Add calendar color support (DAVx5 calendar-color)

Calendars can now have a color (hex, e.g. #3b82f6) that DAVx5 and other CalDAV clients pick up via the Apple/dav4jvm calendar-color property. - db: add calendars.color column with migration for existing DBs; CreateCalendarWithColor, SetCalendarColor, GetCalendarColor; ListCalendars now returns []Calendar{Name, Color} instead of []string - caldav: since go-webdav's caldav.Backend interface has no extension point for vendor properties, wrap the handler with a response-rewriting middleware that injects <calendar-color xmlns="http://apple.com/ns/ical/"> into PROPFIND responses for calendars that have a color set - web: color picker on the "New calendar" form and an inline color swatch/ picker on each calendar card (calendars only, not address books) - nidusctl: `calendar create --color` flag and a new `calendar color` subcommand; `calendar list` now also prints the color if set Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-08-20 06:43:56 +02:00
parent 37399d1ceb
commit ebbc7a2a2b
15 changed files with 618 additions and 163 deletions
@@ -1,11 +1,16 @@
 package caldav

 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/http"
+	"net/http/httptest"
 	"path"
+	"regexp"
+	"strconv"
 	"strings"
 	"time"

@@ -40,9 +45,15 @@ func NewBackend(cfg *config.Config, st *store.Store, dbase *db.DB, logger *slog.
 }

 // NewHandler returns an http.Handler for the /cal/ prefix.
+//
+// It wraps the go-webdav caldav.Handler with a small response-rewriting
+// middleware that injects the non-standard (Apple/DAVx5) calendar-color
+// property into PROPFIND responses for calendar collections, since
+// go-webdav's caldav.Backend interface has no extension point for
+// vendor-specific WebDAV properties.
 func NewHandler(cfg *config.Config, st *store.Store, dbase *db.DB, logger *slog.Logger) http.Handler {
 	b := NewBackend(cfg, st, dbase, logger)
-	return &caldav.Handler{Backend: b}
+	return &colorInjectingHandler{backend: b, next: &caldav.Handler{Backend: b}}
 }

 // -------- caldav.Backend interface --------
@@ -79,19 +90,19 @@ func (b *Backend) ListCalendars(ctx context.Context) ([]caldav.Calendar, error)
 	}

 	var cals []caldav.Calendar
-	for _, name := range names {
-		if err := b.store.EnsureCollection(p.Username, "cal-"+name); err != nil {
-			b.logger.Warn("ensuring calendar directory", "calendar", name, "error", err)
+	for _, cal := range names {
+		if err := b.store.EnsureCollection(p.Username, "cal-"+cal.Name); err != nil {
+			b.logger.Warn("ensuring calendar directory", "calendar", cal.Name, "error", err)
 			continue
 		}
-		cals = append(cals, b.calendarMeta(p.Username, name, name))
+		cals = append(cals, b.calendarMeta(p.Username, cal.Name, cal.Name))
 	}

