export const PERMISSIONS_UPDATED_EVENT = 'permissions-updated';

export type PermissionStatus = 'unknown' | 'loading' | 'ready';

export interface PermissionState {
  permissions: string[];
  status: PermissionStatus;
}

let permissionState: PermissionState = { permissions: [], status: 'unknown' };

function notifyPermissionStateChanged(): void {
  window.dispatchEvent(new Event(PERMISSIONS_UPDATED_EVENT));
}

export function readPermissionState(): PermissionState {
  return permissionState;
}

export function readPermissions(): string[] {
  return permissionState.status === 'ready' ? permissionState.permissions : [];
}

export function beginPermissionVerification(): void {
  permissionState = { permissions: [], status: 'loading' };
  notifyPermissionStateChanged();
}

export function writePermissions(permissions: string[]): void {
  const uniquePermissions = [...new Set(permissions)];
  localStorage.setItem('permissions', JSON.stringify(uniquePermissions));
  permissionState = { permissions: uniquePermissions, status: 'ready' };
  notifyPermissionStateChanged();
}

export function clearPermissions(status: PermissionStatus = 'unknown'): void {
  localStorage.removeItem('permissions');
  permissionState = { permissions: [], status };
  notifyPermissionStateChanged();
}