/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.ssl;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.Socket;
  import java.net.URL;
  import java.nio.file.Files;
  import java.nio.file.OpenOption;
  import java.nio.file.Path;
  import java.security.KeyManagementException;
  import java.security.KeyStore;
  import java.security.KeyStoreException;
  import java.security.NoSuchAlgorithmException;
  import java.security.NoSuchProviderException;
  import java.security.Principal;
  import java.security.PrivateKey;
  import java.security.Provider;
  import java.security.SecureRandom;
  import java.security.Security;
  import java.security.UnrecoverableKeyException;
  import java.security.cert.CertificateException;
  import java.security.cert.X509Certificate;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.LinkedHashSet;
  import java.util.Map;
  import java.util.Set;
  
  import javax.net.ssl.KeyManager;
  import javax.net.ssl.KeyManagerFactory;
  import javax.net.ssl.SSLContext;
  import javax.net.ssl.SSLEngine;
  import javax.net.ssl.SSLSocket;
  import javax.net.ssl.TrustManager;
  import javax.net.ssl.TrustManagerFactory;
  import javax.net.ssl.X509ExtendedKeyManager;
  import javax.net.ssl.X509TrustManager;
  
  import org.apache.hc.core5.util.Args;
  
  /**
   * Builder for {@link javax.net.ssl.SSLContext} instances.
   * <p>
   * Please note: the default Oracle JSSE implementation of {@link SSLContext#init(KeyManager[], TrustManager[], SecureRandom)}
   * accepts multiple key and trust managers, however only only first matching type is ever used.
   * See for example:
   * <a href="http://docs.oracle.com/javase/7/docs/api/javax/net/ssl/SSLContext.html#init%28javax.net.ssl.KeyManager[],%20javax.net.ssl.TrustManager[],%20java.security.SecureRandom%29">
   * SSLContext.html#init
   * </a>
   *
   * @since 4.4
   */
  public class SSLContextBuilder {
  
      static final String TLS   = "TLS";
  
      private String protocol;
      private final Set<KeyManager> keyManagers;
      private String keyManagerFactoryAlgorithm = KeyManagerFactory.getDefaultAlgorithm();
      private String keyStoreType = KeyStore.getDefaultType();
      private final Set<TrustManager> trustManagers;
      private String trustManagerFactoryAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
      private SecureRandom secureRandom;
      private Provider provider;
      private Provider tsProvider;
      private Provider ksProvider;
  
      /**
       * An empty immutable {@code KeyManager} array.
       */
     private static final KeyManager[] EMPTY_KEY_MANAGER_ARRAY = {};
 
     /**
      * An empty immutable {@code TrustManager} array.
      */
     private static final TrustManager[] EMPTY_TRUST_MANAGER_ARRAY = {};
 
 
 
     public static SSLContextBuilder create() {
         return new SSLContextBuilder();
     }
 
     public SSLContextBuilder() {
         this.keyManagers = new LinkedHashSet<>();
         this.trustManagers = new LinkedHashSet<>();
     }
 
     /**
      * Sets the SSLContext algorithm name.
      *
      * @param protocol
      *            the SSLContext algorithm name of the requested protocol. See
      *            the SSLContext section in the <a href=
      *            "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#SSLContext">Java
      *            Cryptography Architecture Standard Algorithm Name
      *            Documentation</a> for more information.
      * @return this builder
      * @see <a href=
      *      "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#SSLContext">Java
      *      Cryptography Architecture Standard Algorithm Name Documentation</a>
      */
     public SSLContextBuilder setProtocol(final String protocol) {
         this.protocol = protocol;
         return this;
     }
 
     public SSLContextBuilder setProvider(final Provider provider) {
         this.provider = provider;
         return this;
     }
 
     public SSLContextBuilder setProvider(final String name) {
         this.provider = Security.getProvider(name);
         return this;
     }
 
     /**
      * Sets the JCA provider to use for creating trust stores.
      * @param provider provider to use for creating trust stores.
      * @return this builder
      * @since 5.2
      */
     public SSLContextBuilder setTrustStoreProvider(final Provider provider) {
         this.tsProvider = provider;
         return this;
     }
 
