Separate date and name in the upcoming events table

The two columns of the table on the start page touched each other, so the entry
read "Donnerstag, 27.08., 19:00 UhrClub Discordia".

The table is created with the classes "table table-condensed", which no
stylesheet of the site defines, and the table styling that the theme applies
inside prose addresses "tbody td". The table is delivered empty and its rows
are added through the DOM, where a tr appended to a table stays a direct child
instead of being put into a tbody the way the HTML parser would. The rows are
therefore outside of any tbody and the padding of the theme never applied.

Give the column holding the date its own padding, and keep the date on one
line, it is one piece of information and reads badly broken after the weekday.

The padding alone does not fit, though. The table stands in a prose column that
the theme limits to 65 characters so that running text stays readable, and a
date and the name of an event next to each other are wider than that, so the
names would be wrapped over several lines. Lift the limit off the column and
put it back on everything in it except the table, which leaves the table room
to grow while the heading and the paragraph around it keep their width.

That much space then has to be filled sensibly. The theme lays a table out as a
block, "table { display: block; overflow: auto }", so that a wide one can be
scrolled sideways, and a block fills its parent instead of shrinking to its
content the way a table does. Spanning the page the entries would all sit at
its left edge. Ask for the width of the content with fit-content, which the
automatic margins then centre.

Addressing the table by its id keeps all of this to the start page and takes
precedence over the theme, whose prose rules are written with :where() and
carry no specificity.

Measured in a browser at 1280, 768 and 500 pixels: date and name share one line
at the first two, the table is 602 pixels wide with the same distance left and
right, and at 500 the column is narrower than the table, so the table fills it
and only the longest name wraps. The page never scrolls sideways.

Fixes: c28f04c6e8 ("switch to ics files; make calendars work; fix some minor issues")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

.gitignore

@@ -202,3 +202,8 @@ $RECYCLE.BIN/
 *.lnk
 
 # End of https://www.toptal.com/developers/gitignore/api/windows,linux,macos,hugo,pycharm+all,vim,direnv
+
+### CCCB ###
+# The calendar the site reads its events from is published next to the site and
+# only downloaded here to look at the site locally, see the README.
+/static/calendars/

README.md

@@ -29,20 +29,34 @@ This is the website of the CCCB.
 
 Every change you make on the project will be reflected in your browser as long as `hugo serve` is running.
 
-The *"Nächste Veranstaltungen"* table on the home page is generated by post-processing in `./build.sh`, not by Hugo, so
-it is **not** visible under `hugo serve`. To preview the fully built site (including the home-page calendar), or to
-ready the site for upload, run:
+The *"Nächste Veranstaltungen"* table on the home page and the calendar under `/verein/calendar/` are rendered in the
+browser by `assets/js/upcoming.js` and `assets/js/calendar.js`. Both fetch `/calendars/all.ics`, which is **not**
+generated by Hugo and is not part of this repo — it is published separately on the web server. Without it both tables
+stay empty. Download the published calendar into `static/`, which Hugo serves under the same path, and they work
+locally, under `hugo serve` as well as in a built site:
+
+```shell
+mkdir -p static/calendars
+curl -o static/calendars/all.ics https://berlin.ccc.de/calendars/all.ics
+```
+
+The file is only there to look at the site, it is not checked in. Download it again whenever you want the events that
+are currently published.
+
+Hugo does generate an `.ics` feed per section (for example `/veranstaltungen/index.ics`) from the `dtstart`, `dtend`
+and `rrule` front matter of the pages in `content/veranstaltungen/`, using the `.ics` templates under `layouts/`.
+
+The site must not make the browser load anything from an external server, so third party JavaScript is checked into
+`assets/js/vendor/` and bundled in by Hugo instead of being pulled from a CDN. See the README there before updating it.
+
+To build the site for upload, run:
 
 ```shell
 ./build.sh
-python3 -m http.server -d public 1313
 ```
 
-`build.sh` replaces the `CALENDAR` placeholder in `index.html` with the upcoming-events table. It depends on Python
-with the `icalendar`, `python-dateutil`, and `pytz` packages, plus a `de_DE.UTF-8` locale (used to format weekday
-names). Inside `nix develop` these are provided automatically.
-
-To build with *nix*: `nix build '.?submodules=1#production-content'`
+This deletes `public/` and runs `hugo` with the parameters from `.hugo-params`. To build with *nix* instead:
+`nix build '.?submodules=1#production-content'`
 
 ## Making a change
 
@@ -59,8 +73,7 @@ To build with *nix*: `nix build '.?submodules=1#production-content'`
 
 ## Nix stuff
 
-- After entering the shell with `nix develop`, hugo is available and `hugo serve` should work
-- Python including required packages will be available, so the `build.sh` should work without a venv
+- After entering the shell with `nix develop`, hugo is available and `hugo serve` and `./build.sh` should work
 - You can build the staging and production builds with `nix build .#staging-content` and
   `nix build .#production-content`
 - Do not update the nixpkgs branch - 25.05 contains a newer hugo version that is incompatible with the theme (last

assets/css/calendar.css

@@ -107,6 +107,10 @@
     font-size: 0.9em;
     margin-bottom: 5px;
   }
+  .event-description {
+    /* Descriptions carry their own line breaks, keep them. */
+    white-space: pre-line;
+  }
   .no-events {
     font-style: italic;
     color: var(--color-text-secondary);

