/*
 * 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.olingo.server.tecsvc.processor;

import java.util.List;
import java.util.Locale;

import org.apache.olingo.commons.api.data.ContextURL;
import org.apache.olingo.commons.api.data.ContextURL.Suffix;
import org.apache.olingo.commons.api.data.Entity;
import org.apache.olingo.commons.api.data.EntitySet;
import org.apache.olingo.commons.api.edm.EdmEntitySet;
import org.apache.olingo.commons.api.format.ContentType;
import org.apache.olingo.commons.api.format.ODataFormat;
import org.apache.olingo.commons.api.http.HttpContentType;
import org.apache.olingo.commons.api.http.HttpHeader;
import org.apache.olingo.commons.api.http.HttpStatusCode;
import org.apache.olingo.server.api.ODataApplicationException;
import org.apache.olingo.server.api.ODataRequest;
import org.apache.olingo.server.api.ODataResponse;
import org.apache.olingo.server.api.deserializer.DeserializerException;
import org.apache.olingo.server.api.processor.ActionEntityCollectionProcessor;
import org.apache.olingo.server.api.processor.ActionEntityProcessor;
import org.apache.olingo.server.api.processor.CountEntityCollectionProcessor;
import org.apache.olingo.server.api.processor.EntityCollectionProcessor;
import org.apache.olingo.server.api.processor.EntityProcessor;
import org.apache.olingo.server.api.processor.MediaEntityProcessor;
import org.apache.olingo.server.api.serializer.EntityCollectionSerializerOptions;
import org.apache.olingo.server.api.serializer.ODataSerializer;
import org.apache.olingo.server.api.serializer.EntitySerializerOptions;
import org.apache.olingo.server.api.serializer.SerializerException;
import org.apache.olingo.server.api.uri.UriInfo;
import org.apache.olingo.server.api.uri.UriResource;
import org.apache.olingo.server.api.uri.UriResourceEntitySet;
import org.apache.olingo.server.api.uri.UriResourceKind;
import org.apache.olingo.server.api.uri.queryoption.ExpandOption;
import org.apache.olingo.server.api.uri.queryoption.SelectOption;
import org.apache.olingo.server.tecsvc.data.DataProvider;

/**
 * Technical Processor for entity-related functionality.
 */
public class TechnicalEntityProcessor extends TechnicalProcessor
    implements EntityCollectionProcessor, ActionEntityCollectionProcessor, CountEntityCollectionProcessor,
        EntityProcessor, ActionEntityProcessor, MediaEntityProcessor {

  public TechnicalEntityProcessor(final DataProvider dataProvider) {
    super(dataProvider);
  }

  @Override
  public void readEntityCollection(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
      final ContentType requestedContentType) throws ODataApplicationException, SerializerException {
    validateOptions(uriInfo.asUriInfoResource());
    blockNavigation(uriInfo);

    final EdmEntitySet edmEntitySet = getEdmEntitySet(uriInfo.asUriInfoResource());
    final EntitySet entitySet = readEntitySetInternal(edmEntitySet,
        uriInfo.getCountOption() != null && uriInfo.getCountOption().getValue());
    if (entitySet == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    } else {
      final ODataFormat format = ODataFormat.fromContentType(requestedContentType);
      ODataSerializer serializer = odata.createSerializer(format);
      final ExpandOption expand = uriInfo.getExpandOption();
      final SelectOption select = uriInfo.getSelectOption();
      response.setContent(serializer.entityCollection(edmEntitySet.getEntityType(), entitySet,
          EntityCollectionSerializerOptions.with()
              .contextURL(format == ODataFormat.JSON_NO_METADATA ? null :
                  getContextUrl(edmEntitySet, false, expand, select))
              .count(uriInfo.getCountOption())
              .expand(expand).select(select)
              .build()));
      response.setStatusCode(HttpStatusCode.OK.getStatusCode());
      response.setHeader(HttpHeader.CONTENT_TYPE, requestedContentType.toContentTypeString());
    }
  }

  @Override
  public void processActionEntityCollection(final ODataRequest request, final ODataResponse response,
                                      final UriInfo uriInfo,
                                      final ContentType requestFormat, final ContentType  responseFormat)
          throws ODataApplicationException, DeserializerException, SerializerException {
    throw new ODataApplicationException("Process entity collection is not supported yet.",
            HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), Locale.ROOT);
  }

