// Shared booking-flow classification logic (server-side).
// The same logic is duplicated in frontend/src/lib/booking-flow.ts for client use.

export const STATUS_COLORS = {
  arrived:     '#3b82f6',  // blue
  confirmed:   '#10b981',  // green
  unconfirmed: '#f59e0b',  // amber
  departed:    '#a855f7',  // purple
  cancelled:   '#94a3b8',  // slate
  blocked:     '#6b7280',  // grey
}

// Extract YYYY-MM-DD from a NewBook datetime string
export function toDateStr(dt) {
  if (!dt) return null
  return String(dt).slice(0, 10)
}

// Extract HH:MM from a NewBook datetime string
export function toTimeStr(dt) {
  if (!dt) return null
  const t = String(dt).slice(11, 16)
  return t || null
}

// Find all bookings for a given site on a specific date.
// A booking occupies a site on viewDate if: arrival <= viewDate < departure
// (departure date is the check-out day, so the room is vacated on that morning)
export function bookingsForSiteOnDate(bookings, siteId, viewDate) {
  return bookings.filter(b => {
    if (String(b.site_id) !== String(siteId)) return false
    const arrival = toDateStr(b.booking_arrival)
    const departure = toDateStr(b.booking_departure)
    if (!arrival || !departure) return false
    return arrival <= viewDate && departure > viewDate
  })
}

// Find the departing booking for a site on viewDate (departure_date === viewDate)
export function departingBookingForSite(bookings, siteId, viewDate) {
  return bookings.find(b =>
    String(b.site_id) === String(siteId) &&
    toDateStr(b.booking_departure) === viewDate
  ) ?? null
}

// Classify a site's booking state for a given view date.
// Returns a rich descriptor used to build the room card.
export function classifyRoom(site, allBookings, viewDate, yesterday, tomorrow) {
  const siteId = String(site.site_id)

  // Primary: booking that occupies the room on viewDate (arrival <= viewDate < departure)
  const todayBookings = bookingsForSiteOnDate(allBookings, siteId, viewDate)
  const departing = departingBookingForSite(allBookings, siteId, viewDate)

  // Adjacent day primary occupants (for border slivers)
  const prevBookings = bookingsForSiteOnDate(allBookings, siteId, yesterday)
  const nextBookings = bookingsForSiteOnDate(allBookings, siteId, tomorrow)

  const prevBooking = prevBookings[0] ?? null
  const nextBooking = nextBookings[0] ?? null

  // Determine flow type
  let flowType = 'vacant'
  let primaryBooking = todayBookings[0] ?? null

  if (primaryBooking) {
    const status = (primaryBooking.booking_status || '').toLowerCase()
    if (status === 'blocked') {
      flowType = 'blocked'
    } else {
      const arrivalDate = toDateStr(primaryBooking.booking_arrival)
      const departureDate = toDateStr(primaryBooking.booking_departure)
      const arrivingToday = arrivalDate === viewDate
      const departingToday = departureDate === viewDate

      if (arrivingToday && departing && String(departing.booking_id) !== String(primaryBooking.booking_id)) {
        // A different booking departs same day this one arrives
        flowType = 'back-to-back'
      } else if (arrivingToday) {
        flowType = 'arrive'
      } else if (departingToday) {
        // Booking departs today but arrival <= viewDate so they were here — shouldn't normally hit
        flowType = 'depart'
      } else {
        flowType = 'stopover'
      }
    }
  } else if (departing) {
    // Room had a departing guest but no incoming booking occupies it today
    primaryBooking = departing
    flowType = 'depart'
  }

  const arrivalDate = primaryBooking ? toDateStr(primaryBooking.booking_arrival) : null
  const departureDate = primaryBooking ? toDateStr(primaryBooking.booking_departure) : null

  return {
    site_id:          siteId,
    site_name:        site.site_name,
    site_status:      site.site_status || 'unknown',
    category_id:      String(site.site_category_id || ''),
    category_name:    site.site_category_name || '',
    category_order:   site.site_category_order ?? 0,
    site_order:       site.site_order ?? 0,

    flow_type:        flowType,
    booking:          primaryBooking,

    // Span flags — does this booking continue across the day boundary?
    spans_previous:   !!primaryBooking && !!arrivalDate && arrivalDate < viewDate,
    spans_next:       !!primaryBooking && !!departureDate && departureDate > viewDate,

    // Adjacent day context for border slivers
    previous_booking: prevBooking,
    next_booking:     nextBooking,
    previous_status:  prevBooking ? (prevBooking.booking_status || '').toLowerCase() : null,
    next_status:      nextBooking ? (nextBooking.booking_status || '').toLowerCase() : null,

    // Departure time info for the wider-border badge
    departing_booking: departing,
    departing_time:    departing ? toTimeStr(departing.booking_departure) : null,
  }
}