assets/css/upcoming.css

@@ -0,0 +1,36 @@
+/* The rows of the table are added by JavaScript and end up as direct children
+   of the table, so the table styling of the theme, which addresses tbody, does
+   not reach them. Separate the date from the name of the event ourselves, and
+   keep the date on one line, it is one piece of information and reads badly
+   broken after the weekday. */
+#upcoming td:first-child {
+  padding-inline-end: 1em;
+  white-space: nowrap;
+}
+
+/* The table stands in a prose column, which the theme limits to 65 characters
+   so that running text stays readable. A date and the name of an event next to
+   each other do not fit into that, so the names were wrapped over several
+   lines. Lift the limit off the column and put it back on everything in it
+   except the table, which leaves the table room to grow while the text around
+   it keeps its width. */
+section.prose:has(> #upcoming) {
+  max-width: none;
+}
+
+section.prose:has(> #upcoming) > :not(#upcoming) {
+  max-width: 65ch;
+  margin-inline: auto;
+}
+
+/* The theme lays a table out as a block, "table { display: block; overflow:
+   auto }", so that a wide one can be scrolled sideways. A block fills its
+   parent instead of shrinking to its content the way a table does, so across
+   the whole width of the page the entries would stay at its left edge.
+   fit-content asks for the width of the content, which the automatic margins
+   then centre, and it never exceeds the column, so a display too narrow for
+   the table still wraps the names instead of overflowing. */
+#upcoming {
+  width: fit-content;
+  margin-inline: auto;
+}

assets/js/calendar.js

@@ -1,449 +1,418 @@
-document.addEventListener('DOMContentLoaded', function() {
-    (function(){
-        let events = [];
-        let eventsByDate = {};
+import ICAL from "./vendor/ical.js";
 
-        // Funktion zum Parsen der ICS-Datei
-        function parseICS(icsText) {
-            let events = [];
-            let lines = icsText.split(/\r?\n/);
-            let event = null;
-            lines.forEach(line => {
-                if (line.startsWith("BEGIN:VEVENT")) {
-                    event = {};
-                } else if (line.startsWith("END:VEVENT")) {
-                    if (event) events.push(event);
-                    event = null;
-                } else if (event) {
-                    let colonIndex = line.indexOf(":");
-                    if (colonIndex > -1) {
-                        let key = line.substring(0, colonIndex);
-                        let value = line.substring(colonIndex + 1);
+const icsUrl = "/calendars/all.ics";
 
-                        // Handle properties with parameters (like TZID)
-                        const baseKey = key.split(";")[0];
+// The club is in Berlin, so the calendar shows Berlin days and Berlin times,
+// no matter which time zone the browser of the visitor is set to.
+const timeZone = "Europe/Berlin";
 
-                        if (baseKey === "DTSTART") {
-                            event.start = value;
-                            event.startParams = key.includes(";") ? key.substring(key.indexOf(";") + 1) : null;
-                        } else if (baseKey === "DTEND") {
-                            event.end = value;
-                            event.endParams = key.includes(";") ? key.substring(key.indexOf(";") + 1) : null;
-                        } else if (baseKey === "SUMMARY") {
-                            event.summary = value;
-                        } else if (baseKey === "DESCRIPTION") {
-                            event.description = value;
-                        } else if (baseKey === "RRULE") {
-                            event.rrule = value;
-                        }
-                    }
-                }
-            });
-            return events;
-        }
+const monthNames = [
+  "Januar", "Februar", "März", "April", "Mai", "Juni",
+  "Juli", "August", "September", "Oktober", "November", "Dezember",
+];
 
