/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
Copyright (C) 2010-2013 kwolekr, Ryan Kwolek <kwolekr@minetest.net>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser 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 "emerge.h"

#include <iostream>
#include <queue>

#include "util/container.h"
#include "util/thread.h"
#include "threading/event.h"

#include "config.h"
#include "constants.h"
#include "environment.h"
#include "log.h"
#include "map.h"
#include "mapblock.h"
#include "mapgen/mg_biome.h"
#include "mapgen/mg_ore.h"
#include "mapgen/mg_decoration.h"
#include "mapgen/mg_schematic.h"
#include "nodedef.h"
#include "profiler.h"
#include "scripting_server.h"
#include "server.h"
#include "serverobject.h"
#include "settings.h"
#include "voxel.h"

class EmergeThread : public Thread {
public:
	bool enable_mapgen_debug_info;
	int id;

	EmergeThread(Server *server, int ethreadid);
	~EmergeThread() = default;

	void *run();
	void signal();

	// Requires queue mutex held
	bool pushBlock(const v3s16 &pos);

	void cancelPendingItems();

	static void runCompletionCallbacks(
		const v3s16 &pos, EmergeAction action,
		const EmergeCallbackList &callbacks);

private:
	Server *m_server;
	ServerMap *m_map;
	EmergeManager *m_emerge;
	Mapgen *m_mapgen;

	Event m_queue_event;
	std::queue<v3s16> m_block_queue;

	bool popBlockEmerge(v3s16 *pos, BlockEmergeData *bedata);

	EmergeAction getBlockOrStartGen(
		const v3s16 &pos, bool allow_gen, MapBlock **block, BlockMakeData *data);
	MapBlock *finishGen(v3s16 pos, BlockMakeData *bmdata,
		std::map<v3s16, MapBlock *> *modified_blocks);

	friend class EmergeManager;
};

class MapEditEventAreaIgnorer
{
public:
	MapEditEventAreaIgnorer(VoxelArea *ignorevariable, const VoxelArea &a):
		m_ignorevariable(ignorevariable)
	{
		if(m_ignorevariable->getVolume() == 0)
			*m_ignorevariable = a;
		else
			m_ignorevariable = NULL;
	}

	~MapEditEventAreaIgnorer()
	{
		if(m_ignorevariable)
		{
			assert(m_ignorevariable->getVolume() != 0);
			*m_ignorevariable = VoxelArea();
		}
	}

private:
	VoxelArea *m_ignorevariable;
};

////
//// EmergeManager
////

EmergeManager::EmergeManager(Server *server)
{
	this->ndef      = server->getNodeDefManager();
	this->biomemgr  = new BiomeManager(server);
	this->oremgr    = new OreManager(server);
	this->decomgr   = new DecorationManager(server);
	this->schemmgr  = new SchematicManager(server);

	// Note that accesses to this variable are not synchronized.
	// This is because the *only* thread ever starting or stopping
	// EmergeThreads should be the ServerThread.

	enable_mapgen_debug_info = g_settings->getBool("enable_mapgen_debug_info");

	// If unspecified, leave a proc for the main thread and one for
	// some other misc thread
	s16 nthreads = 0;
	if (!g_settings->getS16NoEx("num_emerge_threads", nthreads))
		nthreads = Thread::getNumberOfProcessors() - 2;
	if (nthreads < 1)
		nthreads = 1;

	m_qlimit_total = g_settings->getU16("emergequeue_limit_total");
	if (!g_settings->getU16NoEx("emergequeue_limit_diskonly", m_qlimit_diskonly))
		m_qlimit_diskonly = nthreads * 5 + 1;
	if (!g_settings->getU16NoEx("emergequeue_limit_generate", m_qlimit_generate))
		m_qlimit_generate = nthreads + 1;

	// don't trust user input for something very important like this
	if (m_qlimit_total < 1)
		m_qlimit_total = 1;
	if (m_qlimit_diskonly < 1)
		m_qlimit_diskonly = 1;
	if (m_qlimit_generate < 1)
		m_qlimit_generate = 1;

	for (s16 i = 0; i < nthreads; i++)
		m_threads.push_back(new EmergeThread(server, i));

	infostream << "EmergeManager: using " << nthreads << " threads" << std::endl;
}


EmergeManager::~EmergeManager()
{
	for (u32 i = 0; i != m_threads.size(); i++) {
		EmergeThread *thread = m_threads[i];

		if (m_threads_active) {
			thread->stop();
			thread->signal();
			thread->wait();
		}

		delete thread;
		delete m_mapgens[i];
	}

	delete biomemgr;
	delete oremgr;
	delete decomgr;
	delete schemmgr;
}


bool EmergeManager::initMapgens(MapgenParams *params)
{
	if (!m_mapgens.empty())
		return false;

