/**
 *  Copyright (C) 2010 Cloud.com, Inc.  All rights reserved.
 * 
 * This software is licensed under the GNU General Public License v3 or later.
 * 
 * It is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */
package com.cloud.ha;

import java.util.List;

import javax.ejb.Local;

import org.apache.log4j.Logger;

import com.cloud.agent.api.Answer;
import com.cloud.agent.api.CheckOnHostAnswer;
import com.cloud.agent.api.CheckOnHostCommand;
import com.cloud.agent.AgentManager;
import com.cloud.host.HostVO;
import com.cloud.host.Status;
import com.cloud.host.dao.HostDao;
import com.cloud.hypervisor.Hypervisor.HypervisorType;
import com.cloud.utils.component.AdapterBase;
import com.cloud.utils.component.Inject;
import com.cloud.vm.VMInstanceVO;

@Local(value=Investigator.class)
public class XenServerInvestigator extends AdapterBase implements Investigator {
    private final static Logger s_logger = Logger.getLogger(XenServerInvestigator.class);
    @Inject HostDao _hostDao;
    @Inject AgentManager _agentMgr;
    
    protected XenServerInvestigator() {
    }
    
    @Override
    public Status isAgentAlive(HostVO agent) {
        if (agent.getHypervisorType() != HypervisorType.XenServer) {
            return null;
        }
        
        CheckOnHostCommand cmd = new CheckOnHostCommand(agent);
        List<HostVO> neighbors = _hostDao.listByCluster(agent.getClusterId());
        for (HostVO neighbor : neighbors) {
            if (neighbor.getId() == agent.getId() || neighbor.getHypervisorType() != HypervisorType.XenServer) {
                continue;
            }
            Answer answer = _agentMgr.easySend(neighbor.getId(), cmd);
            if (answer != null) {
                CheckOnHostAnswer ans = (CheckOnHostAnswer)answer;
                if (!ans.isDetermined()) {
                    s_logger.debug("Host " + neighbor + " couldn't determine the status of " + agent);
                    continue;
                }
                return ans.isAlive() ? Status.Up : Status.Down;
            }
        }
        
        return null;
    }

    @Override
    public Boolean isVmAlive(VMInstanceVO vm, HostVO host) {
        Status status = isAgentAlive(host);
        if (status == null) {
            return null;
        }
        return status == Status.Up ? true : null;
    }
}