-        // Hilfsfunktion: Parst einen ICS-Datum-String ins Format "YYYY-MM-DD"
-        function parseDateString(icsDateStr) {
-            // Handle different date formats
-            if (!icsDateStr) return null;
-
-            // For basic date format: YYYYMMDD
-            if (icsDateStr.length === 8) {
-                let year = icsDateStr.substring(0, 4);
-                let month = icsDateStr.substring(4, 6);
-                let day = icsDateStr.substring(6, 8);
-                return `${year}-${month}-${day}`;
-            }
-            // For datetime formats: YYYYMMDDTHHmmssZ or YYYYMMDDTHHmmss
-            else if (icsDateStr.includes("T")) {
-                let year = icsDateStr.substring(0, 4);
-                let month = icsDateStr.substring(4, 6);
-                let day = icsDateStr.substring(6, 8);
-                return `${year}-${month}-${day}`;
-            }
-            return null;
+const dayKeyFormat = new Intl.DateTimeFormat("en-US", {
+  timeZone,
+  year: "numeric",
+  month: "2-digit",
+  day: "2-digit",
+});
+
+const timeOfDayFormat = new Intl.DateTimeFormat("de-DE", {
+  timeZone,
+  hour: "2-digit",
+  minute: "2-digit",
+});
+
+let calendar = null;
+let eventsByDate = {};
+let currentYear;
+let currentMonth;
+
+let currentMonthElem;
+let calendarBody;
+let eventPanel;
+let eventDateElem;
+let eventDetailsElem;
+
+/**
+ * The day a point in time falls on in Berlin.
+ *
+ * @param {Date} date The point in time
+ * @returns {string} The day as "YYYY-MM-DD"
+ */
+function dayKey(date) {
+  const parts = {};
+
+  for (const part of dayKeyFormat.formatToParts(date)) {
+    parts[part.type] = part.value;
+  }
+
+  return `${parts.year}-${parts.month}-${parts.day}`;
+}
+
+/**
+ * The days an event covers, so that an event running over several days is
+ * shown on each of them and not only on the day it starts.
+ *
+ * @param {Date} start Start of the event
+ * @param {Date} end End of the event
+ * @returns {string[]} The days as "YYYY-MM-DD"
+ */
+function daysCovered(start, end) {
+  // The end is not part of the event: one ending at midnight belongs to the day
+  // before, and an all day event ends on the day before its DTEND.
+  const lastInstant = new Date(Math.max(start.getTime(), end.getTime() - 1));
+  const lastKey = dayKey(lastInstant);
+  const days = [];
+
+  let key = dayKey(start);
+
+  // The guard keeps a broken event from looping forever, a year of dots on the
+  // same event is well past the point where the calendar is still useful.
+  while (days.length <= 366) {
+    days.push(key);
+
+    if (key === lastKey) {
+      break;
+    }
+
+    // Step to noon UTC of the next day, which is inside the same Berlin day
+    // whether daylight saving time is in effect or not.
+    const [year, month, day] = key.split("-").map(Number);
+    key = dayKey(new Date(Date.UTC(year, month - 1, day + 1, 12)));
+  }
+
+  return days;
+}
+
+/**
+ * Read the URL of an event.
+ *
+ * ICAL.Event does not expose the URL property, so read it from the component.
+ *
+ * @param {ICAL.Event} event The event to read the URL of
+ * @returns {string} The URL, empty when the event has none
+ */
+function eventUrl(event) {
+  return event.component.getFirstPropertyValue("url") ?? "";
+}
+
+/**
+ * Reduce one occurrence of an event to what the calendar displays.
+ *
+ * @param {ICAL.Event} event The event the occurrence belongs to
+ * @param {ICAL.Time} startDate Start of this occurrence
+ * @param {ICAL.Time} endDate End of this occurrence
+ * @returns {{summary: string, description: string, url: string, start: Date, end: Date, allDay: boolean}}
+ */
+function toOccurrence(event, startDate, endDate) {
+  return {
+    summary: event.summary ?? "",
+    description: event.description ?? "",
+    url: eventUrl(event),
+    start: startDate.toJSDate(),
+    end: endDate.toJSDate(),
+    allDay: startDate.isDate,
+  };
+}
+
+/**
+ * Collect everything that takes place in the given month, keyed by day.
+ *
+ * @param {number} year The year of the month
+ * @param {number} month The month, January is 0
+ * @returns {Object<string, Array>} The occurrences per "YYYY-MM-DD"
+ */
+function occurrencesOfMonth(year, month) {
+  const byDate = {};
+
+  if (!calendar) {
+    return byDate;
+  }
+
+  // These bounds only limit how far the recurrences have to be expanded, which
+  // day an occurrence ends up on is decided by its Berlin day below. They are
+  // deliberately generous so that no occurrence is cut off at the edge of the
+  // month by a time zone difference.
+  const from = new Date(year, month, 1);
+  const to = new Date(year, month + 1, 1);
+  from.setDate(from.getDate() - 2);
+  to.setDate(to.getDate() + 2);
+
+  const monthPrefix = `${year}-${String(month + 1).padStart(2, "0")}-`;
+
+  const add = (occurrence) => {
+    for (const key of daysCovered(occurrence.start, occurrence.end)) {
+      if (!key.startsWith(monthPrefix)) {
+        continue;
+      }
+
+      if (!byDate[key]) {
+        byDate[key] = [];
+      }
+
+      byDate[key].push(occurrence);
+    }
+  };
+
+  for (const component of calendar.getAllSubcomponents("vevent")) {
+    const event = new ICAL.Event(component);
+
+    // Occurrences modified via RECURRENCE-ID are reached through the event they
+    // belong to, handling them here as well would show them twice.
+    if (event.isRecurrenceException() || !event.startDate) {
+      continue;
+    }
+
+    if (event.isRecurring()) {
+      const iterator = event.iterator();
+
+      while (true) {
+        const occurrence = iterator.next();
+
+        // Recurrences are chronological, so we are done once one starts after
+        // the month.
+        if (!occurrence || occurrence.toJSDate() >= to) {
+          break;
         }
 
-        // Extract date components from different date formats
-        function getDateComponents(icsDateStr) {
-            if (!icsDateStr) return null;
+        // Details resolve time, name and URL of an occurrence that was
+        // modified via RECURRENCE-ID.
+        const details = event.getOccurrenceDetails(occurrence);
 