     /**
      * Sets the JCA provider name to use for creating trust stores.
      * @param name Name of the provider to use for creating trust stores, the provider must be registered with the JCA.
      * @return this builder
      * @since 5.2
      */
     public SSLContextBuilder setTrustStoreProvider(final String name) throws NoSuchProviderException {
         this.tsProvider = requireNonNullProvider(name);
         return this;
     }
 
     /**
      * Sets the JCA provider to use for creating key stores.
      * @param provider provider to use for creating key stores.
      * @return this builder
      * @since 5.2
      */
     public SSLContextBuilder setKeyStoreProvider(final Provider provider) {
         this.ksProvider = provider;
         return this;
     }
 
     /**
      * Sets the JCA provider name to use for creating key stores.
      * @param name Name of the provider to use for creating key stores, the provider must be registered with the JCA.
      * @return this builder
      * @since 5.2
      */
     public SSLContextBuilder setKeyStoreProvider(final String name) throws NoSuchProviderException {
         this.ksProvider = requireNonNullProvider(name);
         return this;
     }
 
     /**
      * Sets the key store type.
      *
      * @param keyStoreType
      *            the SSLkey store type. See
      *            the KeyStore section in the <a href=
      *            "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyStore">Java
      *            Cryptography Architecture Standard Algorithm Name
      *            Documentation</a> for more information.
      * @return this builder
      * @see <a href=
      *      "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyStore">Java
      *      Cryptography Architecture Standard Algorithm Name Documentation</a>
      * @since 4.4.7
      */
     public SSLContextBuilder setKeyStoreType(final String keyStoreType) {
         this.keyStoreType = keyStoreType;
         return this;
     }
 
     /**
      * Sets the key manager factory algorithm name.
      *
      * @param keyManagerFactoryAlgorithm
      *            the key manager factory algorithm name of the requested protocol. See
      *            the KeyManagerFactory section in the <a href=
      *            "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyManagerFactory">Java
      *            Cryptography Architecture Standard Algorithm Name
      *            Documentation</a> for more information.
      * @return this builder
      * @see <a href=
      *      "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#KeyManagerFactory">Java
      *      Cryptography Architecture Standard Algorithm Name Documentation</a>
      * @since 4.4.7
      */
     public SSLContextBuilder setKeyManagerFactoryAlgorithm(final String keyManagerFactoryAlgorithm) {
         this.keyManagerFactoryAlgorithm = keyManagerFactoryAlgorithm;
         return this;
     }
 
     /**
      * Sets the trust manager factory algorithm name.
      *
      * @param trustManagerFactoryAlgorithm
      *            the trust manager algorithm name of the requested protocol. See
      *            the TrustManagerFactory section in the <a href=
      *            "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#TrustManagerFactory">Java
      *            Cryptography Architecture Standard Algorithm Name
      *            Documentation</a> for more information.
      * @return this builder
      * @see <a href=
      *      "https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#TrustManagerFactory">Java
      *      Cryptography Architecture Standard Algorithm Name Documentation</a>
      * @since 4.4.7
      */
     public SSLContextBuilder setTrustManagerFactoryAlgorithm(final String trustManagerFactoryAlgorithm) {
         this.trustManagerFactoryAlgorithm = trustManagerFactoryAlgorithm;
         return this;
     }
 
     public SSLContextBuilder setSecureRandom(final SecureRandom secureRandom) {
         this.secureRandom = secureRandom;
         return this;
     }
 
     /**
      * @param trustStrategy
      *            custom trust strategy to use; can be {@code null} in which case
      *            only the default trust managers will be used
      */
     public SSLContextBuilder loadTrustMaterial(
             final KeyStore trustStore,
             final TrustStrategy trustStrategy) throws NoSuchAlgorithmException, KeyStoreException {
 
         final String alg = trustManagerFactoryAlgorithm == null ?
                 TrustManagerFactory.getDefaultAlgorithm() : trustManagerFactoryAlgorithm;
 
         final TrustManagerFactory tmFactory = tsProvider == null ?
                 TrustManagerFactory.getInstance(alg) : TrustManagerFactory.getInstance(alg, tsProvider);
 
         tmFactory.init(trustStore);
         final TrustManager[] tms = tmFactory.getTrustManagers();
         if (tms != null) {
             if (trustStrategy != null) {
                 for (int i = 0; i < tms.length; i++) {
                     final TrustManager tm = tms[i];
                     if (tm instanceof X509TrustManager) {
                         tms[i] = new TrustManagerDelegate((X509TrustManager) tm, trustStrategy);
                     }
                 }
             }
             Collections.addAll(this.trustManagers, tms);
         }
         return this;
     }
 
