{{/* get the file name associated with the page */}}
{{- $file := print .Page.File.Dir  -}}
{{/* split by the seperator ("/") */}}
{{- $parts := split $file "/" -}}
{{/* this will grab the first part which is the section (aka product), e.g. `os` */}}
{{- $url_section := index $parts 0 -}}
{{/* grab the current version from the Hugo data file */}}
{{- $versions := index $.Site.Data.versions.current $url_section -}}
{{/* create the version string (e.g. `1.14.x`) */}}
{{- $latest := print $versions.major "." $versions.minor ".x" -}}
{{/* get the language (which is not part of the file name) */}}
{{- $language := .Page.Language.Lang -}}

<script>
    {{/* JS IIFE to isolate variable scope */}}
    (function() {
        {{/* create an array */}}
        var currentVersion = [];
        var currentURLPrefix = "/{{$language}}/{{$url_section}}/{{$latest}}";
        {{/* all the pages registered to the site */}}
        {{ range .Site.AllPages }}
            {{- /* break apart the page's permalink */ -}}
            {{- $permalink_parts := split .RelPermalink "/" -}}
            {{- /* this has the full URL including the language, so grab the language, section, and version */ -}}
            {{- $docs_lang := index $permalink_parts 1 -}}
            {{- $docs_section := index $permalink_parts 2 -}}
            {{- $docs_version := index $permalink_parts 3 -}}
            {{- /* if the page evaluated is the latest version, in the correct section, and correct language */ -}}
            {{- if and (eq $docs_version $latest) (eq $url_section $docs_section) (eq .Language.Lang $docs_lang) -}}
                {{- /* push it into an JS Array */ -}}
                {{- /* remove the initial section (e.g. /en/os/1.14.x) */ -}}
                currentVersion.push("{{ .RelPermalink }}".replace(currentURLPrefix,""));
            {{ end }}
        {{- end -}}
        {{/* new `currentVersion` contains only the valid pages in the correct section/langauge/version */}}
        var docs_location;
        {{/* do we have a hash in the URL? */}}
        if (window.location && window.location.hash) {
            {{/* get the hash portion and snip off the first character (will always be #) */}}
            docs_location = window.location.hash.slice(1); 
            {{/* does it have a trailing slash? If not, add one to match the Hugo output */}}
            if (docs_location[docs_location.length-1] !== '/') { 
                docs_location = docs_location + '/';
            }
            {{/* Is the passed URL fragment in the array? */}}
            if (currentVersion.indexOf(docs_location) !== -1) {
                {{/* reconstruct the URL with the latest version */}}
                location.assign(currentURLPrefix + docs_location);
            } else {
                {{/* otherwise just go to the top of the current version */}}
                location.assign(currentURLPrefix);
            }
        }
    })();
</script>