-            // Basic handling - extract YYYY, MM, DD regardless of format
-            const year = parseInt(icsDateStr.substring(0, 4));
-            const month = parseInt(icsDateStr.substring(4, 6)) - 1; // 0-based months
-            const day = parseInt(icsDateStr.substring(6, 8));
-
-            return { year, month, day };
-        }
-
-        function expandRecurringEvents(event, year, month) {
-            if (!event.rrule) return [event];
-
-            const rruleStr = event.rrule;
-
-            // Get start date components
-            const startComponents = getDateComponents(event.start);
-            if (!startComponents) return [event];
-
-            const startDate = new Date(
-                startComponents.year,
-                startComponents.month,
-                startComponents.day
-            );
-
-            const rangeStart = new Date(year, month, 1);
-            const rangeEnd = new Date(year, month + 1, 0);
-            const expandedEvents = [];
-
-            if (rruleStr.includes("FREQ=WEEKLY") && rruleStr.includes("BYDAY")) {
-                const bydayMatch = rruleStr.match(/BYDAY=([^;]+)/);
-                if (bydayMatch) {
-                    const dayCode = bydayMatch[1];
-                    const dayMap = {
-                        'MO': 1, 'TU': 2, 'WE': 3, 'TH': 4, 'FR': 5, 'SA': 6, 'SU': 0
-                    };
-                    const targetDay = dayMap[dayCode];
-
-                    if (targetDay !== undefined) {
-                        // Create events for each matching day in the month
-                        let day = 1;
-                        while (day <= rangeEnd.getDate()) {
-                            const testDate = new Date(year, month, day);
-                            if (testDate.getDay() === targetDay && testDate >= startDate) {
-                                const newEvent = {...event};
-                                const eventDate = formatDateForICS(testDate);
-
-                                // Preserve time portion from original event
-                                const timePart = event.start.includes('T') ?
-                                    event.start.substring(event.start.indexOf('T')) : '';
-                                const endTimePart = event.end.includes('T') ?
-                                    event.end.substring(event.end.indexOf('T')) : '';
-
-                                newEvent.start = eventDate + timePart;
-                                newEvent.end = eventDate + endTimePart;
-                                expandedEvents.push(newEvent);
-                            }
-                            day++;
-                        }
-                    }
-                }
-            }
-            else if (rruleStr.includes("FREQ=MONTHLY") && rruleStr.includes("BYDAY")) {
-                const bydayMatch = rruleStr.match(/BYDAY=([^;]+)/);
-                if (bydayMatch) {
-                    const intervalMatch = rruleStr.match(/INTERVAL=(\d+)/);
-                    const interval = intervalMatch ? parseInt(intervalMatch[1]) : 1;
-                    const monthsFromStart = (year - startDate.getFullYear()) * 12 + (month - startDate.getMonth());
-                    if (monthsFromStart < 0 || monthsFromStart % interval !== 0) {
-                        return [];
-                    }
-                    const bydays = bydayMatch[1].split(',');
-                    const dayMap = {
-                        'MO': 1, 'TU': 2, 'WE': 3, 'TH': 4, 'FR': 5, 'SA': 6, 'SU': 0
-                    };
-
-                    bydays.forEach(byday => {
-                        const occurrence = parseInt(byday) || 1;
-                        const dayCode = byday.slice(-2);
-                        const dayIndex = dayMap[dayCode];
-
-                        let day = 1;
-                        let count = 0;
-
-                        while (day <= rangeEnd.getDate()) {
-                            const testDate = new Date(year, month, day);
-                            if (testDate.getDay() === dayIndex) {
-                                count++;
-                                if (count === occurrence || (occurrence < 0 && day > rangeEnd.getDate() + occurrence * 7)) {
-                                    const newEvent = {...event};
-                                    const eventDate = new Date(year, month, day);
-
-                                    // Preserve time portion from original event
-                                    const timePart = event.start.includes('T') ?
-                                        event.start.substring(event.start.indexOf('T')) : '';
-                                    const endTimePart = event.end.includes('T') ?
-                                        event.end.substring(event.end.indexOf('T')) : '';
-
-                                    newEvent.start = formatDateForICS(eventDate) + timePart;
-                                    newEvent.end = formatDateForICS(eventDate) + endTimePart;
-                                    expandedEvents.push(newEvent);
-                                }
-                            }
-                            day++;
-                        }
-                    });
-                }
-            }
-
-            return expandedEvents.length > 0 ? expandedEvents : [event];
+        if (details.endDate.toJSDate() > from) {
+          add(toOccurrence(details.item, details.startDate, details.endDate));
         }
-
-        // Kalender initialisieren
-        let currentYear, currentMonth;
-        const currentMonthElem = document.getElementById("current-month");
-        const calendarBody = document.getElementById("calendar-body");
-        const eventPanel = document.getElementById("event-panel");
-        const eventDateElem = document.getElementById("event-date");
-        const eventDetailsElem = document.getElementById("event-details");
-
-        document.getElementById("prev-month").addEventListener("click", function(){
-             currentMonth--;
-             if (currentMonth < 0) {
-                  currentMonth = 11;
-                  currentYear--;
-             }
-             updateEventsForMonth(currentYear, currentMonth);
-        });
-        document.getElementById("next-month").addEventListener("click", function(){
-             currentMonth++;
-             if (currentMonth > 11) {
-              currentMonth = 0;
-              currentYear++;
-             }
-             updateEventsForMonth(currentYear, currentMonth);
+      }
+    } else if (event.startDate.toJSDate() < to && event.endDate.toJSDate() > from) {
+      add(toOccurrence(event, event.startDate, event.endDate));
+    }
+  }
+
+  for (const occurrences of Object.values(byDate)) {
+    occurrences.sort((a, b) => a.start - b.start);
+  }
+
+  return byDate;
+}
+
+function updateEventsForMonth(year, month) {
+  eventsByDate = occurrencesOfMonth(year, month);
+  renderCalendar(year, month);
+}
+
+function renderCalendar(year, month) {
+  // Setze die Monatsbeschriftung (in Deutsch)
+  currentMonthElem.textContent = monthNames[month] + " " + year;
+  calendarBody.innerHTML = "";
+
+  let firstDay = new Date(year, month, 1);
+  let firstDayIndex = (firstDay.getDay() + 6) % 7; // Montag = 0, Dienstag = 1, etc.
+  let daysInMonth = new Date(year, month + 1, 0).getDate();
+
+  let row = document.createElement("tr");
+  // Leere Zellen vor dem 1. Tag
+  for (let i = 0; i < firstDayIndex; i++) {
+    let cell = document.createElement("td");
+    row.appendChild(cell);
+  }
+
+  // Tage hinzufügen
+  for (let day = 1; day <= daysInMonth; day++) {
+    if (row.children.length === 7) {
+      calendarBody.appendChild(row);
+      row = document.createElement("tr");
+    }
+    let cell = document.createElement("td");
+    cell.innerHTML = "<strong>" + day + "</strong>";
+
+    let dayStr = day < 10 ? "0" + day : day;
+    let monthStr = (month + 1) < 10 ? "0" + (month + 1) : (month + 1);
+    let dateKey = year + "-" + monthStr + "-" + dayStr;
+
+    if (eventsByDate[dateKey]) {
+      let dotsContainer = document.createElement("div");
+      dotsContainer.className = "event-dots-container";
+      cell.classList.add("has-event");
+
+      // Gruppe Events nach Typ
+      const events = eventsByDate[dateKey];
+      const hasMembersOnly = events.some(e => e.summary.toLowerCase().includes("members only"));
+      const hasSubbotnik = events.some(e => e.summary.toLowerCase().includes("subbotnik"));
