/*
    * Copyright 2015 Data Archiving and Networked Services (an institute of
    * Koninklijke Nederlandse Akademie van Wetenschappen), King's College London,
    * Georg-August-Universitaet Goettingen Stiftung Oeffentlichen Rechts
    *
    * Licensed under the EUPL, Version 1.1 or – as soon they will be approved by
    * the European Commission - subsequent versions of the EUPL (the "Licence");
    * You may not use this work except in compliance with the Licence.
    * You may obtain a copy of the Licence at:
   *
   * https://joinup.ec.europa.eu/software/page/eupl
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the Licence is distributed on an "AS IS" basis,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the Licence for the specific language governing
   * permissions and limitations under the Licence.
   */
  
  package eu.ehri.extension;
  
  import com.typesafe.config.Config;
  import com.typesafe.config.ConfigFactory;
  import eu.ehri.extension.base.AbstractResource;
  import eu.ehri.project.api.Api;
  import eu.ehri.project.core.Tx;
  import eu.ehri.project.exporters.xml.IndentingXMLStreamWriter;
  import eu.ehri.project.oaipmh.OaiPmhData;
  import eu.ehri.project.oaipmh.OaiPmhExporter;
  import eu.ehri.project.oaipmh.OaiPmhRenderer;
  import eu.ehri.project.oaipmh.OaiPmhState;
  import eu.ehri.project.oaipmh.errors.OaiPmhError;
  import org.neo4j.graphdb.GraphDatabaseService;
  
  import javax.ws.rs.GET;
  import javax.ws.rs.POST;
  import javax.ws.rs.Path;
  import javax.ws.rs.Produces;
  import javax.ws.rs.core.Context;
  import javax.ws.rs.core.HttpHeaders;
  import javax.ws.rs.core.MediaType;
  import javax.ws.rs.core.Response;
  import javax.ws.rs.core.StreamingOutput;
  import javax.xml.stream.XMLOutputFactory;
  import javax.xml.stream.XMLStreamException;
  import java.io.BufferedOutputStream;
  import java.util.List;
  
  
  /**
   * Open Archives Initiative Protocol for Metadata Harvesting
   * (OAI-PMH) 2.0 server implementation.
   */
  @Path(OaiPmhResource.ENDPOINT)
  public class OaiPmhResource extends AbstractResource {
  
      private static final Config config = ConfigFactory.load();
      private static final XMLOutputFactory xmlOutputFactory = XMLOutputFactory.newFactory();
  
      public static final String ENDPOINT = "oaipmh";
      public static final String LIMIT_HEADER_NAME = "X-Limit";
      private static final String DEFAULT_LANG_CODE = "eng";
  
  
  
      public OaiPmhResource(@Context GraphDatabaseService database) {
          super(database);
      }
  
      /**
       * OAI-PMH 2.0 base URL. See specification for usage.
       * <p>
       * http://www.openarchives.org/OAI/openarchivesprotocol.html
       *
       * @return an OAI-PMH XML payload as a chunked response.
       */
      @GET
      @Produces(MediaType.TEXT_XML)
      public Response oaiGet() {
          final int limit = isStreaming() ? -1 : limit(config.getInt("oaipmh.numResponses"));
          return Response.ok((StreamingOutput) out -> {
              try (final Tx tx = beginTx();
                   final BufferedOutputStream bufferedOut = new BufferedOutputStream(out);
                   final IndentingXMLStreamWriter sw = new IndentingXMLStreamWriter(
                           xmlOutputFactory.createXMLStreamWriter(bufferedOut))) {
                  Api api = anonymousApi();
                  OaiPmhExporter oaiPmh = new OaiPmhExporter(
                          OaiPmhData.create(api),
                          OaiPmhRenderer.defaultRenderer(api, DEFAULT_LANG_CODE),
                          config);
                  try {
                      OaiPmhState state = OaiPmhState.parse(uriInfo.getRequestUri().getQuery(), limit);
                      oaiPmh.performVerb(sw, state);
                      tx.success();
                  } catch (OaiPmhError error) {
                      oaiPmh.error(sw, error.getCode(), error.getMessage(), null);
                  }
              } catch (XMLStreamException e) {
                  throw new RuntimeException(e);
             }
         }).header(HttpHeaders.CONTENT_TYPE,
                 MediaType.TEXT_XML + "; charset=utf-8")
                 .build();
     }
 
     @POST
     @Produces(MediaType.TEXT_XML)
     public Response oaiPost() {
         return oaiGet();
     }
 
     private int limit(int defaultLimit) {
         // Allow overriding the limit via a header. This is safe since
         // we stream requests. It's also very handy for testing.
         List<String> limit = requestHeaders.getRequestHeader(LIMIT_HEADER_NAME);
         if (limit == null || limit.size() < 1) {
             return defaultLimit;
         } else {
             try {
                 return Integer.parseInt(limit.get(0));
             } catch (NumberFormatException e) {
                 return defaultLimit;
             }
         }
     }
 }