/* Copyright (C) 2024 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @file
 * Common code and setup code for CCmpPathfinder.
 */

#include "precompiled.h"

#include "CCmpPathfinder_Common.h"

#include "simulation2/MessageTypes.h"
#include "simulation2/components/ICmpObstruction.h"
#include "simulation2/components/ICmpObstructionManager.h"
#include "simulation2/components/ICmpTerrain.h"
#include "simulation2/components/ICmpWaterManager.h"
#include "simulation2/helpers/HierarchicalPathfinder.h"
#include "simulation2/helpers/LongPathfinder.h"
#include "simulation2/helpers/MapEdgeTiles.h"
#include "simulation2/helpers/Rasterize.h"
#include "simulation2/helpers/VertexPathfinder.h"
#include "simulation2/serialization/SerializedPathfinder.h"
#include "simulation2/serialization/SerializedTypes.h"

#include "ps/CLogger.h"
#include "ps/CStr.h"
#include "ps/Profile.h"
#include "ps/XML/Xeromyces.h"
#include "renderer/Scene.h"

#include <type_traits>

REGISTER_COMPONENT_TYPE(Pathfinder)

void CCmpPathfinder::Init(const CParamNode& UNUSED(paramNode))
{
	m_GridSize = 0;
	m_Grid = NULL;
	m_TerrainOnlyGrid = NULL;

	FlushAIPathfinderDirtinessInformation();

	m_NextAsyncTicket = 1;

	m_AtlasOverlay = NULL;

	size_t workerThreads = Threading::TaskManager::Instance().GetNumberOfWorkers();
	// Store one vertex pathfinder for each thread (including the main thread).
	while (m_VertexPathfinders.size() < workerThreads + 1)
		m_VertexPathfinders.emplace_back(m_GridSize, m_TerrainOnlyGrid);
	m_LongPathfinder = std::make_unique<LongPathfinder>();
	m_PathfinderHier = std::make_unique<HierarchicalPathfinder>();

	// Set up one future for each worker thread.
	m_Futures.resize(workerThreads);

	// Register Relax NG validator
	CXeromyces::AddValidator(g_VFS, "pathfinder", "simulation/data/pathfinder.rng");

	// Since this is used as a system component (not loaded from an entity template),
	// we can't use the real paramNode (it won't get handled properly when deserializing),
	// so load the data from a special XML file.
	CParamNode externalParamNode;
	CParamNode::LoadXML(externalParamNode, L"simulation/data/pathfinder.xml", "pathfinder");

	// Paths are computed:
	//  - Before MT_Update
	//  - Before MT_MotionUnitFormation
	//  -  asynchronously between turn end and turn start.
	// The latter of these must compute all outstanding requests, but the former two are capped
	// to avoid spending too much time there (since the latter are threaded and thus much 'cheaper').
	// This loads that maximum number (note that it's per computation call, not per turn for now).
	const CParamNode pathingSettings = externalParamNode.GetChild("Pathfinder");
	m_MaxSameTurnMoves = (u16)pathingSettings.GetChild("MaxSameTurnMoves").ToInt();

	const CParamNode::ChildrenMap& passClasses = externalParamNode.GetChild("Pathfinder").GetChild("PassabilityClasses").GetChildren();
	for (CParamNode::ChildrenMap::const_iterator it = passClasses.begin(); it != passClasses.end(); ++it)
	{
		std::string name = it->first;
		ENSURE((int)m_PassClasses.size() <= PASS_CLASS_BITS);
		pass_class_t mask = PASS_CLASS_MASK_FROM_INDEX(m_PassClasses.size());
		m_PassClasses.push_back(PathfinderPassability(mask, it->second));
		m_PassClassMasks[name] = mask;
	}
}

CCmpPathfinder::~CCmpPathfinder() {};

void CCmpPathfinder::Deinit()
{
	SetDebugOverlay(false); // cleans up memory

	m_Futures.clear();

	SAFE_DELETE(m_AtlasOverlay);

	SAFE_DELETE(m_Grid);
	SAFE_DELETE(m_TerrainOnlyGrid);
}

template<>
struct SerializeHelper<LongPathRequest>
{
	template<typename S>
	void operator()(S& serialize, const char* UNUSED(name), Serialize::qualify<S, LongPathRequest> value)
	{
		serialize.NumberU32_Unbounded("ticket", value.ticket);
		serialize.NumberFixed_Unbounded("x0", value.x0);
		serialize.NumberFixed_Unbounded("z0", value.z0);
		Serializer(serialize, "goal", value.goal);
		serialize.NumberU16_Unbounded("pass class", value.passClass);
		serialize.NumberU32_Unbounded("notify", value.notify);
	}
};

