// **********************************************************************
//
// Copyright (c) 2003-2005 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************

#include <IceUtil/StringUtil.h>
#include <Freeze/Freeze.h>
#include <IceGrid/Database.h>
#include <IceGrid/TraceLevels.h>
#include <IceGrid/Util.h>
#include <IceGrid/DescriptorHelper.h>

#include <algorithm>
#include <functional>
#include <iterator>

using namespace std;
using namespace IceGrid;

const string Database::_descriptorDbName = "applications";
const string Database::_nodeDbName = "nodes";
const string Database::_adapterDbName = "adapters";
const string Database::_objectDbName = "objects";

namespace IceGrid
{

struct AddComponent : std::unary_function<ComponentDescriptorPtr&, void>
{
    AddComponent(Database& database, const Database::ServerEntryPtr& entry) : _database(database), _entry(entry)
    {
    }

    void
    operator()(const ComponentDescriptorPtr& desc)
    {
	_database.addComponent(_entry, desc);
    }

    Database& _database;
    const Database::ServerEntryPtr _entry;
};

struct AddServerName : std::unary_function<InstanceDescriptor&, void>
{
    AddServerName(set<string>& names) : _names(names)
    {
    }

    void
    operator()(const InstanceDescriptor& instance)
    {
	if(!_names.insert(instance.descriptor->name).second)
	{
	    DeploymentException ex;
	    ex.reason = "invalid descriptor: duplicated server `" + instance.descriptor->name + "'";
	    throw ex;
	}
    }

    set<string>& _names;
};

struct AddAdapterId : std::unary_function<ComponentDescriptorPtr&, void>
{
    AddAdapterId(set<string>& ids) : _ids(ids)
    {
    }

    void 
    operator()(const ComponentDescriptorPtr& desc)
    {
	for(AdapterDescriptorSeq::const_iterator p = desc->adapters.begin(); p != desc->adapters.end(); ++p)
	{
	    if(p->id.empty())
	    {
		DeploymentException ex;
		ex.reason = "invalid descriptor: empty adapter id for adapter `" + p->name + "' in `" + desc->name 
		    + "'";
		throw ex;
	    }
	    if(!_ids.insert(p->id).second)
	    {
		DeploymentException ex;
		ex.reason = "invalid descriptor: duplicated adapter id `" + p->id + "'";
		throw ex;
	    }
	}
    }

    set<string>& _ids;
};

struct AddObjectId : std::unary_function<ComponentDescriptorPtr&, void>
{
    AddObjectId(set<Ice::Identity>& ids) : _ids(ids)
    {
    }

    void 
    operator()(const ComponentDescriptorPtr& desc)
    {
	for(AdapterDescriptorSeq::const_iterator p = desc->adapters.begin(); p != desc->adapters.end(); ++p)
	{
	    for(ObjectDescriptorSeq::const_iterator q = p->objects.begin(); q != p->objects.end(); ++q)
	    {
		if(!q->proxy)
		{
		    DeploymentException ex;
		    ex.reason = "invalid descriptor: object proxy is null in `" + desc->name + "'";
		    throw ex;
		}
		if(!_ids.insert(q->proxy->ice_getIdentity()).second)
		{
		    DeploymentException ex;
		    ex.reason = "invalid descriptor: duplicated object id `" + 
			Ice::identityToString(q->proxy->ice_getIdentity()) + "'";
		    throw ex;
		}
	    }
	}
    }

    set<Ice::Identity>& _ids;
};

//
// A default servant for adapter objects registered directly in the
// registry database.
//
class AdapterI : public Adapter
{
public:

    AdapterI(const DatabasePtr& database) : _database(database)
    {
    }

    virtual void
    activate_async(const AMD_Adapter_activatePtr& cb, const Ice::Current& current)
    {
	cb->ice_response(_database->getAdapterDirectProxy(current.id.name));
    }

    virtual Ice::ObjectPrx 
    getDirectProxy(const Ice::Current& current) const
    {
	return _database->getAdapterDirectProxy(current.id.name);
    }

    virtual void 
    setDirectProxy(const ::Ice::ObjectPrx& proxy, const ::Ice::Current& current)
    {
	_database->setAdapterDirectProxy(current.id.name, proxy);
    }

    virtual void 
    destroy(const ::Ice::Current& current)
    {
	_database->setAdapterDirectProxy(current.id.name, 0);
    }

private:

    const DatabasePtr _database;
};

