/**
 * Licensed 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.aurora.scheduler.http.api.security;

import javax.inject.Singleton;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.inject.AbstractModule;

import org.apache.aurora.common.args.Arg;
import org.apache.aurora.common.args.CmdLine;
import org.apache.shiro.config.Ini;
import org.apache.shiro.realm.text.IniRealm;

/**
 * Provides an implementation of a Shiro {@link IniRealm} that uses a flat shiro.ini file for
 * authentication and authorization. Should be used in conjunction with the
 * {@link org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter} or other filter that
 * produces {@link org.apache.shiro.authc.UsernamePasswordToken}s.
 *
 * <p>
 * Another filter may still be used for authentication, in which case the ini file can still be
 * used to provide authorization configuration and the passwords will be ignored.
 */
public class IniShiroRealmModule extends AbstractModule {
  @CmdLine(name = "shiro_ini_path",
      help = "Path to shiro.ini for authentication and authorization configuration.")
  private static final Arg<Ini> SHIRO_INI_PATH = Arg.create(null);

  private final Optional<Ini> ini;

  public IniShiroRealmModule() {
    this(Optional.fromNullable(SHIRO_INI_PATH.get()));
  }

  @VisibleForTesting
  IniShiroRealmModule(Ini ini) {
    this(Optional.of(ini));
  }

  private IniShiroRealmModule(Optional<Ini> ini) {
    this.ini = ini;
  }

  @Override
  protected void configure() {
    if (ini.isPresent()) {
      bind(Ini.class).toInstance(ini.get());
    } else {
      addError("shiro.ini is required.");
    }

    try {
      ShiroUtils.addRealmBinding(binder()).toConstructor(IniRealm.class.getConstructor(Ini.class));
    } catch (NoSuchMethodException e) {
      addError(e);
    }
    bind(IniRealm.class).in(Singleton.class);
  }
}