{{/*
  ARGS: .lang .page .componentName

  RETURNS: .lang if truthy, otherwise the language extracted from
  .page.RelPermalink when of the form `/docs/languages/LANG/...` optionally
  prefixed with a locale code.

  EXAMPLE: when .page is `docs/languages/go/...`, the return value is `go`.
*/ -}}

{{ $lang := .lang -}}
{{ if not $lang }}
  {{ $matches := findRESubmatch `docs/languages/([^/]+)` .page.RelPermalink -}}
  {{ $lang = index (index $matches 0) 1 -}}
  {{ if not $lang -}}
    {{ $msg := printf "%q: Cannot determine language from page file path." .page.File.Path -}}
    {{ $fix := printf "Add a language argument to the shortcode or partial call of %q" .componentName -}}
    {{ errorf "%s %s" $msg $fix -}}
  {{ end -}}
{{ end -}}

{{ return $lang -}}