feat(web): add calendar event 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/store"
 	"git.arnef.de/arnef/nidus/internal/web/templates"
 	ical "github.com/emersion/go-ical"
 )
@@ -636,6 +637,70 @@ func newEventFormDefaults(calRef, dateParam string) templates.EventFormData {
 	}
 }
 
+// handleEventView renders the read-only detail view for a single event. It
+// is the landing page when a user clicks an event in the month/week grid;
+// writable calendars link from here to the edit page.
+func (s *Server) handleEventView(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		w.Header().Set("Allow", "GET")
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	username := userFromContext(r.Context())
+	ref := r.PathValue("ref")
+	id := r.PathValue("id")
+
+	if !eventIDRe.MatchString(id) {
+		http.NotFound(w, r)
+		return
+	}
+	color, form, err := s.eventForDisplay(username, ref, id)
+	if errors.Is(err, store.ErrNotFound) {
+		http.NotFound(w, r)
+		return
+	}
+	if err != nil {
+		s.handleCalRefError(w, r, err)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	_ = templates.EventDetail(username, templates.EventDetailData{Form: form, Color: color}).Render(context.Background(), w)
+}
+
+// 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.
+func (s *Server) eventForDisplay(username, ref, id string) (color string, form templates.EventFormData, err error) {
+	owner, name, err := s.resolveCalRef(username, ref, false)
+	if err != nil {
+		return "", form, err
+	}
+	data, err := s.store.GetObject(owner, "cal-"+name, id)
+	if err != nil {
+		return "", form, err
+	}
+	form, err = eventFormFromICS(id, data)
+	if err != nil {
+		s.logger.Error("decoding event", "error", err)
+		return "", form, err
+	}
+	form.CalRef = ref
+	label := name
+	if owner != username {
+		label = name + " (" + s.dbase.DisplayName(owner) + ")"
+	}
+	form.CalendarLabel = label
+	form.Writable = owner == username
+	if !form.Writable {
+		if share, err := s.dbase.CalendarShareFor(owner, name, username); err == nil {
+			form.Writable = share.Permission == db.PermWrite
+		}
+	}
+	color, _ = s.dbase.GetCalendarColor(owner, name)
+	return color, form, nil
+}
+
 func (s *Server) handleEventEdit(w http.ResponseWriter, r *http.Request) {
 	username := userFromContext(r.Context())
 	ref := r.PathValue("ref")