//
// A servant locator for the default servant above.
//
class AdapterServantLocator : public Ice::ServantLocator
{
public:

    AdapterServantLocator(const DatabasePtr& database) : _adapter(new AdapterI(database))
    {
    }

    virtual Ice::ObjectPtr
    locate(const Ice::Current& current, Ice::LocalObjectPtr& cookie)
    {
	return _adapter;
    }

    virtual void
    finished(const Ice::Current&, const Ice::ObjectPtr&, const Ice::LocalObjectPtr&)
    {
    }

    virtual void
    deactivate(const std::string&)
    {
    }
    
private:

    const AdapterPtr _adapter;
};

}

Database::Database(const Ice::CommunicatorPtr& communicator, 
		   const Ice::ObjectAdapterPtr& adapter,
		   const string& envName,
		   const TraceLevelsPtr& traceLevels) :
    _communicator(communicator),
    _internalAdapter(adapter),
    _envName(envName),
    _traceLevels(traceLevels),
    _connection(Freeze::createConnection(communicator, envName)),
    _descriptors(_connection, _descriptorDbName),
    _nodes(_connection, _nodeDbName),
    _objects(_connection, _objectDbName),
    _adapters(_connection, _adapterDbName)
{
    //
    // Register a default servant to manage manually registered object adapters.
    //
    _internalAdapter->addServantLocator(new AdapterServantLocator(this), "IceGridAdapter");

    //
    // Cache the servers.
    //
    for(StringApplicationDescriptorDict::const_iterator p = _descriptors.begin(); p != _descriptors.end(); ++p)
    {
	for(InstanceDescriptorSeq::const_iterator q = p->second->servers.begin(); q != p->second->servers.end(); ++q)
	{
	    addServer(*q);
	}
    }
}

Database::~Database()
{
}

void
Database::addApplicationDescriptor(const ApplicationDescriptorPtr& descriptor)
{
    ServerEntrySeq entries;
    {
	Lock sync(*this);
	
	//
	// We first ensure that the application doesn't already exist
	// and that the application components don't already exist.
	//
	if(_descriptors.find(descriptor->name) != _descriptors.end())
	{
	    ApplicationExistsException ex;
	    ex.name = descriptor->name;
	    throw ex;
	}

	//
	// Ensure that the application servers, adapters and objects
	// aren't already registered.
	//
	set<string> servers;
	for_each(descriptor->servers.begin(), descriptor->servers.end(), AddServerName(servers));
	try
	{
	    for_each(servers.begin(), servers.end(), objFunc(*this, &Database::checkServerForAddition));
	}
	catch(const ServerExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "server `" + e.name + "' is already registered"; 
	    throw ex;
	}

	set<string> adapterIds;
	for_each(descriptor->servers.begin(), descriptor->servers.end(), forEachComponent(AddAdapterId(adapterIds)));
	try
	{
	    for_each(adapterIds.begin(), adapterIds.end(), objFunc(*this, &Database::checkAdapterForAddition));
	}
	catch(const AdapterExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "adapter `" + e.id + "' is already registered"; 
	    throw ex;
	}

	set<Ice::Identity> objectIds;
	for_each(descriptor->servers.begin(), descriptor->servers.end(), forEachComponent(AddObjectId(objectIds)));
	try
	{
	    for_each(objectIds.begin(), objectIds.end(), objFunc(*this, &Database::checkObjectForAddition));
	}
	catch(const ObjectExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "object `" + Ice::identityToString(e.id) + "' is already registered"; 
	    throw ex;
	}

	//
	// Register the application servers.
	//
	addServers(descriptor->servers, servers, entries);

	//
	// Save the application descriptor.
	//
	_descriptors.put(make_pair(descriptor->name, descriptor));
    }

    if(_traceLevels->application > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->applicationCat);
	out << "added application `" << descriptor->name << "'";
    }

    //
    // Synchronize the servers on the nodes.
    //
    for_each(entries.begin(), entries.end(), IceUtil::voidMemFun(&Database::ServerEntry::sync));
}

void
Database::updateApplicationDescriptor(const ApplicationDescriptorPtr& newDesc)
{
    ServerEntrySeq entries;
    {
	Lock sync(*this);

	//
	// Find the application to update.
	//
	StringApplicationDescriptorDict::const_iterator p = _descriptors.find(newDesc->name);
	if(p == _descriptors.end())
	{
	    ApplicationNotExistException ex;
	    ex.name = newDesc->name;
	    throw ex;
	}
	ApplicationDescriptorPtr origDesc = p->second;