+      const hasBastelabend = events.some(e => e.summary.toLowerCase().includes("bastelabend"));
+      const hasSpieleabend = events.some(e => e.summary.toLowerCase().includes("spieleabend"));
+      const hasRegular = events.some(e => {
+        const title = e.summary.toLowerCase();
+        return !title.includes("members only") &&
+              !title.includes("subbotnik") &&
+              !title.includes("bastelabend") &&
+              !title.includes("spieleabend");
+      });
+
+      // Füge Dots entsprechend der Event-Typen hinzu
+      if (hasMembersOnly) {
+        let dot = document.createElement("div");
+        dot.className = "event-dot event-dot-red";
+        dotsContainer.appendChild(dot);
+      }
+      if (hasSubbotnik || hasBastelabend || hasSpieleabend) {
+        let dot = document.createElement("div");
+        dot.className = "event-dot event-dot-orange";
+        dotsContainer.appendChild(dot);
+      }
+      if (hasRegular) {
+        let dot = document.createElement("div");
+        dot.className = "event-dot event-dot-greenyellow";
+        dotsContainer.appendChild(dot);
+      }
+
+      cell.appendChild(dotsContainer);
+      cell.dataset.dateKey = dateKey;
+      cell.addEventListener("click", function() {
+        // Clear previous selections
+        document.querySelectorAll('.selected-day').forEach(el => {
+          el.classList.remove('selected-day');
         });
-
-        function updateEventsForMonth(year, month) {
-            // Clear existing events for this month view
-            eventsByDate = {};
-
-            // Process each event, expanding recurring ones
-            events.forEach(ev => {
-                if (ev.rrule) {
-                    // For recurring events, expand them for current month
-                    const expandedEvents = expandRecurringEvents(ev, year, month);
-                    expandedEvents.forEach(expandedEv => {
-                        let dateKey = parseDateString(expandedEv.start);
-                        if (dateKey) {
-                            if (!eventsByDate[dateKey]) {
-                                eventsByDate[dateKey] = [];
-                            }
-                            eventsByDate[dateKey].push(expandedEv);
-                        }
-                    });
-                } else {
-                    // For regular events, check if they fall in current month
-                    let dateKey = parseDateString(ev.start);
-                    if (dateKey) {
-                        // Check if this event belongs to current month view
-                        const eventYear = parseInt(dateKey.split('-')[0]);
-                        const eventMonth = parseInt(dateKey.split('-')[1]) - 1;
-
-                        if (eventYear === year && eventMonth === month) {
-                            if (!eventsByDate[dateKey]) {
-                                eventsByDate[dateKey] = [];
-                            }
-                            eventsByDate[dateKey].push(ev);
-                        }
-                    }
-                }
-            });
-
-            renderCalendar(year, month);
-        }
-
-        function renderCalendar(year, month) {
-            // Setze die Monatsbeschriftung (in Deutsch)
-            const monthNames = ["Januar", "Februar", "März", "April", "Mai", "Juni", "Juli", "August", "September", "Oktober", "November", "Dezember"];
-            currentMonthElem.textContent = monthNames[month] + " " + year;
-            calendarBody.innerHTML = "";
-
-            let firstDay = new Date(year, month, 1);
-            let firstDayIndex = (firstDay.getDay() + 6) % 7; // Montag = 0, Dienstag = 1, etc.
-            let daysInMonth = new Date(year, month + 1, 0).getDate();
-
-            let row = document.createElement("tr");
-            // Leere Zellen vor dem 1. Tag
-            for (let i = 0; i < firstDayIndex; i++){
-                let cell = document.createElement("td");
-                row.appendChild(cell);
-            }
-
-            // Tage hinzufügen
-            for (let day = 1; day <= daysInMonth; day++){
-                if (row.children.length === 7) {
-                    calendarBody.appendChild(row);
-                    row = document.createElement("tr");
-                }
-                let cell = document.createElement("td");
-                cell.innerHTML = "<strong>" + day + "</strong>";
-
-                let dayStr = day < 10 ? "0" + day : day;
-                let monthStr = (month + 1) < 10 ? "0" + (month + 1) : (month + 1);
-                let dateKey = year + "-" + monthStr + "-" + dayStr;
-
-                if (eventsByDate[dateKey]) {
-                    let dotsContainer = document.createElement("div");
-                    dotsContainer.className = "event-dots-container";
-                    cell.classList.add("has-event");
-
-                    // Gruppe Events nach Typ
-                    const events = eventsByDate[dateKey];
-                    const hasMembersOnly = events.some(e => e.summary.toLowerCase().includes("members only"));
-                    const hasSubbotnik = events.some(e => e.summary.toLowerCase().includes("subbotnik"));
-                    const hasBastelabend = events.some(e => e.summary.toLowerCase().includes("bastelabend"));
-                    const hasSpieleabend = events.some(e => e.summary.toLowerCase().includes("spieleabend"));
-                    const hasRegular = events.some(e => {
-                        const title = e.summary.toLowerCase();
-                        return !title.includes("members only") &&
-                              !title.includes("subbotnik") &&
-                              !title.includes("bastelabend") &&
-                              !title.includes("spieleabend");
-                    });
-
-                    // Füge Dots entsprechend der Event-Typen hinzu
-                    if (hasMembersOnly) {
-                        let dot = document.createElement("div");
-                        dot.className = "event-dot event-dot-red";
-                        dotsContainer.appendChild(dot);
-                    }
-                    if (hasSubbotnik || hasBastelabend || hasSpieleabend) {
-                        let dot = document.createElement("div");
-                        dot.className = "event-dot event-dot-orange";
-                        dotsContainer.appendChild(dot);
-                    }
-                    if (hasRegular) {
-                        let dot = document.createElement("div");
-                        dot.className = "event-dot event-dot-greenyellow";
-                        dotsContainer.appendChild(dot);
-                    }
-
-                    cell.appendChild(dotsContainer);
-                    cell.dataset.dateKey = dateKey;
-                    cell.addEventListener("click", function() {
-                        // Clear previous selections
-                        document.querySelectorAll('.selected-day').forEach(el => {
-                            el.classList.remove('selected-day');
-                        });
-                        cell.classList.add('selected-day');
-                        showEventDetails(dateKey);
-                    });
-                }
-                row.appendChild(cell);
-            }
-            // Falls die letzte Zeile nicht komplett ist
-            while (row.children.length < 7) {
-                let cell = document.createElement("td");
-                row.appendChild(cell);
-            }
-            calendarBody.appendChild(row);
-        }
-
-        function createEventLink(eventTitle) {
-            if (eventTitle.startsWith("Datengarten")) {
-                // Extract the number after "Datengarten "
-                const match = eventTitle.match(/Datengarten\s+(\d+)/i);
-                if (match && match[1]) {
-                    return `https://berlin.ccc.de/datengarten/${match[1]}/`;
-                }
-            }
-
-            // For other titles, convert to lowercase and use as path
-            const slug = eventTitle.toLowerCase().replace(/\s+/g, '-').replace(/[^\w-]/g, '');
-            return `https://berlin.ccc.de/page/${slug}/`;
-        }
-
-        function showEventDetails(dateKey) {
-            const events = eventsByDate[dateKey];
-            eventDateElem.textContent = formatDate(dateKey);
-            eventDetailsElem.innerHTML = "";
-
-            if (events && events.length > 0) {
-                events.forEach(ev => {
