feat(web): show ICS subscription events in detail view

internal/web/calendar.go

@@ -18,6 +18,7 @@ import (
 	"git.arnef.de/arnef/nidus/internal/birthdays"
 	"git.arnef.de/arnef/nidus/internal/db"
 	"git.arnef.de/arnef/nidus/internal/icalfix"
+	"git.arnef.de/arnef/nidus/internal/icssub"
 	"git.arnef.de/arnef/nidus/internal/store"
 	"git.arnef.de/arnef/nidus/internal/web/templates"
 	ical "github.com/emersion/go-ical"
@@ -650,12 +651,17 @@ func (s *Server) handleEventView(w http.ResponseWriter, r *http.Request) {
 	ref := r.PathValue("ref")
 	id := r.PathValue("id")
 
+	// For ICS subscriptions, ref is "!<name>" and id is the stable
+	// icssub.EventID (already ".ics"-suffixed). For regular calendars,
+	// ref is a bare name or "owner~name" and id is a "<hex>.ics" filename
+	// from the eventIDRe character set. Both shapes share the same
+	// "hex/alnum .ics" shape, so we only need the regex check.
 	if !eventIDRe.MatchString(id) {
 		http.NotFound(w, r)
 		return
 	}
 	color, form, err := s.eventForDisplay(username, ref, id)
-	if errors.Is(err, store.ErrNotFound) {
+	if errors.Is(err, store.ErrNotFound) || errors.Is(err, errCalendarNotFound) {
 		http.NotFound(w, r)
 		return
 	}
@@ -670,8 +676,12 @@ func (s *Server) handleEventView(w http.ResponseWriter, r *http.Request) {
 // eventForDisplay resolves a calendar reference for read access, loads and
 // decodes the event with the given id, populates the form's display fields
 // (CalRef, CalendarLabel, Writable), and returns the calendar's color for
-// the detail view's header dot.
+// the detail view's header dot. It handles both ordinary (stored) events
+// and ICS-subscription events (ref "!<name>").
 func (s *Server) eventForDisplay(username, ref, id string) (color string, form templates.EventFormData, err error) {
+	if strings.HasPrefix(ref, icsRefPrefix) {
+		return s.icsEventForDisplay(username, ref, id)
+	}
 	owner, name, err := s.resolveCalRef(username, ref, false)
 	if err != nil {
 		return "", form, err
@@ -701,6 +711,35 @@ func (s *Server) eventForDisplay(username, ref, id string) (color string, form t
 	return color, form, nil
 }
 
+// icsEventForDisplay resolves one of username's ICS subscriptions named
+// ref[len(!):] and looks up the event whose icssub.EventID hashes to id.
+// Returns the subscription's display color and a form with Writable=false.
+func (s *Server) icsEventForDisplay(username, ref, id string) (color string, form templates.EventFormData, err error) {
+	name := strings.TrimPrefix(ref, icsRefPrefix)
+	sub, err := s.dbase.GetICSSubscription(username, name)
+	if err != nil {
+		return "", form, errCalendarNotFound
+	}
+	cal, err := s.icsCache.Get(sub.URL)
+	if err != nil {
+		return "", form, err
+	}
+	for _, ev := range cal.Events() {
+		if icssub.EventID(ev) != id {
+			continue
+		}
+		form, err = eventFormFromComponent(id, ev)
+		if err != nil {
+			return "", form, err
+		}
+		form.CalRef = ref
+		form.CalendarLabel = name
+		form.Writable = false
+		return sub.Color, form, nil
+	}
+	return "", form, errCalendarNotFound
+}
+
 func (s *Server) handleEventEdit(w http.ResponseWriter, r *http.Request) {
 	username := userFromContext(r.Context())
 	ref := r.PathValue("ref")
@@ -1264,11 +1303,11 @@ func (s *Server) addBirthdayEvents(username string, entry calendarEntry, gridSta
 }
 
 // addICSEvents fetches entry's remote ICS/webcal calendar (via s.icsCache,
-// which caches it for a while so every month-view render doesn't re-fetch
-// from origin) and places each VEVENT's occurrence onto the month grid,
-// the same way a stored calendar object would be. There's no per-event
-// edit page for these (the source is external and read-only), so each
-// event's LinkURL is left pointing nowhere useful ("#").
+// which uses stale-while-revalidate so a month-view render never blocks on
+// network I/O) and places each VEVENT's occurrence onto the month grid,
+// the same way a stored calendar object would be. Each event's ID is the
+// stable icssub.EventID hash, which routes through the read-only detail
+// page (eventForDisplay → icsEventForDisplay).
 func (s *Server) addICSEvents(entry calendarEntry, gridStart, gridEnd time.Time, loc *time.Location, dayIndex map[string]int, days []templates.MonthDay) error {
 	cal, err := s.icsCache.Get(entry.ICSURL)
 	if err != nil {
@@ -1276,8 +1315,11 @@ func (s *Server) addICSEvents(entry calendarEntry, gridStart, gridEnd time.Time,
 	}
 
 	const totalDays = 42
-	for i, ev := range cal.Events() {
-		id := fmt.Sprintf("ics-%d", i)
+	for _, ev := range cal.Events() {
+		id := icssub.EventID(ev)
+		if id == "" {
+			continue
+		}
 		form, err := eventFormFromComponent(id, ev)
 		if err != nil {
 			continue
@@ -1311,7 +1353,6 @@ func (s *Server) addICSEvents(entry calendarEntry, gridStart, gridEnd time.Time,
 				Summary:  form.Summary,
 				TimeText: timeText,
 				AllDay:   form.AllDay,
-				LinkURL:  "#",
 			})
 		}
 	}