/*
    * Copyright 2019 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.netty5.handler.ssl.util;
  
  import io.netty5.util.concurrent.FastThreadLocal;
  import io.netty5.util.internal.StringUtil;
  
  import javax.net.ssl.KeyManager;
  import javax.net.ssl.KeyManagerFactory;
  import javax.net.ssl.KeyManagerFactorySpi;
  import javax.net.ssl.ManagerFactoryParameters;
  import javax.net.ssl.X509ExtendedKeyManager;
  import javax.net.ssl.X509KeyManager;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.KeyStore;
  import java.security.KeyStoreException;
  import java.security.Provider;
  import java.util.Objects;
  
  /**
   * Helps to implement a custom {@link KeyManagerFactory}.
   */
  public abstract class SimpleKeyManagerFactory extends KeyManagerFactory {
  
      private static final Provider PROVIDER = new Provider("", "0.0", "") {
          private static final long serialVersionUID = -2680540247105807895L;
      };
  
      /**
       * {@link SimpleKeyManagerFactorySpi} must have a reference to {@link SimpleKeyManagerFactory}
       * to delegate its callbacks back to {@link SimpleKeyManagerFactory}.  However, it is impossible to do so,
       * because {@link KeyManagerFactory} requires {@link KeyManagerFactorySpi} 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 FastThreadLocal }.
       */
      private static final FastThreadLocal<SimpleKeyManagerFactorySpi> CURRENT_SPI =
              new FastThreadLocal<>() {
                  @Override
                  protected SimpleKeyManagerFactorySpi initialValue() {
                      return new SimpleKeyManagerFactorySpi();
                  }
              };
  
      /**
       * Creates a new instance.
       */
      protected SimpleKeyManagerFactory() {
          this(StringUtil.EMPTY_STRING);
      }
  
      /**
       * Creates a new instance.
       *
       * @param name the name of this {@link KeyManagerFactory}
       */
      protected SimpleKeyManagerFactory(String name) {
          super(CURRENT_SPI.get(), PROVIDER, Objects.requireNonNull(name, "name"));
          CURRENT_SPI.get().init(this);
          CURRENT_SPI.remove();
      }
  
      /**
       * Initializes this factory with a source of certificate authorities and related key material.
       *
       * @see KeyManagerFactorySpi#engineInit(KeyStore, char[])
       */
      protected abstract void engineInit(KeyStore keyStore, char[] var2) throws Exception;
  
      /**
       * Initializes this factory with a source of provider-specific key material.
       *
       * @see KeyManagerFactorySpi#engineInit(ManagerFactoryParameters)
       */
      protected abstract void engineInit(ManagerFactoryParameters managerFactoryParameters) throws Exception;
  
      /**
       * Returns one key manager for each type of key material.
       *
       * @see KeyManagerFactorySpi#engineGetKeyManagers()
       */
      protected abstract KeyManager[] engineGetKeyManagers();
  
      private static final class SimpleKeyManagerFactorySpi extends KeyManagerFactorySpi {
  
          private SimpleKeyManagerFactory parent;
         private volatile KeyManager[] keyManagers;
 
         void init(SimpleKeyManagerFactory parent) {
             this.parent = parent;
         }
 
         @Override
         protected void engineInit(KeyStore keyStore, char[] pwd) throws KeyStoreException {
             try {
                 parent.engineInit(keyStore, pwd);
             } 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 KeyManager[] engineGetKeyManagers() {
             KeyManager[] keyManagers = this.keyManagers;
             if (keyManagers == null) {
                 keyManagers = parent.engineGetKeyManagers();
                 wrapIfNeeded(keyManagers);
                 this.keyManagers = keyManagers;
             }
             return keyManagers.clone();
         }
 
         private static void wrapIfNeeded(KeyManager[] keyManagers) {
             for (int i = 0; i < keyManagers.length; i++) {
                 final KeyManager tm = keyManagers[i];
                 if (tm instanceof X509KeyManager && !(tm instanceof X509ExtendedKeyManager)) {
                     keyManagers[i] = new X509KeyManagerWrapper((X509KeyManager) tm);
                 }
             }
         }
     }
 }