/*******************************************************************************
 * Copyright 2013 SAP AG
 * 
 * Licensed 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 com.sap.core.odata.core.edm.provider;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;

import com.sap.core.odata.api.ODataServiceVersion;
import com.sap.core.odata.api.edm.EdmEntitySetInfo;
import com.sap.core.odata.api.edm.EdmServiceMetadata;
import com.sap.core.odata.api.edm.provider.DataServices;
import com.sap.core.odata.api.edm.provider.EdmProvider;
import com.sap.core.odata.api.edm.provider.EntityContainer;
import com.sap.core.odata.api.edm.provider.EntitySet;
import com.sap.core.odata.api.edm.provider.EntityType;
import com.sap.core.odata.api.edm.provider.Property;
import com.sap.core.odata.api.edm.provider.Schema;
import com.sap.core.odata.api.ep.EntityProviderException;
import com.sap.core.odata.api.exception.ODataException;
import com.sap.core.odata.core.ep.producer.XmlMetadataProducer;
import com.sap.core.odata.core.ep.util.CircleStreamBuffer;

/**
 * @author SAP AG
 */
public class EdmServiceMetadataImplProv implements EdmServiceMetadata {

  private EdmProvider edmProvider;
  private String dataServiceVersion;
  private List<Schema> schemas;
  private List<EdmEntitySetInfo> entitySetInfos;

  public EdmServiceMetadataImplProv(final EdmProvider edmProvider) {
    this.edmProvider = edmProvider;
  }

  @Override
  public InputStream getMetadata() throws ODataException {
    if (schemas == null) {
      schemas = edmProvider.getSchemas();
    }

    OutputStreamWriter writer = null;
    CircleStreamBuffer csb = new CircleStreamBuffer();
    EntityProviderException cachedException = null;
    DataServices metadata = new DataServices().setSchemas(schemas).setDataServiceVersion(getDataServiceVersion());

    try {
      writer = new OutputStreamWriter(csb.getOutputStream(), "UTF-8");
      XMLStreamWriter xmlStreamWriter = XMLOutputFactory.newInstance().createXMLStreamWriter(writer);
      XmlMetadataProducer.writeMetadata(metadata, xmlStreamWriter, null);
      return csb.getInputStream();
    } catch (XMLStreamException e) {
      cachedException = new EntityProviderException(EntityProviderException.COMMON, e);
      throw cachedException;
    } catch (UnsupportedEncodingException e) {
      cachedException = new EntityProviderException(EntityProviderException.COMMON, e);
      throw cachedException;
    } finally {// NOPMD (suppress DoNotThrowExceptionInFinally)
      if (writer != null) {
        try {
          writer.close();
        } catch (IOException e) {
          if (cachedException != null) {
            throw cachedException;
          } else {
            throw new EntityProviderException(EntityProviderException.COMMON, e);
          }
        }
      }
    }
  }

  @Override
  public String getDataServiceVersion() throws ODataException {
    if (schemas == null) {
      schemas = edmProvider.getSchemas();
    }

    if (dataServiceVersion == null) {
      dataServiceVersion = ODataServiceVersion.V10;

      if (schemas != null) {
        for (Schema schema : schemas) {
          List<EntityType> entityTypes = schema.getEntityTypes();
          if (entityTypes != null) {
            for (EntityType entityType : entityTypes) {
              List<Property> properties = entityType.getProperties();
              if (properties != null) {
                for (Property property : properties) {
                  if (property.getCustomizableFeedMappings() != null) {
                    if (property.getCustomizableFeedMappings().getFcKeepInContent() != null) {
                      if (!property.getCustomizableFeedMappings().getFcKeepInContent()) {
                        dataServiceVersion = ODataServiceVersion.V20;
                        return dataServiceVersion;
                      }
                    }
                  }
                }
                if (entityType.getCustomizableFeedMappings() != null) {
                  if (entityType.getCustomizableFeedMappings().getFcKeepInContent() != null) {
                    if (entityType.getCustomizableFeedMappings().getFcKeepInContent()) {
                      dataServiceVersion = ODataServiceVersion.V20;
                      return dataServiceVersion;
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
    return dataServiceVersion;
  }

  @Override
  public List<EdmEntitySetInfo> getEntitySetInfos() throws ODataException {
    if (entitySetInfos == null) {
      entitySetInfos = new ArrayList<EdmEntitySetInfo>();

      if (schemas == null) {
        schemas = edmProvider.getSchemas();
      }

      for (Schema schema : schemas) {
        for (EntityContainer entityContainer : schema.getEntityContainers()) {
          for (EntitySet entitySet : entityContainer.getEntitySets()) {
            EdmEntitySetInfo entitySetInfo = new EdmEntitySetInfoImplProv(entitySet, entityContainer);
            entitySetInfos.add(entitySetInfo);
          }
        }
      }

    }

    return entitySetInfos;
  }
}