/*
    * Copyright 2025 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.internal.ThrowableUtil;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.security.Provider;
  import java.security.Security;
  import javax.net.ssl.SSLEngine;
  
  /**
   * Contains methods that can be used to detect if BouncyCastle is available.
   */
  public final class BouncyCastleUtil {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(BouncyCastleUtil.class);
  
      private static final String BC_PROVIDER_NAME = "BC";
      private static final String BC_PROVIDER = "org.bouncycastle.jce.provider.BouncyCastleProvider";
      private static final String BC_FIPS_PROVIDER_NAME = "BCFIPS";
      private static final String BC_FIPS_PROVIDER = "org.bouncycastle.jcajce.provider.BouncyCastleFipsProvider";
      private static final String BC_JSSE_PROVIDER_NAME = "BCJSSE";
      private static final String BC_JSSE_PROVIDER = "org.bouncycastle.jsse.provider.BouncyCastleJsseProvider";
      private static final String BC_PEMPARSER = "org.bouncycastle.openssl.PEMParser";
      private static final String BC_JSSE_SSLENGINE = "org.bouncycastle.jsse.BCSSLEngine";
      private static final String BC_JSSE_ALPN_SELECTOR = "org.bouncycastle.jsse.BCApplicationProtocolSelector";
  
      private static volatile Throwable unavailabilityCauseBcProv;
      private static volatile Throwable unavailabilityCauseBcPkix;
      private static volatile Throwable unavailabilityCauseBcTls;
      private static volatile Provider bcProviderJce;
      private static volatile Provider bcProviderJsse;
      private static volatile Class<? extends SSLEngine> bcSSLEngineClass;
      private static volatile boolean attemptedLoading;
  
      /**
       * Indicate whether the BouncyCastle Java Crypto Extensions provider is available.
       */
      public static boolean isBcProvAvailable() {
          ensureLoaded();
          return unavailabilityCauseBcProv == null;
      }
  
      /**
       * Indicate whether the BouncyCastle Public-Key Infrastructure utilities are available.
       */
      public static boolean isBcPkixAvailable() {
          ensureLoaded();
          return unavailabilityCauseBcPkix == null;
      }
  
      /**
       * Indicate whether the BouncyCastle Java Secure Socket Extensions provider is available.
       */
      public static boolean isBcTlsAvailable() {
          ensureLoaded();
          return unavailabilityCauseBcTls == null;
      }
  
      /**
       * @return the cause if unavailable. {@code null} if available.
       */
      public static Throwable unavailabilityCauseBcProv() {
          ensureLoaded();
          return unavailabilityCauseBcProv;
      }
  
      /**
       * @return the cause if unavailable. {@code null} if available.
       */
      public static Throwable unavailabilityCauseBcPkix() {
          ensureLoaded();
          return unavailabilityCauseBcPkix;
      }
  
      /**
       * @return the cause if unavailable. {@code null} if available.
       */
      public static Throwable unavailabilityCauseBcTls() {
          ensureLoaded();
          return unavailabilityCauseBcTls;
      }
  
     /**
      * Indicates whether the given SSLEngine is implemented by BouncyCastle.
      */
     public static boolean isBcJsseInUse(SSLEngine engine) {
         ensureLoaded();
         Class<? extends SSLEngine> bcEngineClass = bcSSLEngineClass;
         return bcEngineClass != null && bcEngineClass.isInstance(engine);
     }
 
     /**
      * Get the BouncyCastle Java Crypto Extensions provider, or throw an exception if it is unavailable.
      */
     public static Provider getBcProviderJce() {
         ensureLoaded();
         Throwable cause = unavailabilityCauseBcProv;
         Provider provider = bcProviderJce;
         if (cause != null || provider == null) {
             throw new IllegalStateException(cause);
         }
         return provider;
     }
 
     /**
      * Get the BouncyCastle Java Secure Socket Extensions provider, or throw an exception if it is unavailable.
      */
     public static Provider getBcProviderJsse() {
         ensureLoaded();
         Throwable cause = unavailabilityCauseBcTls;
         Provider provider = bcProviderJsse;
         if (cause != null || provider == null) {
             throw new IllegalStateException(cause);
         }
         return provider;
     }
 