internal/web/event_detail_test.go

@@ -0,0 +1,209 @@
+package web
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"git.arnef.de/arnef/nidus/internal/db"
+)
+
+// seedEvent stores an all-day event (one-day span) in owner's calendar cal
+// under object id, with the given summary/location/description. Used to set
+// up events that handleEventView should render.
+func seedEvent(t *testing.T, s *Server, owner, cal, id, summary, location, description string) {
+	t.Helper()
+	data := "BEGIN:VCALENDAR\r\n" +
+		"VERSION:2.0\r\n" +
+		"PRODID:-//nidus//test//EN\r\n" +
+		"BEGIN:VEVENT\r\n" +
+		"UID:" + strings.TrimSuffix(id, ".ics") + "\r\n" +
+		"DTSTAMP:20260101T000000Z\r\n" +
+		"SUMMARY:" + summary + "\r\n" +
+		"LOCATION:" + location + "\r\n" +
+		"DESCRIPTION:" + description + "\r\n" +
+		"DTSTART;VALUE=DATE:20260805\r\n" +
+		"DTEND;VALUE=DATE:20260806\r\n" +
+		"END:VEVENT\r\n" +
+		"END:VCALENDAR\r\n"
+	if err := s.store.PutObject(owner, "cal-"+cal, id, []byte(data)); err != nil {
+		t.Fatalf("PutObject: %v", err)
+	}
+}
+
+// getEventDetail issues GET /calendar/{ref}/{id} as the session identified by
+// cookie and returns the recorded response.
+func getEventDetail(t *testing.T, handler http.Handler, cookie *http.Cookie, ref, id string) *httptest.ResponseRecorder {
+	t.Helper()
+	path := "/calendar/" + url.PathEscape(ref) + "/" + url.PathEscape(id)
+	req := httptest.NewRequest(http.MethodGet, path, nil)
+	req.AddCookie(cookie)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+	return rr
+}
+
+func TestEventDetailShowsOwnEvent(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	cookie := loginAs(t, handler, "alice", "password")
+
+	id := "aabbccddeeff.ics"
+	seedEvent(t, s, "alice", "work", id, "Team standup", "Meetroom A", "Daily sync with the team")
+
+	rr := getEventDetail(t, handler, cookie, "work", id)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", rr.Code, rr.Body.String())
+	}
+	body := rr.Body.String()
+	for _, want := range []string{
+		"Team standup",             // summary / title
+		"Meetroom A",               // location
+		"Daily sync with the team", // description
+		"work",                     // calendar label
+		">Edit",                    // writable → Edit link present
+		"Export .ics",
+	} {
+		if !strings.Contains(body, want) {
+			t.Errorf("expected body to contain %q, got:\n%s", want, body)
+		}
+	}
+}
+
+func TestEventDetailReadOnlySharedHasNoEdit(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	aliceCookie := loginAs(t, handler, "alice", "password")
+	bobCookie := loginAs(t, handler, "bob", "password")
+
+	id := "123456.ics"
+	seedEvent(t, s, "bob", "personal", id, "Bob lunch", "Cafe", "Lunch plans")
+	if err := s.dbase.ShareCalendar("bob", "personal", "alice", db.PermRead); err != nil {
+		t.Fatalf("ShareCalendar: %v", err)
+	}
+
+	// alice (read share) can view but not edit.
+	rr := getEventDetail(t, handler, aliceCookie, "bob~personal", id)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("alice view: expected 200, got %d: %s", rr.Code, rr.Body.String())
+	}
+	body := rr.Body.String()
+	if !strings.Contains(body, "Bob lunch") {
+		t.Errorf("alice: expected body to contain summary, got:\n%s", body)
+	}
+	if !strings.Contains(body, "shared with you as read-only") {
+		t.Errorf("alice: expected read-only notice, got:\n%s", body)
+	}
+	if strings.Contains(body, ">Edit") {
+		t.Errorf("alice: Edit link should not be present on a read-only share, got:\n%s", body)
+	}
+
+	// bob (owner) can still see the Edit link.
+	rrBob := getEventDetail(t, handler, bobCookie, "personal", id)
+	if rrBob.Code != http.StatusOK {
+		t.Fatalf("bob view own: expected 200, got %d", rrBob.Code)
+	}
+	if !strings.Contains(rrBob.Body.String(), ">Edit") {
+		t.Errorf("bob: expected Edit link, got:\n%s", rrBob.Body.String())
+	}
+}
+
+func TestEventDetailWriteShareHasEditLink(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	cookie := loginAs(t, handler, "alice", "password")
+
+	seedEvent(t, s, "bob", "personal", "a1b2c3.ics", "Bob meeting", "Office", "Sync")
+	if err := s.dbase.ShareCalendar("bob", "personal", "alice", db.PermWrite); err != nil {
+		t.Fatalf("ShareCalendar: %v", err)
+	}
+	rr := getEventDetail(t, handler, cookie, "bob~personal", "a1b2c3.ics")
+	if rr.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", rr.Code, rr.Body.String())
+	}
+	body := rr.Body.String()
+	if !strings.Contains(body, ">Edit") {
+		t.Errorf("write share should expose Edit link, got:\n%s", body)
+	}
+	if strings.Contains(body, "shared with you as read-only") {
+		t.Errorf("write share should not show read-only notice, got:\n%s", body)
+	}
+}
+
+func TestEventDetailNotFound(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	cookie := loginAs(t, handler, "alice", "password")
+
+	// Valid calendar, missing object.
+	if rr := getEventDetail(t, handler, cookie, "work", "doesnotexist.ics"); rr.Code != http.StatusNotFound {
+		t.Fatalf("missing event: expected 404, got %d", rr.Code)
+	}
+	// Unknown calendar ref.
+	if rr := getEventDetail(t, handler, cookie, "does_not_exist", "0000.ics"); rr.Code != http.StatusNotFound {
+		t.Fatalf("unknown calendar: expected 404, got %d", rr.Code)
+	}
+	// Invalid id shape (rejected by eventIDRe before store access).
+	if rr := getEventDetail(t, handler, cookie, "work", "bad/../etc/passwd.ics"); rr.Code != http.StatusNotFound {
+		t.Fatalf("invalid id: expected 404, got %d", rr.Code)
+	}
+}
+
+func TestEventDetailRequiresLogin(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	req := httptest.NewRequest(http.MethodGet, "/calendar/work/anything.ics", nil)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+	if rr.Code != http.StatusSeeOther {
+		t.Fatalf("expected redirect to login, got %d", rr.Code)
+	}
+}
+
+func TestEventDetailRejectsNonGet(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	cookie := loginAs(t, handler, "alice", "password")
+	req := httptest.NewRequest(http.MethodPost, "/calendar/work/anything.ics", nil)
+	req.AddCookie(cookie)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+	if rr.Code != http.StatusMethodNotAllowed {
+		t.Fatalf("expected 405 for POST, got %d", rr.Code)
+	}
+}
+
+// TestEditRouteStillResolves guards against the new detail route
+// (/calendar/{ref}/{id}) shadowing the more specific edit/delete/export
+// routes under the same {ref}+{id} prefix in Go's ServeMux.
+func TestEditRouteStillResolves(t *testing.T) {
+	s := newTestServer(t)
+	handler := s.Handler(emptyStaticFS{})
+	cookie := loginAs(t, handler, "alice", "password")
+
+	id := "cafebabe00.ics"
+	seedEvent(t, s, "alice", "work", id, "Edit me", "Room", "Note")
+
+	// GET the edit form — must still hit handleEventEdit, not the detail view.
+	req := httptest.NewRequest(http.MethodGet, "/calendar/work/cafebabe00.ics/edit", nil)
+	req.AddCookie(cookie)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("edit GET: expected 200, got %d: %s", rr.Code, rr.Body.String())
+	}
+	if !strings.Contains(rr.Body.String(), "Edit event") || !strings.Contains(rr.Body.String(), "<form") {
+		t.Fatalf("expected the edit form to render, got:\n%s", rr.Body.String())
+	}
+
+	// The delete route still works (redirect to /web/calendar on success).
+	req = httptest.NewRequest(http.MethodPost, "/calendar/work/cafebabe00.ics/delete", nil)
+	req.AddCookie(cookie)
+	rr = httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+	if rr.Code != http.StatusSeeOther {
+		t.Fatalf("delete: expected 303 redirect, got %d: %s", rr.Code, rr.Body.String())
+	}
+}

