hugo-theme/layouts/shortcodes/calendar.html

{{ $date:= .Get "date" }}
{{ if not $date }}
  {{ errorf "Error: 'date' is a required parameter." }}
{{ end }}
{{ $date := time.AsTime $date }}

{{ $month := $date.Month | int }}
{{ $year := $date.Year }}

{{ $t1 := printf "%4d-%02d-01" $year $month }}
{{ $t1 := time.AsTime $t1 }}
{{ $t2 := $t1.AddDate 0 1 0 }}

{{ $daysInMonth := $t2.Sub $t1 }}
{{ $daysInMonth := $daysInMonth.Hours }}
{{ $daysInMonth := div $daysInMonth 24 }}

<div class="calendar">
  {{ if eq .Site.Language.Lang "pl" }}
    {{ $polish_month_names := slice "Styczeń" "Luty" "Marzec" "Kwiecień" "Maj" "Czerwiec" "Lipiec" "Sierpień" "Wrzesień" "Październik" "Listopad" "Grudzień" }}
    {{ $month := sub $month 1}}
    {{ $label := index $polish_month_names $month }}
    <a class="month">{{ printf "%s %d" $label $year }}</a>
  {{ else }}
    <a class="month">{{ time.Format "January 2006" $t1 }}</a>
  {{ end }}

  <div class="weekdays" >
    {{ $days := slice "sun" "mon" "tues" "wend" "thurs" "fri" "sat" }}
    {{ range $days }}<p>{{ i18n (printf "days.%s" .) }}</p>{{ end }}
  </div>

  <div class="days">
  {{ $padding := $t1.Weekday | int }}
	{{ if gt $padding 0 }}
    {{ range seq 1 $padding }}
      <div class="pad-day"></div>
    {{ end }}
	{{ end }}

  {{ range seq 1 $daysInMonth }}
    <div class="day" onclick="simulateLinkClick()" >
      {{ $startDate := time.AsTime ( printf "%4d-%02d-%02dT00:00:00" $year $month . ) }}
      {{ $endDate := time.AsTime ( printf "%4d-%02d-%02dT23:59:59" $year $month . ) }}
      <h3 class="day-num">{{ . }}</h3>
      <h3 class="mobile-date">{{ $startDate | time.Format ":date_long" }} </h3>

      {{ $eventCount := 0 }}
      {{ range where $.Site.RegularPages "Section" "eq" "events" }}
        {{ $eventStart := time.AsTime .Params.start_date }}
        {{ $eventEnd := time.AsTime .Params.end_date }}
        
        {{ if and ( or ($eventEnd.After $startDate) ($eventEnd.Equal $startDate)) (or ( $eventStart.Before $endDate ) ( $eventStart.Equal $endDate )) }}
          {{ $eventCount = add $eventCount 1 }}
          <div class="event" >
            <a href="{{ .RelPermalink }}">{{.Title}}</a>
          </div>
        {{ end }}        
    {{ end }}
    {{ if gt $eventCount 1 }}
      {{ errorf "Error: Multiple events per day currently unsuported" }}
    {{ end }}
    </div>
  {{ end }}
  </div>
</div>

<script>
function simulateLinkClick() {
  var link = document.querySelector('.day a');
  if (link) {
    link.click();
  }
}
</script>