{{- /*
  Favicons by convention: each well-known filename is linked if it exists in static/.
  Drop the files in and they are picked up - there is nothing to configure.

  The names are the ones favicon generators produce, so a standard icon set works
  as-is: https://realfavicongenerator.net

  themeColor keeps reading the long-standing top-level param.

  A site whose icons are named differently can override this partial.

  What Google asks of a favicon, which is what shapes the decisions here
  (https://developers.google.com/search/docs/appearance/favicon-in-search):

    - It reads the favicon from the HOME PAGE only, so at least one rel="icon" has to
      exist there. That is why the warning at the foot of this file fires on the home
      page alone: warning on every page would say nothing extra.
    - The icon should be square, ideally a multiple of 48px (48, 96, 144...).
    - It must be crawlable, so do not block it in robots.txt.
    - Its URL should stay STABLE, because Google caches it.

  That last point is why there is deliberately no fingerprint and no ?v= query here. A
  URL that moved with the bytes would defeat the caching Google is doing on purpose.

  It also has a consequence beyond this file, for whoever configures caching. Because
  these filenames carry no content hash, a long `immutable` Cache-Control would pin a
  replaced icon in visitors' caches indefinitely. Something short, a week or so, is the
  right choice for them, unlike the fingerprinted assets under /css/ and /js/. This
  theme sets no Cache-Control itself, so that is a decision for the site.
*/ -}}
{{- $icons := slice
      (dict "file" "favicon.svg"          "rel" "icon"             "type" "image/svg+xml")
      (dict "file" "favicon.png"          "rel" "icon"             "type" "image/png")
      (dict "file" "favicon-96x96.png"    "rel" "icon"             "type" "image/png" "sizes" "96x96")
      (dict "file" "favicon.ico"          "rel" "shortcut icon")
      (dict "file" "apple-touch-icon.png" "rel" "apple-touch-icon" "sizes" "180x180")
-}}
{{- $found := 0 -}}
{{- range $icons -}}
  {{- if os.FileExists (printf "static/%s" .file) -}}
    {{- $found = add $found 1 }}
  {{- /* type through safeHTMLAttr, as in head/opengraph.html: interpolated into a plain
         attribute, the "+" of image/svg+xml comes out as +. */ -}}
  <link rel="{{ .rel }}"{{ with .type }} {{ printf "type=%q" . | safeHTMLAttr }}{{ end }}{{ with .sizes }} sizes="{{ . }}"{{ end }} href="{{ .file | absURL }}">
  {{- end -}}
{{- end }}

{{- if os.FileExists "static/apple-touch-icon.png" }}
  <meta name="apple-mobile-web-app-title" content="{{ site.Title }}">
{{- end }}

{{- if os.FileExists "static/site.webmanifest" }}
  <link rel="manifest" href="{{ `site.webmanifest` | absURL }}">
{{- end }}

{{- with site.Params.themeColor }}
  <meta name="theme-color" content="{{ . }}">
{{- end }}

{{- /* Google reads the favicon from the home page, so that is the only page worth
       warning about, and once is enough. */ -}}
{{- if and .IsHome (eq $found 0) -}}
  {{- warnf "head/favicons: no favicon found in static/ - search engines will show none. Expected one of favicon.svg, favicon.png, favicon-96x96.png, favicon.ico." -}}
{{- end -}}