Scrum4Me/stores/product-workspace/screen-state.ts

// Expliciete schermstaat voor de Product Backlog page.
//
// Consolideert de vandaag verspreide schermstaat-afleiding (page.tsx,
// sprint-switcher.tsx, new-sprint-trigger.tsx, save-sprint-button.tsx) tot één
// pure, testbare functie. Zie docs/architecture/product-backlog-workflow.md,
// sectie "To-be: expliciete state machine".
//
// PRODUCT_NOT_ACTIVE en DEMO_MODE blijven bewust BUITEN ScreenState — het zijn
// cross-cutting gates, geen knopen in de state machine.

export type ScreenState =
  | { kind: 'NO_SPRINT' }
  | { kind: 'DRAFT' }
  | { kind: 'ACTIVE'; building: boolean }
  | { kind: 'EDITING'; building: boolean }

export interface ScreenStateInput {
  activeSprintItem: { id: string } | null // SSR-prop uit page.tsx
  buildingSprintIds: string[] // SSR-prop uit page.tsx
  hasPendingDraft: boolean // user-settings store
  pendingAdds: string[] // product-workspace store: sprintMembership.pending.adds
  pendingRemoves: string[] // product-workspace store: sprintMembership.pending.removes
}

export function deriveScreenState(i: ScreenStateInput): ScreenState {
  if (i.hasPendingDraft) return { kind: 'DRAFT' } // draft wint van alles
  if (i.activeSprintItem) {
    const building = i.buildingSprintIds.includes(i.activeSprintItem.id)
    const dirty = i.pendingAdds.length > 0 || i.pendingRemoves.length > 0
    return dirty ? { kind: 'EDITING', building } : { kind: 'ACTIVE', building }
  }
  return { kind: 'NO_SPRINT' }
}