template<>
struct SerializeHelper<ShortPathRequest>
{
	template<typename S>
	void operator()(S& serialize, const char* UNUSED(name), Serialize::qualify<S, ShortPathRequest> value)
	{
		serialize.NumberU32_Unbounded("ticket", value.ticket);
		serialize.NumberFixed_Unbounded("x0", value.x0);
		serialize.NumberFixed_Unbounded("z0", value.z0);
		serialize.NumberFixed_Unbounded("clearance", value.clearance);
		serialize.NumberFixed_Unbounded("range", value.range);
		Serializer(serialize, "goal", value.goal);
		serialize.NumberU16_Unbounded("pass class", value.passClass);
		serialize.Bool("avoid moving units", value.avoidMovingUnits);
		serialize.NumberU32_Unbounded("group", value.group);
		serialize.NumberU32_Unbounded("notify", value.notify);
	}
};

template<typename S>
void CCmpPathfinder::SerializeCommon(S& serialize)
{
	Serializer(serialize, "long requests", m_LongPathRequests.m_Requests);
	Serializer(serialize, "short requests", m_ShortPathRequests.m_Requests);
	serialize.NumberU32_Unbounded("next ticket", m_NextAsyncTicket);
	serialize.NumberU16_Unbounded("grid size", m_GridSize);
}

void CCmpPathfinder::Serialize(ISerializer& serialize)
{
	SerializeCommon(serialize);
}

void CCmpPathfinder::Deserialize(const CParamNode& paramNode, IDeserializer& deserialize)
{
	Init(paramNode);

	SerializeCommon(deserialize);
}

void CCmpPathfinder::HandleMessage(const CMessage& msg, bool UNUSED(global))
{
	switch (msg.GetType())
	{
	case MT_RenderSubmit:
	{
		const CMessageRenderSubmit& msgData = static_cast<const CMessageRenderSubmit&> (msg);
		RenderSubmit(msgData.collector);
		break;
	}
	case MT_TerrainChanged:
	{
		const CMessageTerrainChanged& msgData = static_cast<const CMessageTerrainChanged&>(msg);
		m_TerrainDirty = true;
		MinimalTerrainUpdate(msgData.i0, msgData.j0, msgData.i1, msgData.j1);
		break;
	}
	case MT_WaterChanged:
	case MT_ObstructionMapShapeChanged:
		m_TerrainDirty = true;
		UpdateGrid();
		break;
	case MT_Deserialized:
		UpdateGrid();
		// In case we were serialised with requests pending, we need to process them.
		if (!m_ShortPathRequests.m_Requests.empty() || !m_LongPathRequests.m_Requests.empty())
		{
			ENSURE(CmpPtr<ICmpObstructionManager>(GetSystemEntity()));
			StartProcessingMoves(false);
		}
		break;
	}
}

void CCmpPathfinder::RenderSubmit(SceneCollector& collector)
{
	g_VertexPathfinderDebugOverlay.RenderSubmit(collector);
	m_PathfinderHier->RenderSubmit(collector);
}

void CCmpPathfinder::SetDebugPath(entity_pos_t x0, entity_pos_t z0, const PathGoal& goal, pass_class_t passClass)
{
	m_LongPathfinder->SetDebugPath(*m_PathfinderHier, x0, z0, goal, passClass);
}

void CCmpPathfinder::SetDebugOverlay(bool enabled)
{
	g_VertexPathfinderDebugOverlay.SetDebugOverlay(enabled);
	m_LongPathfinder->SetDebugOverlay(enabled);
}

void CCmpPathfinder::SetHierDebugOverlay(bool enabled)
{
	m_PathfinderHier->SetDebugOverlay(enabled, &GetSimContext());
}

void CCmpPathfinder::GetDebugData(u32& steps, double& time, Grid<u8>& grid) const
{
	m_LongPathfinder->GetDebugData(steps, time, grid);
}

void CCmpPathfinder::SetAtlasOverlay(bool enable, pass_class_t passClass)
{
	if (enable)
	{
		if (!m_AtlasOverlay)
			m_AtlasOverlay = new AtlasOverlay(this, passClass);
		m_AtlasOverlay->m_PassClass = passClass;
	}
	else
		SAFE_DELETE(m_AtlasOverlay);
}

pass_class_t CCmpPathfinder::GetPassabilityClass(const std::string& name) const
{
	std::map<std::string, pass_class_t>::const_iterator it = m_PassClassMasks.find(name);
	if (it == m_PassClassMasks.end())
	{
		LOGERROR("Invalid passability class name '%s'", name.c_str());
		return 0;
	}

	return it->second;
}

void CCmpPathfinder::GetPassabilityClasses(std::map<std::string, pass_class_t>& passClasses) const
{
	passClasses = m_PassClassMasks;
}

