/**
 * Mirrors backend `event-edit-policy.ts` for host/admin edit UI.
 * Keep in sync when changing the lock matrix.
 */

export const EVENT_SENSITIVE_FIELDS = [
  'startsAt',
  'endsAt',
  'provinceId',
  'cityId',
  'address',
  'lat',
  'lng',
  'isFree',
  'price',
  'cancellationFeePercent',
  'cancellationFeePercent12To24Hours',
  'cancellationFeePercentMoreThan24Hours',
  'genderRestriction',
  'ageRestriction',
] as const

export type EventSensitiveField = (typeof EVENT_SENSITIVE_FIELDS)[number]

export interface EventEditPolicy {
  canEdit: boolean
  hasActiveBookings: boolean
  minCapacity: number
  lockedFields: ReadonlySet<EventSensitiveField>
  /** When true, behavioral settings (discoverability, etc.) cannot change. */
  lockBehavioralSettings: boolean
}

const TERMINAL = new Set(['cancelled', 'completed'])
const LIVE = new Set(['published', 'full'])

export function isTerminalEventStatus(status: string): boolean {
  return TERMINAL.has(status)
}

export function isLiveEventStatus(status: string): boolean {
  return LIVE.has(status)
}

/**
 * Slug cannot change on terminal events.
 * Live slug changes go through pending revisions (applied on admin approve).
 */
export function isEventSlugLocked(status: string): boolean {
  return TERMINAL.has(status)
}

/**
 * Event is locked for mutations when it reached a terminal status OR its
 * scheduled end time has passed (covers early complete vs clock end).
 */
export function isEventEnded(status: string, endsAt: string | Date, now: Date = new Date()): boolean {
  if (isTerminalEventStatus(status)) return true

  return new Date(endsAt).getTime() <= now.getTime()
}

export function resolveEventEditPolicy(status: string, bookedCount: number, reservedCapacity = 0): EventEditPolicy {
  const occupied = bookedCount + reservedCapacity
  const minCapacity = Math.max(1, occupied)

  if (isTerminalEventStatus(status)) {
    return {
      canEdit: false,
      hasActiveBookings: bookedCount > 0,
      minCapacity,
      lockedFields: new Set(EVENT_SENSITIVE_FIELDS),
      lockBehavioralSettings: true,
    }
  }

  if (status === 'draft' || !LIVE.has(status)) {
    return {
      canEdit: true,
      hasActiveBookings: false,
      minCapacity,
      lockedFields: new Set(),
      lockBehavioralSettings: false,
    }
  }

  const hasActiveBookings = bookedCount > 0

  return {
    canEdit: true,
    hasActiveBookings,
    minCapacity,
    lockedFields: hasActiveBookings ? new Set(EVENT_SENSITIVE_FIELDS) : new Set(),
    lockBehavioralSettings: hasActiveBookings,
  }
}

export function isFieldLocked(policy: EventEditPolicy, field: EventSensitiveField): boolean {
  return policy.lockedFields.has(field)
}