/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.handler.ssl.util;
  
  import io.netty.util.concurrent.FastThreadLocal;
  import io.netty.util.internal.ObjectUtil;
  
  import javax.net.ssl.ManagerFactoryParameters;
  import javax.net.ssl.TrustManager;
  import javax.net.ssl.TrustManagerFactory;
  import javax.net.ssl.TrustManagerFactorySpi;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.KeyStore;
  import java.security.KeyStoreException;
  import java.security.Provider;
  
  /**
   * Helps to implement a custom {@link TrustManagerFactory}.
   */
  public abstract class SimpleTrustManagerFactory extends TrustManagerFactory {
  
      private static final Provider PROVIDER = new Provider("", 0.0, "") {
          private static final long serialVersionUID = -2680540247105807895L;
      };
  
      /**
       * {@link SimpleTrustManagerFactorySpi} must have a reference to {@link SimpleTrustManagerFactory}
       * to delegate its callbacks back to {@link SimpleTrustManagerFactory}.  However, it is impossible to do so,
       * because {@link TrustManagerFactory} requires {@link TrustManagerFactorySpi} at construction time and
       * does not provide a way to access it later.
       *
       * To work around this issue, we use an ugly hack which uses a {@link ThreadLocal}.
       */
      private static final FastThreadLocal<SimpleTrustManagerFactorySpi> CURRENT_SPI =
              new FastThreadLocal<SimpleTrustManagerFactorySpi>() {
                  @Override
                  protected SimpleTrustManagerFactorySpi initialValue() {
                      return new SimpleTrustManagerFactorySpi();
                  }
              };
  
      /**
       * Creates a new instance.
       */
      protected SimpleTrustManagerFactory() {
          this("");
      }
  
      /**
       * Creates a new instance.
       *
       * @param name the name of this {@link TrustManagerFactory}
       */
      protected SimpleTrustManagerFactory(String name) {
          super(CURRENT_SPI.get(), PROVIDER, name);
          CURRENT_SPI.get().init(this);
          CURRENT_SPI.remove();
  
          ObjectUtil.checkNotNull(name, "name");
      }
  
      /**
       * Initializes this factory with a source of certificate authorities and related trust material.
       *
       * @see TrustManagerFactorySpi#engineInit(KeyStore)
       */
      protected abstract void engineInit(KeyStore keyStore) throws Exception;
  
      /**
       * Initializes this factory with a source of provider-specific key material.
       *
       * @see TrustManagerFactorySpi#engineInit(ManagerFactoryParameters)
       */
      protected abstract void engineInit(ManagerFactoryParameters managerFactoryParameters) throws Exception;
  
      /**
       * Returns one trust manager for each type of trust material.
       *
       * @see TrustManagerFactorySpi#engineGetTrustManagers()
       */
      protected abstract TrustManager[] engineGetTrustManagers();
  
      static final class SimpleTrustManagerFactorySpi extends TrustManagerFactorySpi {
  
          private SimpleTrustManagerFactory parent;
         private volatile TrustManager[] trustManagers;
 
         void init(SimpleTrustManagerFactory parent) {
             this.parent = parent;
         }
 
         @Override
         protected void engineInit(KeyStore keyStore) throws KeyStoreException {
             try {
                 parent.engineInit(keyStore);
             } catch (KeyStoreException e) {
                 throw e;
             } catch (Exception e) {
                 throw new KeyStoreException(e);
             }
         }
 
         @Override
         protected void engineInit(
                 ManagerFactoryParameters managerFactoryParameters) throws InvalidAlgorithmParameterException {
             try {
                 parent.engineInit(managerFactoryParameters);
             } catch (InvalidAlgorithmParameterException e) {
                 throw e;
             } catch (Exception e) {
                 throw new InvalidAlgorithmParameterException(e);
             }
         }
 
         @Override
         protected TrustManager[] engineGetTrustManagers() {
             TrustManager[] trustManagers = this.trustManagers;
             if (trustManagers == null) {
                 trustManagers = parent.engineGetTrustManagers();
                 this.trustManagers = trustManagers;
             }
             return trustManagers.clone();
         }
     }
 }