Function calculateStreaks

src/utils/stats.ts:853–931

(dailyActivity: DailyActivity[])

}

function calculateStreaks(dailyActivity: DailyActivity[]): StreakInfo {
  if (dailyActivity.length === 0) {
    return {
      currentStreak: 0,
      longestStreak: 0,
      currentStreakStart: null,
      longestStreakStart: null,
      longestStreakEnd: null,
    }
  }

  const today = new Date()
  today.setHours(0, 0, 0, 0)

  // Calculate current streak (working backwards from today)
  let currentStreak = 0
  let currentStreakStart: string | null = null
  const checkDate = new Date(today)

  // Build a set of active dates for quick lookup
  const activeDates = new Set(dailyActivity.map(d => d.date))

  while (true) {
    const dateStr = toDateString(checkDate)
    if (!activeDates.has(dateStr)) {
      break
    }
    currentStreak++
    currentStreakStart = dateStr
    checkDate.setDate(checkDate.getDate() - 1)
  }

  // Calculate longest streak
  let longestStreak = 0
  let longestStreakStart: string | null = null
  let longestStreakEnd: string | null = null

  if (dailyActivity.length > 0) {
    const sortedDates = Array.from(activeDates).sort()
    let tempStreak = 1
    let tempStart = sortedDates[0]!

    for (let i = 1; i < sortedDates.length; i++) {
      const prevDate = new Date(sortedDates[i - 1]!)
      const currDate = new Date(sortedDates[i]!)

      const dayDiff = Math.round(
        (currDate.getTime() - prevDate.getTime()) / (1000 * 60 * 60 * 24),
      )

      if (dayDiff === 1) {
        tempStreak++
      } else {
        if (tempStreak > longestStreak) {
          longestStreak = tempStreak
          longestStreakStart = tempStart
          longestStreakEnd = sortedDates[i - 1]!
        }