// 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
}

// Match a booking to a site ID. NewBook sometimes uses booking_site_id instead of site_id.
function siteMatches(b, siteId) {
  const bid = String(b.site_id || b.booking_site_id || '')
  return bid === String(siteId)
}

// 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 (!siteMatches(b, 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 =>
    siteMatches(b, 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)

  // Prefer bookings arriving TODAY over stopovers — handles the case where NewBook
  // still shows a previous stay as active when a new booking has already arrived.
  const todayArriving = todayBookings.filter(b => toDateStr(b.booking_arrival) === viewDate)
  let primaryBooking  = todayArriving[0] ?? todayBookings[0] ?? null

  // If an arriving booking is primary AND there's also a non-arriving booking in
  // todayBookings, treat that as the departing context (B2B where departure date
  // hasn't been updated in NewBook yet).
  let effectiveDeparting = departing
  if (!effectiveDeparting && todayArriving.length > 0 && todayBookings.length > todayArriving.length) {
    effectiveDeparting = todayBookings.find(b => toDateStr(b.booking_arrival) !== viewDate) ?? null
  }

  // Adjacent day primary occupants (for border brackets)
  const prevBooking = bookingsForSiteOnDate(allBookings, siteId, yesterday)[0] ?? null
  const nextBooking = bookingsForSiteOnDate(allBookings, siteId, tomorrow)[0]  ?? null

  // Determine flow type
  let flowType = 'vacant'

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

      if (arrivingToday && effectiveDeparting &&
          String(effectiveDeparting.booking_id) !== String(primaryBooking.booking_id)) {
        flowType = 'back-to-back'
      } else if (arrivingToday) {
        flowType = 'arrive'
      } else if (departingToday) {
        flowType = 'depart'
      } else {
        flowType = 'stopover'
      }
    }
  } else if (effectiveDeparting) {
    primaryBooking = effectiveDeparting
    flowType = 'depart'
  }

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

  // spans_next: booking is ALSO active tomorrow (departure strictly after tomorrow).
  // Using > tomorrow (not > viewDate) so a booking departing tomorrow does NOT extend
  // the card right — it ends tonight and its right border should be visible.
  const spansNext = !!primaryBooking && !!departureDate && departureDate > tomorrow

  // Previous-day bracket: use real NewBook status so the sliver remains 'arrived'
  // (wide, with checkout time) until the guest actually checks out and NewBook
  // flips the status to 'departed'. Do not override — let real status drive colour.
  const prevStatus = prevBooking ? (prevBooking.booking_status || '').toLowerCase() : null

  // NewBook may return category info as flat fields or a nested object.
  const catId   = site.site_category_id   ?? site.category_id   ?? site.category?.id   ?? null
  const catName = site.site_category_name ?? site.category_name ?? site.category?.name ?? ''
  const catOrd  = site.site_category_order ?? site.category_order ?? site.category?.order ?? 0

  return {
    site_id:        siteId,
    site_name:      site.site_name,
    site_status:    site.site_status || 'unknown',
    category_id:    catId != null ? String(catId) : '',
    category_name:  catName,
    category_order: catOrd,
    site_order:     site.site_order ?? 0,

    flow_type: flowType,
    booking:   primaryBooking,

    spans_previous: !!primaryBooking && !!arrivalDate   && arrivalDate < viewDate,
    spans_next:     spansNext,

    previous_booking: prevBooking,
    next_booking:     nextBooking,
    previous_status:  prevStatus,
    next_status:      nextBooking ? (nextBooking.booking_status || '').toLowerCase() : null,

    departing_booking: effectiveDeparting,
    departing_time:    effectiveDeparting ? toTimeStr(effectiveDeparting.booking_departure) : null,
  }
}