     /**
      * @since 5.2
      */
     public SSLContextBuilder loadTrustMaterial(
             final Path file) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         return loadTrustMaterial(file, null);
     }
 
     /**
      * @since 5.2
      */
     public SSLContextBuilder loadTrustMaterial(
             final Path file,
             final char[] storePassword) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         return loadTrustMaterial(file, storePassword, null);
     }
 
     /**
      * @since 5.2
      */
     public SSLContextBuilder loadTrustMaterial(
             final Path file,
             final char[] storePassword,
             final TrustStrategy trustStrategy,
             final OpenOption... openOptions) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         Args.notNull(file, "Truststore file");
         return loadTrustMaterial(loadKeyStore(file, storePassword, openOptions), trustStrategy);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final TrustStrategy trustStrategy) throws NoSuchAlgorithmException, KeyStoreException {
         return loadTrustMaterial(null, trustStrategy);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final File file,
             final char[] storePassword,
             final TrustStrategy trustStrategy) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         Args.notNull(file, "Truststore file");
         return loadTrustMaterial(file.toPath(), storePassword, trustStrategy);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final File file,
             final char[] storePassword) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         return loadTrustMaterial(file, storePassword, null);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final File file) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         return loadTrustMaterial(file, null);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final URL url,
             final char[] storePassword,
             final TrustStrategy trustStrategy) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         Args.notNull(url, "Truststore URL");
         return loadTrustMaterial(loadKeyStore(url, storePassword), trustStrategy);
     }
 
     public SSLContextBuilder loadTrustMaterial(
             final URL url,
             final char[] storePassword) throws NoSuchAlgorithmException, KeyStoreException, CertificateException, IOException {
         return loadTrustMaterial(url, storePassword, null);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final KeyStore keyStore,
             final char[] keyPassword,
             final PrivateKeyStrategy aliasStrategy)
             throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException {
 
         final String alg = keyManagerFactoryAlgorithm == null ?
                 KeyManagerFactory.getDefaultAlgorithm() : keyManagerFactoryAlgorithm;
 
         final KeyManagerFactory kmFactory = ksProvider == null ?
                 KeyManagerFactory.getInstance(alg) : KeyManagerFactory.getInstance(alg, ksProvider);
 
         kmFactory.init(keyStore, keyPassword);
         final KeyManager[] kms = kmFactory.getKeyManagers();
         if (kms != null) {
             if (aliasStrategy != null) {
                 for (int i = 0; i < kms.length; i++) {
                     final KeyManager km = kms[i];
                     if (km instanceof X509ExtendedKeyManager) {
                         kms[i] = new KeyManagerDelegate((X509ExtendedKeyManager) km, aliasStrategy);
                     }
                 }
             }
             Collections.addAll(keyManagers, kms);
         }
         return this;
     }
 
     /**
      * @since 5.2
      */
     public SSLContextBuilder loadKeyMaterial(
             final Path file,
             final char[] storePassword,
             final char[] keyPassword,
             final OpenOption... openOptions) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         return loadKeyMaterial(file, storePassword, keyPassword, null, openOptions);
     }
 