	this->mgparams = params;

	for (u32 i = 0; i != m_threads.size(); i++) {
		Mapgen *mg = Mapgen::createMapgen(params->mgtype, i, params, this);
		m_mapgens.push_back(mg);
	}

	return true;
}


Mapgen *EmergeManager::getCurrentMapgen()
{
	if (!m_threads_active)
		return NULL;

	for (u32 i = 0; i != m_threads.size(); i++) {
		if (m_threads[i]->isCurrentThread())
			return m_threads[i]->m_mapgen;
	}

	return NULL;
}


void EmergeManager::startThreads()
{
	if (m_threads_active)
		return;

	for (u32 i = 0; i != m_threads.size(); i++)
		m_threads[i]->start();

	m_threads_active = true;
}


void EmergeManager::stopThreads()
{
	if (!m_threads_active)
		return;

	// Request thread stop in parallel
	for (u32 i = 0; i != m_threads.size(); i++) {
		m_threads[i]->stop();
		m_threads[i]->signal();
	}

	// Then do the waiting for each
	for (u32 i = 0; i != m_threads.size(); i++)
		m_threads[i]->wait();

	m_threads_active = false;
}


bool EmergeManager::isRunning()
{
	return m_threads_active;
}


bool EmergeManager::enqueueBlockEmerge(
	session_t peer_id,
	v3s16 blockpos,
	bool allow_generate,
	bool ignore_queue_limits)
{
	u16 flags = 0;
	if (allow_generate)
		flags |= BLOCK_EMERGE_ALLOW_GEN;
	if (ignore_queue_limits)
		flags |= BLOCK_EMERGE_FORCE_QUEUE;

	return enqueueBlockEmergeEx(blockpos, peer_id, flags, NULL, NULL);
}


bool EmergeManager::enqueueBlockEmergeEx(
	v3s16 blockpos,
	session_t peer_id,
	u16 flags,
	EmergeCompletionCallback callback,
	void *callback_param)
{
	EmergeThread *thread = NULL;
	bool entry_already_exists = false;

	{
		MutexAutoLock queuelock(m_queue_mutex);

		if (!pushBlockEmergeData(blockpos, peer_id, flags,
				callback, callback_param, &entry_already_exists))
			return false;

		if (entry_already_exists)
			return true;

		thread = getOptimalThread();
		thread->pushBlock(blockpos);
	}

	thread->signal();

	return true;
}


//
// Mapgen-related helper functions
//


// TODO(hmmmm): Move this to ServerMap
v3s16 EmergeManager::getContainingChunk(v3s16 blockpos)
{
	return getContainingChunk(blockpos, mgparams->chunksize);
}

// TODO(hmmmm): Move this to ServerMap
v3s16 EmergeManager::getContainingChunk(v3s16 blockpos, s16 chunksize)
{
	s16 coff = -chunksize / 2;
	v3s16 chunk_offset(coff, coff, coff);

	return getContainerPos(blockpos - chunk_offset, chunksize)
		* chunksize + chunk_offset;
}


int EmergeManager::getSpawnLevelAtPoint(v2s16 p)
{
	if (m_mapgens.empty() || !m_mapgens[0]) {
		errorstream << "EmergeManager: getSpawnLevelAtPoint() called"
			" before mapgen init" << std::endl;
		return 0;
	}

	return m_mapgens[0]->getSpawnLevelAtPoint(p);
}


int EmergeManager::getGroundLevelAtPoint(v2s16 p)
{
	if (m_mapgens.empty() || !m_mapgens[0]) {
		errorstream << "EmergeManager: getGroundLevelAtPoint() called"
			" before mapgen init" << std::endl;
		return 0;
	}

	return m_mapgens[0]->getGroundLevelAtPoint(p);
}

// TODO(hmmmm): Move this to ServerMap
bool EmergeManager::isBlockUnderground(v3s16 blockpos)
{
#if 0
	v2s16 p = v2s16((blockpos.X * MAP_BLOCKSIZE) + MAP_BLOCKSIZE / 2,
					(blockpos.Y * MAP_BLOCKSIZE) + MAP_BLOCKSIZE / 2);
	int ground_level = getGroundLevelAtPoint(p);
	return blockpos.Y * (MAP_BLOCKSIZE + 1) <= min(water_level, ground_level);
#endif

