export const CHECKLIST_KEY_V1 = 'magikarp-checklist-v1';
export const CHECKLIST_KEY_V2 = 'magikarp-checklist-v2';

export type VariantKey = 'base' | 'holofoil' | 'reverseHolofoil';
export type VariantState = Partial<Record<VariantKey, boolean>>;
export type ChecklistV2 = Record<string, VariantState>; // cardId -> variant flags

// Legacy loader (v1)
export function loadChecklistV1(): Set<string> {
  if (typeof window === 'undefined') return new Set();
  try {
    const raw = localStorage.getItem(CHECKLIST_KEY_V1);
    if (!raw) return new Set();
    const arr = JSON.parse(raw) as string[];
    return new Set(arr);
  } catch {
    return new Set();
  }
}

// New storage (v2)
export function loadChecklist(): ChecklistV2 {
  if (typeof window === 'undefined') return {};
  try {
    const v2 = localStorage.getItem(CHECKLIST_KEY_V2);
    if (v2) return JSON.parse(v2) as ChecklistV2;
    // migrate from v1 if present
    const v1 = loadChecklistV1();
    if (v1.size === 0) return {};
    const migrated: ChecklistV2 = {};
    v1.forEach((id) => {
      migrated[id] = { base: true };
    });
    saveChecklist(migrated);
    return migrated;
  } catch {
    return {};
  }
}

export function saveChecklist(state: ChecklistV2) {
  if (typeof window === 'undefined') return;
  try {
    localStorage.setItem(CHECKLIST_KEY_V2, JSON.stringify(state));
  } catch {
    // ignore
  }
}