{{ $scratch := newScratch }}
{{ $baseURL := replaceRE `\/$` "" .Site.BaseURL }}

<!-- Set the current page as the default canonical URL -->
{{ $scratch.Set "canonicalURL" (print $baseURL .RelPermalink) }}

<!-- Set canonical URL using 'canonical' frontmatter -->
{{ if .Page.Params.canonical }}
  {{ $scratch.Set "canonicalURL" (print $baseURL .Page.Params.canonical) }}

<!--
Set canonical URL from pages with the same shared source. Select one page from
those that share the same source using the following product priority order:

1. enterprise
2. core
3. cloud-dedicated
4. clustered
5. cloud-serverless
6. v2
7. cloud
-->
{{ else if .Page.Params.source }}
  {{ $productPriority := slice
    "/enterprise/"
    "/core/"
    "/cloud-dedicated/"
    "/clustered/"
    "/cloud-serverless/"
    "/v2/"
    "/cloud/"
  }}
  {{ range where (sort .Site.Pages "Section" "desc") "Params.source" "eq" .Page.Params.source }}
    {{ $pagePath := .RelPermalink }}
    {{ range $productPriority }}
      {{ if in $pagePath . }}
        {{ $scratch.Set "canonicalURL" (print $baseURL $pagePath) }}
      {{ end }}         
    {{ end }}
  {{ end }}
{{ end }}

{{ $canonicalURL := $scratch.Get "canonicalURL" }}

<link rel="canonical" href="{{ $canonicalURL }}" />