/*
    * 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.userdirectory;
  
  import static org.opencastproject.db.Queries.namedQuery;
  
  import org.opencastproject.db.DBSession;
  import org.opencastproject.db.DBSessionFactory;
  import org.opencastproject.security.api.Group;
  import org.opencastproject.security.api.Role;
  import org.opencastproject.security.api.RoleProvider;
  import org.opencastproject.security.api.SecurityService;
  import org.opencastproject.security.api.UnauthorizedException;
  import org.opencastproject.security.api.User;
  import org.opencastproject.security.api.UserProvider;
  import org.opencastproject.security.impl.jpa.JpaOrganization;
  import org.opencastproject.security.impl.jpa.JpaRole;
  import org.opencastproject.security.impl.jpa.JpaUserReference;
  import org.opencastproject.userdirectory.api.AAIRoleProvider;
  import org.opencastproject.userdirectory.api.UserReferenceProvider;
  import org.opencastproject.userdirectory.utils.UserDirectoryUtils;
  import org.opencastproject.util.NotFoundException;
  import org.opencastproject.util.function.ThrowingConsumer;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  
  import org.apache.commons.lang3.tuple.Pair;
  import org.osgi.service.component.ComponentContext;
  import org.osgi.service.component.annotations.Activate;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Optional;
  import java.util.Set;
  import java.util.concurrent.TimeUnit;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  
  import javax.persistence.EntityManager;
  import javax.persistence.EntityManagerFactory;
  import javax.persistence.TypedQuery;
  
  /**
   * Manages and locates users references using JPA.
   */
  @Component(
      property = {
          "service.description=Provides a user reference directory"
      },
      immediate = true,
      service = { UserProvider.class, RoleProvider.class, UserReferenceProvider.class, JpaUserReferenceProvider.class }
  )
  public class JpaUserReferenceProvider implements UserReferenceProvider, UserProvider, RoleProvider {
  
    /** The logger */
    private static final Logger logger = LoggerFactory.getLogger(JpaUserReferenceProvider.class);
  
    public static final String PROVIDER_NAME = "matterhorn-reference";
  
    /** Username constant used in JSON formatted users */
    public static final String USERNAME = "username";
  
    /** Role constant used in JSON formatted users */
    public static final String ROLES = "roles";
  
    /** Encoding expected from all inputs */
    public static final String ENCODING = "UTF-8";
  
    /** The security service */
    protected SecurityService securityService = null;
  
   /** Group Role provider */
   protected JpaGroupRoleProvider groupRoleProvider;
 
   /** Role provider */
   protected AAIRoleProvider roleProvider;
 
   /** The delimiter for the User cache */
   private static final String DELIMITER = ";==;";
 
   /** A cache of users, which lightens the load on the SQL server */
   private LoadingCache<String, Object> cache = null;
 
   /** A token to store in the miss cache */
   protected final Object nullToken = new Object();
 
   /** The factory used to generate the entity manager */
   protected EntityManagerFactory emf = null;
 
   protected DBSessionFactory dbSessionFactory;
 
   protected DBSession db;
 
   /** OSGi DI */
   @Reference(target = "(osgi.unit.name=org.opencastproject.common)")
   void setEntityManagerFactory(EntityManagerFactory emf) {
     this.emf = emf;
   }
 
   @Reference
   public void setDBSessionFactory(DBSessionFactory dbSessionFactory) {
     this.dbSessionFactory = dbSessionFactory;
   }
 
   /**
    * @param securityService
    *          the securityService to set
    */
   @Reference
   public void setSecurityService(SecurityService securityService) {
     this.securityService = securityService;
   }
 
   /**
    * @param groupRoleProvider
    *          the GroupRoleProvider to set
    */
   @Reference
   public void setGroupRoleProvider(JpaGroupRoleProvider groupRoleProvider) {
     this.groupRoleProvider = groupRoleProvider;
   }
 
   /**
    * Callback for activation of this component.
    *
    * @param cc
    *          the component context
    */
   @Activate
   public void activate(ComponentContext cc) {
     logger.debug("activate");
 
