/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * 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 org.teiid.translator.odata4;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import org.apache.olingo.commons.api.http.HttpStatusCode;
import org.teiid.core.util.ObjectConverterUtil;
import org.teiid.language.AggregateFunction;
import org.teiid.language.QueryExpression;
import org.teiid.language.Select;
import org.teiid.metadata.RuntimeMetadata;
import org.teiid.translator.DataNotAvailableException;
import org.teiid.translator.ExecutionContext;
import org.teiid.translator.ResultSetExecution;
import org.teiid.translator.TranslatorException;
import org.teiid.translator.odata4.ODataMetadataProcessor.ODataType;
import org.teiid.translator.ws.BinaryWSProcedureExecution;
import org.teiid.translator.WSConnection;

public class ODataQueryExecution extends BaseQueryExecution implements ResultSetExecution {

	private ODataSQLVisitor visitor;
	private int countResponse = -1;
	private Class<?>[] expectedColumnTypes;
	private ODataResponse response;
	private boolean isCount;

	public ODataQueryExecution(ODataExecutionFactory translator,
	                           QueryExpression command, ExecutionContext executionContext,
	                           RuntimeMetadata metadata, WSConnection connection) throws TranslatorException {
		super(translator, executionContext, metadata, connection);

		this.visitor = new ODataSQLVisitor(this.translator, metadata);
		this.visitor.visitNode(command);
		if (command instanceof Select) {
			Select select = (Select) command;
			if (select.getGroupBy() == null && select.getDerivedColumns().get(0).getExpression() instanceof AggregateFunction) {
				this.isCount = true;
			}
		}
		if (!this.visitor.exceptions.isEmpty()) {
			throw visitor.exceptions.get(0);
		}

		this.expectedColumnTypes = command.getColumnTypes();
	}

	@Override
	public void execute() throws TranslatorException {
		final String URI = this.visitor.buildURL("");

		if (isCount) {
			Map<String, List<String>> headers = new TreeMap<String, List<String>>();
			headers.put("Accept", Arrays.asList("text/plain"));  //$NON-NLS-1$ //$NON-NLS-2$

			BinaryWSProcedureExecution execution = invokeHTTP("GET", URI, null, headers); //$NON-NLS-1$
			if (execution.getResponseCode() != HttpStatusCode.OK.getStatusCode()) {
				throw buildError(execution);
			}

			Blob blob = (Blob) execution.getOutputParameterValues().get(0);
			try {
				this.countResponse = Integer.parseInt(ObjectConverterUtil.convertToString(blob.getBinaryStream()));
			} catch (IOException e) {
				throw new TranslatorException(e);
			} catch (SQLException e) {
				throw new TranslatorException(e);
			}
		} else {
			InputStream payload = executeQuery(
					"GET", URI, null, null, ////$NON-NLS-1$
					new HttpStatusCode[]{
							HttpStatusCode.OK,
							HttpStatusCode.NO_CONTENT,
							HttpStatusCode.NOT_FOUND
					});
			this.response = new ODataResponse(payload,
					ODataType.ENTITY_COLLECTION, this.visitor.getODataQuery().getRootDocument()) {
				@Override
				public InputStream nextBatch(java.net.URI uri) throws TranslatorException {
					return executeSkipToken(uri, URI.toString(),
							new HttpStatusCode[]{
									HttpStatusCode.OK,
									HttpStatusCode.NO_CONTENT,
									HttpStatusCode.NOT_FOUND
							});
				}
			};
		}
	}

	@Override
	public List<?> next() throws TranslatorException, DataNotAvailableException {

		if (isCount && this.countResponse != -1) {
			int count = this.countResponse;
			this.countResponse = -1;
			return Arrays.asList(count);
		}

		if (this.response != null) {
			Map<String, Object> row = this.response.getNext();
			if (row != null) {
				return buildRow(visitor.getODataQuery().getRootDocument().getTable(),
						visitor.getProjectedColumns(),
						this.expectedColumnTypes, row);
			}
		}
		return null;
	}

	@Override
	public void close() {
	}

	@Override
	public void cancel() throws TranslatorException {
	}
}