	//
	// Ensure that the new application servers aren't already
	// registered.
	//
	set<string> oldSvrs;
	set<string> newSvrs;
	for_each(origDesc->servers.begin(), origDesc->servers.end(), AddServerName(oldSvrs));
	for_each(newDesc->servers.begin(), newDesc->servers.end(), AddServerName(newSvrs));

	set<string> added, removed, updated; 
	set_intersection(newSvrs.begin(), newSvrs.end(), oldSvrs.begin(), oldSvrs.end(), set_inserter(updated));
	set_difference(oldSvrs.begin(), oldSvrs.end(), newSvrs.begin(), newSvrs.end(), set_inserter(removed));
	set_difference(newSvrs.begin(), newSvrs.end(), oldSvrs.begin(), oldSvrs.end(), set_inserter(added));
	try
	{
	    for_each(added.begin(), added.end(), objFunc(*this, &Database::checkServerForAddition));
	}
	catch(const ServerExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "server `" + e.name + "' is already registered"; 
	    throw ex;
	}

	//
	// Ensure that the new application adapters aren't already
	// registered.
	//
	set<string> oldAdpts;
	set<string> newAdpts;
	for_each(origDesc->servers.begin(), origDesc->servers.end(), forEachComponent(AddAdapterId(oldAdpts)));
	for_each(newDesc->servers.begin(), newDesc->servers.end(), forEachComponent(AddAdapterId(newAdpts)));

	set<string> addedAdpts;
	set_difference(newAdpts.begin(), newAdpts.end(), oldAdpts.begin(), oldAdpts.end(), set_inserter(addedAdpts));
	try
	{
	    for_each(addedAdpts.begin(), addedAdpts.end(), objFunc(*this, &Database::checkAdapterForAddition));
	}
	catch(const AdapterExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "adapter `" + e.id + "' is already registered"; 
	    throw ex;
	}	

	//
	// Ensure that the new application objects aren't already
	// registered.
	//
	set<Ice::Identity> oldObjs;
	set<Ice::Identity> newObjs;
	for_each(origDesc->servers.begin(), origDesc->servers.end(), forEachComponent(AddObjectId(oldObjs)));
	for_each(newDesc->servers.begin(), newDesc->servers.end(), forEachComponent(AddObjectId(newObjs)));

	set<Ice::Identity> addedObjs;
	set_difference(newObjs.begin(), newObjs.end(), oldObjs.begin(), oldObjs.end(), set_inserter(addedObjs));
	try
	{
	    for_each(addedObjs.begin(), addedObjs.end(), objFunc(*this, &Database::checkObjectForAddition));
	}
	catch(const ObjectExistsException& e)
	{
	    DeploymentException ex;
	    ex.reason = "object `" + Ice::identityToString(e.id) + "' is already registered"; 
	    throw ex;
	}	

	//
	// Register the new servers, unregister the old ones and
	// update the updated ones.
	//
	addServers(newDesc->servers, added, entries);
	updateServers(origDesc, newDesc, updated, entries);
	removeServers(origDesc->servers, removed, entries);

	_descriptors.put(make_pair(newDesc->name, newDesc));
    }    

    if(_traceLevels->application > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->applicationCat);
	out << "updated application `" << newDesc->name << "'";
    }

    for_each(entries.begin(), entries.end(), IceUtil::voidMemFun(&Database::ServerEntry::sync));
}

void
Database::removeApplicationDescriptor(const std::string& name)
{
    ApplicationDescriptorPtr descriptor;
    ServerEntrySeq entries;
    {
	Lock sync(*this);

	StringApplicationDescriptorDict::iterator p = _descriptors.find(name);
	if(p == _descriptors.end())
	{
	    throw ApplicationNotExistException();
	}
	
	descriptor = p->second;
	_descriptors.erase(p);

	set<string> servers;
	for_each(descriptor->servers.begin(), descriptor->servers.end(), AddServerName(servers));
	removeServers(descriptor->servers, servers, entries);
    }

    if(_traceLevels->application > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->applicationCat);
	out << "removed application `" << name << "'";
    }

    for_each(entries.begin(), entries.end(), IceUtil::voidMemFun(&Database::ServerEntry::sync));
}

ApplicationDescriptorPtr
Database::getApplicationDescriptor(const std::string& name)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringApplicationDescriptorDict descriptors(connection, _descriptorDbName); 
    