     /**
      * Returns the public {@link SSLEngine} sub-class that is used by bouncy-castle or {@code null} if
      * it can't be loaded.
      *
      * @return engine class.
      */
     public static Class<? extends SSLEngine> getBcSSLEngineClass() {
         ensureLoaded();
         return bcSSLEngineClass;
     }
 
     /**
      * Reset the loaded providers. Useful for testing, to redo the loading under different conditions.
      */
     static void reset() {
         attemptedLoading = false;
         unavailabilityCauseBcProv = null;
         unavailabilityCauseBcPkix = null;
         unavailabilityCauseBcTls = null;
         bcProviderJce = null;
         bcProviderJsse = null;
         bcSSLEngineClass = null;
     }
 
     private static void ensureLoaded() {
         if (!attemptedLoading) {
             tryLoading();
         }
     }
 
     @SuppressWarnings("unchecked")
     private static void tryLoading() {
         AccessController.doPrivileged((PrivilegedAction<?>) () -> {
             try {
                 // Check for bcprov-jdk18on or bc-fips:
                 Provider provider = Security.getProvider(BC_PROVIDER_NAME);
                 if (provider == null) {
                     provider = Security.getProvider(BC_FIPS_PROVIDER_NAME);
                 }
                 if (provider == null) {
                     ClassLoader classLoader = BouncyCastleUtil.class.getClassLoader();
                     Class<Provider> bcProviderClass;
                     try {
                         bcProviderClass = (Class<Provider>) Class.forName(BC_PROVIDER, true, classLoader);
                     } catch (ClassNotFoundException e) {
                         try {
                             bcProviderClass = (Class<Provider>) Class.forName(BC_FIPS_PROVIDER, true, classLoader);
                         } catch (ClassNotFoundException ex) {
                             ThrowableUtil.addSuppressed(e, ex);
                             throw e;
                         }
                     }
                     provider = bcProviderClass.getConstructor().newInstance();
                 }
                 bcProviderJce = provider;
                 logger.debug("Bouncy Castle provider available");
             } catch (Throwable e) {
                 logger.debug("Cannot load Bouncy Castle provider", e);
                 unavailabilityCauseBcProv = e;
             }
 
             try {
                 // Check for bcpkix-jdk18on:
                 ClassLoader classLoader = BouncyCastleUtil.class.getClassLoader();
                 Provider provider = bcProviderJce;
                 if (provider != null) {
                     // Use provider class loader in case it was loaded by the system loader.
                     classLoader = provider.getClass().getClassLoader();
                 }
                 Class.forName(BC_PEMPARSER, true, classLoader);
                 logger.debug("Bouncy Castle PKIX available");
             } catch (Throwable e) {
                 logger.debug("Cannot load Bouncy Castle PKIX", e);
                 unavailabilityCauseBcPkix = e;
             }
 
             try {
                 // Check for bctls-jdk18on:
                 ClassLoader classLoader = BouncyCastleUtil.class.getClassLoader();
                 Provider provider = Security.getProvider(BC_JSSE_PROVIDER_NAME);
                 if (provider != null) {
                     // Use provider class loader in case it was loaded by the system loader.
                     classLoader = provider.getClass().getClassLoader();
                 } else {
                     Class<?> providerClass = Class.forName(BC_JSSE_PROVIDER, true, classLoader);
                     provider = (Provider) providerClass.getConstructor().newInstance();
                 }
                 bcSSLEngineClass = (Class<? extends SSLEngine>) Class.forName(BC_JSSE_SSLENGINE, true, classLoader);
                 Class.forName(BC_JSSE_ALPN_SELECTOR, true, classLoader);
                 bcProviderJsse = provider;
                 logger.debug("Bouncy Castle JSSE available");
             } catch (Throwable e) {
                 logger.debug("Cannot load Bouncy Castle TLS", e);
                 unavailabilityCauseBcTls = e;
             }
             attemptedLoading = true;
             return null;
         });
     }
 
     private BouncyCastleUtil() {
     }
 }