-                    let eventItem = document.createElement("div");
-                    eventItem.className = "event-item";
-
-                    let eventTitle = document.createElement("div");
-                    eventTitle.className = "event-title";
-
-                    // Create a link for the event title
-                    let titleLink = document.createElement("h");
-                    titleLink.textContent = ev.summary;
-                    titleLink.target = "_blank";
-                    eventTitle.appendChild(titleLink);
-
-                    eventItem.appendChild(eventTitle);
-
-                    let eventTime = document.createElement("div");
-                    eventTime.className = "event-time";
-                    eventTime.textContent = `Start: ${formatTime(ev.start)}, End: ${formatTime(ev.end)}`;
-                    eventItem.appendChild(eventTime);
-
-                            if (ev.description) {
-                              let eventDescription = document.createElement("div");
-                              eventDescription.className = "event-description";
-
-                              // Check if the description is a URL and make it a clickable link
-                              if (ev.description.trim().startsWith('http')) {
-                                let linkElement = document.createElement("a");
-                                linkElement.href = ev.description.trim();
-                                linkElement.textContent = ev.description.trim();
-                                linkElement.target = "_blank";
-                                eventDescription.innerHTML = '';
-                                eventDescription.appendChild(linkElement);
-                              } else {
-                                eventDescription.textContent = ev.description;
-                              }
-
-                              eventItem.appendChild(eventDescription);
-                            }
-
-                              eventDetailsElem.appendChild(eventItem);
-                });
-            } else {
-                let noEvents = document.createElement("div");
-                noEvents.className = "no-events";
-                noEvents.textContent = "Keine Veranstaltungen an diesem Tag.";
-                eventDetailsElem.appendChild(noEvents);
-            }
-
-            eventPanel.style.display = "block";
-        }
-
-        function formatDate(dateStr) {
-            // Convert YYYY-MM-DD to DD.MM.YYYY
-            const parts = dateStr.split("-");
-            return `${parts[2]}.${parts[1]}.${parts[0]}`;
-        }
-
-        function formatTime(icsTimeStr) {
-            // Format time for display
-            if (!icsTimeStr) return "";
-
-            if (icsTimeStr.length === 8) {
-                // All-day event
-                return "Ganztägig";
-            } else if (icsTimeStr.includes("T")) {
-                // Time-specific event (with or without timezone)
-                const timeStart = icsTimeStr.indexOf("T") + 1;
-                const hour = icsTimeStr.substring(timeStart, timeStart + 2);
-                const minute = icsTimeStr.substring(timeStart + 2, timeStart + 4);
-                return `${hour}:${minute}`;
-            }
-            return icsTimeStr;
-        }
-
-        function formatDateForICS(date) {
-            const year = date.getFullYear();
-            const month = (date.getMonth() + 1).toString().padStart(2, '0');
-            const day = date.getDate().toString().padStart(2, '0');
-            return `${year}${month}${day}`;
-        }
-
-        // ICS-Datei abrufen und Events verarbeiten
-        fetch('/calendars/all.ics')
-        .then(response => response.text())
-        .then(data => {
-            events = parseICS(data);
-
-            // Initialize with current date
-            let today = new Date();
-            currentYear = today.getFullYear();
-            currentMonth = today.getMonth();
-
-            // Process events for current month
-            updateEventsForMonth(currentYear, currentMonth);
-        })
-        .catch(err => console.error('Fehler beim Laden der ICS-Datei:', err));
-    })();
+        cell.classList.add('selected-day');
+        showEventDetails(dateKey);
+      });
+    }
+    row.appendChild(cell);
+  }
+  // Falls die letzte Zeile nicht komplett ist
+  while (row.children.length < 7) {
+    let cell = document.createElement("td");
+    row.appendChild(cell);
+  }
+  calendarBody.appendChild(row);
+}
+
+/**
+ * Build the entry of a single event in the detail panel.
+ *
+ * @param {Object} occurrence The occurrence to show
+ * @returns {HTMLElement} The entry
+ */
+function renderEventItem(occurrence) {
+  const item = document.createElement("div");
+  item.className = "event-item";
+
+  const title = document.createElement("div");
+  title.className = "event-title";
+
+  if (occurrence.url) {
+    const link = document.createElement("a");
+    link.href = occurrence.url;
+    link.textContent = occurrence.summary;
+    title.appendChild(link);
+  } else {
+    title.textContent = occurrence.summary;
+  }
+
+  item.appendChild(title);
+
+  const time = document.createElement("div");
+  time.className = "event-time";
+  time.textContent = formatTimeRange(occurrence);
+  item.appendChild(time);
+
+  if (occurrence.description) {
+    const description = document.createElement("div");
+    description.className = "event-description";
+    description.textContent = occurrence.description;
+    item.appendChild(description);
+  }
+
+  return item;
+}
+
+function showEventDetails(dateKey) {
+  const occurrences = eventsByDate[dateKey];
+  eventDateElem.textContent = formatDate(dateKey);
+  eventDetailsElem.innerHTML = "";
+
+  if (occurrences && occurrences.length > 0) {
+    for (const occurrence of occurrences) {
+      eventDetailsElem.appendChild(renderEventItem(occurrence));
+    }
+  } else {
+    let noEvents = document.createElement("div");
+    noEvents.className = "no-events";
+    noEvents.textContent = "Keine Veranstaltungen an diesem Tag.";
+    eventDetailsElem.appendChild(noEvents);
+  }
+
+  eventPanel.style.display = "block";
+}
+
+function formatDate(dateStr) {
+  // Convert YYYY-MM-DD to DD.MM.YYYY
+  const parts = dateStr.split("-");
+  return `${parts[2]}.${parts[1]}.${parts[0]}`;
+}
+
+/**
+ * Describe when an occurrence takes place, in Berlin time.
+ *
+ * @param {Object} occurrence The occurrence to describe
+ * @returns {string} The description
+ */
+function formatTimeRange(occurrence) {
+  if (occurrence.allDay) {
+    return "Ganztägig";
+  }
+
+  const start = timeOfDayFormat.format(occurrence.start);
+  const end = timeOfDayFormat.format(occurrence.end);
+
+  return `Start: ${start}, End: ${end}`;
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+  currentMonthElem = document.getElementById("current-month");
+  calendarBody = document.getElementById("calendar-body");
+  eventPanel = document.getElementById("event-panel");
+  eventDateElem = document.getElementById("event-date");
+  eventDetailsElem = document.getElementById("event-details");
+
+  document.getElementById("prev-month").addEventListener("click", function() {
+    currentMonth--;
+    if (currentMonth < 0) {
+      currentMonth = 11;
+      currentYear--;
+    }
+    updateEventsForMonth(currentYear, currentMonth);
+  });
+  document.getElementById("next-month").addEventListener("click", function() {
+    currentMonth++;
+    if (currentMonth > 11) {
+      currentMonth = 0;
+      currentYear++;
+    }
+    updateEventsForMonth(currentYear, currentMonth);
+  });
+
+  // Show the grid of the current month right away, the events are filled in
+  // once the calendar has been loaded.
+  const today = new Date();
+  currentYear = today.getFullYear();
+  currentMonth = today.getMonth();
+  updateEventsForMonth(currentYear, currentMonth);
+
+  fetch(icsUrl)
+    .then(response => {
+      // Without this an error page would be handed to the parser below, which
+      // then fails with a confusing complaint about the calendar syntax.
+      if (!response.ok) {
+        throw new Error(`${icsUrl}: ${response.status} ${response.statusText}`);
+      }
+
+      return response.text();
+    })
+    .then(icsText => {
+      calendar = new ICAL.Component(ICAL.parse(icsText));
+      updateEventsForMonth(currentYear, currentMonth);
+    })
+    .catch(err => console.error("Fehler beim Laden der ICS-Datei:", err));
 });