    StringApplicationDescriptorDict::const_iterator p = descriptors.find(name);
    if(p == descriptors.end())
    {
	ApplicationNotExistException ex;
	ex.name = name;
	throw ex;
    }

    return p->second;
}

Ice::StringSeq
Database::getAllApplications(const string& expression)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringApplicationDescriptorDict descriptors(connection, _descriptorDbName);
    return getMatchingKeys<StringApplicationDescriptorDict>(descriptors, expression);
}

void 
Database::addNode(const string& name, const NodePrx& node)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringApplicationDescriptorDict descriptors(connection, _descriptorDbName);
    
    while(true)
    {
	NodePrx oldNode;
	try
	{
	    oldNode = getNode(name);
	    oldNode->ice_ping();
	    throw NodeActiveException();
	}
	catch(const NodeNotExistException&)
	{
	}
	catch(const Ice::LocalException&)
	{
	}

	IceUtil::Mutex::Lock sync(*this);

	Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
	StringObjectProxyDict dict(connection, _nodeDbName);

	StringObjectProxyDict::iterator p = dict.find(name);
	if(p != dict.end())
	{
	    if(oldNode && oldNode != p->second)
	    {
		continue;
	    }

	    p.set(node);
	    
	    if(_traceLevels->node > 0)
	    {
		Ice::Trace out(_traceLevels->logger, _traceLevels->nodeCat);
		out << "updated node `" << name << "' proxy";
	    }
	}
	else
	{
	    dict.put(make_pair(name, node));
	    
 	    if(_traceLevels->node > 0)
 	    {
 		Ice::Trace out(_traceLevels->logger, _traceLevels->nodeCat);
 		out << "added node `" << name << "'";
 	    }
	}

	setAdapterDirectProxy("IceGrid.Node." + name, node);
	break;
    }
}

NodePrx 
Database::getNode(const string& name) const
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringObjectProxyDict dict(connection, _nodeDbName); 

    StringObjectProxyDict::iterator p = dict.find(name);
    if(p != dict.end())
    {
	try
	{
	    return NodePrx::checkedCast(p->second);
	}
	catch(const Ice::ObjectNotExistException&)
	{
	}
	catch(const Ice::LocalException&)
	{
	    return NodePrx::uncheckedCast(p->second);
	}
    }
    throw NodeNotExistException();
}

void 
Database::removeNode(const string& name)
{
    //
    // TODO: Remove the node servers
    //

    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringObjectProxyDict dict(connection, _nodeDbName);

    StringObjectProxyDict::iterator p = dict.find(name);
    if(p == dict.end())
    {
	throw NodeNotExistException();
    }
    
    dict.erase(p);

    setAdapterDirectProxy("IceGrid.Node." + name, 0);
    
    if(_traceLevels->node > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->nodeCat);
 	out << "removed node `" << name << "'";
    }
}

Ice::StringSeq 
Database::getAllNodes(const string& expression)
{
    set<string> nodes;
    {
	Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
	StringObjectProxyDict dict(connection, _nodeDbName); 
	Ice::StringSeq r = getMatchingKeys<StringObjectProxyDict>(dict, expression);
	nodes.insert(r.begin(), r.end());
    }
    {
	Lock sync(*this);
	Ice::StringSeq r = getMatchingKeys<map<string, set<string> > >(_serversByNode, expression);
	nodes.insert(r.begin(), r.end());
    }
    return Ice::StringSeq(nodes.begin(), nodes.end());
}

InstanceDescriptor
Database::getServerDescriptor(const std::string& name)
{
    ServerDescriptorPtr descriptor;
    {
	Lock sync(*this);
	map<string, ServerEntryPtr>::const_iterator p = _servers.find(name);
	if(p == _servers.end())
	{
	    ServerNotExistException ex;
	    ex.name = name;
	    throw ex;
	}
	descriptor = p->second->getDescriptor();
    }
    assert(descriptor);
    ApplicationDescriptorPtr app = getApplicationDescriptor(descriptor->application);
    for(InstanceDescriptorSeq::const_iterator p = app->servers.begin(); p != app->servers.end(); ++p)
    {
	if(p->descriptor->name == descriptor->name)
	{
	    return *p;
	}
    }

    ServerNotExistException ex;
    ex.name = name;
    throw ex;
}

ServerPrx
Database::getServer(const string& name)
{
    ServerEntryPtr entry;
    {
	Lock sync(*this);
	map<string, ServerEntryPtr>::const_iterator p = _servers.find(name);
	if(p != _servers.end())
	{
	    entry = p->second;
	}
    }
    if(!entry)
    {
	ServerNotExistException ex;
	ex.name = name;
	throw ex;
    }
    return entry->getProxy();
}