     /**
      * @since 5.2
      */
     public SSLContextBuilder loadKeyMaterial(
             final Path file,
             final char[] storePassword,
             final char[] keyPassword,
             final PrivateKeyStrategy aliasStrategy,
             final OpenOption... openOptions) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         Args.notNull(file, "Keystore file");
         return loadKeyMaterial(loadKeyStore(file, storePassword, openOptions), keyPassword, aliasStrategy);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final KeyStore keyStore,
             final char[] keyPassword) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException {
         return loadKeyMaterial(keyStore, keyPassword, null);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final File file,
             final char[] storePassword,
             final char[] keyPassword,
             final PrivateKeyStrategy aliasStrategy) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         Args.notNull(file, "Keystore file");
         return loadKeyMaterial(file.toPath(), storePassword, keyPassword, aliasStrategy);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final File file,
             final char[] storePassword,
             final char[] keyPassword) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         return loadKeyMaterial(file, storePassword, keyPassword, null);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final URL url,
             final char[] storePassword,
             final char[] keyPassword,
             final PrivateKeyStrategy aliasStrategy) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         Args.notNull(url, "Keystore URL");
         return loadKeyMaterial(loadKeyStore(url, storePassword), keyPassword, aliasStrategy);
     }
 
     public SSLContextBuilder loadKeyMaterial(
             final URL url,
             final char[] storePassword,
             final char[] keyPassword) throws NoSuchAlgorithmException, KeyStoreException, UnrecoverableKeyException, CertificateException, IOException {
         return loadKeyMaterial(url, storePassword, keyPassword, null);
     }
 
     protected void initSSLContext(
             final SSLContext sslContext,
             final Collection<KeyManager> keyManagers,
             final Collection<TrustManager> trustManagers,
             final SecureRandom secureRandom) throws KeyManagementException {
         sslContext.init(
                 !keyManagers.isEmpty() ? keyManagers.toArray(EMPTY_KEY_MANAGER_ARRAY) : null,
                 !trustManagers.isEmpty() ? trustManagers.toArray(EMPTY_TRUST_MANAGER_ARRAY) : null,
                 secureRandom);
     }
 
     private KeyStore loadKeyStore(final Path file, final char[] password, final OpenOption... openOptions)
             throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
         final KeyStore keyStore = KeyStore.getInstance(keyStoreType);
         try (final InputStream inputStream = Files.newInputStream(file, openOptions)) {
             keyStore.load(inputStream, password);
         }
         return keyStore;
     }
 
     private KeyStore loadKeyStore(final URL url, final char[] password)
             throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
         final KeyStore keyStore = KeyStore.getInstance(keyStoreType);
         try (final InputStream inputStream = url.openStream()) {
             keyStore.load(inputStream, password);
         }
         return keyStore;
     }
 
     public SSLContext build() throws NoSuchAlgorithmException, KeyManagementException {
         final SSLContext sslContext;
         final String protocolStr = this.protocol != null ? this.protocol : TLS;
         if (this.provider != null) {
             sslContext = SSLContext.getInstance(protocolStr, this.provider);
         } else {
             sslContext = SSLContext.getInstance(protocolStr);
         }
         initSSLContext(sslContext, keyManagers, trustManagers, secureRandom);
         return sslContext;
     }
 
     static class TrustManagerDelegate implements X509TrustManager {
 
         private final X509TrustManager trustManager;
         private final TrustStrategy trustStrategy;
 
         TrustManagerDelegate(final X509TrustManager trustManager, final TrustStrategy trustStrategy) {
             this.trustManager = trustManager;
             this.trustStrategy = trustStrategy;
         }
 
         @Override
         public void checkClientTrusted(
                 final X509Certificate[] chain, final String authType) throws CertificateException {
             this.trustManager.checkClientTrusted(chain, authType);
         }
 
         @Override
         public void checkServerTrusted(
                 final X509Certificate[] chain, final String authType) throws CertificateException {
             if (!this.trustStrategy.isTrusted(chain, authType)) {
                 this.trustManager.checkServerTrusted(chain, authType);
             }
         }
 
         @Override
         public X509Certificate[] getAcceptedIssuers() {
             return this.trustManager.getAcceptedIssuers();
         }
 
     }
 
     static class KeyManagerDelegate extends X509ExtendedKeyManager {
 
         private final X509ExtendedKeyManager keyManager;
         private final PrivateKeyStrategy aliasStrategy;
 
