{{- /*
    For a given comic page, renders a nav bar.

    This navbar contains a link to the following:
    - first page
    - previous chapter (if applicable)
    - previous page
    - next page
    - next chapter (if applicable)
    - last page

    Chapter navigation is only shown if:
    - site parameter silicate.pages.show_chapter_nav is true
    - there is at least a comic section in the given page comic series

    Expect a comic page as argument.

    Example usage: {{ partial "comic/nav.html" . }}
*/}}

{{- $first_page := partial "func/FirstPageRecursive.html" .FirstSection }}
{{- $last_page := partial "func/LastPageRecursive.html" .FirstSection }}

{{- $prev_chapter := partial "func/PrevLeafSection.html" . }}
{{- $next_chapter := partial "func/NextLeafSection.html" . }}

{{/*
    we use Reverse before Next and Prev because they use descending weight
    ordering instead of the default ascending order.

    Also, this will not cross beyond the current section / chapter,
    we need to go look at the prev / next chapter too if we don't
    directly find a page.
*/}}
{{- $prev_page := false }}
{{- $next_page := false }}

{{- with .Parent.Pages.Reverse.Prev . }}
    {{- $prev_page = . }}
{{- else with $prev_chapter }}
    {{- $prev_page = index .Pages.Reverse 0 }}
{{- end }}

{{- with .Parent.Pages.Reverse.Next . }}
    {{- $next_page = . }}
{{- else with $next_chapter }}
    {{- $next_page = index .Pages 0 }}
{{- end }}

{{- $has_chapters := gt .FirstSection.Sections.Len 0 }}
{{- $show_chapter_nav := and .Site.Params.silicate.pages.show_chapter_nav $has_chapters }}

{{- $prev_chapter_first_page := false }}
{{- $next_chapter_first_page := false }}
{{- if $show_chapter_nav }}

    {{- with $prev_chapter }}
        {{- $prev_chapter_first_page = partial "func/FirstPageRecursive.html" . }}
    {{- end }}

    {{- with $next_chapter }}
        {{- $next_chapter_first_page = partial "func/FirstPageRecursive.html" . }}
    {{- end }}
{{- end }}

{{- /*
    As a note, the newlines and use of `{{-` with no `-}}`
    is important : since elements under the `nav` will
    be shown as `inline-block`, newline in HTML adds
    a litteral space between the elements.

    If newlines are not consistent, spaces won't be either
    and spacing of nav buttons will be uneven.
*/}}

<nav class="page-nav">
    {{- if not ($first_page.Eq .)}}
    <a href="{{ $first_page.RelPermalink }}" title="First Page">&#8606;</a>
    {{- else}}
    <span class="disabled">&#8606;</span>
    {{- end}}

    {{- if $show_chapter_nav }}
    {{- with $prev_chapter_first_page }}
    <a href="{{ .RelPermalink }}" title="Previous Chapter">&#8612;</a>
    {{- else}}
    <span class="disabled">&#8612;</span>
    {{- end}}
    {{- end }}

    {{- with $prev_page }}
    <a href="{{ .RelPermalink }}" title="Previous Page">&larr;</a>
    {{- else}}
    <span class="disabled">&larr;</span>
    {{- end}}

    {{- with $next_page }}
    <a href="{{ .RelPermalink }}" title="Next Page">&rarr;</a>
    {{- else }}
    <span class="disabled">&rarr;</span>
    {{- end }}

    {{- if $show_chapter_nav }}
    {{- with $next_chapter_first_page }}
    <a href="{{ .RelPermalink }}" title="Next Chapter">&#8614;</a>
    {{- else}}
    <span class="disabled">&#8614;</span>
    {{- end}}
    {{- end }}

    {{- if not ($last_page.Eq .) }}
    <a href="{{ $last_page.RelPermalink }}" title="Last Page">&#8608;</a>
    {{- else }}
    <span class="disabled">&#8608;</span>
    {{- end }}
</nav>