/***************************************************************************
 *   Copyright (C) 2005 by Joris Guisson                                   *
 *   joris.guisson@gmail.com                                               *
 *                                                                         *
 *   This program 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 2 of the License, or     *
 *   (at your option) 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ***************************************************************************/
#include <util/functions.h>
#include <util/log.h>
#include <torrent/globals.h>
#include "database.h"

using namespace bt;

namespace dht
{
	DBItem::DBItem()
	{
		memset(item,0,9);
		time_stamp = bt::GetCurrentTime();
	}
	
	DBItem::DBItem(const bt::Uint8* ip_port)
	{
		memcpy(item,ip_port,6);
		time_stamp = bt::GetCurrentTime();
	}
	
	DBItem::DBItem(const DBItem & it)
	{
		memcpy(item,it.item,6);
		time_stamp = it.time_stamp;	
	}
	
	DBItem::~DBItem()
	{}
		
	bool DBItem::expired(bt::TimeStamp now) const
	{
		return (now - time_stamp >= MAX_ITEM_AGE);
	}
	
	DBItem & DBItem::operator = (const DBItem & it)
	{
		memcpy(item,it.item,6);
		time_stamp = it.time_stamp;	
		return *this;
	}

	///////////////////////////////////////////////
	
	Database::Database()
	{
		items.setAutoDelete(true);
	}


	Database::~Database()
	{}

	void Database::store(const dht::Key & key,const DBItem & dbi)
	{
		DBItemList* dbl = items.find(key);
		if (!dbl)
		{
			dbl = new DBItemList();
			items.insert(key,dbl);
		}
		dbl->append(dbi);
	}
	
	void Database::sample(const dht::Key & key,DBItemList & tdbl,bt::Uint32 max_entries)
	{
		DBItemList* dbl = items.find(key);
		if (!dbl)
			return;
		
		if (dbl->count() < max_entries)
		{
			DBItemList::iterator i = dbl->begin();
			while (i != dbl->end())
			{
				tdbl.append(*i);
				i++;
			}
		}
		else
		{
			Uint32 num_added = 0;
			DBItemList::iterator i = dbl->begin();
			while (i != dbl->end() && num_added < max_entries)
			{
				tdbl.append(*i);
				num_added++;
				i++;
			}
		}
	}
	
	void Database::expire(bt::TimeStamp now)
	{
		bt::PtrMap<dht::Key,DBItemList>::iterator itr = items.begin();
		while (itr != items.end())
		{
			DBItemList* dbl = itr->second;
			// newer keys are inserted at the back
			// so we can stop when we hit the first key which is not expired
			while (dbl->count() > 0 && dbl->first().expired(now))
			{
				dbl->pop_front();
			}
			itr++;
		}
	}
	
	dht::Key Database::genToken(Uint32 ip,Uint16 port)
	{
		Uint8 tdata[14];
		TimeStamp now = bt::GetCurrentTime();
		// generate a hash of the ip port and the current time
		// should prevent anybody from crapping things up
		bt::WriteUint32(tdata,0,ip);
		bt::WriteUint16(tdata,4,port);
		bt::WriteUint64(tdata,6,now);
			
		dht::Key token = SHA1Hash::generate(tdata,14);
		// keep track of the token, tokens will expire after a while
		tokens.insert(token,now);
		return token;
	}
	
	bool Database::checkToken(const dht::Key & token,Uint32 ip,Uint16 port)
	{
		// the token must be in the map
		if (!tokens.contains(token))
		{
			Out(SYS_DHT|LOG_DEBUG) << "Unknown token" << endl;
			return false;
		}
		
		// in the map so now get the timestamp and regenerate the token
		// using the IP and port of the sender
		TimeStamp ts = tokens[token];
		Uint8 tdata[14];
		bt::WriteUint32(tdata,0,ip);
		bt::WriteUint16(tdata,4,port);
		bt::WriteUint64(tdata,6,ts);
		dht::Key ct = SHA1Hash::generate(tdata,14);
		// compare the generated token to the one received
		if (token != ct)  // not good, this peer didn't went through the proper channels
		{
			Out(SYS_DHT|LOG_DEBUG) << "Invalid token" << endl;
			return false;
		}
		// expire the token
		tokens.erase(token);
		return true;
	}
	
	bool Database::contains(const dht::Key & key) const
	{
		return items.find(key) != 0;
	}
	
	void Database::insert(const dht::Key & key)
	{
		DBItemList* dbl = items.find(key);
		if (!dbl)
		{
			dbl = new DBItemList();
			items.insert(key,dbl);
		}
	}
}