{{/* description: per-page excerpt wins over site-wide description */}}
{{ $description := .Site.Language.Params.siteDescription }}
{{ with .Params.excerpt }}{{ $description = . }}{{ end }}

{{/* og:type: "article" only for single content pages that have a date */}}
{{ $ogType := "website" }}
{{ if and (eq .Kind "page") .Date }}{{ $ogType = "article" }}{{ end }}

{{/* og:image: page image wins; fall back to lamp for homepage, dark thumbnail for articles */}}
{{ $defaultImage := "images/default_thumbnail_dark.png" }}
{{ if .IsHome }}{{ $defaultImage = "images/lampD.png" }}{{ end }}
{{ $ogImage := printf "%s%s" .Site.BaseURL $defaultImage }}
{{ with .Params.image }}{{ $ogImage = printf "%s%s" $.Site.BaseURL (strings.TrimLeft "/" .) }}{{ end }}

{{/* author: page-level param wins; fall back to site param */}}
{{ $author := .Site.Params.author }}
{{ with .Params.author }}{{ $author = . }}{{ end }}

<meta name="description" content="{{ $description }}">

<meta property="og:title" content="{{ .Title }}">
<meta property="og:description" content="{{ $description }}">
<meta property="og:type" content="{{ $ogType }}">
<meta property="og:url" content="{{ .Permalink }}">
<meta property="og:site_name" content="{{ .Site.Title }}">
<meta property="og:locale" content="{{ .Site.Language.Params.locale }}">
<meta property="og:image" content="{{ $ogImage }}">

{{ if eq $ogType "article" }}
<meta property="article:published_time" content="{{ .Date.Format "2006-01-02T15:04:05Z07:00" }}">
<meta property="article:author" content="{{ $author }}">
{{ end }}

<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:title" content="{{ .Title }}">
<meta name="twitter:description" content="{{ $description }}">
<meta name="twitter:image" content="{{ $ogImage }}">
{{ with .Site.Params.twitterHandle }}
<meta name="twitter:site" content="@{{ . }}">
{{ end }}

{{/* SEO: Self-referencing canonical */}}
<link rel="canonical" href="{{ .Permalink }}">

{{/* SEO: hreflang alternates for all language variants */}}
{{ range .AllTranslations }}
<link rel="alternate" hreflang="{{ .Language.Lang }}" href="{{ .Permalink }}">
{{ end }}
{{/* x-default: EN version (served at root /) */}}
{{ range .AllTranslations }}
  {{ if eq .Language.Lang "en" }}
<link rel="alternate" hreflang="x-default" href="{{ .Permalink }}">
  {{ end }}
{{ end }}