interface Schedule {
  /** Schedule is enabled (default: true) */
  enabled?: boolean

  /** Start date (inclusive) - content won't show before this */
  startAt?: DateString | Date

  /** End date (inclusive) - content won't show after this */
  endAt?: DateString | Date

  /** Days of the week when content can show (0=Sunday, 6=Saturday) */
  daysOfWeek?: DayOfWeek[]

  /** Time range during the day when content can show */
  timeOfDay?: TimeRange

  /** Use user's detected timezone (default: true) */
  useUserTimezone?: boolean

  /** Override timezone (IANA timezone name) */
  timezone?: string

  /** Blackout periods when content should not show */
  blackouts?: BlackoutPeriod[]

  /** Recurring pattern for the schedule */
  recurring?: RecurringPattern

  /** Custom metadata */
  metadata?: Record<string, unknown>
}

const schedule: Schedule = {
  enabled: true,
  startAt: '2024-01-15',
  endAt: '2024-12-31',
  daysOfWeek: [1, 2, 3, 4, 5],
  timeOfDay: { start: '09:00', end: '17:00' },
  useUserTimezone: true,
}

interface TimeRange {
  /** Start time in HH:MM format (24-hour) */
  start: TimeString
  /** End time in HH:MM format (24-hour) */
  end: TimeString
}

type TimeString = `${string}:${string}`

const businessHours: TimeRange = {
  start: '09:00',
  end: '17:00',
}

const overnightShift: TimeRange = {
  start: '22:00',
  end: '06:00', // Crosses midnight
}

interface DateRange {
  /** Start date (inclusive) in YYYY-MM-DD format */
  start?: DateString
  /** End date (inclusive) in YYYY-MM-DD format */
  end?: DateString
}

type DateString = `${string}-${string}-${string}`

const q1: DateRange = {
  start: '2024-01-01',
  end: '2024-03-31',
}

type DayOfWeek = 0 | 1 | 2 | 3 | 4 | 5 | 6

// 0 = Sunday
// 1 = Monday
// 2 = Tuesday
// 3 = Wednesday
// 4 = Thursday
// 5 = Friday
// 6 = Saturday

const weekdays: DayOfWeek[] = [1, 2, 3, 4, 5]
const weekends: DayOfWeek[] = [0, 6]

type DayName =
  | 'sunday'
  | 'monday'
  | 'tuesday'
  | 'wednesday'
  | 'thursday'
  | 'friday'
  | 'saturday'

const DAY_NAMES: readonly DayName[] = [
  'sunday',
  'monday',
  'tuesday',
  'wednesday',
  'thursday',
  'friday',
  'saturday',
]

interface BlackoutPeriod {
  /** Unique identifier */
  id: string
  /** Start date/time of the blackout */
  start: DateString | Date
  /** End date/time of the blackout */
  end: DateString | Date
  /** Optional reason for the blackout */
  reason?: string
}

const blackout: BlackoutPeriod = {
  id: 'holiday-freeze',
  start: '2024-12-20',
  end: '2024-12-31',
  reason: 'Year-end code freeze',
}

interface RecurringPattern {
  /** Type of recurrence */
  type: 'daily' | 'weekly' | 'monthly' | 'yearly'

  /** Interval between occurrences (e.g., every 2 weeks) */
  interval?: number

  /** For weekly: which days of the week */
  daysOfWeek?: DayOfWeek[]

  /** For monthly: which day of the month (1-31) */
  dayOfMonth?: number

  /** For yearly: which month (1-12) */
  month?: number

  /** Maximum number of occurrences */
  maxOccurrences?: number

  /** End date for the recurrence */
  endDate?: DateString
}

// Every Monday
const weekly: RecurringPattern = {
  type: 'weekly',
  daysOfWeek: [1],
}

// First of every month
const monthly: RecurringPattern = {
  type: 'monthly',
  dayOfMonth: 1,
}

// Every Christmas
const yearly: RecurringPattern = {
  type: 'yearly',
  month: 12,
  dayOfMonth: 25,
}

interface ScheduleResult {
  /** Whether the schedule is currently active */
  isActive: boolean
  /** Quick reason code if inactive */
  reason?: ScheduleInactiveReason
}

const result: ScheduleResult = {
  isActive: false,
  reason: 'wrong_time',
}

interface ScheduleStatus {
  /** Whether the schedule is currently active */
  isActive: boolean

