{{- /*
  Returns the URL for a given licence, either from the site data or from a defined URL.

  @params licences_data Site data of licences, indexed by SPDX IDs.
  @params licence   Licence identifier.
  @params licence_link  Manually-defined licence URL. Optional.
  */
-}}

<!-- Validation -->

{{- if ( not ( isset . "licences_data" ) ) -}}
    {{- errorf "No licence data passed to partial" -}}
{{- end -}}

{{- if ( not ( isset . "licence" ) ) -}}
    {{- errorf "No licence requested in partial" -}}
{{- end -}}

<!-- Variable assignment -->

{{- $licences_data := .licences_data -}}
{{- $licence := .licence -}}
{{- $licence_link := .licence_link -}}

{{- $final_licence_link := "" -}}

<!-- Rendering -->

{{- if ( index $licences_data $licence ) -}}
    {{- if eq ( index $licences_data $licence ) $licence_link -}}
        {{- warnf "Redundant license link '%s' defined, it already exists in the site data" ( index $licences_data $licence ) -}}
        {{- $final_licence_link = ( index $licences_data $licence ) -}}
    {{- else -}}
        {{- if ( and ( $licence_link ) ( not ( eq ( index $licences_data $licence ) $licence_link ) ) ) -}}
            {{- warnf "Licence '%s' has a different link ('%s') defined in the site data, using '%s' instead" $licence ( index $licences_data $licence ) $licence_link -}}
        {{- end -}}
        {{- $final_licence_link = $licence_link -}}
    {{- end -}}
   
{{- else if $licence_link -}}
    {{- warnidf "licence-link-not-in-site-data" "License link '%s' for licence '%s' should be in the site data, unless it's rarely used" $licence_link $licence -}}
    {{- $final_licence_link = $licence_link -}}
{{- end -}}

{{- return $final_licence_link -}}