Feature: per-viewer colors for shared calendars (#345)

lib/__tests__/shared-calendar-colors.test.ts

@@ -0,0 +1,77 @@
+import { describe, it, expect } from 'vitest';
+import type { Calendar } from '@/lib/jmap/types';
+import {
+  CALENDAR_COLORS,
+  sharedCalendarColorKey,
+  pickUnusedCalendarColor,
+} from '../shared-calendar-colors';
+
+function makeCal(overrides: Partial<Calendar>): Calendar {
+  return {
+    id: 'cal-1',
+    name: 'Cal',
+    description: null,
+    color: null,
+    sortOrder: 0,
+    isSubscribed: true,
+    isVisible: true,
+    isDefault: false,
+    includeInAvailability: 'all',
+    defaultAlertsWithTime: null,
+    defaultAlertsWithoutTime: null,
+    timeZone: null,
+    shareWith: null,
+    myRights: {} as Calendar['myRights'],
+    ...overrides,
+  };
+}
+
+describe('sharedCalendarColorKey', () => {
+  it('is built from local account, JMAP account, and the original id', () => {
+    const cal = makeCal({
+      id: 'acct-9:cal-7',
+      originalId: 'cal-7',
+      accountId: 'acct-9',
+      localAccountId: 'slot-2',
+    });
+    expect(sharedCalendarColorKey(cal)).toBe('slot-2|acct-9|cal-7');
+  });
+
+  it('is stable regardless of the Pro-shell id prefix', () => {
+    // Same underlying calendar, shown once under the active account (bare id)
+    // and once cross-account (prefixed id) - both must map to one key.
+    const active = makeCal({ id: 'acct-9:cal-7', originalId: 'cal-7', accountId: 'acct-9', localAccountId: 'slot-2' });
+    const prefixed = makeCal({ id: 'slot-2::acct-9:cal-7', originalId: 'cal-7', accountId: 'acct-9', localAccountId: 'slot-2' });
+    expect(sharedCalendarColorKey(active)).toBe(sharedCalendarColorKey(prefixed));
+  });
+
+  it('falls back to the id when originalId is absent', () => {
+    const cal = makeCal({ id: 'cal-7', accountId: 'acct-9' });
+    expect(sharedCalendarColorKey(cal)).toBe('|acct-9|cal-7');
+  });
+});
+
+describe('pickUnusedCalendarColor', () => {
+  it('returns a palette color not present in usedColors', () => {
+    const used = CALENDAR_COLORS.slice(0, CALENDAR_COLORS.length - 1);
+    const picked = pickUnusedCalendarColor(used);
+    expect(picked).toBe(CALENDAR_COLORS[CALENDAR_COLORS.length - 1]);
+  });
+
+  it('ignores case when comparing used colors', () => {
+    const used = CALENDAR_COLORS.slice(0, -1).map((c) => c.toUpperCase());
+    expect(pickUnusedCalendarColor(used)).toBe(CALENDAR_COLORS[CALENDAR_COLORS.length - 1]);
+  });
+
+  it('still returns a palette color once every color is taken', () => {
+    expect(CALENDAR_COLORS).toContain(pickUnusedCalendarColor(CALENDAR_COLORS));
+  });
+
+  it('always returns a valid palette color for a small used set', () => {
+    for (let i = 0; i < 50; i++) {
+      const picked = pickUnusedCalendarColor(['#3b82f6']);
+      expect(CALENDAR_COLORS).toContain(picked);
+      expect(picked).not.toBe('#3b82f6');
+    }
+  });
+});

lib/jmap/types.ts

@@ -488,6 +488,10 @@ export interface Calendar {
   // can route mutations to the right client. Distinct from `accountId`
   // which is the JMAP server's own account UUID.
   localAccountId?: string;
+  // Set when `color` has been replaced by the viewer's local override for a
+  // shared calendar (see lib/shared-calendar-colors). When true, the override
+  // wins over per-event colors so the whole shared calendar paints uniformly.
+  colorIsLocalOverride?: boolean;
 }
 
 export interface CalendarRights {

lib/shared-calendar-colors.ts

@@ -0,0 +1,55 @@
+import type { Calendar } from '@/lib/jmap/types';
+
+/**
+ * Palette of calendar colors offered in the color picker. Defined here (rather
+ * than in the settings UI component) so non-React modules can reuse it without
+ * pulling in component code. The settings color picker re-exports this.
+ */
+export const CALENDAR_COLORS = [
+  "#3b82f6", // blue
+  "#ef4444", // red
+  "#22c55e", // green
+  "#f59e0b", // amber
+  "#8b5cf6", // violet
+  "#ec4899", // pink
+  "#14b8a6", // teal
+  "#f97316", // orange
+  "#06b6d4", // cyan
+  "#84cc16", // lime
+  "#6366f1", // indigo
+  "#a855f7", // purple
+  "#e11d48", // rose
+  "#0ea5e9", // sky
+  "#10b981", // emerald
+  "#d946ef", // fuchsia
+];
+
+/**
+ * Stable key for a shared calendar's local color override. Independent of the
+ * Pro-shell id prefix (which changes with the active account), so the override
+ * survives shell-mode and account switches. Built from the owning JMAP account
+ * + the calendar's original server id.
+ */
+export function sharedCalendarColorKey(
+  cal: Pick<Calendar, 'id' | 'originalId' | 'accountId' | 'localAccountId'>,
+): string {
+  const localAccount = cal.localAccountId ?? '';
+  const account = cal.accountId ?? '';
+  const id = cal.originalId ?? cal.id;
+  return `${localAccount}|${account}|${id}`;
+}
+
+/**
+ * Pick a random palette color not present in `usedColors`. Once every palette
+ * entry is taken, fall back to a random palette color (collisions are
+ * unavoidable past CALENDAR_COLORS.length calendars).
+ */
+export function pickUnusedCalendarColor(usedColors: Iterable<string>): string {
+  const used = new Set<string>();
+  for (const c of usedColors) {
+    if (c) used.add(c.toLowerCase());
+  }
+  const available = CALENDAR_COLORS.filter((c) => !used.has(c.toLowerCase()));
+  const pool = available.length > 0 ? available : CALENDAR_COLORS;
+  return pool[Math.floor(Math.random() * pool.length)];
+}