     // Setup the caches
     cache = CacheBuilder.newBuilder().expireAfterWrite(1, TimeUnit.MINUTES).build(new CacheLoader<>() {
       @Override
       public Object load(String id) {
         String[] key = id.split(DELIMITER);
         logger.trace("Loading user '{}':'{}' from reference database", key[0], key[1]);
         User user = loadUserFromDB(key[0], key[1]);
         return user == null ? nullToken : user;
       }
     });
 
     // Set up persistence
     db = dbSessionFactory.createSession(emf);
   }
 
   @Override
   public String getName() {
     return PROVIDER_NAME;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString() {
     return getClass().getName();
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.security.api.RoleProvider#getRolesForUser(String)
    */
   @Override
   public List<Role> getRolesForUser(String userName) {
     if (roleProvider != null) {
       return roleProvider.getRolesForUser(userName);
     }
 
     ArrayList<Role> roles = new ArrayList<>();
     User user = loadUser(userName);
     if (user != null) {
       roles.addAll(user.getRoles());
     }
     return roles;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.security.api.UserProvider#findUsers(String, int, int)
    */
   @Override
   public Iterator<User> findUsers(String query, int offset, int limit) {
     if (query == null) {
       throw new IllegalArgumentException("Query must be set");
     }
     String orgId = securityService.getOrganization().getId();
     return db.exec(findUserReferencesByQueryQuery(orgId, query, limit, offset)).stream()
         .map(ref -> ref.toUser(PROVIDER_NAME))
         .collect(Collectors.toList())
         .iterator();
   }
 
   @Override
   public Iterator<User> findUsers(Collection<String> userNames) {
     String orgId = securityService.getOrganization().getId();
     return db.exec(findUsersByUserNameQuery(orgId, userNames)).stream()
         .map(ref -> ref.toUser(PROVIDER_NAME))
         .collect(Collectors.toList())
         .iterator();
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.security.api.RoleProvider#findRoles(String, Role.Target, int, int)
    */
   @Override
   public Iterator<Role> findRoles(String query, Role.Target target, int offset, int limit) {
     if (roleProvider == null) {
       return Collections.emptyIterator();
     }
     return roleProvider.findRoles(query, target, offset, limit);
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.security.api.UserProvider#loadUser(java.lang.String)
    */
   @Override
   public User loadUser(String userName) {
     String orgId = securityService.getOrganization().getId();
     return loadUserFromCache(userName, orgId);
   }
 
   /**
    * Loads a user from persistence
    *
    * @param userName
    *          the user name
    * @param organization
    *          the organization id
    * @return the loaded user or <code>null</code> if not found
    */
   private User loadUserFromDB(String userName, String organization) {
     return db.exec(findUserReferenceQuery(userName, organization))
         .map(ref -> ref.toUser(PROVIDER_NAME))
         .orElse(null);
   }
 
   /**
    * Loads a user from cache
    *
    * @param userName
    *          the user name
    * @param organization
    *          the organization id
    * @return the loaded user or <code>null</code> if not found
    */
   private User loadUserFromCache(String userName, String organization) {
     Object user = cache.getUnchecked(userName.concat(DELIMITER).concat(organization));
     if (user == nullToken) {
       return null;
     } else {
       return (User) user;
     }
   }
 
   @Override
   public Iterator<User> getUsers() {
     String orgId = securityService.getOrganization().getId();
     return db.exec(findUserReferences(orgId, 0, 0)).stream()
         .map(ref -> ref.toUser(PROVIDER_NAME))
         .collect(Collectors.toList())
         .iterator();
   }
 
   /**
    * Return the roles
    *
    * @return the roles
    */
   public Iterator<Role> getRoles() {
     if (roleProvider == null) {
       return Collections.emptyIterator();
     }
     return roleProvider.getRoles();
   }
 
   /**
    * {@inheritDoc}
    *
    * @see org.opencastproject.security.api.UserProvider#getOrganization()
    */
   @Override
   public String getOrganization() {
     return ALL_ORGANIZATIONS;
   }
 