Ice::StringSeq
Database::getAllServers(const string& expression)
{
    Lock sync(*this);
    return getMatchingKeys<map<string, ServerEntryPtr> >(_servers, expression);
}

Ice::StringSeq
Database::getAllNodeServers(const string& node)
{
    Lock sync(*this);
    map<string, set<string> >::const_iterator p = _serversByNode.find(node);
    if(p == _serversByNode.end())
    {
	return Ice::StringSeq();
    }
    return Ice::StringSeq(p->second.begin(), p->second.end());
}

void
Database::setAdapterDirectProxy(const string& id, const Ice::ObjectPrx& proxy)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringObjectProxyDict adapters(connection, _adapterDbName); 
    if(proxy)
    {
	StringObjectProxyDict::iterator p = adapters.find(id);
	if(p != adapters.end())
	{
	    p.set(proxy);

	    if(_traceLevels->adapter > 0)
	    {
		Ice::Trace out(_traceLevels->logger, _traceLevels->adapterCat);
		out << "added adapter `" << id << "'";
	    }
	}
	else
	{
	    adapters.put(make_pair(id, proxy));

	    if(_traceLevels->adapter > 0)
	    {
		Ice::Trace out(_traceLevels->logger, _traceLevels->adapterCat);
		out << "updated adapter `" << id << "'";
	    }
	}
    }
    else
    {
	adapters.erase(id);
    }
}

Ice::ObjectPrx
Database::getAdapterDirectProxy(const string& id)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringObjectProxyDict adapters(connection, _adapterDbName); 
    StringObjectProxyDict::const_iterator p = adapters.find(id);
    if(p != adapters.end())
    {
	return p->second;
    }
    return 0;
}

AdapterPrx
Database::getAdapter(const string& id)
{
    //
    // TODO: Perhaps we should also cache the adapter proxies here
    // instead of doing multiple lookups.
    //

    //
    // First we check if the given adapter id is associated to a
    // server, if that's the case we get the adapter proxy from the
    // server.
    //
    ServerEntryPtr entry;
    {
	Lock sync(*this);
	map<string, ServerEntryPtr>::const_iterator p = _serversByAdapterId.find(id);
	if(p != _serversByAdapterId.end())
	{
	    entry = p->second;
	}
    }
    if(entry)
    {
	return entry->getAdapter(id);
    }

    //
    // Otherwise, we check the adapter endpoint table -- if there's an
    // entry the adapter is managed by the registry itself.
    //
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    StringObjectProxyDict adapters(connection, _adapterDbName); 
    if(adapters.find(id) != adapters.end())
    {
	Ice::Identity identity;
	identity.category = "IceGridAdapter";
	identity.name = id;
	return AdapterPrx::uncheckedCast(_internalAdapter->createDirectProxy(identity));
    }

    AdapterNotExistException ex;
    ex.id = id;
    throw ex;
}

Ice::StringSeq
Database::getAllAdapters(const string& expression)
{
    Lock sync(*this);
    vector<string> result;
    vector<string> ids;
    ids = getMatchingKeys<map<string, ServerEntryPtr> >(_serversByAdapterId, expression);
    result.swap(ids);
    ids = getMatchingKeys<StringObjectProxyDict>(_adapters, expression);
    result.insert(result.end(), ids.begin(), ids.end());
    return result;
}

void
Database::addObjectDescriptor(const ObjectDescriptor& object)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName); 
    const Ice::Identity id = object.proxy->ice_getIdentity();
    if(objects.find(id) != objects.end())
    {
	ObjectExistsException ex;
	ex.id = id;
	throw ex;
    }
    objects.put(make_pair(id, object));

    if(_traceLevels->object > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->objectCat);
	out << "added object `" << Ice::identityToString(id) << "'";
    }
}

void
Database::removeObjectDescriptor(const Ice::Identity& id)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName); 
    if(objects.find(id) == objects.end())
    {
	ObjectNotExistException ex;
	ex.id = id;
	throw ex;
    }
    objects.erase(id);

    if(_traceLevels->object > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->objectCat);
	out << "removed object `" << Ice::identityToString(id) << "'";
    }
}

void
Database::updateObjectDescriptor(const Ice::ObjectPrx& proxy)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName); 
    const Ice::Identity id = proxy->ice_getIdentity();
    IdentityObjectDescDict::iterator p = objects.find(id);
    if(p == objects.end())
    {
	ObjectNotExistException ex;
	ex.id = id;
	throw ex;
    }
    ObjectDescriptor desc = p->second;
    desc.proxy = proxy;
    p.set(desc);

    if(_traceLevels->object > 0)
    {
	Ice::Trace out(_traceLevels->logger, _traceLevels->objectCat);
	out << "updated object `" << Ice::identityToString(id) << "'";
    }
}

