export const pad2 = (n: number) => String(n).padStart(2, '0')

export const pad3 = (n: number) => String(n).padStart(3, '0')

export const formatTimestamp = (d: Date) => {
  const yyyy = d.getFullYear()
  const mm = pad2(d.getMonth() + 1)
  const dd = pad2(d.getDate())
  const hh = pad2(d.getHours())
  const mi = pad2(d.getMinutes())
  const ss = pad2(d.getSeconds())
  const ms = pad3(d.getMilliseconds())
  return `${yyyy}${mm}${dd}_${hh}${mi}${ss}_${ms}`
}

export const formatDate = (date: Date) => {
  const yyyy = date.getFullYear()
  const mm = pad2(date.getMonth() + 1)
  const dd = pad2(date.getDate())
  return `${yyyy}-${mm}-${dd}`
}

export const formatTime = (date: Date) => {
  const hh = pad2(date.getHours())
  const mm = pad2(date.getMinutes())
  const ss = pad2(date.getSeconds())
  return `${hh}:${mm}:${ss}`
}

export const formatDateTime = (date: Date) => {
  return `${formatDate(date)} ${formatTime(date)}`
}

export const getTodayDate = (): string => {
  return formatDate(new Date())
}

export const getTomorrowDate = (): string => {
  const tomorrow = new Date()
  tomorrow.setDate(tomorrow.getDate() + 1)
  return formatDate(tomorrow)
}

export const formatDateDisplay = (dateStr: string): string => {
  const today = getTodayDate()
  const tomorrow = getTomorrowDate()
  if (dateStr === today) return '今天'
  if (dateStr === tomorrow) return '明天'
  const [year, month, day] = dateStr.split('-')
  const currentYear = new Date().getFullYear()
  if (parseInt(year) === currentYear) {
    return `${parseInt(month)}月${parseInt(day)}日`
  }
  return `${year}年${parseInt(month)}月${parseInt(day)}日`
}

export const formatDuration = (ms: number): string => {
  const seconds = Math.floor(ms / 1000)
  const minutes = Math.floor(seconds / 60)
  const hours = Math.floor(minutes / 60)

  if (hours > 0) {
    const remainingMinutes = minutes % 60
    return `${hours}小时${remainingMinutes > 0 ? `${remainingMinutes}分钟` : ''}`
  }
  if (minutes > 0) {
    return `${minutes}分钟`
  }
  return `${seconds}秒`
}

export const formatDurationShort = (ms: number): string => {
  const seconds = Math.floor(ms / 1000)
  const minutes = Math.floor(seconds / 60)
  const hours = Math.floor(minutes / 60)

  if (hours > 0) {
    const remainingMinutes = minutes % 60
    return remainingMinutes > 0 ? `${hours}h${remainingMinutes}m` : `${hours}h`
  }
  if (minutes > 0) {
    return `${minutes}m`
  }
  return `${seconds}s`
}

export const getWeekStart = (date: Date): Date => {
  const d = new Date(date)
  const day = d.getDay()
  const diff = d.getDate() - day + (day === 0 ? -6 : 1)
  d.setDate(diff)
  d.setHours(0, 0, 0, 0)
  return d
}

export const getWeekEnd = (date: Date): Date => {
  const weekStart = getWeekStart(date)
  const weekEnd = new Date(weekStart)
  weekEnd.setDate(weekStart.getDate() + 6)
  return weekEnd
}

export const getMonthStart = (date: Date): Date => {
  return new Date(date.getFullYear(), date.getMonth(), 1)
}

export const getMonthEnd = (date: Date): Date => {
  return new Date(date.getFullYear(), date.getMonth() + 1, 0)
}

export const getYearStart = (date: Date): Date => {
  return new Date(date.getFullYear(), 0, 1)
}

export const getYearEnd = (date: Date): Date => {
  return new Date(date.getFullYear(), 11, 31)
}

export const isSameDay = (date1: Date, date2: Date): boolean => {
  return formatDate(date1) === formatDate(date2)
}

export const isToday = (date: Date): boolean => {
  return isSameDay(date, new Date())
}

export const addDays = (date: Date, days: number): Date => {
  const result = new Date(date)
  result.setDate(result.getDate() + days)
  return result
}

export const addMonths = (date: Date, months: number): Date => {
  const result = new Date(date)
  result.setMonth(result.getMonth() + months)
  return result
}

export const addYears = (date: Date, years: number): Date => {
  const result = new Date(date)
  result.setFullYear(result.getFullYear() + years)
  return result
}

export const parseDate = (dateStr: string): Date | null => {
  const match = dateStr.match(/^(\d{4})-(\d{2})-(\d{2})$/)
  if (!match) return null
  const [, year, month, day] = match
  return new Date(parseInt(year), parseInt(month) - 1, parseInt(day))
}

export const getDaysInMonth = (year: number, month: number): number => {
  return new Date(year, month, 0).getDate()
}

export const getDayOfWeek = (date: Date): string => {
  const days = ['周日', '周一', '周二', '周三', '周四', '周五', '周六']
  return days[date.getDay()]
}