/*
	This file is part of cpp-ethereum.

	cpp-ethereum 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
	(at your option) any later version.

	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file DownloadMan.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#include "DownloadMan.h"
using namespace std;
using namespace dev;
using namespace dev::eth;

size_t const c_maxDownloadAhead = 50000; // Must not be higher than BlockQueue::c_maxUnknownCount

DownloadMan::Overview DownloadMan::overview() const
{
	ReadGuard l(m_lock);
	Overview ret;
	ret.firstIncomplete = m_blocksGot.firstOut();
	ret.lastComplete = ret.lastStarted = m_blocksGot.lastIn();// TODO: lastStarted properly
	ret.total = m_blocksGot.size();
	return ret;
}

DownloadSub::DownloadSub(DownloadMan& _man): m_man(&_man)
{
	WriteGuard l(m_man->x_subs);
	m_man->m_subs.insert(this);
}

DownloadSub::~DownloadSub()
{
	Guard fl(m_fetch);
	if (m_man)
	{
		WriteGuard l(m_man->x_subs);
		m_man->m_subs.erase(this);
	}
}

h256Hash DownloadSub::nextFetch(unsigned _n)
{
	Guard l(m_fetch);

	if (m_remaining.size())
		return m_remaining;

	m_asked.clear();
	m_indices.clear();
	m_remaining.clear();

	if (!m_man || m_man->chainEmpty())
		return h256Hash();

	RangeMask<unsigned> downloaded = m_man->taken(true);
	m_asked = (~(m_man->taken(false) + m_attempted)).lowest(_n);
	if (m_asked.empty() || m_asked.lastIn() - downloaded.firstOut() >= c_maxDownloadAhead)
		m_asked = (~(downloaded + m_attempted)).lowest(_n);
	m_attempted += m_asked;
	for (auto i: m_asked)
	{
		auto x = m_man->m_chain[i];
		m_remaining.insert(x);
		m_indices[x] = i;
	}
	return m_remaining;
}

bool DownloadSub::noteBlock(h256 _hash)
{
	Guard l(m_fetch);
	if (m_man && m_indices.count(_hash))
		m_man->m_blocksGot += m_indices[_hash];
	bool ret = !!m_remaining.count(_hash);
	m_remaining.erase(_hash);
	return ret;
}