  @Override
  public void countEntityCollection(final ODataRequest request, ODataResponse response, final UriInfo uriInfo)
          throws ODataApplicationException, SerializerException {
    validateOptions(uriInfo.asUriInfoResource());
    blockNavigation(uriInfo);

    final List<UriResource> resourceParts = uriInfo.asUriInfoResource().getUriResourceParts();
    final EntitySet entitySet =
        readEntitySetInternal(((UriResourceEntitySet) resourceParts.get(resourceParts.size() - 2)).getEntitySet(),
            true);
    if (entitySet == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    } else {
      response.setContent(odata.createFixedFormatSerializer().count(entitySet.getCount()));
      response.setStatusCode(HttpStatusCode.OK.getStatusCode());
      response.setHeader(HttpHeader.CONTENT_TYPE, HttpContentType.TEXT_PLAIN);
    }
  }

  @Override
  public void readEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
      final ContentType requestedContentType) throws ODataApplicationException, SerializerException {
    validateOptions(uriInfo.asUriInfoResource());
    blockNavigation(uriInfo);

    final EdmEntitySet edmEntitySet = getEdmEntitySet(uriInfo.asUriInfoResource());
    final UriResourceEntitySet resourceEntitySet = (UriResourceEntitySet) uriInfo.getUriResourceParts().get(0);
    final Entity entity = dataProvider.read(edmEntitySet, resourceEntitySet.getKeyPredicates());

    if (entity == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    } else {
      final ODataFormat format = ODataFormat.fromContentType(requestedContentType);
      ODataSerializer serializer = odata.createSerializer(format);
      final ExpandOption expand = uriInfo.getExpandOption();
      final SelectOption select = uriInfo.getSelectOption();
      response.setContent(serializer.entity(edmEntitySet.getEntityType(), entity,
          EntitySerializerOptions.with()
              .contextURL(format == ODataFormat.JSON_NO_METADATA ? null :
                  getContextUrl(edmEntitySet, true, expand, select))
              .expand(expand).select(select)
              .build()));
      response.setStatusCode(HttpStatusCode.OK.getStatusCode());
      response.setHeader(HttpHeader.CONTENT_TYPE, requestedContentType.toContentTypeString());
    }
  }

  @Override
  public void readMediaEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
                              final ContentType responseFormat) throws ODataApplicationException, SerializerException {
    blockNavigation(uriInfo);
    final UriResourceEntitySet resourceEntitySet = (UriResourceEntitySet) uriInfo.getUriResourceParts().get(0);
    final Entity entity = dataProvider.read(resourceEntitySet.getEntitySet(), resourceEntitySet.getKeyPredicates());
    if (entity == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    } else {
      response.setContent(odata.createFixedFormatSerializer().binary(dataProvider.readMedia(entity)));
      response.setStatusCode(HttpStatusCode.OK.getStatusCode());
      response.setHeader(HttpHeader.CONTENT_TYPE, entity.getMediaContentType());
    }
  }

  @Override
  public void createMediaEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
                                final ContentType requestFormat, final ContentType responseFormat)
          throws ODataApplicationException, DeserializerException, SerializerException {

    blockNavigation(uriInfo);
    final UriResourceEntitySet resourceEntitySet = (UriResourceEntitySet) uriInfo.getUriResourceParts().get(0);
    final EdmEntitySet edmEntitySet = resourceEntitySet.getEntitySet();
    Entity entity = null;
    if (edmEntitySet.getEntityType().hasStream()) {
      if (requestFormat == null) {
        throw new ODataApplicationException("The content type has not been set in the request.",
                HttpStatusCode.BAD_REQUEST.getStatusCode(), Locale.ROOT);
      }
      entity = dataProvider.create(edmEntitySet);
      dataProvider.setMedia(entity, odata.createFixedFormatDeserializer().binary(request.getBody()),
              requestFormat.toContentTypeString());
    } else {
      throw new ODataApplicationException("Requested Entity is not a media resource.",
              HttpStatusCode.BAD_REQUEST.getStatusCode(), Locale.ROOT);
    }

    final ODataFormat format = ODataFormat.fromContentType(responseFormat);
    ODataSerializer serializer = odata.createSerializer(format);
    response.setContent(serializer.entity(edmEntitySet.getEntityType(), entity,
            EntitySerializerOptions.with()
                    .contextURL(format == ODataFormat.JSON_NO_METADATA ? null :
                            getContextUrl(edmEntitySet, true, null, null))
                    .build()));
    response.setStatusCode(HttpStatusCode.CREATED.getStatusCode());
    response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
    response.setHeader(HttpHeader.LOCATION,
            request.getRawBaseUri() + '/' + odata.createUriHelper().buildCanonicalURL(edmEntitySet, entity));
  }