	// Use a simple heuristic; the above method is wildly inaccurate anyway.
	return blockpos.Y * (MAP_BLOCKSIZE + 1) <= mgparams->water_level;
}

bool EmergeManager::pushBlockEmergeData(
	v3s16 pos,
	u16 peer_requested,
	u16 flags,
	EmergeCompletionCallback callback,
	void *callback_param,
	bool *entry_already_exists)
{
	u16 &count_peer = m_peer_queue_count[peer_requested];

	if ((flags & BLOCK_EMERGE_FORCE_QUEUE) == 0) {
		if (m_blocks_enqueued.size() >= m_qlimit_total)
			return false;

		if (peer_requested != PEER_ID_INEXISTENT) {
			u16 qlimit_peer = (flags & BLOCK_EMERGE_ALLOW_GEN) ?
				m_qlimit_generate : m_qlimit_diskonly;
			if (count_peer >= qlimit_peer)
				return false;
		}
	}

	std::pair<std::map<v3s16, BlockEmergeData>::iterator, bool> findres;
	findres = m_blocks_enqueued.insert(std::make_pair(pos, BlockEmergeData()));

	BlockEmergeData &bedata = findres.first->second;
	*entry_already_exists   = !findres.second;

	if (callback)
		bedata.callbacks.emplace_back(callback, callback_param);

	if (*entry_already_exists) {
		bedata.flags |= flags;
	} else {
		bedata.flags = flags;
		bedata.peer_requested = peer_requested;

		count_peer++;
	}

	return true;
}


bool EmergeManager::popBlockEmergeData(v3s16 pos, BlockEmergeData *bedata)
{
	std::map<v3s16, BlockEmergeData>::iterator it;
	std::unordered_map<u16, u16>::iterator it2;

	it = m_blocks_enqueued.find(pos);
	if (it == m_blocks_enqueued.end())
		return false;

	*bedata = it->second;

	it2 = m_peer_queue_count.find(bedata->peer_requested);
	if (it2 == m_peer_queue_count.end())
		return false;

	u16 &count_peer = it2->second;
	assert(count_peer != 0);
	count_peer--;

	m_blocks_enqueued.erase(it);

	return true;
}


EmergeThread *EmergeManager::getOptimalThread()
{
	size_t nthreads = m_threads.size();

	FATAL_ERROR_IF(nthreads == 0, "No emerge threads!");

	size_t index = 0;
	size_t nitems_lowest = m_threads[0]->m_block_queue.size();

	for (size_t i = 1; i < nthreads; i++) {
		size_t nitems = m_threads[i]->m_block_queue.size();
		if (nitems < nitems_lowest) {
			index = i;
			nitems_lowest = nitems;
		}
	}

	return m_threads[index];
}


////
//// EmergeThread
////

EmergeThread::EmergeThread(Server *server, int ethreadid) :
	enable_mapgen_debug_info(false),
	id(ethreadid),
	m_server(server),
	m_map(NULL),
	m_emerge(NULL),
	m_mapgen(NULL)
{
	m_name = "Emerge-" + itos(ethreadid);
}


void EmergeThread::signal()
{
	m_queue_event.signal();
}


bool EmergeThread::pushBlock(const v3s16 &pos)
{
	m_block_queue.push(pos);
	return true;
}


void EmergeThread::cancelPendingItems()
{
	MutexAutoLock queuelock(m_emerge->m_queue_mutex);

	while (!m_block_queue.empty()) {
		BlockEmergeData bedata;
		v3s16 pos;

		pos = m_block_queue.front();
		m_block_queue.pop();

		m_emerge->popBlockEmergeData(pos, &bedata);

		runCompletionCallbacks(pos, EMERGE_CANCELLED, bedata.callbacks);
	}
}


void EmergeThread::runCompletionCallbacks(const v3s16 &pos, EmergeAction action,
	const EmergeCallbackList &callbacks)
{
	for (size_t i = 0; i != callbacks.size(); i++) {
		EmergeCompletionCallback callback;
		void *param;

		callback = callbacks[i].first;
		param    = callbacks[i].second;

		callback(pos, action, param);
	}
}


bool EmergeThread::popBlockEmerge(v3s16 *pos, BlockEmergeData *bedata)
{
	MutexAutoLock queuelock(m_emerge->m_queue_mutex);

	if (m_block_queue.empty())
		return false;

	*pos = m_block_queue.front();
	m_block_queue.pop();

	m_emerge->popBlockEmergeData(*pos, bedata);

	return true;
}


EmergeAction EmergeThread::getBlockOrStartGen(
	const v3s16 &pos, bool allow_gen, MapBlock **block, BlockMakeData *bmdata)
{
	MutexAutoLock envlock(m_server->m_env_mutex);