void CCmpPathfinder::GetPassabilityClasses(std::map<std::string, pass_class_t>& nonPathfindingPassClasses, std::map<std::string, pass_class_t>& pathfindingPassClasses) const
{
	for (const std::pair<const std::string, pass_class_t>& pair : m_PassClassMasks)
	{
		if ((GetPassabilityFromMask(pair.second)->m_Obstructions == PathfinderPassability::PATHFINDING))
			pathfindingPassClasses[pair.first] = pair.second;
		else
			nonPathfindingPassClasses[pair.first] = pair.second;
	}
}

const PathfinderPassability* CCmpPathfinder::GetPassabilityFromMask(pass_class_t passClass) const
{
	for (const PathfinderPassability& passability : m_PassClasses)
	{
		if (passability.m_Mask == passClass)
			return &passability;
	}

	return NULL;
}

const Grid<NavcellData>& CCmpPathfinder::GetPassabilityGrid()
{
	if (!m_Grid)
		UpdateGrid();

	return *m_Grid;
}

/**
 * Given a grid of passable/impassable navcells (based on some passability mask),
 * computes a new grid where a navcell is impassable (per that mask) if
 * it is <=clearance navcells away from an impassable navcell in the original grid.
 * The results are ORed onto the original grid.
 *
 * This is used for adding clearance onto terrain-based navcell passability.
 *
 * TODO PATHFINDER: might be nicer to get rounded corners by measuring clearances as
 * Euclidean distances; currently it effectively does dist=max(dx,dy) instead.
 * This would only really be a problem for big clearances.
 */
static void ExpandImpassableCells(Grid<NavcellData>& grid, u16 clearance, pass_class_t mask)
{
	PROFILE3("ExpandImpassableCells");

	u16 w = grid.m_W;
	u16 h = grid.m_H;

	// First expand impassable cells horizontally into a temporary 1-bit grid
	Grid<u8> tempGrid(w, h);
	for (u16 j = 0; j < h; ++j)
	{
		// New cell (i,j) is blocked if (i',j) blocked for any i-clearance <= i' <= i+clearance

		// Count the number of blocked cells around i=0
		u16 numBlocked = 0;
		for (u16 i = 0; i <= clearance && i < w; ++i)
			if (!IS_PASSABLE(grid.get(i, j), mask))
				++numBlocked;

		for (u16 i = 0; i < w; ++i)
		{
			// Store a flag if blocked by at least one nearby cell
			if (numBlocked)
				tempGrid.set(i, j, 1);

			// Slide the numBlocked window along:
			// remove the old i-clearance value, add the new (i+1)+clearance
			// (avoiding overflowing the grid)
			if (i >= clearance && !IS_PASSABLE(grid.get(i-clearance, j), mask))
				--numBlocked;
			if (i+1+clearance < w && !IS_PASSABLE(grid.get(i+1+clearance, j), mask))
				++numBlocked;
		}
	}

	for (u16 i = 0; i < w; ++i)
	{
		// New cell (i,j) is blocked if (i,j') blocked for any j-clearance <= j' <= j+clearance
		// Count the number of blocked cells around j=0
		u16 numBlocked = 0;
		for (u16 j = 0; j <= clearance && j < h; ++j)
			if (tempGrid.get(i, j))
				++numBlocked;

		for (u16 j = 0; j < h; ++j)
		{
			// Add the mask if blocked by at least one nearby cell
			if (numBlocked)
				grid.set(i, j, grid.get(i, j) | mask);

			// Slide the numBlocked window along:
			// remove the old j-clearance value, add the new (j+1)+clearance
			// (avoiding overflowing the grid)
			if (j >= clearance && tempGrid.get(i, j-clearance))
				--numBlocked;
			if (j+1+clearance < h && tempGrid.get(i, j+1+clearance))
				++numBlocked;
		}
	}
}

Grid<u16> CCmpPathfinder::ComputeShoreGrid(bool expandOnWater)
{
	PROFILE3("ComputeShoreGrid");

	CmpPtr<ICmpWaterManager> cmpWaterManager(GetSystemEntity());

	// TODO: these bits should come from ICmpTerrain
	CTerrain& terrain = GetSimContext().GetTerrain();

	// avoid integer overflow in intermediate calculation
	const u16 shoreMax = 32767;

	u16 shoreGridSize = terrain.GetTilesPerSide();

	// First pass - find underwater tiles
	Grid<u8> waterGrid(shoreGridSize, shoreGridSize);
	for (u16 j = 0; j < shoreGridSize; ++j)
	{
		for (u16 i = 0; i < shoreGridSize; ++i)
		{
			fixed x, z;
			Pathfinding::TerrainTileCenter(i, j, x, z);

			bool underWater = cmpWaterManager && (cmpWaterManager->GetWaterLevel(x, z) > terrain.GetExactGroundLevelFixed(x, z));
			waterGrid.set(i, j, underWater ? 1 : 0);
		}
	}