internal/web/server.go

@@ -65,6 +65,7 @@ func (s *Server) Handler(staticFS http.FileSystem) http.Handler {
 	mux.HandleFunc("/calendar", s.requireLogin(s.handleCalendarMonth))
 	mux.HandleFunc("/calendar/week", s.requireLogin(s.handleCalendarWeek))
 	mux.HandleFunc("/calendar/new", s.requireLogin(s.handleEventNew))
+	mux.HandleFunc("/calendar/{ref}/{id}", s.requireLogin(s.handleEventView))
 	mux.HandleFunc("/calendar/{ref}/import", s.requireLogin(s.handleCalendarImport))
 	mux.HandleFunc("/calendar/{ref}/export", s.requireLogin(s.handleCalendarExportAll))
 	mux.HandleFunc("/calendar/{ref}/{id}/edit", s.requireLogin(s.handleEventEdit))

internal/web/templates/calendar.templ

@@ -3,6 +3,7 @@ package templates
 import "fmt"
 import "strconv"
 import "strings"
+import "time"
 
 // CalendarSummary is one calendar (own or shared) shown in the combined
 // month view's legend.
@@ -24,9 +25,9 @@ type EventSummary struct {
 	Summary  string
 	TimeText string // e.g. "14:00" or "" for all-day events
 	AllDay   bool
-	// LinkURL overrides the default "/web/calendar/{CalRef}/{ID}/edit"
-	// link target, used by virtual/read-only calendars (e.g. birthdays)
-	// that don't have an editable event object of their own.
+	// LinkURL overrides the default "/web/calendar/{CalRef}/{ID}" (detail
+	// view) link target, used by virtual/read-only calendars (e.g.
+	// birthdays) that don't have an editable event object of their own.
 	LinkURL string
 }
 
@@ -100,6 +101,14 @@ type EventFormData struct {
 	EndTime       string // "HH:MM", empty when AllDay
 }
 