  /** Reason for being inactive */
  reason?: ScheduleInactiveReason

  /** Human-readable explanation */
  message?: string

  /** When the schedule will next become active */
  nextActiveAt?: Date

  /** When the schedule will next become inactive */
  nextInactiveAt?: Date

  /** Current blackout period if in one */
  currentBlackout?: {
    id: string
    reason?: string
    endsAt: Date
  }

  /** Debug information */
  debug?: {
    evaluatedAt: Date
    timezone: string
    localTime: string
    dayOfWeek: number
  }
}

const status: ScheduleStatus = {
  isActive: false,
  reason: 'wrong_time',
  message: 'Outside time range (9:00 AM - 5:00 PM)',
  nextActiveAt: new Date('2024-02-15T09:00:00Z'),
}

type ScheduleInactiveReason =
  | 'disabled' // Schedule explicitly disabled
  | 'not_started' // Before start date
  | 'ended' // After end date
  | 'wrong_day' // Not on allowed day of week
  | 'wrong_time' // Outside allowed time range
  | 'blackout' // In a blackout period
  | 'outside_business_hours' // Outside business hours
  | 'recurring_mismatch' // Doesn't match recurring pattern

interface ScheduleEvaluationOptions {
  /** Override the current date/time for testing */
  now?: Date
  /** User's detected timezone */
  userTimezone?: string
}

const options: ScheduleEvaluationOptions = {
  now: new Date('2024-02-15T10:00:00Z'),
  userTimezone: 'America/New_York',
}

const result = isScheduleActive(schedule, options)

interface BusinessHours {
  /** Default hours for days not explicitly configured */
  default?: DayHours
  /** Hours by day of week */
  days?: BusinessHoursMap
  /** Override timezone */
  timezone?: string
  /** Holidays or closure dates (YYYY-MM-DD format) */
  holidays?: string[]
}

type BusinessHoursMap = {
  [K in DayOfWeek]?: DayHours
}

interface DayHours {
  /** Whether the business is open on this day */
  open: boolean
  /** Time ranges when open (allows split hours) */
  hours?: TimeRange[]
}

const hours: BusinessHours = {
  default: { open: false },
  days: {
    1: { open: true, hours: [{ start: '09:00', end: '17:00' }] },
    2: { open: true, hours: [{ start: '09:00', end: '17:00' }] },
    3: {
      open: true,
      hours: [
        { start: '09:00', end: '12:00' },
        { start: '13:00', end: '17:00' }, // Lunch break
      ],
    },
  },
  holidays: ['2024-12-25', '2024-01-01'],
}

interface UseScheduleOptions {
  /** Refresh interval in milliseconds (default: 60000) */
  refreshInterval?: number
  /** Disable auto-refresh */
  disableAutoRefresh?: boolean
  /** Override timezone */
  timezone?: string
}

interface UseScheduleReturn extends ScheduleResult {
  isActive: boolean
  reason?: ScheduleInactiveReason
  /** Manually refresh the schedule status */
  refresh: () => void
  /** Last evaluation timestamp */
  lastCheckedAt: Date
  /** Current timezone being used */
  timezone: string
}

interface UseScheduleStatusOptions {
  /** Refresh interval in milliseconds (default: 60000) */
  refreshInterval?: number
  /** Disable auto-refresh */
  disableAutoRefresh?: boolean
  /** Override timezone */
  timezone?: string
  /** Include debug information in status */
  debug?: boolean
}

interface UseScheduleStatusReturn extends ScheduleStatus {
  /** Manually refresh the schedule status */
  refresh: () => void
  /** Last evaluation timestamp */
  lastCheckedAt: Date
  /** Current timezone being used */
  timezone: string
}

function isScheduleActive(result: ScheduleResult): result is { isActive: true } {
  return result.isActive
}

function hasBlackout(
  status: ScheduleStatus
): status is ScheduleStatus & { currentBlackout: NonNullable<ScheduleStatus['currentBlackout']> } {
  return status.currentBlackout !== undefined
}