	// Second pass - find shore tiles
	Grid<u16> shoreGrid(shoreGridSize, shoreGridSize);
	for (u16 j = 0; j < shoreGridSize; ++j)
	{
		for (u16 i = 0; i < shoreGridSize; ++i)
		{
			// Find a land tile
			if (!waterGrid.get(i, j))
			{
				// If it's bordered by water, it's a shore tile
				if ((i > 0 && waterGrid.get(i-1, j)) || (i > 0 && j < shoreGridSize-1 && waterGrid.get(i-1, j+1)) || (i > 0 && j > 0 && waterGrid.get(i-1, j-1))
					|| (i < shoreGridSize-1 && waterGrid.get(i+1, j)) || (i < shoreGridSize-1 && j < shoreGridSize-1 && waterGrid.get(i+1, j+1)) || (i < shoreGridSize-1 && j > 0 && waterGrid.get(i+1, j-1))
					|| (j > 0 && waterGrid.get(i, j-1)) || (j < shoreGridSize-1 && waterGrid.get(i, j+1))
					)
					shoreGrid.set(i, j, 0);
				else
					shoreGrid.set(i, j, shoreMax);
			}
			// If we want to expand on water, we want water tiles not to be shore tiles
			else if (expandOnWater)
				shoreGrid.set(i, j, shoreMax);
		}
	}

	// Expand influences on land to find shore distance
	for (u16 y = 0; y < shoreGridSize; ++y)
	{
		u16 min = shoreMax;
		for (u16 x = 0; x < shoreGridSize; ++x)
		{
			if (!waterGrid.get(x, y) || expandOnWater)
			{
				u16 g = shoreGrid.get(x, y);
				if (g > min)
					shoreGrid.set(x, y, min);
				else if (g < min)
					min = g;

				++min;
			}
		}
		for (u16 x = shoreGridSize; x > 0; --x)
		{
			if (!waterGrid.get(x-1, y) || expandOnWater)
			{
				u16 g = shoreGrid.get(x-1, y);
				if (g > min)
					shoreGrid.set(x-1, y, min);
				else if (g < min)
					min = g;

				++min;
			}
		}
	}
	for (u16 x = 0; x < shoreGridSize; ++x)
	{
		u16 min = shoreMax;
		for (u16 y = 0; y < shoreGridSize; ++y)
		{
			if (!waterGrid.get(x, y) || expandOnWater)
			{
				u16 g = shoreGrid.get(x, y);
				if (g > min)
					shoreGrid.set(x, y, min);
				else if (g < min)
					min = g;

				++min;
			}
		}
		for (u16 y = shoreGridSize; y > 0; --y)
		{
			if (!waterGrid.get(x, y-1) || expandOnWater)
			{
				u16 g = shoreGrid.get(x, y-1);
				if (g > min)
					shoreGrid.set(x, y-1, min);
				else if (g < min)
					min = g;

				++min;
			}
		}
	}

	return shoreGrid;
}

void CCmpPathfinder::UpdateGrid()
{
	PROFILE3("UpdateGrid");

	CmpPtr<ICmpTerrain> cmpTerrain(GetSimContext(), SYSTEM_ENTITY);
	if (!cmpTerrain)
		return; // error

	u16 gridSize = cmpTerrain->GetMapSize() / Pathfinding::NAVCELL_SIZE_INT;
	if (gridSize == 0)
		return;

	// If the terrain was resized then delete the old grid data
	if (m_Grid && m_GridSize != gridSize)
	{
		SAFE_DELETE(m_Grid);
		SAFE_DELETE(m_TerrainOnlyGrid);
	}

	// Initialise the terrain data when first needed
	if (!m_Grid)
	{
		m_GridSize = gridSize;
		m_Grid = new Grid<NavcellData>(m_GridSize, m_GridSize);
		SAFE_DELETE(m_TerrainOnlyGrid);
		m_TerrainOnlyGrid = new Grid<NavcellData>(m_GridSize, m_GridSize);

		m_DirtinessInformation = { true, true, Grid<u8>(m_GridSize, m_GridSize) };
		m_AIPathfinderDirtinessInformation = m_DirtinessInformation;

		m_TerrainDirty = true;
	}

	// The grid should be properly initialized and clean. Checking the latter is expensive so do it only for debugging.
#ifdef NDEBUG
	ENSURE(m_DirtinessInformation.dirtinessGrid.compare_sizes(m_Grid));
#else
	ENSURE(m_DirtinessInformation.dirtinessGrid == Grid<u8>(m_GridSize, m_GridSize));
#endif

	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
	cmpObstructionManager->UpdateInformations(m_DirtinessInformation);

	if (!m_DirtinessInformation.dirty && !m_TerrainDirty)
		return;

	// If the terrain has changed, recompute m_Grid
	// Else, use data from m_TerrainOnlyGrid and add obstructions
	if (m_TerrainDirty)
	{
		TerrainUpdateHelper();

