/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache 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://www.apache.org/licenses/LICENSE-2.0
   *
   * 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.apache.shiro.realm;
  
  import org.apache.shiro.authc.AuthenticationException;
  import org.apache.shiro.authc.AuthenticationInfo;
  import org.apache.shiro.authc.AuthenticationToken;
  import org.apache.shiro.authc.ExpiredCredentialsException;
  import org.apache.shiro.authc.LockedAccountException;
  import org.apache.shiro.authc.SimpleAccount;
  import org.apache.shiro.authc.UsernamePasswordToken;
  import org.apache.shiro.authz.AuthorizationInfo;
  import org.apache.shiro.authz.SimpleRole;
  import org.apache.shiro.subject.PrincipalCollection;
  import org.apache.shiro.util.CollectionUtils;
  
  import java.util.HashSet;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.locks.ReadWriteLock;
  import java.util.concurrent.locks.ReentrantReadWriteLock;
  
  /**
   * A simple implementation of the {@link Realm Realm} interface that
   * uses a set of configured user accounts and roles to support authentication and authorization.  Each account entry
   * specifies the username, password, and roles for a user.  Roles can also be mapped
   * to permissions and associated with users.
   * <p/>
   * User accounts and roles are stored in two {@code Map}s in memory, so it is expected that the total number of either
   * is not sufficiently large.
   *
   * @since 0.1
   */
  public class SimpleAccountRealm extends AuthorizingRealm {
  
      //TODO - complete JavaDoc
      protected final Map<String, SimpleAccount> users; //username-to-SimpleAccount
      protected final Map<String, SimpleRole> roles; //roleName-to-SimpleRole
      protected final ReadWriteLock USERS_LOCK;
      protected final ReadWriteLock ROLES_LOCK;
  
      public SimpleAccountRealm() {
          this.users = new LinkedHashMap<String, SimpleAccount>();
          this.roles = new LinkedHashMap<String, SimpleRole>();
          USERS_LOCK = new ReentrantReadWriteLock();
          ROLES_LOCK = new ReentrantReadWriteLock();
          //SimpleAccountRealms are memory-only realms - no need for an additional cache mechanism since we're
          //already as memory-efficient as we can be:
          setCachingEnabled(false);
      }
  
      public SimpleAccountRealm(String name) {
          this();
          setName(name);
      }
  
      protected SimpleAccount getUser(String username) {
          USERS_LOCK.readLock().lock();
          try {
              return this.users.get(username);
          } finally {
              USERS_LOCK.readLock().unlock();
          }
      }
  
      public boolean accountExists(String username) {
          return getUser(username) != null;
      }
  
      public void addAccount(String username, String password) {
          addAccount(username, password, (String[]) null);
      }
  
      public void addAccount(String username, String password, String... roles) {
          Set<String> roleNames = CollectionUtils.asSet(roles);
          SimpleAccount account = new SimpleAccount(username, password, getName(), roleNames, null);
          add(account);
      }
  
      protected String getUsername(SimpleAccount account) {
          return getUsername(account.getPrincipals());
      }
 
     protected String getUsername(PrincipalCollection principals) {
         return getAvailablePrincipal(principals).toString();
     }
 
     protected void add(SimpleAccount account) {
         String username = getUsername(account);
         USERS_LOCK.writeLock().lock();
         try {
             this.users.put(username, account);
         } finally {
             USERS_LOCK.writeLock().unlock();
         }
     }
 
     protected SimpleRole getRole(String rolename) {
         ROLES_LOCK.readLock().lock();
         try {
             return roles.get(rolename);
         } finally {
             ROLES_LOCK.readLock().unlock();
         }
     }
 
     public boolean roleExists(String name) {
         return getRole(name) != null;
     }
 
     public void addRole(String name) {
         add(new SimpleRole(name));
     }
 
     protected void add(SimpleRole role) {
         ROLES_LOCK.writeLock().lock();
         try {
             roles.put(role.getName(), role);
         } finally {
             ROLES_LOCK.writeLock().unlock();
         }
     }
 
     protected static Set<String> toSet(String delimited, String delimiter) {
         if (delimited == null || delimited.trim().equals("")) {
             return null;
         }
 
         Set<String> values = new HashSet<String>();
         String[] rolenamesArray = delimited.split(delimiter);
         for (String s : rolenamesArray) {
             String trimmed = s.trim();
             if (trimmed.length() > 0) {
                 values.add(trimmed);
             }
         }
 
         return values;
     }
 
     protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {
         UsernamePasswordToken upToken = (UsernamePasswordToken) token;
         SimpleAccount account = getUser(upToken.getUsername());
 
         if (account != null) {
 
             if (account.isLocked()) {
                 throw new LockedAccountException("Account [" + account + "] is locked.");
             }
             if (account.isCredentialsExpired()) {
                 String msg = "The credentials for account [" + account + "] are expired";
                 throw new ExpiredCredentialsException(msg);
             }
 
         }
 
         return account;
     }
 
     protected AuthorizationInfo doGetAuthorizationInfo(PrincipalCollection principals) {
         String username = getUsername(principals);
         USERS_LOCK.readLock().lock();
         try {
             return this.users.get(username);
         } finally {
             USERS_LOCK.readLock().unlock();
         }
     }
 }