	// 1). Attempt to fetch block from memory
	*block = m_map->getBlockNoCreateNoEx(pos);
	if (*block && !(*block)->isDummy()) {
		if ((*block)->isGenerated())
			return EMERGE_FROM_MEMORY;
	} else {
		// 2). Attempt to load block from disk if it was not in the memory
		*block = m_map->loadBlock(pos);
		if (*block && (*block)->isGenerated())
			return EMERGE_FROM_DISK;
	}

	// 3). Attempt to start generation
	if (allow_gen && m_map->initBlockMake(pos, bmdata))
		return EMERGE_GENERATED;

	// All attempts failed; cancel this block emerge
	return EMERGE_CANCELLED;
}


MapBlock *EmergeThread::finishGen(v3s16 pos, BlockMakeData *bmdata,
	std::map<v3s16, MapBlock *> *modified_blocks)
{
	MutexAutoLock envlock(m_server->m_env_mutex);
	ScopeProfiler sp(g_profiler,
		"EmergeThread: after Mapgen::makeChunk", SPT_AVG);

	/*
		Perform post-processing on blocks (invalidate lighting, queue liquid
		transforms, etc.) to finish block make
	*/
	m_map->finishBlockMake(bmdata, modified_blocks);

	MapBlock *block = m_map->getBlockNoCreateNoEx(pos);
	if (!block) {
		errorstream << "EmergeThread::finishGen: Couldn't grab block we "
			"just generated: " << PP(pos) << std::endl;
		return NULL;
	}

	v3s16 minp = bmdata->blockpos_min * MAP_BLOCKSIZE;
	v3s16 maxp = bmdata->blockpos_max * MAP_BLOCKSIZE +
				 v3s16(1,1,1) * (MAP_BLOCKSIZE - 1);

	// Ignore map edit events, they will not need to be sent
	// to anybody because the block hasn't been sent to anybody
	MapEditEventAreaIgnorer ign(
		&m_server->m_ignore_map_edit_events_area,
		VoxelArea(minp, maxp));

	/*
		Run Lua on_generated callbacks
	*/
	try {
		m_server->getScriptIface()->environment_OnGenerated(
			minp, maxp, m_mapgen->blockseed);
	} catch (LuaError &e) {
		m_server->setAsyncFatalError("Lua: finishGen" + std::string(e.what()));
	}

	/*
		Clear generate notifier events
	*/
	Mapgen *mg = m_emerge->getCurrentMapgen();
	mg->gennotify.clearEvents();

	EMERGE_DBG_OUT("ended up with: " << analyze_block(block));

	/*
		Activate the block
	*/
	m_server->m_env->activateBlock(block, 0);

	return block;
}


void *EmergeThread::run()
{
	BEGIN_DEBUG_EXCEPTION_HANDLER

	v3s16 pos;

	m_map    = (ServerMap *)&(m_server->m_env->getMap());
	m_emerge = m_server->m_emerge;
	m_mapgen = m_emerge->m_mapgens[id];
	enable_mapgen_debug_info = m_emerge->enable_mapgen_debug_info;

</span>
<span class="hl com">it under the terms of the GNU Lesser General Public License as published by</span>
<span class="hl com">the Free Software Foundation; either version 2.1 of the License, or</span>
<span class="hl com">(at your option) any later version.</span>
<span class="hl com"></span>
<span class="hl com">This program is distributed in the hope that it will be useful,</span>
<span class="hl com">but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<span class="hl com">MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the</span>
<span class="hl com">GNU Lesser General Public License for more details.</span>
<span class="hl com"></span>
<span class="hl com">You should have received a copy of the GNU Lesser General Public License along</span>
<span class="hl com">with this program; if not, write to the Free Software Foundation, Inc.,</span>
<span class="hl com">51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.</span>
<span class="hl com">*/</span>

<span class="hl ppc">#ifndef NODEDEF_HEADER</span>
<span class="hl ppc">#define NODEDEF_HEADER</span>

<span class="hl ppc">#include</span> <span class="hl pps">&quot;irrlichttypes_bloated.h&quot;</span><span class="hl ppc"></span>
<span class="hl ppc">#include &lt;string&gt;</span>
<span class="hl ppc">#include &lt;iostream&gt;</span>
<span class="hl ppc">#include &lt;map&gt;</span>
<span class="hl ppc">#include &lt;list&gt;</span>
<span class="hl ppc">#include</span> <span class="hl pps">&quot;mapnode.h&quot;</span><span class="hl ppc"></span>
<span class="hl ppc">#ifndef SERVER</span>
<span class="hl ppc">#include</span> <span class="hl pps">&quot;tile.h&quot;</span><span class="hl ppc"></span>
<span class="hl ppc">#endif</span>
<span class="hl ppc">#include</span> <span class=