		*m_Grid = *m_TerrainOnlyGrid;

		m_TerrainDirty = false;
		m_DirtinessInformation.globallyDirty = true;
	}
	else if (m_DirtinessInformation.globallyDirty)
	{
		ENSURE(m_Grid->compare_sizes(m_TerrainOnlyGrid));
		memcpy(m_Grid->m_Data, m_TerrainOnlyGrid->m_Data, (m_Grid->m_W)*(m_Grid->m_H)*sizeof(NavcellData));
	}
	else
	{
		ENSURE(m_Grid->compare_sizes(m_TerrainOnlyGrid));

		for (u16 j = 0; j < m_DirtinessInformation.dirtinessGrid.m_H; ++j)
			for (u16 i = 0; i < m_DirtinessInformation.dirtinessGrid.m_W; ++i)
				if (m_DirtinessInformation.dirtinessGrid.get(i, j) == 1)
					m_Grid->set(i, j, m_TerrainOnlyGrid->get(i, j));
	}

	// Add obstructions onto the grid
	cmpObstructionManager->Rasterize(*m_Grid, m_PassClasses, m_DirtinessInformation.globallyDirty);

	// Update the long-range and hierarchical pathfinders.
	if (m_DirtinessInformation.globallyDirty)
	{
		std::map<std::string, pass_class_t> nonPathfindingPassClasses, pathfindingPassClasses;
		GetPassabilityClasses(nonPathfindingPassClasses, pathfindingPassClasses);
		m_LongPathfinder->Reload(m_Grid);
		m_PathfinderHier->Recompute(m_Grid, nonPathfindingPassClasses, pathfindingPassClasses);
	}
	else
	{
		m_LongPathfinder->Update(m_Grid);
		m_PathfinderHier->Update(m_Grid, m_DirtinessInformation.dirtinessGrid);
	}

	// Remember the necessary updates that the AI pathfinder will have to perform as well
	m_AIPathfinderDirtinessInformation.MergeAndClear(m_DirtinessInformation);
}

void CCmpPathfinder::MinimalTerrainUpdate(int itile0, int jtile0, int itile1, int jtile1)
{
	TerrainUpdateHelper(false, itile0, jtile0, itile1, jtile1);
}

void CCmpPathfinder::TerrainUpdateHelper(bool expandPassability, int itile0, int jtile0, int itile1, int jtile1)
{
	PROFILE3("TerrainUpdateHelper");

	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
	CmpPtr<ICmpWaterManager> cmpWaterManager(GetSimContext(), SYSTEM_ENTITY);
	CmpPtr<ICmpTerrain> cmpTerrain(GetSimContext(), SYSTEM_ENTITY);
	CTerrain& terrain = GetSimContext().GetTerrain();

	if (!cmpTerrain || !cmpObstructionManager)
		return;

	u16 gridSize = cmpTerrain->GetMapSize() / Pathfinding::NAVCELL_SIZE_INT;
	if (gridSize == 0)
		return;

	const bool needsNewTerrainGrid = !m_TerrainOnlyGrid || m_GridSize != gridSize;
	if (needsNewTerrainGrid)
	{
		m_GridSize = gridSize;

		SAFE_DELETE(m_TerrainOnlyGrid);
		m_TerrainOnlyGrid = new Grid<NavcellData>(m_GridSize, m_GridSize);

		// If this update comes from a map resizing, we must reinitialize the other grids as well
		if (!m_TerrainOnlyGrid->compare_sizes(m_Grid))
		{
			SAFE_DELETE(m_Grid);
			m_Grid = new Grid<NavcellData>(m_GridSize, m_GridSize);

			m_DirtinessInformation = { true, true, Grid<u8>(m_GridSize, m_GridSize) };
			m_AIPathfinderDirtinessInformation = m_DirtinessInformation;
		}
	}

	Grid<u16> shoreGrid = ComputeShoreGrid();

	const bool partialTerrainGridUpdate =
		!expandPassability && !needsNewTerrainGrid &&
		itile0 != -1 && jtile0 != -1 && itile1 != -1 && jtile1 != -1;
	int istart = 0, iend = m_GridSize;
	int jstart = 0, jend = m_GridSize;
	if (partialTerrainGridUpdate)
	{
		// We need to extend the boundaries by 1 tile, because slope and ground
		// level are calculated by multiple neighboring tiles.
		// TODO: add CTerrain constant instead of 1.
		istart = Clamp<int>((itile0 - 1) * Pathfinding::NAVCELLS_PER_TERRAIN_TILE, 0, m_GridSize);
		iend = Clamp<int>((itile1 + 1) * Pathfinding::NAVCELLS_PER_TERRAIN_TILE, 0, m_GridSize);
		jstart = Clamp<int>((jtile0 - 1) * Pathfinding::NAVCELLS_PER_TERRAIN_TILE, 0, m_GridSize);
		jend = Clamp<int>((jtile1 + 1) * Pathfinding::NAVCELLS_PER_TERRAIN_TILE, 0, m_GridSize);
	}