+// EventDetailData is everything the read-only event detail view needs: the
+// decoded event itself (Form, including its ID/CalRef/Writable display
+// metadata) plus the calendar's color for the header dot.
+type EventDetailData struct {
+	Form  EventFormData
+	Color string // calendar color, "" if unset
+}
+
 templ MonthView(username string, data MonthViewData) {
 	@Layout("Calendar", username) {
 		<div class="flex items-center justify-between mb-6 gap-4 flex-wrap">
@@ -301,7 +310,7 @@ func eventLinkURL(ev EventSummary) string {
 	if ev.LinkURL != "" {
 		return ev.LinkURL
 	}
-	return "/web/calendar/" + ev.CalRef + "/" + ev.ID + "/edit"
+	return "/web/calendar/" + ev.CalRef + "/" + ev.ID
 }
 
 // eventTextColor returns a color derived from hex, darkened if needed so
@@ -355,6 +364,119 @@ func clampByte(v float64) int {
 
 
 
+// EventDetail is the read-only detail view for a single event, opened when
+// the user clicks an event in the month or week grid. It shows the
+// event's fields and, when the calendar is writable, offers an Edit link.
+templ EventDetail(username string, data EventDetailData) {
+	@Layout("Calendar", username) {
+		<div class="flex items-center justify-between gap-3 flex-wrap mb-6">
+			<a href="/web/calendar" class="text-sm text-indigo-600 hover:underline">&larr; Calendar</a>
+			<div class="flex items-center gap-3">
+				if data.Form.Writable {
+					<a href={ templ.URL("/web/calendar/" + data.Form.CalRef + "/" + data.Form.ID + "/edit") }
+						class="bg-indigo-600 text-white rounded-md px-3 py-1.5 text-sm font-medium hover:bg-indigo-700">
+						Edit
+					</a>
+				}
+				<a href={ templ.URL("/web/calendar/" + data.Form.CalRef + "/" + data.Form.ID + "/export") }
+					class="bg-white border border-gray-300 rounded-md px-3 py-1.5 text-sm font-medium text-gray-700 hover:bg-gray-50">
+					Export .ics
+				</a>
+			</div>
+		</div>
+
+		<div class="bg-white rounded-lg border border-gray-200 p-6 max-w-2xl">
+			<div class="flex items-start gap-3 border-b border-gray-100 pb-5 mb-5">
+				<span class="w-3 h-3 rounded-full mt-2 shrink-0 ring-1 ring-inset ring-black/10" style={ "background-color: " + colorOrDefault(data.Color) }></span>
+				<div class="min-w-0">
+					<h1 class="text-2xl font-semibold break-words leading-tight">{ data.Form.Summary }</h1>
+					<p class="text-sm text-gray-500 mt-1">{ data.Form.CalendarLabel }</p>
+				</div>
+			</div>
+
+			if !data.Form.Writable {
+				<p class="mb-5 text-sm text-amber-700 bg-amber-50 border border-amber-200 rounded px-3 py-2">
+					This calendar was shared with you as read-only — you can view this event but not change it.
+				</p>
+			}
+
+			<dl class="space-y-4">
+				<div>
+					<dt class="text-xs font-medium uppercase tracking-wide text-gray-400 mb-1">When</dt>
+					<dd class="text-base text-gray-900">{ eventRangeText(data.Form) }</dd>
+				</div>
+				if data.Form.Location != "" {
+					<div>
+						<dt class="text-xs font-medium uppercase tracking-wide text-gray-400 mb-1">Location</dt>
+						<dd class="text-base text-gray-900 break-words">{ data.Form.Location }</dd>
+					</div>
+				}
+				if data.Form.Description != "" {
+					<div>
+						<dt class="text-xs font-medium uppercase tracking-wide text-gray-400 mb-1">Description</dt>
+						<dd class="text-base text-gray-900 whitespace-pre-wrap break-words">{ data.Form.Description }</dd>
+					</div>
+				}
+			</dl>
+		</div>
+	}
+}
+
+// eventRangeText renders a human-readable "when" string for an event:
+// a single timed event reads "Aug 5, 2026, 14:00 – 15:00"; a multi-day
+// range reads "Aug 5 – 7, 2026"; a single all-day date reads
+// "August 5, 2026".
+func eventRangeText(f EventFormData) string {
+	if f.AllDay {
+		if f.StartDate != f.EndDate {
+			s, err := dateOnly(f.StartDate)
+			if err != nil {
+				return f.StartDate
+			}
+			e, err := dateOnly(f.EndDate)
+			if err != nil {
+				return f.EndDate
+			}
+			if s.Year() == e.Year() && s.Month() == e.Month() {
+				return fmt.Sprintf("%s – %s, %d", s.Format("Jan 2"), e.Format("2"), s.Year())
+			}
+			return fmt.Sprintf("%s – %s", s.Format("Jan 2, 2006"), e.Format("Jan 2, 2006"))
+		}
+		d, err := dateOnly(f.StartDate)
+		if err != nil {
+			return f.StartDate
+		}
+		return d.Format("January 2, 2006")
+	}
+
+	s, err := dateTime(f.StartDate, f.StartTime)
+	if err != nil {
+		return f.StartDate
+	}
+	e, err := dateTime(f.EndDate, f.EndTime)
+	if err != nil {
+		return s.Format("January 2, 2006, 15:04")
+	}
+	if s.Day() == e.Day() {
+		return fmt.Sprintf("%s, %s – %s", s.Format("January 2, 2006"), s.Format("15:04"), e.Format("15:04"))
+	}
+	if s.Year() == e.Year() && s.Month() == e.Month() {
+		return fmt.Sprintf("%s – %s, %d", s.Format("Jan 2, 15:04"), e.Format("15:04"), s.Year())
+	}
+	return fmt.Sprintf("%s – %s", s.Format("Jan 2, 2006, 15:04"), e.Format("Jan 2, 2006, 15:04"))
+}
+
+func dateOnly(ds string) (time.Time, error) {
+	return time.ParseInLocation("2006-01-02", ds, time.Local)
+}
+
+func dateTime(ds, ts string) (time.Time, error) {
+	if ts == "" {
+		return time.ParseInLocation("2006-01-02", ds, time.Local)
+	}
+	return time.ParseInLocation("2006-01-02T15:04", ds+"T"+ts, time.Local)
+}
+
 templ EventForm(username string, data EventFormData, errMsg string) {
 	@Layout("Calendar", username) {
 		<a href="/web/calendar" class="text-sm text-indigo-600 hover:underline">&larr; Calendar</a>