ObjectDescriptor
Database::getObjectDescriptor(const Ice::Identity& id)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName);    
    IdentityObjectDescDict::const_iterator p = objects.find(id);
    if(p == objects.end())
    {
	ObjectNotExistException ex;
	ex.id = id;
	throw ex;
    }
    return p->second;
}

Ice::ObjectPrx
Database::getObjectByType(const string& type)
{
    Ice::ObjectProxySeq objs = getObjectsWithType(type);
    return objs[rand() % objs.size()];
}

Ice::ObjectProxySeq
Database::getObjectsWithType(const string& type)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName);    
    Ice::ObjectProxySeq proxies;
    for(IdentityObjectDescDict::const_iterator p = objects.findByType(type); p != objects.end(); ++p)
    {
	proxies.push_back(p->second.proxy);
    }
    if(proxies.empty())
    {
	throw ObjectNotExistException();
    }
    return proxies;
}

ObjectDescriptorSeq
Database::getAllObjectDescriptors(const string& expression)
{
    Freeze::ConnectionPtr connection = Freeze::createConnection(_communicator, _envName);
    IdentityObjectDescDict objects(connection, _objectDbName); 
    ObjectDescriptorSeq descriptors;
    for(IdentityObjectDescDict::const_iterator p = objects.begin(); p != objects.end(); ++p)
    {
	if(expression.empty() ||
	   IceUtil::match(Ice::identityToString(p->second.proxy->ice_getIdentity()), expression, true))
	{
	    descriptors.push_back(p->second);
	}
    }
    return descriptors;
}

void
Database::checkServerForAddition(const string& name)
{
    if(_servers.find(name) != _servers.end())
    {
	ServerExistsException ex;
	ex.name = name;
	throw ex;
    }
}

void
Database::checkAdapterForAddition(const string& id)
{
    if(_serversByAdapterId.find(id) != _serversByAdapterId.end() || _adapters.find(id) != _adapters.end())
    {
	AdapterExistsException ex;
	ex.id = id;
	throw ex;
    }
}

void
Database::checkObjectForAddition(const Ice::Identity& objectId)
{
    if(_objects.find(objectId) != _objects.end())
    {
	ObjectExistsException ex;
	ex.id = objectId;
	throw ex;
    }
}

void 
Database::addServers(const InstanceDescriptorSeq& servers, const set<string>& names, ServerEntrySeq& entries)
{
    for(InstanceDescriptorSeq::const_iterator p = servers.begin(); p != servers.end(); ++p)
    {
	if(names.find(p->descriptor->name) == names.end())
	{
	    continue;
	}
	entries.push_back(addServer(*p));
    }
}

void 
Database::updateServers(const ApplicationDescriptorPtr& oldAppDesc, const ApplicationDescriptorPtr& newAppDesc,
			const set<string>& names, ServerEntrySeq& entries)
{
    ApplicationDescriptorHelper oldAppDescHelper(_communicator, oldAppDesc);
    ApplicationDescriptorHelper newAppDescHelper(_communicator, newAppDesc);

    for(InstanceDescriptorSeq::const_iterator p = newAppDesc->servers.begin(); p != newAppDesc->servers.end(); ++p)
    {
	if(names.find(p->descriptor->name) == names.end())
	{
	    continue;
	}

	for(InstanceDescriptorSeq::const_iterator q = oldAppDesc->servers.begin(); q != oldAppDesc->servers.end(); ++q)
	{
	    if(p->descriptor->name == q->descriptor->name)
	    {
		if(ServerDescriptorHelper(oldAppDescHelper, ServerDescriptorPtr::dynamicCast(q->descriptor)) !=
		   ServerDescriptorHelper(newAppDescHelper, ServerDescriptorPtr::dynamicCast(p->descriptor)))
		{
		    entries.push_back(updateServer(*p));
		}
		break;
	    }
	}
    }
}

void
Database::removeServers(const InstanceDescriptorSeq& servers, const set<string>& names, ServerEntrySeq& entries)
{
    for(InstanceDescriptorSeq::const_iterator p = servers.begin(); p != servers.end(); ++p)
    {
	if(names.find(p->descriptor->name) == names.end())
	{
	    continue;
	}
	entries.push_back(removeServer(*p));
    }
}

