import { UserToken } from '@axinom/mosaic-core';

type RequiredPermissionsArgs =
  | [string[], string[]]
  | [UserToken['permissions'], UserToken['permissions']];

/**
 * Checks whether the `requiredPermissions` are satisfied by the `grantedPermissions` or not.
 * Having at least one of the required permissions granted satisfies this permission requirement.
 * @param requiredPermissions The required permissions.
 * @param grantedPermissions The current permissions of the user.
 */
export function requiredPermissionsExists(
  requiredPermissions: string[],
  grantedPermissions: string[],
): boolean;

/**
 * Checks whether the `requiredPermissions` are satisfied by the `grantedPermissions` per each service.
 * Having at least one of the required permissions granted per each service satisfies this permission requirement.
 * @param requiredPermissions The required permissions. Should be an object of shape { [serviceId: string]: string[] }.
 * @param grantedPermissions The current permissions of the user. Should be an object of shape { [serviceId: string]: string[] }.
 */
export function requiredPermissionsExists(
  requiredPermissions: UserToken['permissions'],
  grantedPermissions: UserToken['permissions'],
): boolean;

export function requiredPermissionsExists(
  ...args: RequiredPermissionsArgs
): boolean {
  const [requiredPermissions, grantedPermissions] = args;

  if (Array.isArray(requiredPermissions) && Array.isArray(grantedPermissions)) {
    return requiredPermissions.some((permission) =>
      grantedPermissions.includes(permission),
    );
  }

  if (
    !Array.isArray(requiredPermissions) &&
    !Array.isArray(grantedPermissions)
  ) {
    const services = Object.keys(requiredPermissions);
    if (services.length === 0) {
      return true;
    }
    for (const service in services) {
      const serviceName = services[service];
      if (grantedPermissions[serviceName]) {
        return requiredPermissionsExists(
          requiredPermissions[serviceName],
          grantedPermissions[serviceName],
        );
      }
    }
    return false;
  }

  // Unreachable: the overloads guarantee both args are always the same type.
  return false;
}