/*
 * Copyright 2013 Eediom Inc.
 * 
 * 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.araqne.logdb.query.command;

import java.util.List;

import org.araqne.logdb.DriverQueryCommand;
import org.araqne.logdb.FieldOrdering;
import org.araqne.logdb.MetadataCallback;
import org.araqne.logdb.MetadataService;
import org.araqne.logdb.QueryContext;
import org.araqne.logdb.QueryStopReason;
import org.araqne.logdb.QueryTask.TaskStatus;
import org.araqne.logdb.Row;

public class SystemCommand extends DriverQueryCommand implements FieldOrdering {
	private QueryContext context;
	private String commandName;
	private String objectType;
	private String args;
	private MetadataService metadataService;
	private MetadataCallbackWriter metadataWriter;

	public SystemCommand(String commandName, QueryContext context, String objectType, String args, MetadataService metadataService) {
		this.commandName = commandName;
		this.context = context;
		this.objectType = objectType;
		this.args = args;
		this.metadataService = metadataService;
		this.metadataWriter = new MetadataCallbackWriter();
	}

	@Override
	public String getName() {
		return commandName;
	}

	@Override
	public void run() {
		try {
			metadataService.query(context, objectType, args, metadataWriter);
		} catch (IllegalStateException e) {
			// ignore query cancelled by user
			if (e.getMessage() == null || !e.getMessage().contains("result writer is already closed"))
				throw e;
		}
	}

	@Override
	public void onClose(QueryStopReason reason) {
	}

	private class MetadataCallbackWriter implements MetadataCallback {
		@Override
		public boolean isCancelled() {
			return task.getStatus() == TaskStatus.CANCELED;
		}

		@Override
		public void onPush(Row log) {
			pushPipe(log);
		}
	}

	@Override
	public String toString() {
		String arguments = args;
		if (!arguments.isEmpty())
			arguments = " " + arguments;
		return commandName + " " + objectType + arguments;
	}
	
	@Override
	public List<String> getFieldOrder() {
		return metadataService.getFieldOrder(objectType);
	}
}