  @Override
  public void createEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
                           final ContentType requestFormat, final ContentType responseFormat)
      throws ODataApplicationException, DeserializerException, SerializerException {

    throw new ODataApplicationException("Entity creation is not supported yet.",
            HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), Locale.ROOT);
  }

  @Override
  public void updateEntity(final ODataRequest request, final ODataResponse response,
                           final UriInfo uriInfo, final ContentType requestFormat,
                           final ContentType responseFormat)
          throws ODataApplicationException, DeserializerException, SerializerException {
    throw new ODataApplicationException("Entity update is not supported yet.",
            HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), Locale.ROOT);
  }

  @Override
  public void updateMediaEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo,
                                final ContentType requestFormat, final ContentType responseFormat)
      throws ODataApplicationException, DeserializerException, SerializerException {
    blockNavigation(uriInfo);
    final UriResourceEntitySet resourceEntitySet = (UriResourceEntitySet) uriInfo.getUriResourceParts().get(0);
    final EdmEntitySet edmEntitySet = resourceEntitySet.getEntitySet();
    final Entity entity = dataProvider.read(edmEntitySet, resourceEntitySet.getKeyPredicates());
    if (entity == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    }
    if (requestFormat == null) {
      throw new ODataApplicationException("The content type has not been set in the request.",
          HttpStatusCode.BAD_REQUEST.getStatusCode(), Locale.ROOT);
    }
    dataProvider.setMedia(entity, odata.createFixedFormatDeserializer().binary(request.getBody()),
        requestFormat.toContentTypeString());

    final ODataFormat format = ODataFormat.fromContentType(responseFormat);
    ODataSerializer serializer = odata.createSerializer(format);
    response.setContent(serializer.entity(edmEntitySet.getEntityType(), entity,
        EntitySerializerOptions.with()
            .contextURL(format == ODataFormat.JSON_NO_METADATA ? null :
                getContextUrl(edmEntitySet, true, null, null))
            .build()));
    response.setStatusCode(HttpStatusCode.OK.getStatusCode());
    response.setHeader(HttpHeader.CONTENT_TYPE, responseFormat.toContentTypeString());
  }

  @Override
  public void deleteEntity(final ODataRequest request, ODataResponse response, final UriInfo uriInfo)
      throws ODataApplicationException {
    blockNavigation(uriInfo);
    final UriResourceEntitySet resourceEntitySet = (UriResourceEntitySet) uriInfo.getUriResourceParts().get(0);
    final Entity entity = dataProvider.read(resourceEntitySet.getEntitySet(), resourceEntitySet.getKeyPredicates());
    if (entity == null) {
      throw new ODataApplicationException("Nothing found.", HttpStatusCode.NOT_FOUND.getStatusCode(), Locale.ROOT);
    } else {
      dataProvider.delete(resourceEntitySet.getEntitySet(), entity);
      response.setStatusCode(HttpStatusCode.NO_CONTENT.getStatusCode());
    }
  }

  @Override
  public void processActionEntity(final ODataRequest request, final ODataResponse response,
                            final UriInfo uriInfo, final ContentType requestFormat,
                            final ContentType responseFormat)
          throws ODataApplicationException, DeserializerException, SerializerException {
    throw new ODataApplicationException("Process entity is not supported yet.",
            HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), Locale.ROOT);
  }

  private void blockNavigation(final UriInfo uriInfo) throws ODataApplicationException {
    final List<UriResource> parts = uriInfo.asUriInfoResource().getUriResourceParts();
    if (parts.size() > 2
        || parts.size() == 2
            && parts.get(1).getKind() != UriResourceKind.count
            && parts.get(1).getKind() != UriResourceKind.value) {
      throw new ODataApplicationException("Invalid resource type.",
          HttpStatusCode.NOT_IMPLEMENTED.getStatusCode(), Locale.ROOT);
    }
  }

  private EntitySet readEntitySetInternal(final EdmEntitySet edmEntitySet, final boolean withCount)
      throws DataProvider.DataProviderException {
    EntitySet entitySet = dataProvider.readAll(edmEntitySet);
    // TODO: set count (correctly) and next link
    if (withCount && entitySet.getCount() == null) {
      entitySet.setCount(entitySet.getEntities().size());
    }
    return entitySet;
  }

  private ContextURL getContextUrl(final EdmEntitySet entitySet, final boolean isSingleEntity,
      final ExpandOption expand, final SelectOption select) throws SerializerException {
    return ContextURL.with().entitySet(entitySet)
        .selectList(odata.createUriHelper()
            .buildContextURLSelectList(entitySet.getEntityType(), expand, select))
        .suffix(isSingleEntity ? Suffix.ENTITY : null)
        .build();
  }
}