	// Compute initial terrain-dependent passability
	for (int j = jstart; j < jend; ++j)
	{
		for (int i = istart; i < iend; ++i)
		{
			// World-space coordinates for this navcell
			fixed x, z;
			Pathfinding::NavcellCenter(i, j, x, z);

			// Terrain-tile coordinates for this navcell
			int itile = i / Pathfinding::NAVCELLS_PER_TERRAIN_TILE;
			int jtile = j / Pathfinding::NAVCELLS_PER_TERRAIN_TILE;

			// Gather all the data potentially needed to determine passability:

			fixed height = terrain.GetExactGroundLevelFixed(x, z);

			fixed water;
			if (cmpWaterManager)
				water = cmpWaterManager->GetWaterLevel(x, z);

			fixed depth = water - height;

			// Exact slopes give kind of weird output, so just use rough tile-based slopes
			fixed slope = terrain.GetSlopeFixed(itile, jtile);

			// Get world-space coordinates from shoreGrid (which uses terrain tiles)
			fixed shoredist = fixed::FromInt(shoreGrid.get(itile, jtile)).MultiplyClamp(TERRAIN_TILE_SIZE);

			// Compute the passability for every class for this cell
			NavcellData t = 0;
			for (const PathfinderPassability& passability : m_PassClasses)
				if (!passability.IsPassable(depth, slope, shoredist))
					t |= passability.m_Mask;

			m_TerrainOnlyGrid->set(i, j, t);
		}
	}

	// Compute off-world passability
	const int edgeSize = MAP_EDGE_TILES * Pathfinding::NAVCELLS_PER_TERRAIN_TILE;

	NavcellData edgeMask = 0;
	for (const PathfinderPassability& passability : m_PassClasses)
		edgeMask |= passability.m_Mask;

	int w = m_TerrainOnlyGrid->m_W;
	int h = m_TerrainOnlyGrid->m_H;

	if (cmpObstructionManager->GetPassabilityCircular())
	{
		for (int j = jstart; j < jend; ++j)
		{
			for (int i = istart; i < iend; ++i)
			{
				// Based on CCmpRangeManager::LosIsOffWorld
				// but tweaked since it's tile-based instead.
				// (We double all the values so we can handle half-tile coordinates.)
				// This needs to be slightly tighter than the LOS circle,
				// else units might get themselves lost in the SoD around the edge.

				int dist2 = (i*2 + 1 - w)*(i*2 + 1 - w)
					+ (j*2 + 1 - h)*(j*2 + 1 - h);

				if (dist2 >= (w - 2*edgeSize) * (h - 2*edgeSize))
					m_TerrainOnlyGrid->set(i, j, m_TerrainOnlyGrid->get(i, j) | edgeMask);
			}
		}
	}
	else
	{
		for (u16 j = 0; j < h; ++j)
			for (u16 i = 0; i < edgeSize; ++i)
				m_TerrainOnlyGrid->set(i, j, m_TerrainOnlyGrid->get(i, j) | edgeMask);
		for (u16 j = 0; j < h; ++j)
			for (u16 i = w-edgeSize+1; i < w; ++i)
				m_TerrainOnlyGrid->set(i, j, m_TerrainOnlyGrid->get(i, j) | edgeMask);
		for (u16 j = 0; j < edgeSize; ++j)
			for (u16 i = edgeSize; i < w-edgeSize+1; ++i)
				m_TerrainOnlyGrid->set(i, j, m_TerrainOnlyGrid->get(i, j) | edgeMask);
		for (u16 j = h-edgeSize+1; j < h; ++j)
			for (u16 i = edgeSize; i < w-edgeSize+1; ++i)
				m_TerrainOnlyGrid->set(i, j, m_TerrainOnlyGrid->get(i, j) | edgeMask);
	}

	if (!expandPassability)
		return;

	// Expand the impassability grid, for any class with non-zero clearance,
	// so that we can stop units getting too close to impassable navcells.
	// Note: It's not possible to perform this expansion once for all passabilities
	// with the same clearance, because the impassable cells are not necessarily the
	// same for all these passabilities.
	for (PathfinderPassability& passability : m_PassClasses)
	{
		if (passability.m_Clearance == fixed::Zero())
			continue;

		int clearance = (passability.m_Clearance / Pathfinding::NAVCELL_SIZE).ToInt_RoundToInfinity();
		ExpandImpassableCells(*m_TerrainOnlyGrid, clearance, passability.m_Mask);
	}
}

