feat: countdown anniversaries and birthdays like ticktick

frontend/src/lib/mvp-utils.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { dateKey, defaultView, habitWeek, isHabitComplete, isHabitScheduledToday, isTaskView, nextHabitSwipeValue, numericHabitInputValue, previousHabitSwipeValue, quickTaskFields, shouldToggleRowSwipe } from './mvp-utils'
+import { countdownDayText, countdownKindLabel, dateKey, defaultView, habitWeek, isHabitComplete, isHabitScheduledToday, isTaskView, nextHabitSwipeValue, numericHabitInputValue, previousHabitSwipeValue, quickTaskFields, shouldToggleRowSwipe } from './mvp-utils'
 
 describe('MVP view utilities', () => {
   it('formats a local date as YYYY-MM-DD', () => {
@@ -63,6 +63,15 @@ describe('MVP view utilities', () => {
     expect(previousHabitSwipeValue('numeric', 0)).toBe(0)
   })
 
+  it('renders countdown labels from date-only day values', () => {
+    expect(countdownDayText(8)).toBe('还有 8 天')
+    expect(countdownDayText(0)).toBe('就是今天')
+    expect(countdownDayText(-12)).toBe('已经 12 天')
+    expect(countdownKindLabel('countdown')).toBe('倒数日')
+    expect(countdownKindLabel('anniversary')).toBe('纪念日')
+    expect(countdownKindLabel('birthday')).toBe('生日')
+  })
+
   it('toggles a row for a deliberate mostly-horizontal swipe', () => {
     expect(shouldToggleRowSwipe(78, 8)).toBe(true)
     expect(shouldToggleRowSwipe(88, 28)).toBe(true)

frontend/src/lib/mvp-utils.ts

@@ -76,6 +76,16 @@ export function numericHabitInputValue(input: number | string | undefined) {
   return Number.isFinite(value) && value >= 0 ? value : null
 }
 
+export function countdownDayText(days: number) {
+  if (days > 0) return `还有 ${days} 天`
+  if (days === 0) return '就是今天'
+  return `已经 ${Math.abs(days)} 天`
+}
+
+export function countdownKindLabel(kind: string) {
+  return ({ countdown: '倒数日', anniversary: '纪念日', birthday: '生日' } as Record<string, string>)[kind] ?? '倒数日'
+}
+
 export function shouldToggleRowSwipe(deltaX: number, deltaY: number) {
   return deltaX >= 64 && deltaX > Math.abs(deltaY) * 1.5
 }