assets/js/upcoming.js

@@ -1,13 +1,25 @@
-import ICAL from "https://unpkg.com/ical.js/dist/ical.min.js";
+import ICAL from "./vendor/ical.js";
+
+/**
+ * Read the URL of an event.
+ *
+ * ICAL.Event does not expose the URL property, so read it from the component.
+ *
+ * @param {ICAL.Event} event The event to read the URL of
+ * @returns {string} The URL, empty when the event has none
+ */
+function eventUrl(event) {
+  return event.component.getFirstPropertyValue("url") ?? "";
+}
 
 /**
  * Parse an ICS calendar and return upcoming event occurrences.
  *
  * @param {string} icsText The contents of the .ics file
- * @param {Date} now Events must start after this date
+ * @param {Date} now Events must still be running at this date
  * @param {number} maxEvents Maximum number of events to return
  * @param {number} maxDays Maximum number of days into the future
- * @returns {{start: Date, name: string, url: string}[]}
+ * @returns {{start: Date, name: string, url: string}[]} url is empty when the event has no URL
  */
 function getUpcomingEvents(icsText, now, maxEvents, maxDays) {
   const jcal = ICAL.parse(icsText);
@@ -21,6 +33,12 @@ function getUpcomingEvents(icsText, now, maxEvents, maxDays) {
   for (const component of calendar.getAllSubcomponents("vevent")) {
     const event = new ICAL.Event(component);
 
+    // Occurrences modified via RECURRENCE-ID are reached through the event they
+    // belong to, listing them here as well would show them twice.
+    if (event.isRecurrenceException()) {
+      continue;
+    }
+
     if (!event.startDate) {
       continue;
     }
@@ -35,30 +53,33 @@ function getUpcomingEvents(icsText, now, maxEvents, maxDays) {
           break;
         }
 