 	// Also include any extra calendars that exist on disk but aren't registered
 	disk, _ := b.store.ListCollections(p.Username)
 	configured := make(map[string]bool)
-	for _, n := range names {
-		configured["cal-"+n] = true
+	for _, cal := range names {
+		configured["cal-"+cal.Name] = true
 	}
 	for _, dir := range disk {
 		if strings.HasPrefix(dir, "cal-") && !configured[dir] {
@@ -386,3 +397,127 @@ func hashBytes(data []byte) uint64 {
 	}
 	return h
 }
+
+// -------- calendar-color PROPFIND injection --------
+
+// calCollectionPathRe matches a calendar collection's own path (e.g.
+// "/cal/home/work/"), as opposed to a calendar object inside it (e.g.
+// "/cal/home/work/abc123.ics") or the home-set/principal path.
+var calCollectionPathRe = regexp.MustCompile(`^/cal/home/[^/]+/$`)
+
+// colorInjectingHandler wraps a caldav.Handler and post-processes PROPFIND
+// responses to add the non-standard `calendar-color` property (in Apple's
+// "http://apple.com/ns/ical/" namespace) that DAVx5 and other clients read
+// to color-code synced calendars. go-webdav's caldav.Backend interface has
+// no extension point for vendor properties like this, so the response XML
+// is rewritten after the fact instead.
+type colorInjectingHandler struct {
+	backend *Backend
+	next    http.Handler
+}
+
+func (h *colorInjectingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != "PROPFIND" || h.backend.dbase == nil {
+		h.next.ServeHTTP(w, r)
+		return
+	}
+
+	// Only bother rewriting if the client asked for calendar-color
+	// specifically, or for all properties (propname/allprop requests, or
+	// no body at all, are treated as "all properties" by most clients).
+	var reqBody []byte
+	if r.Body != nil {
+		reqBody, _ = readAllAndReset(&r.Body)
+	}
+	wantsColor := len(reqBody) == 0 || bytes.Contains(reqBody, []byte("calendar-color")) || bytes.Contains(reqBody, []byte("allprop"))
+	if !wantsColor {
+		h.next.ServeHTTP(w, r)
+		return
+	}
+
+	rec := httptest.NewRecorder()
+	h.next.ServeHTTP(rec, r)
+
+	for k, vs := range rec.Header() {
+		for _, v := range vs {
+			w.Header().Add(k, v)
+		}
+	}
+
+	body := rec.Body.Bytes()
+	if rec.Code == http.StatusMultiStatus && strings.Contains(rec.Header().Get("Content-Type"), "xml") {
+		body = h.injectCalendarColors(r.Context(), body)
+		w.Header().Set("Content-Length", strconv.Itoa(len(body)))
+	}
+	w.WriteHeader(rec.Code)
+	_, _ = w.Write(body)
+}
+
+// responseBlockRe matches a single <response>...</response> element
+// (non-greedy) inside a multistatus document, capturing its href.
+var responseBlockRe = regexp.MustCompile(`(?s)<response[^>]*>.*?<href[^>]*>([^<]*)</href>.*?</response>`)
+
+// injectCalendarColors scans a multistatus PROPFIND response body and, for
+// each <response> whose href is a calendar collection with a color set,
+// inserts a <apple:calendar-color xmlns:apple="http://apple.com/ns/ical/">
+// element into its first 200 OK <prop>.
+func (h *colorInjectingHandler) injectCalendarColors(ctx context.Context, body []byte) []byte {
+	p := auth.FromContext(ctx)
+	if p == nil {
+		return body
+	}
+
+	return responseBlockRe.ReplaceAllFunc(body, func(block []byte) []byte {
+		m := responseBlockRe.FindSubmatch(block)
+		if m == nil {
+			return block
+		}
+		href := string(m[1])
+		if !calCollectionPathRe.MatchString(href) {
+			return block
+		}
+		localName := strings.TrimSuffix(strings.TrimPrefix(href, calHomePath()), "/")
+		owner, realName, _, err := h.backend.resolveCalendar(p.Username, localName, false)
+		if err != nil {
+			return block
+		}
+		color, err := h.backend.dbase.GetCalendarColor(owner, realName)
+		if err != nil || color == "" {
+			return block
+		}
+		propEl := []byte(`<prop xmlns="DAV:">`)
+		idx := bytes.Index(block, propEl)
+		if idx < 0 {
+			return block
+		}
+		insertAt := idx + len(propEl)
+		colorEl := []byte(fmt.Sprintf(`<calendar-color xmlns="http://apple.com/ns/ical/">%s</calendar-color>`, xmlEscapeColor(color)))
+		out := make([]byte, 0, len(block)+len(colorEl))
+		out = append(out, block[:insertAt]...)
+		out = append(out, colorEl...)
+		out = append(out, block[insertAt:]...)
+		return out
+	})
+}
+
+// xmlEscapeColor returns color formatted as an 8-digit ARGB/RGBA hex value
+// (as Apple's calendar-color property expects), padding a plain 6-digit
+// "#RRGGBB" (as produced by an HTML <input type="color">) with a fully
+// opaque alpha channel.
+func xmlEscapeColor(color string) string {
+	if len(color) == 7 && color[0] == '#' {
+		return color + "FF"
+	}
+	return color
+}
+
+// readAllAndReset reads body fully and replaces it with a fresh reader over
+// the same bytes, so downstream handlers can still consume it.
+func readAllAndReset(body *io.ReadCloser) ([]byte, error) {
+	data, err := io.ReadAll(*body)
+	if err != nil {
+		return nil, err
+	}
+	*body = io.NopCloser(bytes.NewReader(data))
+	return data, nil
+}