   /**
    * {@inheritDoc}
    */
   public void addUserReference(JpaUserReference user, String mechanism) {
     db.execTx(em -> {
       // Create a JPA user with an encoded password.
       Set<JpaRole> roles = UserDirectoryPersistenceUtil.saveRolesQuery(user.getRoles()).apply(em);
       JpaOrganization organization = UserDirectoryPersistenceUtil.saveOrganizationQuery(
           (JpaOrganization) user.getOrganization()).apply(em);
       JpaUserReference userReference = new JpaUserReference(user.getUsername(), user.getName(), user.getEmail(),
           mechanism, user.getLastLogin(), organization, roles);
 
       // Then save the user reference
       Optional<JpaUserReference> foundUserRef = findUserReferenceQuery(user.getUsername(),
           user.getOrganization().getId()).apply(em);
       if (foundUserRef.isPresent()) {
         throw new IllegalStateException("User '" + user.getUsername() + "' already exists");
       }
       em.persist(userReference);
     });
     // There is still a race when this method is executed multiple times. However, the user reference is unlikely to be
     // different.
     cache.put(user.getUsername() + DELIMITER + user.getOrganization().getId(), user.toUser(PROVIDER_NAME));
     updateGroupMembership(user);
   }
 
   /**
    * {@inheritDoc}
    */
   public void updateUserReference(JpaUserReference user) {
     db.execTx(em -> {
       Optional<JpaUserReference> foundUserRef = findUserReferenceQuery(user.getUsername(),
           user.getOrganization().getId()).apply(em);
       if (foundUserRef.isEmpty()) {
         throw new IllegalStateException("User '" + user.getUsername() + "' does not exist");
       }
       foundUserRef.get().setName(user.getName());
       foundUserRef.get().setEmail(user.getEmail());
       foundUserRef.get().setLastLogin(user.getLastLogin());
       foundUserRef.get().setRoles(UserDirectoryPersistenceUtil.saveRolesQuery(user.getRoles()).apply(em));
       em.merge(foundUserRef.get());
     });
     // There is still a race when this method is executed multiple times. However, the user reference is unlikely to be
     // different.
     cache.put(user.getUsername() + DELIMITER + user.getOrganization().getId(), user.toUser(PROVIDER_NAME));
     updateGroupMembership(user);
   }
 
   /**
    * Updates a user's groups based on assigned roles
    *
    * @param user
    *          the user for whom groups should be updated
    */
   private void updateGroupMembership(JpaUserReference user) {
     logger.debug("updateGroupMembership({}, roles={})", user.getUsername(), user.getRoles().size());
     List<String> internalGroupRoles = new ArrayList<>();
 
     for (Role role : user.getRoles()) {
       if (Role.Type.GROUP.equals(role.getType())
           || (Role.Type.INTERNAL.equals(role.getType()) && role.getName().startsWith(Group.ROLE_PREFIX))) {
         internalGroupRoles.add(role.getName());
       }
     }
 
     groupRoleProvider.updateGroupMembershipFromRoles(
         user.getUsername(),
         user.getOrganization().getId(),
         internalGroupRoles
     );
   }
 
   /**
    * Returns the persisted user reference by the user name and organization id
    *
    * @param userName
    *          the user name
    * @param organizationId
    *          the organization id
    * @return the user or <code>null</code> if not found
    */
   public JpaUserReference findUserReference(String userName, String organizationId) {
     return db.exec(findUserReferenceQuery(userName, organizationId))
         .orElse(null);
   }
 
   /**
    * Returns the persisted user reference by the user name and organization id
    *
    * @param userName
    *          the user name
    * @param organizationId
    *          the organization id
    * @return the user or <code>null</code> if not found
    */
   private Function<EntityManager, Optional<JpaUserReference>> findUserReferenceQuery(String userName,
       String organizationId) {
     return namedQuery.findOpt(
         "UserReference.findByUsername",
         JpaUserReference.class,
         Pair.of("u", userName),
         Pair.of("org", organizationId)
     );
   }
 