-        const start = occurrence.toJSDate();
-
         // Recurrences are chronological, so we're done
         // once we pass the end of our search window.
-        if (start > end) {
+        if (occurrence.toJSDate() > end) {
           break;
         }
 
-        if (start > now) {
+        // Details resolve time, name and URL of an occurrence that was
+        // modified via RECURRENCE-ID.
+        const details = event.getOccurrenceDetails(occurrence);
+
+        // A running event stays listed until it is over, so filter on its end.
+        if (details.endDate.toJSDate() > now) {
           events.push({
-            start,
-            name: event.summary ?? "",
-            url: event.url ?? "",
+            start: details.startDate.toJSDate(),
+            name: details.item.summary ?? "",
+            url: eventUrl(details.item),
           });
         }
       }
     } else {
       const start = event.startDate.toJSDate();
 
-      if (start > now && start <= end) {
+      if (start <= end && event.endDate.toJSDate() > now) {
         events.push({
           start,
           name: event.summary ?? "",
-          url: event.url ?? "",
+          url: eventUrl(event),
         });
       }
     }
@@ -80,7 +101,15 @@ document.addEventListener("DOMContentLoaded", () => {
 
   const table = document.getElementById("upcoming");
   fetch(ics)
-    .then(response => response.text())
+    .then(response => {
+      // Without this an error page would be handed to the parser below, which
+      // then fails with a confusing complaint about the calendar syntax.
+      if (!response.ok) {
+        throw new Error(`${ics}: ${response.status} ${response.statusText}`);
+      }
+
+      return response.text();
+    })
     .then(icsText => {
       getUpcomingEvents(icsText, now, max_items, max_days).forEach(event => {
         const row = document.createElement("tr");
@@ -88,26 +117,35 @@ document.addEventListener("DOMContentLoaded", () => {
         const colBegin = document.createElement("td");
 
         const formattedStart = event.start.toLocaleString("de-DE", {
+          // The events take place in Berlin, so name their time in Berlin time
+          // instead of in the time zone the visitor happens to be in.
+          timeZone: "Europe/Berlin",
           weekday: "long",
           day: "2-digit",
           month: "2-digit",
           hour: "2-digit",
           minute: "2-digit",
-        }).replace(",", "");
+        });
 
-        colBegin.innerText = `${formattedStart.replace(" ", ", ")} Uhr`;
+        colBegin.innerText = `${formattedStart} Uhr`;
         row.appendChild(colBegin);
 
         const colName = document.createElement("td");
 
-        const a = document.createElement("a");
-        a.href = event.url;
-        a.text = event.name;
+        if (event.url) {
+          const a = document.createElement("a");
+          a.href = event.url;
+          a.text = event.name;
+
+          colName.appendChild(a);
+        } else {
+          colName.innerText = event.name;
+        }
 
-        colName.appendChild(a);
         row.appendChild(colName);
 
         table.appendChild(row);
       });
-    });
+    })
+    .catch(err => console.error("Fehler beim Laden der Termine:", err));
 });

assets/js/vendor/README.md

@@ -0,0 +1,19 @@
+# Vendored JavaScript
+
+Third party code is checked in here instead of being loaded from a CDN, so that the website does not make the visitor's
+browser fetch anything from an external server.
+
+Hugo bundles and minifies these files into the scripts that reference them, so the unminified source is checked in.
+
+## ical.js
+
+- Version: 2.2.1
+- Source: <https://unpkg.com/ical.js@2.2.1/dist/ical.js>
+- Upstream: <https://github.com/kewisch/ical.js>
+- License: MPL-2.0 (see the header of `ical.js`)
+
+To update, download the `dist/ical.js` of the wanted release and replace the file, keeping the version above in sync:
+
+```shell
+curl -o assets/js/vendor/ical.js https://unpkg.com/ical.js@<version>/dist/ical.js
+```

content/_index.md

@@ -25,9 +25,6 @@ description: "Startseite CCCB mit Kurzkalender"
 
 ### Nächste Veranstaltungen
 
-<table id="upcoming" class="table table-condensed">
-</table>
+{{< upcoming >}}
 
 Weitere Termine findest du im [Veranstaltungskalender](/verein/calendar/).
-
-<script type="module" src="/js/upcoming.js"></script>

layouts/shortcodes/calendar.html

@@ -1,4 +1,4 @@
-{{ $js := resources.Get "js/calendar.js" }}
+{{ $js := resources.Get "js/calendar.js" | js.Build (dict "minify" true "format" "esm" "target" "es2020") | fingerprint }}
 {{ $css := resources.Get "css/calendar.css" }}
 
 <div class="calendar-container">
@@ -6,7 +6,7 @@
     <link rel="stylesheet" href="{{ .RelPermalink }}">
   {{ end }}
   {{ with $js }}
-    <script src="{{ .RelPermalink }}"></script>
+    <script type="module" src="{{ .RelPermalink }}" integrity="{{ .Data.Integrity }}"></script>
   {{ end }}
   
   <div id="calendar">

layouts/shortcodes/upcoming.html

@@ -0,0 +1,5 @@
+{{- $css := resources.Get "css/upcoming.css" | minify | fingerprint -}}
+{{- $js := resources.Get "js/upcoming.js" | js.Build (dict "minify" true "format" "esm" "target" "es2020") | fingerprint -}}
+<link rel="stylesheet" href="{{ $css.RelPermalink }}" integrity="{{ $css.Data.Integrity }}">
+<table id="upcoming" class="table table-condensed"></table>
+<script type="module" src="{{ $js.RelPermalink }}" integrity="{{ $js.Data.Integrity }}"></script>