import type { Permission } from '@/lib/auth/permissions'

/**
 * Lebenszyklus einer Akte, siehe docs/05-akten-und-vorlagen.md.
 *
 *   DRAFT ──► OPEN ──► REVIEW ──► CLOSED ──► ARCHIVED
 *               │ ▲        │
 *               ▼ │        └──► OPEN (Rückgabe zur Nachbesserung)
 *            DORMANT
 *
 *   SEALED ist aus jedem Zustand erreichbar und nur mit Recht 'admin' oder
 *   Stufe 5 lesbar.
 */
export type CaseStatusName =
  | 'DRAFT'
  | 'OPEN'
  | 'DORMANT'
  | 'REVIEW'
  | 'CLOSED'
  | 'ARCHIVED'
  | 'SEALED'

export type Transition = {
  from: CaseStatusName
  to: CaseStatusName
  permission: Permission
  /** Verlangt eine Begründung, die als Vermerk im Verlauf landet. */
  requiresReason?: boolean
  /** Verlangt, dass alle `requiredToClose`-Felder gefüllt sind. */
  requiresCompleteSections?: boolean
}

export const TRANSITIONS: readonly Transition[] = [
  { from: 'DRAFT', to: 'OPEN', permission: 'case.edit' },
  { from: 'OPEN', to: 'DORMANT', permission: 'case.edit' },
  { from: 'DORMANT', to: 'OPEN', permission: 'case.edit' },
  { from: 'OPEN', to: 'REVIEW', permission: 'case.edit' },
  { from: 'REVIEW', to: 'OPEN', permission: 'case.edit' },
  { from: 'REVIEW', to: 'CLOSED', permission: 'case.close', requiresCompleteSections: true },
  { from: 'CLOSED', to: 'OPEN', permission: 'case.reopen', requiresReason: true },
  { from: 'CLOSED', to: 'ARCHIVED', permission: 'case.close' },
]

/** SEALED erreicht man aus jedem Zustand, aber nur mit dem Recht 'admin'. */
export const SEAL_PERMISSION: Permission = 'admin'

export function findTransition(
  from: CaseStatusName,
  to: CaseStatusName,
): Transition | undefined {
  if (to === 'SEALED' && from !== 'SEALED') {
    return { from, to, permission: SEAL_PERMISSION, requiresReason: true }
  }
  return TRANSITIONS.find((t) => t.from === from && t.to === to)
}

export function allowedTargets(from: CaseStatusName): CaseStatusName[] {
  const targets = TRANSITIONS.filter((t) => t.from === from).map((t) => t.to)
  if (from !== 'SEALED') targets.push('SEALED')
  return targets
}