internal/web/templates/calendar_test.go

@@ -33,6 +33,54 @@ func TestEventTextColorDarkensLightColors(t *testing.T) {
 	}
 }
 
+// TestEventRangeText pins the human-readable "When" strings shown on the
+// event detail view so any change to date formatting is intentional.
+func TestEventRangeText(t *testing.T) {
+	cases := []struct {
+		name string
+		form EventFormData
+		want string
+	}{
+		{
+			name: "single allday date",
+			form: EventFormData{AllDay: true, StartDate: "2026-08-05", EndDate: "2026-08-05"},
+			want: "August 5, 2026",
+		},
+		{
+			name: "all-day multi-day same month",
+			form: EventFormData{AllDay: true, StartDate: "2026-08-05", EndDate: "2026-08-07"},
+			want: "Aug 5 – 7, 2026",
+		},
+		{
+			name: "all-day multi-day different months",
+			form: EventFormData{AllDay: true, StartDate: "2026-08-30", EndDate: "2026-09-02"},
+			want: "Aug 30, 2026 – Sep 2, 2026",
+		},
+		{
+			name: "timed same day",
+			form: EventFormData{AllDay: false, StartDate: "2026-08-05", StartTime: "14:00", EndDate: "2026-08-05", EndTime: "15:00"},
+			want: "August 5, 2026, 14:00 – 15:00",
+		},
+		{
+			name: "timed different days same month",
+			form: EventFormData{AllDay: false, StartDate: "2026-08-05", StartTime: "23:30", EndDate: "2026-08-06", EndTime: "01:00"},
+			want: "Aug 5, 23:30 – 01:00, 2026",
+		},
+		{
+			name: "timed different months",
+			form: EventFormData{AllDay: false, StartDate: "2026-08-31", StartTime: "10:00", EndDate: "2026-09-01", EndTime: "11:00"},
+			want: "Aug 31, 2026, 10:00 – Sep 1, 2026, 11:00",
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := eventRangeText(c.form); got != c.want {
+				t.Errorf("eventRangeText(%+v) = %q, want %q", c.form, got, c.want)
+			}
+		})
+	}
+}
+
 func TestEventTextColorFallsBackForInvalidInput(t *testing.T) {
 	if got := eventTextColor(""); got != colorOrDefault("") {
 		t.Errorf("eventTextColor(\"\") = %s, want the same default colorOrDefault returns", got)