/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community License, Version 2.0 (the "License"); you may not use this file
    * except in compliance with the License. You may obtain a copy of the License
   * at:
   *
   *   http://opensource.org/licenses/ecl2.txt
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  package org.opencastproject.security.jwt;
  
  import org.opencastproject.security.api.GroupProvider;
  import org.opencastproject.security.api.JaxbOrganization;
  import org.opencastproject.security.api.JaxbRole;
  import org.opencastproject.security.api.Role;
  import org.opencastproject.security.api.SecurityService;
  import org.opencastproject.security.api.User;
  import org.opencastproject.security.api.UserProvider;
  import org.opencastproject.userdirectory.api.AAIRoleProvider;
  import org.opencastproject.userdirectory.api.UserReferenceProvider;
  
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.regex.Pattern;
  
  /**
   * Role provider for users authenticated based on JWTs.
   */
  public class JWTRoleProvider implements AAIRoleProvider, GroupProvider {
  
    /** Security service */
    private final SecurityService securityService;
  
    /** User reference provider */
    private final UserReferenceProvider userReferenceProvider;
  
    public JWTRoleProvider(SecurityService securityService, UserReferenceProvider userReferenceProvider) {
      this.securityService = securityService;
      this.userReferenceProvider = userReferenceProvider;
    }
  
    @Override
    public Iterator<Role> getRoles() {
      JaxbOrganization organization = JaxbOrganization.fromOrganization(securityService.getOrganization());
      HashSet<Role> roles = new HashSet<>();
      roles.add(new JaxbRole(organization.getAnonymousRole(), organization));
      roles.addAll(securityService.getUser().getRoles());
      return roles.iterator();
    }
  
    @Override
    public List<Role> getRolesForUser(String userName) {
      ArrayList<Role> roles = new ArrayList<>();
      User user = userReferenceProvider.loadUser(userName);
      if (user != null) {
        roles.addAll(user.getRoles());
      }
      return roles;
    }
  
    @Override
    public String getOrganization() {
      return UserProvider.ALL_ORGANIZATIONS;
    }
  
    @Override
    public Iterator<Role> findRoles(String query, Role.Target target, int offset, int limit) {
      if (query == null) {
        throw new IllegalArgumentException("Query must be set");
      }
      HashSet<Role> foundRoles = new HashSet<Role>();
      for (Iterator<Role> it = getRoles(); it.hasNext();) {
        Role role = it.next();
        if (like(role.getName(), query) || like(role.getDescription(), query)) {
          foundRoles.add(role);
        }
      }
      return offsetLimitCollection(offset, limit, foundRoles).iterator();
  
    }
  
    /**
     * Slices a given hash set with a given offset and a given limit of entries.
     *
     * @param offset The offset.
    * @param limit The limit for the number of entries.
    * @param entries The original entries.
    * @return The sliced hash set.
    */
   private <T> HashSet<T> offsetLimitCollection(int offset, int limit, HashSet<T> entries) {
     HashSet<T> result = new HashSet<T>();
     int i = 0;
     for (T entry : entries) {
       if (limit != 0 && result.size() >= limit) {
         break;
       }
       if (i >= offset) {
         result.add(entry);
       }
       i++;
     }
     return result;
   }
 
   /**
    * Evaluates whether a given query matches on a string.
    *
    * @param string The string.
    * @param query The query.
    * @return <code>true</code> if the query matches, <code>false</code> otherwise.
    */
   private boolean like(String string, final String query) {
     if (string == null) {
       return false;
     }
 
     String regex = query.replace("_", ".").replace("%", ".*?");
     Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.DOTALL);
     return p.matcher(string).matches();
   }
 
   @Override
   public List<Role> getRolesForGroup(String groupName) {
     return null;
   }
 
 }