Database::ServerEntryPtr
Database::addServer(const InstanceDescriptor& instance)
{
    const ServerDescriptorPtr descriptor = ServerDescriptorPtr::dynamicCast(instance.descriptor);
    ServerEntryPtr entry;
    map<string, ServerEntryPtr>::const_iterator q = _servers.find(descriptor->name);
    if(q != _servers.end())
    {
	entry = q->second;
	entry->update(descriptor);
    }
    else
    {
	entry = new ServerEntry(*this, descriptor);
	_servers.insert(make_pair(descriptor->name, entry));
    }
    
    map<string, set<string> >::iterator p = _serversByNode.find(descriptor->node);
    if(p == _serversByNode.end())
    {
	p = _serversByNode.insert(make_pair(descriptor->node, set<string>())).first;
    }
    p->second.insert(p->second.begin(), descriptor->name);

    forEachComponent(AddComponent(*this, entry))(instance);
    return entry;
}

Database::ServerEntryPtr
Database::updateServer(const InstanceDescriptor& instance)
{
    //
    // Get the server entry and the current descriptor then check
    // if the server descriptor really changed.	
    //
    const ServerDescriptorPtr descriptor = ServerDescriptorPtr::dynamicCast(instance.descriptor);
    ServerEntryPtr entry;
    map<string, ServerEntryPtr>::const_iterator q = _servers.find(descriptor->name);
    assert(q != _servers.end());

    entry = q->second;
    ServerDescriptorPtr old = entry->getDescriptor();

    //
    // If the node changed, move the server from the old node to the
    // new one.
    //
    if(old->node != descriptor->node)
    {
	map<string, set<string> >::iterator p = _serversByNode.find(old->node);
	assert(p != _serversByNode.end());
	p->second.erase(old->name);
	if(p->second.empty())
	{
	    _serversByNode.erase(p);
	}
	p = _serversByNode.find(descriptor->node);
	if(p == _serversByNode.end())
	{
	    p = _serversByNode.insert(make_pair(descriptor->node, set<string>())).first;
	}
	p->second.insert(p->second.begin(), descriptor->name);
    }
    
    //
    // Remove the object adapters and objects from the old descriptor. 
    //
    forEachComponent(objFunc(*this, &Database::removeComponent))(old);
    
    //
    // Update the server entry.
    //
    entry->update(descriptor);

    //
    // Add the new object adapters and objects.
    //
    forEachComponent(AddComponent(*this, entry))(instance);
    return entry;
}

Database::ServerEntryPtr
Database::removeServer(const InstanceDescriptor& instance)
{
    const ServerDescriptorPtr descriptor = ServerDescriptorPtr::dynamicCast(instance.descriptor);
    ServerEntryPtr entry;
    map<string, ServerEntryPtr>::iterator q = _servers.find(descriptor->name);
    assert(q != _servers.end());
    
    map<string, set<string> >::iterator p = _serversByNode.find(descriptor->node);
    assert(p != _serversByNode.end());
    p->second.erase(descriptor->name);
    if(p->second.empty())
    {
	_serversByNode.erase(p);
    }
    
    entry = q->second;
    entry->update(0);
    
    //
    // Remove the object adapters and objects.
    //
    forEachComponent(objFunc(*this, &Database::removeComponent))(instance);
    return entry;
}

void
Database::clearServer(const std::string& name)
{
    Lock sync(*this);
    map<string, ServerEntryPtr>::iterator p = _servers.find(name);
    if(p != _servers.end())
    {
	if(p->second->canRemove())
	{
	    _servers.erase(p);
	}
    }
}

void
Database::addComponent(const ServerEntryPtr& entry, const ComponentDescriptorPtr& component)
{
    for(AdapterDescriptorSeq::const_iterator q = component->adapters.begin() ; q != component->adapters.end(); ++q)
    {
	_serversByAdapterId.insert(make_pair(q->id, entry));
	for(ObjectDescriptorSeq::const_iterator r = q->objects.begin(); r != q->objects.end(); ++r)
	{
	    _objects.put(make_pair(r->proxy->ice_getIdentity(), *r));
	}
    }
}

void
Database::removeComponent(const ComponentDescriptorPtr& component)
{
    for(AdapterDescriptorSeq::const_iterator q = component->adapters.begin() ; q != component->adapters.end(); ++q)
    {
	_serversByAdapterId.erase(q->id);
	for(ObjectDescriptorSeq::const_iterator r = q->objects.begin(); r != q->objects.end(); ++r)
	{
	    _objects.erase(r->proxy->ice_getIdentity());
	}
    }
}