         KeyManagerDelegate(final X509ExtendedKeyManager keyManager, final PrivateKeyStrategy aliasStrategy) {
             this.keyManager = keyManager;
             this.aliasStrategy = aliasStrategy;
         }
 
         @Override
         public String[] getClientAliases(
                 final String keyType, final Principal[] issuers) {
             return this.keyManager.getClientAliases(keyType, issuers);
         }
 
         public Map<String, PrivateKeyDetails> getClientAliasMap(
                 final String[] keyTypes, final Principal[] issuers) {
             final Map<String, PrivateKeyDetails> validAliases = new HashMap<>();
             for (final String keyType: keyTypes) {
                 putPrivateKeyDetails(validAliases, keyType, this.keyManager.getClientAliases(keyType, issuers));
             }
             return validAliases;
         }
 
         public Map<String, PrivateKeyDetails> getServerAliasMap(
                 final String keyType, final Principal[] issuers) {
             final Map<String, PrivateKeyDetails> validAliases = new HashMap<>();
             putPrivateKeyDetails(validAliases, keyType, this.keyManager.getServerAliases(keyType, issuers));
             return validAliases;
         }
 
         private void putPrivateKeyDetails(final Map<String, PrivateKeyDetails> validAliases, final String keyType,
                 final String[] aliases) {
             if (aliases != null) {
                 for (final String alias: aliases) {
                     validAliases.put(alias, new PrivateKeyDetails(keyType, this.keyManager.getCertificateChain(alias)));
                 }
             }
         }
 
         @Override
         public String chooseClientAlias(
                 final String[] keyTypes, final Principal[] issuers, final Socket socket) {
             final Map<String, PrivateKeyDetails> validAliases = getClientAliasMap(keyTypes, issuers);
             return this.aliasStrategy.chooseAlias(validAliases,
                     socket instanceof SSLSocket ? ((SSLSocket) socket).getSSLParameters() : null);
         }
 
         @Override
         public String[] getServerAliases(
                 final String keyType, final Principal[] issuers) {
             return this.keyManager.getServerAliases(keyType, issuers);
         }
 
         @Override
         public String chooseServerAlias(
                 final String keyType, final Principal[] issuers, final Socket socket) {
             final Map<String, PrivateKeyDetails> validAliases = getServerAliasMap(keyType, issuers);
             return this.aliasStrategy.chooseAlias(validAliases,
                     socket instanceof SSLSocket ? ((SSLSocket) socket).getSSLParameters() : null);
         }
 
         @Override
         public X509Certificate[] getCertificateChain(final String alias) {
             return this.keyManager.getCertificateChain(alias);
         }
 
         @Override
         public PrivateKey getPrivateKey(final String alias) {
             return this.keyManager.getPrivateKey(alias);
         }
 
         @Override
         public String chooseEngineClientAlias(
                 final String[] keyTypes, final Principal[] issuers, final SSLEngine sslEngine) {
             final Map<String, PrivateKeyDetails> validAliases = getClientAliasMap(keyTypes, issuers);
             return this.aliasStrategy.chooseAlias(validAliases, sslEngine.getSSLParameters());
         }
 
         @Override
         public String chooseEngineServerAlias(
                 final String keyType, final Principal[] issuers, final SSLEngine sslEngine) {
             final Map<String, PrivateKeyDetails> validAliases = getServerAliasMap(keyType, issuers);
             return this.aliasStrategy.chooseAlias(validAliases, sslEngine.getSSLParameters());
         }
 
     }
 
     private Provider requireNonNullProvider(final String name) throws NoSuchProviderException {
         final Provider provider = Security.getProvider(name);
         if (provider == null) {
             throw new NoSuchProviderException(name);
         }
         return provider;
     }
 
     @Override
     public String toString() {
         return "[provider=" + provider + ", protocol=" + protocol + ", keyStoreType=" + keyStoreType
                 + ", keyManagerFactoryAlgorithm=" + keyManagerFactoryAlgorithm + ", keyManagers=" + keyManagers
                 + ", trustManagerFactoryAlgorithm=" + trustManagerFactoryAlgorithm + ", trustManagers=" + trustManagers
                 + ", secureRandom=" + secureRandom + "]";
     }
 
 }