/*
    * 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.
   */
  package org.apache.syncope.core.logic.oidc;
  
  import com.nimbusds.oauth2.sdk.ParseException;
  import com.nimbusds.oauth2.sdk.id.Issuer;
  import com.nimbusds.openid.connect.sdk.SubjectType;
  import com.nimbusds.openid.connect.sdk.op.OIDCProviderMetadata;
  import java.io.IOException;
  import java.net.URI;
  import java.net.http.HttpClient;
  import java.net.http.HttpRequest;
  import java.net.http.HttpResponse;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Optional;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  import org.apache.syncope.common.lib.to.OIDCC4UIProviderTO;
  import org.apache.syncope.core.persistence.api.entity.OIDCC4UIProvider;
  import org.pac4j.core.http.callback.NoParameterCallbackUrlResolver;
  import org.pac4j.oidc.client.OidcClient;
  import org.pac4j.oidc.config.OidcConfiguration;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Basic in-memory cache for available {@link OidcClient} instances.
   */
  public class OIDCClientCache {
  
      protected static final Logger LOG = LoggerFactory.getLogger(OIDCClientCache.class);
  
      protected static final Function<String, String> DISCOVERY_URI =
              issuer -> issuer + "/.well-known/openid-configuration";
  
      public static void importMetadata(final OIDCC4UIProviderTO opTO)
              throws IOException, InterruptedException, ParseException {
  
          String discoveryDocumentURI = DISCOVERY_URI.apply(opTO.getIssuer());
          HttpResponse<String> response = HttpClient.newBuilder().build().send(
                  HttpRequest.newBuilder(URI.create(discoveryDocumentURI)).GET().build(),
                  HttpResponse.BodyHandlers.ofString());
  
          OIDCProviderMetadata metadata = OIDCProviderMetadata.parse(response.body());
  
          opTO.setIssuer(
                  Optional.ofNullable(metadata.getIssuer()).map(Issuer::getValue).orElse(null));
          opTO.setJwksUri(
                  Optional.ofNullable(metadata.getJWKSetURI()).map(URI::toASCIIString).orElse(null));
          opTO.setAuthorizationEndpoint(
                  Optional.ofNullable(metadata.getAuthorizationEndpointURI()).map(URI::toASCIIString).orElse(null));
          opTO.setTokenEndpoint(
                  Optional.ofNullable(metadata.getTokenEndpointURI()).map(URI::toASCIIString).orElse(null));
          opTO.setUserinfoEndpoint(
                  Optional.ofNullable(metadata.getUserInfoEndpointURI()).map(URI::toASCIIString).orElse(null));
          opTO.setEndSessionEndpoint(
                  Optional.ofNullable(metadata.getEndSessionEndpointURI()).map(URI::toASCIIString).orElse(null));
          Optional.ofNullable(metadata.getScopes()).ifPresent(s -> opTO.getScopes().addAll(s.toStringList()));
      }
  
      protected final List<OidcClient> cache = Collections.synchronizedList(new ArrayList<>());
  
      public Optional<OidcClient> get(final String opName) {
          return cache.stream().filter(c -> opName.equals(c.getName())).findFirst();
      }
  
      public OidcClient add(final OIDCC4UIProvider op, final String callbackUrl) {
          OIDCProviderMetadata metadata = new OIDCProviderMetadata(
                  new Issuer(op.getIssuer()),
                  List.of(SubjectType.PUBLIC),
                  Optional.ofNullable(op.getJwksUri()).map(URI::create).orElse(null));
          metadata.setAuthorizationEndpointURI(
                  Optional.ofNullable(op.getAuthorizationEndpoint()).map(URI::create).orElse(null));
          metadata.setTokenEndpointURI(
                  Optional.ofNullable(op.getTokenEndpoint()).map(URI::create).orElse(null));
          metadata.setUserInfoEndpointURI(
                  Optional.ofNullable(op.getUserinfoEndpoint()).map(URI::create).orElse(null));
          metadata.setEndSessionEndpointURI(
                  Optional.ofNullable(op.getEndSessionEndpoint()).map(URI::create).orElse(null));
  
          OidcConfiguration cfg = new OidcConfiguration();
         cfg.setClientId(op.getClientID());
         cfg.setSecret(op.getClientSecret());
         cfg.setProviderMetadata(metadata);
         cfg.setScope(op.getScopes().stream().collect(Collectors.joining(" ")));
         cfg.setUseNonce(false);
         cfg.setLogoutHandler(new NoOpLogoutHandler());
 
         OidcClient client = new OidcClient(cfg);
         client.setName(op.getName());
         client.setCallbackUrlResolver(new NoParameterCallbackUrlResolver());
         client.setCallbackUrl(callbackUrl);
         client.init();
 
         cache.add(client);
         return client;
     }
 
     public boolean removeAll(final String opName) {
         return cache.removeIf(c -> opName.equals(c.getName()));
     }
 }