Database::ServerEntry::ServerEntry(Database& database, const ServerDescriptorPtr& descriptor) :
    _database(database), 
    _load(descriptor),
    _synchronizing(false)
{
}

void
Database::ServerEntry::sync()
{
    map<string, AdapterPrx> adapters;
    try
    {
	sync(adapters);
    }
    catch(const NodeUnreachableException&)
    {
    }
}

void
Database::ServerEntry::update(const ServerDescriptorPtr& descriptor)
{
    Lock sync(*this);
    if(_loaded && (!descriptor || descriptor->node != _loaded->node))
    {
	assert(!_destroy);
	_destroy = _loaded;
    }
    else if(_load && (!descriptor || descriptor->node != _load->node))
    {
	assert(!_destroy);
	_destroy = _load;
    }

    _load = descriptor;
    _loaded = 0;
    _proxy = 0;
    _adapters.clear();
}

ServerDescriptorPtr
Database::ServerEntry::getDescriptor()
{
    Lock sync(*this);
    if(_proxy)
    {
	return _loaded;
    }
    else 
    {
	return _load;
    }
}

ServerPrx
Database::ServerEntry::getProxy()
{
    ServerPrx proxy;
    {
	Lock sync(*this);
	if(_proxy) // Synced
	{
	    proxy = _proxy;
	}
    }

    if(proxy)
    {
	try
	{
	    proxy->ice_ping();
	    return proxy;
	}
	catch(const Ice::LocalException& ex)
	{
	}
    }

    StringAdapterPrxDict adapters;
    return sync(adapters);
}

AdapterPrx
Database::ServerEntry::getAdapter(const string& id)
{
    AdapterPrx proxy;
    {
	Lock sync(*this);
	if(_proxy) // Synced
	{
	    proxy = _adapters[id];
	}
    }

    if(proxy)
    {
	try
	{
	    proxy->ice_ping();
	    return proxy;
	}
	catch(const Ice::LocalException& ex)
	{
	}
    }

    StringAdapterPrxDict adapters;
    sync(adapters);
    return adapters[id];
}

ServerPrx
Database::ServerEntry::sync(map<string, AdapterPrx>& adapters)
{
    ServerDescriptorPtr load;
    ServerDescriptorPtr destroy;
    {
	Lock sync(*this);
	while(_synchronizing)
	{
	    wait();
	}

	if(!_load && !_destroy)
	{
	    _load = _loaded; // Re-load the current server.
	}

	_synchronizing = true;
	load = _load;
	destroy = _destroy;
    }

    ServerPrx proxy;
    try
    {
	if(destroy)
	{
	    try
	    {
		_database.getNode(destroy->node)->destroyServer(destroy);
	    }
	    catch(const NodeNotExistException& ex)
	    {
		if(!load)
		{
		    throw NodeUnreachableException();
		}
	    }
	    catch(Ice::LocalException& ex)
	    {
		if(!load)
		{
		    throw NodeUnreachableException();
		}
	    }
	}

	if(load)
	{
	    try
	    {
		proxy = _database.getNode(load->node)->loadServer(load, adapters);
	    }
	    catch(const NodeNotExistException& ex)
	    {
		throw NodeUnreachableException();
	    }
	    catch(Ice::LocalException& ex)
	    {
		throw NodeUnreachableException();
	    }
	}
    }
    catch(const NodeUnreachableException& ex)
    {
	{
	    Lock sync(*this);
	    _synchronizing = false;
	    _destroy = 0;
	    notifyAll();
	}
	if(!load && destroy)
	{
	    _database.clearServer(destroy->name);
	}
	throw;
    }

    {
	Lock sync(*this);
	_synchronizing = false;
	_loaded = _load;
	_load = 0;
	_destroy = 0;
	_proxy = proxy;
	_adapters = adapters;
	notifyAll();
    }
    if(!load && destroy)
    {
	_database.clearServer(destroy->name);
    }
    return proxy;
}

bool
Database::ServerEntry::canRemove()
{
     Lock sync(*this);
     return !_loaded && !_load && !_destroy;
}