Hugoで頭のいいページネーションを作成する

pagination.html

{{ $paginator := .Paginator }}

{{ $adjacent_links := 2 }}
{{ $max_links      := (add (mul $adjacent_links 2) 1) }}
{{ $lower_limit    := (add $adjacent_links 1) }}
{{ $upper_limit    := (sub $paginator.TotalPages $adjacent_links) }}

{{ if gt $paginator.TotalPages 1 }}
<div class="page">
        <ul>

        <!-- Goto First page. -->
        {{ if ne $paginator.PageNumber 1 }}
        <li class="pagination__item pagination__item--first">
                <a class="pagination__link pagination__link--first" href="{{ $paginator.First.URL }}">
                        <i class="fa fa-angle-double-left"></i>
                </a>
        </li>
        {{ end }}

        <!-- Previous page. -->
        {{ if $paginator.HasPrev }}
        <li class="pagination__item pagination__item--previous">
                <a href="{{ $paginator.Prev.URL }}" class="pagination__link pagination__link--previous">
                        <i class="fa fa-angle-left"></i></a>
                </a>
        </li>
        {{ end }}


        <!-- logic for calculating middle numbers -->
        {{ range $paginator.Pagers }}

        <!-- use Scratch to avoid scope error -->
        {{ $.Scratch.Set "page_number_flag" false }}

        <!-- if there is enough pages -->
        {{ if gt $paginator.TotalPages $max_links }}


                <!-- Lower limit pages. -->
                <!-- If the user is on a page which is in the lower limit.  -->
                {{ if le $paginator.PageNumber $lower_limit }}

                        <!-- If the current loop page is less than max_links. -->
                        {{ if le .PageNumber $max_links }}
                                {{ $.Scratch.Set "page_number_flag" true }}
                        {{ end }}

                <!-- Upper limit pages. -->
                <!-- If the user is on a page which is in the upper limit. -->
                {{ else if ge $paginator.PageNumber $upper_limit }}

                        <!-- If the current loop page is greater than total pages minus $max_links -->
                        {{ if gt .PageNumber (sub $paginator.TotalPages $max_links) }}
                                {{ $.Scratch.Set "page_number_flag" true }}
                        {{ end }}

                <!-- Middle pages. -->
                {{ else }}
                        {{ if and ( ge .PageNumber (sub $paginator.PageNumber $adjacent_links) ) ( le .PageNumber (add $paginator.PageNumber $adjacent_links) ) }}
                                {{ $.Scratch.Set "page_number_flag" true }}
                        {{ end }}

                {{ end }}

        <!-- Simple page numbers. -->
        {{ else }}
                {{ $.Scratch.Set "page_number_flag" true }}
        {{ end }}
        
        <!-- Output page numbers. -->
        {{ if eq ($.Scratch.Get "page_number_flag") true }}
        <li {{ if eq . $paginator }} class="active" {{ end }}>
                <a href="{{ .URL }}">
                        {{ .PageNumber }}
                </a>
        </li>
        {{ end }}


        <!-- end range -->              
        {{ end }}

        <!-- Next page. -->
        {{ if $paginator.HasNext }}
        <li class="pagination__item pagination__item--next">
                <a href="{{ $paginator.Next.URL }}">
                        <i class="fa fa-angle-right"></i>
                </a>
        </li>
        {{ end }}

        <!-- Last page. -->
        {{ if ne $paginator.PageNumber $paginator.TotalPages }}
        <li class="pagination__item pagination__item--last">
                <a href="{{ $paginator.Last.URL }}">
                        <i class="fa fa-angle-double-right"></i>
                </a>
        </li>
        {{ end }}
    </ul>
</div>
{{ end }}