   /**
    * Returns a list of user references by a search query if set or all user references if search query is
    * <code>null</code>
    *
    * @param orgId
    *          the organization identifier
    * @param query
    *          the query to search
    * @param limit
    *          the limit
    * @param offset
    *          the offset
    * @return the user references list
    */
   private Function<EntityManager, List<JpaUserReference>> findUserReferencesByQueryQuery(String orgId, String query,
       int limit, int offset) {
     return em -> {
       TypedQuery<JpaUserReference> q = em.createNamedQuery("UserReference.findByQuery", JpaUserReference.class)
           .setMaxResults(limit)
           .setFirstResult(offset);
       q.setParameter("query", query.toUpperCase());
       q.setParameter("org", orgId);
       return q.getResultList();
     };
   }
 
   /**
    * Returns user references for specific user names (and an organization)
    * @param orgId The organization to search for
    * @param names The names to search for
    * @return the user references list
    */
   private Function<EntityManager, List<JpaUserReference>> findUsersByUserNameQuery(String orgId,
       Collection<String> names) {
     return em -> {
       if (names.isEmpty()) {
         return Collections.emptyList();
       }
       TypedQuery<JpaUserReference> q = em.createNamedQuery("UserReference.findAllByUserNames", JpaUserReference.class);
       q.setParameter("org", orgId);
       q.setParameter("names", names);
       return q.getResultList();
     };
   }
 
   /**
    * Returns all user references
    *
    * @param orgId
    *          the organization identifier
    * @param limit
    *          the limit
    * @param offset
    *          the offset
    * @return the user references list
    */
   private Function<EntityManager, List<JpaUserReference>> findUserReferences(String orgId, int limit, int offset) {
     return em -> {
       TypedQuery<JpaUserReference> q = em.createNamedQuery("UserReference.findAll", JpaUserReference.class)
           .setMaxResults(limit)
           .setFirstResult(offset);
       q.setParameter("org", orgId);
       return q.getResultList();
     };
   }
 
   @Override
   public long countUsers() {
     String orgId = securityService.getOrganization().getId();
     return db.exec(namedQuery.find(
         "UserReference.countAll",
         Number.class,
         Pair.of("org", orgId)
     )).longValue();
   }
 
   @Override
   public void invalidate(String userName) {
     String orgId = securityService.getOrganization().getId();
     cache.invalidate(userName.concat(DELIMITER).concat(orgId));
   }
 
   /**
    * Delete the given user
    *
    * @param username
    *          the name of the user to delete
    * @param orgId
    *          the organization id
    * @throws NotFoundException
    *          if the requested user is not exist
    * @throws org.opencastproject.security.api.UnauthorizedException
    *          if you havn't permissions to delete an admin user (only admins may do that)
    * @throws Exception
    */
   public void deleteUser(String username, String orgId) throws NotFoundException, UnauthorizedException, Exception {
     User user = loadUser(username);
     if (user != null && !UserDirectoryUtils.isCurrentUserAuthorizedHandleRoles(securityService, user.getRoles())) {
       throw new UnauthorizedException("The user is not allowed to delete an admin user");
     }
 
     // Remove the user's group membership
     groupRoleProvider.removeMemberFromAllGroups(username, orgId);
 
     // Remove the user
     db.execTxChecked(deleteUserQuery(username, orgId));
 
     cache.invalidate(username + DELIMITER + orgId);
   }
 
   private ThrowingConsumer<EntityManager, NotFoundException> deleteUserQuery(String username, String orgId) {
     return em -> {
       Optional<JpaUserReference> user = findUserReferenceQuery(username, orgId).apply(em);
       if (user.isEmpty()) {
         throw new NotFoundException("User with name " + username + " does not exist");
       }
       em.remove(em.merge(user.get()));
     };
   }
 
   public void setRoleProvider(RoleProvider roleProvider) {
     this.roleProvider = (AAIRoleProvider) roleProvider;
   }
 }