//////////////////////////////////////////////////////////

u32 CCmpPathfinder::ComputePathAsync(entity_pos_t x0, entity_pos_t z0, const PathGoal& goal, pass_class_t passClass, entity_id_t notify)
{
	LongPathRequest req = { m_NextAsyncTicket++, x0, z0, goal, passClass, notify };
	m_LongPathRequests.m_Requests.push_back(req);
	return req.ticket;
}

u32 CCmpPathfinder::ComputeShortPathAsync(entity_pos_t x0, entity_pos_t z0, entity_pos_t clearance, entity_pos_t range,
                                          const PathGoal& goal, pass_class_t passClass, bool avoidMovingUnits,
                                          entity_id_t group, entity_id_t notify)
{
	ShortPathRequest req = { m_NextAsyncTicket++, x0, z0, clearance, range, goal, passClass, avoidMovingUnits, group, notify };
	m_ShortPathRequests.m_Requests.push_back(req);
	return req.ticket;
}

void CCmpPathfinder::ComputePathImmediate(entity_pos_t x0, entity_pos_t z0, const PathGoal& goal, pass_class_t passClass, WaypointPath& ret) const
{
	m_LongPathfinder->ComputePath(*m_PathfinderHier, x0, z0, goal, passClass, ret);
}

WaypointPath CCmpPathfinder::ComputeShortPathImmediate(const ShortPathRequest& request) const
{
	return m_VertexPathfinders.front().ComputeShortPath(request, CmpPtr<ICmpObstructionManager>(GetSystemEntity()));
}

template<typename T>
template<typename U>
void CCmpPathfinder::PathRequests<T>::Compute(const CCmpPathfinder& cmpPathfinder, const U& pathfinder)
{
	static_assert((std::is_same_v<T, LongPathRequest> && std::is_same_v<U, LongPathfinder>) ||
				  (std::is_same_v<T, ShortPathRequest> && std::is_same_v<U, VertexPathfinder>));
	size_t maxN = m_Results.size();
	size_t startIndex = m_Requests.size() - m_Results.size();
	do
	{
		size_t workIndex = m_NextPathToCompute++;
		if (workIndex >= maxN)
			break;
		const T& req = m_Requests[startIndex + workIndex];
		PathResult& result = m_Results[workIndex];
		result.ticket = req.ticket;
		result.notify = req.notify;
		if constexpr (std::is_same_v<T, LongPathRequest>)
			pathfinder.ComputePath(*cmpPathfinder.m_PathfinderHier, req.x0, req.z0, req.goal, req.passClass, result.path);
		else
			result.path = pathfinder.ComputeShortPath(req, CmpPtr<ICmpObstructionManager>(cmpPathfinder.GetSystemEntity()));
		if (workIndex == maxN - 1)
			m_ComputeDone = true;
	}
	while (true);
}

void CCmpPathfinder::SendRequestedPaths()
{
	PROFILE2("SendRequestedPaths");

	if (!m_LongPathRequests.m_ComputeDone || !m_ShortPathRequests.m_ComputeDone)
	{
		// Also start computing on the main thread to finish faster.
		m_ShortPathRequests.Compute(*this, m_VertexPathfinders.front());
		m_LongPathRequests.Compute(*this, *m_LongPathfinder);
	}
	// We're done, get the exceptions from the futures.
	for (Future<void>& future : m_Futures)
		future.Get();

	{
		PROFILE2("PostMessages");
		for (PathResult& path : m_ShortPathRequests.m_Results)
		{
			CMessagePathResult msg(path.ticket, path.path);
			GetSimContext().GetComponentManager().PostMessage(path.notify, msg);
		}

		for (PathResult& path : m_LongPathRequests.m_Results)
		{
			CMessagePathResult msg(path.ticket, path.path);
			GetSimContext().GetComponentManager().PostMessage(path.notify, msg);
		}
	}
	m_ShortPathRequests.ClearComputed();
	m_LongPathRequests.ClearComputed();
}

void CCmpPathfinder::StartProcessingMoves(bool useMax)
{
	m_ShortPathRequests.PrepareForComputation(useMax ? m_MaxSameTurnMoves : 0);
	m_LongPathRequests.PrepareForComputation(useMax ? m_MaxSameTurnMoves : 0);

	Threading::TaskManager& taskManager = Threading::TaskManager::Instance();
	for (size_t i = 0; i < m_Futures.size(); ++i)
	{
		ENSURE(!m_Futures[i].Valid());
		// Pass the i+1th vertex pathfinder to keep the first for the main thread,
		// each thread get its own instance to avoid conflicts in cached data.
		m_Futures[i] = taskManager.PushTask([&pathfinder=*this, &vertexPfr=m_VertexPathfinders[i + 1]]() {
			PROFILE2("Async pathfinding");
			pathfinder.m_ShortPathRequests.Compute(pathfinder, vertexPfr);
			pathfinder.m_LongPathRequests.Compute(pathfinder, *pathfinder.m_LongPathfinder);
		});
	}
}


