import { check } from 'meteor/check';
import deepMerge from '/imports/utils/deepMerge';

export class Acl {

  constructor(config, Users) {
    this.Users = Users;
    this.config = config;
  }

  can(permission, credentials) {
    check(permission, String);
    const permissions = this.getPermissions(credentials);

    if (permissions) {
      return this.fetchPermission(permission, permissions);
    }

    return false;
  }

  fetchPermission(permission, permissions) {
    if (!permission) return false;

    if (Match.test(permissions, String)) {
      return permissions.indexOf(permission) > -1;
    } else if (Match.test(permissions, Array)) {
      return permissions.some(internalAcl => (this.fetchPermission(permission, internalAcl)));
    } else if (Match.test(permissions, Object)) {
      if (permission.indexOf('.') > -1) {
        return this.fetchPermission(permission.substring(permission.indexOf('.') + 1),
          permissions[permission.substring(0, permission.indexOf('.'))]);
      }
      return permissions[permission];
    }
    return false;
  }

  getPermissions(credentials) {
    if (!credentials) {
      return false;
    }

    const meetingId = credentials.meetingId;
    const userId = credentials.requesterUserId;

    const user = this.Users.findOne({
      meetingId,
      userId,
    });

    const containRole = Acl.containsRole(user);

    if (containRole) {
      const roles = user.roles;
      let permissions = {};

      roles.forEach((role) => {
        permissions = deepMerge(permissions, this.config[role]);
      });

      return permissions;
    }
    return false;
  }

  static containsRole(user) {
    return Match.test(user, Object) &&
        Match.test(user.roles, Array);
  }
}