo := "img/avatar-icon.png" }}
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <link rel="canonical" href="{{ $perm }}">
 <link rel="me" title="Mastodon" href="{{ .Site.Author.mastodonlink }}" />
 <link rel="me" title="Github" href="{{ .Site.Author.githublink }}" />
-<link rel="author" href="{{ .Site.BaseURL }}humans.txt" type="text/plain" />
+<link rel="author" href="{{ $base }}humans.txt" type="text/plain" />
 <link rel="webmention" href="https://jam.brainbaking.com/webmention" />
 <link rel="pingback" href="https://jam.brainbaking.com/pingback" />
 
@@ -57,10 +58,14 @@
     </style>
   {{ end }}
 {{ else }}
-  {{ $match := findRE `!\[\]\((.+).jpg` .RawContent 1 }}
+  {{ $match := findRE `!\[(.*)\]\((.+).(jpg|png|gif)` .RawContent 1 }}
   {{ range $match }}
-    {{ $relthumb := replace . "![](" "" }}
-    {{ $thumb = printf "%s%s" $perm $relthumb }}
+    {{ $relthumb := replaceRE `!\[(.*)\]\(` "" . }}
+    {{ if hasPrefix $relthumb "/" }}
+      {{ $thumb = printf "%s%s" $base $relthumb }}
+    {{ else }}
+      {{ $thumb = printf "%s%s" $perm $relthumb }}
+    {{ end }}
   {{ end }}
 {{ end }}
 <meta name="twitter:image" property="og:image" content="{{ $thumb }}" />
@@ -90,7 +95,7 @@
     "@type" : "BlogPosting",
     "mainEntityOfPage": {
          "@type": "WebPage",
-         "@id": {{ .Site.BaseURL }}
+         "@id": {{ $base }}
     },
     "articleSection" : "{{ .Section }}",
     "name" : {{ .Title }},
@@ -118,7 +123,7 @@
     "publisher": {
     	"@type": "Organization",
     	"name": "{{ .Site.Title }}",
-      "url": {{ .Site.BaseURL }},
+      "url": {{ $base }},
     	"logo": {
     		"@type": "ImageObject",
     		"url": {{ $logo | absURL }},