//////////////////////////////////////////////////////////

bool CCmpPathfinder::IsGoalReachable(entity_pos_t x0, entity_pos_t z0, const PathGoal& goal, pass_class_t passClass)
{
	PROFILE2("IsGoalReachable");

	u16 i, j;
	Pathfinding::NearestNavcell(x0, z0, i, j, m_GridSize, m_GridSize);
	if (!IS_PASSABLE(m_Grid->get(i, j), passClass))
		m_PathfinderHier->FindNearestPassableNavcell(i, j, passClass);

	return m_PathfinderHier->IsGoalReachable(i, j, goal, passClass);
}

bool CCmpPathfinder::CheckMovement(const IObstructionTestFilter& filter,
	entity_pos_t x0, entity_pos_t z0, entity_pos_t x1, entity_pos_t z1, entity_pos_t r,
	pass_class_t passClass) const
{
	PROFILE2_IFSPIKE("Check Movement", 0.001);

	// Test against obstructions first. filter may discard pathfinding-blocking obstructions.
	// Use more permissive version of TestLine to allow unit-unit collisions to overlap slightly.
	// This makes movement smoother and more natural for units, overall.
	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSystemEntity());
	if (!cmpObstructionManager || cmpObstructionManager->TestLine(filter, x0, z0, x1, z1, r, true))
		return false;

	// Then test against the terrain grid. This should not be necessary
	// But in case we allow terrain to change it will become so.
	return Pathfinding::CheckLineMovement(x0, z0, x1, z1, passClass, *m_TerrainOnlyGrid);
}

ICmpObstruction::EFoundationCheck CCmpPathfinder::CheckUnitPlacement(const IObstructionTestFilter& filter,
	entity_pos_t x, entity_pos_t z, entity_pos_t r,	pass_class_t passClass, bool UNUSED(onlyCenterPoint)) const
{
	// Check unit obstruction
	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSystemEntity());
	if (!cmpObstructionManager)
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_ERROR;

	if (cmpObstructionManager->TestUnitShape(filter, x, z, r, NULL))
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION;

	// Test against terrain and static obstructions:

	u16 i, j;
	Pathfinding::NearestNavcell(x, z, i, j, m_GridSize, m_GridSize);
	if (!IS_PASSABLE(m_Grid->get(i, j), passClass))
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_TERRAIN_CLASS;

	// (Static obstructions will be redundantly tested against in both the
	// obstruction-shape test and navcell-passability test, which is slightly
	// inefficient but shouldn't affect behaviour)

	return ICmpObstruction::FOUNDATION_CHECK_SUCCESS;
}

ICmpObstruction::EFoundationCheck CCmpPathfinder::CheckBuildingPlacement(const IObstructionTestFilter& filter,
	entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w,
	entity_pos_t h, entity_id_t id, pass_class_t passClass) const
{
	return CCmpPathfinder::CheckBuildingPlacement(filter, x, z, a, w, h, id, passClass, false);
}


ICmpObstruction::EFoundationCheck CCmpPathfinder::CheckBuildingPlacement(const IObstructionTestFilter& filter,
	entity_pos_t x, entity_pos_t z, entity_pos_t a, entity_pos_t w,
	entity_pos_t h, entity_id_t id, pass_class_t passClass, bool UNUSED(onlyCenterPoint)) const
{
	// Check unit obstruction
	CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSystemEntity());
	if (!cmpObstructionManager)
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_ERROR;

	if (cmpObstructionManager->TestStaticShape(filter, x, z, a, w, h, NULL))
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_OBSTRUCTS_FOUNDATION;

	// Test against terrain:

	ICmpObstructionManager::ObstructionSquare square;
	CmpPtr<ICmpObstruction> cmpObstruction(GetSimContext(), id);
	if (!cmpObstruction || !cmpObstruction->GetObstructionSquare(square))
		return ICmpObstruction::FOUNDATION_CHECK_FAIL_NO_OBSTRUCTION;

	entity_pos_t expand;
	const PathfinderPassability* passability = GetPassabilityFromMask(passClass);
	if (passability)
		expand = passability->m_Clearance;

	SimRasterize::Spans spans;
	SimRasterize::RasterizeRectWithClearance(spans, square, expand, Pathfinding::NAVCELL_SIZE);
	for (const SimRasterize::Span& span : spans)
	{
		i16 i0 = span.i0;
		i16 i1 = span.i1;
		i16 j = span.j;

		// Fail if any span extends outside the grid
		if (i0 < 0 || i1 > m_TerrainOnlyGrid->m_W || j < 0 || j > m_TerrainOnlyGrid->m_H)
			return ICmpObstruction::FOUNDATION_CHECK_FAIL_TERRAIN_CLASS;

		// Fail if any span includes an impassable tile
		for (i16 i = i0; i < i1; ++i)
			if (!IS_PASSABLE(m_TerrainOnlyGrid->get(i, j), passClass))
				return ICmpObstruction::FOUNDATION_CHECK_FAIL_TERRAIN_CLASS;
	}

	return ICmpObstruction::FOUNDATION_CHECK_SUCCESS;
}