{{- /*
Calendar link for one date of a tour, shown as a calendar icon: an .ics file (iCalendar), which
Apple Calendar, Outlook, Thunderbird and most other calendar apps can open. On Android,
assets/js/calendar.js turns it into a link that adds the date in Google Calendar.
Meant for the list of dates on a tour page:

  * Tag 1 (27.12.) **17:30 Uhr** {{< calendar date="2026-12-27" time="17:30" duration="210" >}}

Params: date (YYYY-MM-DD), time (HH:MM, local time in Hamburg), duration in minutes
(optional, else tours.<slug>.duration in data/schedule/<event>.yaml), title (optional, else the
title of this date in the schedule data, else the page title).
*/ -}}
{{- $page := .Page -}}
{{- $lang := $page.Language.Name -}}
{{- $other := cond (eq $lang "de") "en" "de" -}}
{{- $event := $page.Section -}}
{{- $slug := $page.File.ContentBaseName -}}
{{- $date := .Get "date" -}}
{{- $time := .Get "time" -}}
{{- if not (and (findRE `^\d{4}-\d{2}-\d{2}$` $date) (findRE `^\d{2}:\d{2}$` $time)) -}}
  {{- errorf "calendar: date must be YYYY-MM-DD and time HH:MM, got %q %q: %s" $date $time .Position -}}
{{- end -}}

{{- $data := dict -}}
{{- with hugo.Data.schedule }}{{ with index . $event }}{{ $data = . }}{{ end }}{{ end -}}
{{- $tourData := dict -}}
{{- with $data.tours }}{{ with index . $slug }}{{ $tourData = . }}{{ end }}{{ end -}}
{{- /* This date in the schedule, for its title. */ -}}
{{- $slot := dict -}}
{{- range $data.days -}}
  {{- if eq .date $date -}}
    {{- range .tours }}{{ if and (eq .tour $slug) (eq .time $time) }}{{ $slot = . }}{{ end }}{{ end -}}
  {{- end -}}
{{- end -}}

{{- $title := .Get "title" -}}
{{- if not $title }}{{ with $slot.title }}{{ $title = index . $lang | default (index . $other) }}{{ end }}{{ end -}}
{{- $title = $title | default $page.Title -}}

{{- $minutes := int (.Get "duration" | default ($tourData.duration | default 0)) -}}
{{- if not $minutes -}}
  {{- warnidf "warning-calendar-duration" "calendar: no duration for %s on %s %s, the calendar entry has no end time: %s" $slug $date $time .Position -}}
{{- end -}}

{{- $start := time.AsTime (printf "%sT%s:00" $date $time) "Europe/Berlin" -}}
{{- $end := $start.Add (time.ParseDuration (printf "%dm" $minutes)) -}}
{{- $utc := "20060102T150405Z" -}}

{{- /* Everyone meets at the Hackertours desk, which is where the routes on the map start. */ -}}
{{- $location := i18n "calendar_meeting_point" -}}
{{- with $data.map }}{{ with .origin }}{{ with .name -}}
  {{- $location = printf "%s, %s" $location (index . $lang | default (index . $other)) -}}
{{- end }}{{ end }}{{ end -}}
{{- /* The front matter summary: .Summary would render this page again from inside its own shortcode. */ -}}
{{- $summary := $page.Params.summary | default $page.Description | default "" -}}
{{- $description := printf "%s\n\n%s" ($page.RenderString $summary | plainify | htmlUnescape | strings.TrimSpace) $page.Permalink -}}

{{- $ics := printf "BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//CCC Hansestadt Hamburg//Hackertours//%s\r\nCALSCALE:GREGORIAN\r\nMETHOD:PUBLISH\r\nBEGIN:VEVENT\r\n" (upper $lang) -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "UID" "value" (printf "%s-%s-%s-%s@%s" $event $slug $date (replace $time ":" "") (urls.Parse site.BaseURL).Host))) -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "DTSTAMP" "value" ($page.Lastmod.UTC.Format $utc))) -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "DTSTART" "value" ($start.UTC.Format $utc))) -}}
{{- if $minutes }}{{ $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "DTEND" "value" ($end.UTC.Format $utc))) }}{{ end -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "SUMMARY" "value" $title "text" true)) -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "LOCATION" "value" $location "text" true)) -}}
{{- with $data.map }}{{ with .origin }}{{ with .geo -}}
  {{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "GEO" "value" (printf "%v;%v" .lat .lon))) -}}
{{- end }}{{ end }}{{ end -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "DESCRIPTION" "value" $description "text" true)) -}}
{{- $ics = printf "%s%s" $ics (partial "ics-line.html" (dict "name" "URL" "value" $page.Permalink)) -}}
{{- $ics = printf "%sEND:VEVENT\r\nEND:VCALENDAR\r\n" $ics -}}

{{- $file := printf "%s-%s-%s.ics" $slug $date (replace $time ":" "") -}}
{{- $icsFile := resources.FromString (path.Join (strings.TrimPrefix "/" $page.RelPermalink) $file) $ics -}}
{{- /* The icon is the same for every date, so the link name for screen readers includes the date. */ -}}
{{- $when := printf "%s %s" ($start | time.Format "Mon 2.1.") $time -}}
{{- /* Android's Google Calendar app can't open .ics files; there, calendar.js uses this link instead. */ -}}
{{- $google := printf "https://calendar.google.com/calendar/render?%s" (querify
  "action" "TEMPLATE"
  "text" $title
  "dates" (printf "%s/%s" ($start.UTC.Format $utc) ($end.UTC.Format $utc))
  "details" $description
  "location" $location
  "ctz" "Europe/Berlin"
) -}}
<a class="tour-calendar" href="{{ $icsFile.RelPermalink }}" download="{{ $file }}" title="{{ i18n "calendar_ics" }}" data-google-href="{{ $google }}" data-google-title="{{ i18n "calendar_google" }}" data-google-label="{{ i18n "calendar_google" }} {{ $when }}">{{ partial "fa-icon.html" "regular/calendar-plus" }}<span class="visually-hidden">{{ i18n "calendar_ics" }} {{ $when }}</span></a>
{{- /* chomp */ -}}