/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com.                */

#include "gameworld.h"
#include "entities/character.h"
#include "entity.h"
#include "gamecontext.h"
#include "gamecontroller.h"
#include "player.h"

#include <engine/shared/config.h>

#include <algorithm>
#include <utility>

//////////////////////////////////////////////////
// game world
//////////////////////////////////////////////////
CGameWorld::CGameWorld()
{
	m_pGameServer = 0x0;
	m_pConfig = 0x0;
	m_pServer = 0x0;

	m_Paused = false;
	m_ResetRequested = false;
	for(auto &pFirstEntityType : m_apFirstEntityTypes)
		pFirstEntityType = 0;
}

CGameWorld::~CGameWorld()
{
	// delete all entities
	for(auto &pFirstEntityType : m_apFirstEntityTypes)
		while(pFirstEntityType)
			delete pFirstEntityType; // NOLINT(clang-analyzer-cplusplus.NewDelete)
}

void CGameWorld::SetGameServer(CGameContext *pGameServer)
{
	m_pGameServer = pGameServer;
	m_pConfig = m_pGameServer->Config();
	m_pServer = m_pGameServer->Server();
}

CEntity *CGameWorld::FindFirst(int Type)
{
	return Type < 0 || Type >= NUM_ENTTYPES ? 0 : m_apFirstEntityTypes[Type];
}

int CGameWorld::FindEntities(vec2 Pos, float Radius, CEntity **ppEnts, int Max, int Type)
{
	if(Type < 0 || Type >= NUM_ENTTYPES)
		return 0;

	int Num = 0;
	for(CEntity *pEnt = m_apFirstEntityTypes[Type]; pEnt; pEnt = pEnt->m_pNextTypeEntity)
	{
		if(distance(pEnt->m_Pos, Pos) < Radius + pEnt->m_ProximityRadius)
		{
			if(ppEnts)
				ppEnts[Num] = pEnt;
			Num++;
			if(Num == Max)
				break;
		}
	}

	return Num;
}

void CGameWorld::InsertEntity(CEntity *pEnt)
{
#ifdef CONF_DEBUG
	for(CEntity *pCur = m_apFirstEntityTypes[pEnt->m_ObjType]; pCur; pCur = pCur->m_pNextTypeEntity)
		dbg_assert(pCur != pEnt, "err");
#endif

	// insert it
	if(m_apFirstEntityTypes[pEnt->m_ObjType])
		m_apFirstEntityTypes[pEnt->m_ObjType]->m_pPrevTypeEntity = pEnt;
	pEnt->m_pNextTypeEntity = m_apFirstEntityTypes[pEnt->m_ObjType];
	pEnt->m_pPrevTypeEntity = 0x0;
	m_apFirstEntityTypes[pEnt->m_ObjType] = pEnt;
}

void CGameWorld::RemoveEntity(CEntity *pEnt)
{
	// not in the list
	if(!pEnt->m_pNextTypeEntity && !pEnt->m_pPrevTypeEntity && m_apFirstEntityTypes[pEnt->m_ObjType] != pEnt)
		return;

	// remove
	if(pEnt->m_pPrevTypeEntity)
		pEnt->m_pPrevTypeEntity->m_pNextTypeEntity = pEnt->m_pNextTypeEntity;
	else
		m_apFirstEntityTypes[pEnt->m_ObjType] = pEnt->m_pNextTypeEntity;
	if(pEnt->m_pNextTypeEntity)
		pEnt->m_pNextTypeEntity->m_pPrevTypeEntity = pEnt->m_pPrevTypeEntity;

	// keep list traversing valid
	if(m_pNextTraverseEntity == pEnt)
		m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;

	pEnt->m_pNextTypeEntity = 0;
	pEnt->m_pPrevTypeEntity = 0;
}

//
void CGameWorld::Snap(int SnappingClient)
{
	for(CEntity *pEnt = m_apFirstEntityTypes[ENTTYPE_CHARACTER]; pEnt;)
	{
		m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
		pEnt->Snap(SnappingClient);
		pEnt = m_pNextTraverseEntity;
	}

	for(int i = 0; i < NUM_ENTTYPES; i++)
	{
		if(i == ENTTYPE_CHARACTER)
			continue;

		for(CEntity *pEnt = m_apFirstEntityTypes[i]; pEnt;)
		{
			m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
			pEnt->Snap(SnappingClient);
			pEnt = m_pNextTraverseEntity;
		}
	}
}

void CGameWorld::Reset()
{
	// reset all entities
	for(auto *pEnt : m_apFirstEntityTypes)
		for(; pEnt;)
		{
			m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
			pEnt->Reset();
			pEnt = m_pNextTraverseEntity;
		}
	RemoveEntities();

	GameServer()->m_pController->OnReset();
	RemoveEntities();

	m_ResetRequested = false;

	GameServer()->CreateAllEntities(false);
}

void CGameWorld::RemoveEntitiesFromPlayer(int PlayerId)
{
	RemoveEntitiesFromPlayers(&PlayerId, 1);
}

void CGameWorld::RemoveEntitiesFromPlayers(int PlayerIds[], int NumPlayers)
{
	for(auto *pEnt : m_apFirstEntityTypes)
	{
		for(; pEnt;)
		{
			m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
			for(int i = 0; i < NumPlayers; i++)
			{
				if(pEnt->GetOwnerID() == PlayerIds[i])
				{
					RemoveEntity(pEnt);
					pEnt->Destroy();
					break;
				}
			}
			pEnt = m_pNextTraverseEntity;
		}
	}
}

void CGameWorld::RemoveEntities()
{
	// destroy objects marked for destruction
	for(auto *pEnt : m_apFirstEntityTypes)
		for(; pEnt;)
		{
			m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
			if(pEnt->m_MarkedForDestroy)
			{
				RemoveEntity(pEnt);
				pEnt->Destroy();
			}
			pEnt = m_pNextTraverseEntity;
		}
}

bool distCompare(std::pair<float, int> a, std::pair<float, int> b)
{
	return (a.first < b.first);
}

void CGameWorld::UpdatePlayerMaps()
{
	if(Server()->Tick() % g_Config.m_SvMapUpdateRate != 0)
		return;

	std::pair<float, int> Dist[MAX_CLIENTS];
	for(int i = 0; i < MAX_CLIENTS; i++)
	{
		if(!Server()->ClientIngame(i))
			continue;
		if(Server()->GetClientVersion(i) >= VERSION_DDNET_OLD)
			continue;
		int *pMap = Server()->GetIdMap(i);

		// compute distances
		for(int j = 0; j < MAX_CLIENTS; j++)
		{
			Dist[j].second = j;
			if(j == i)
				continue;
			if(!Server()->ClientIngame(j) || !GameServer()->m_apPlayers[j])
			{
				Dist[j].first = 1e10;
				continue;
			}
			CCharacter *pChr = GameServer()->m_apPlayers[j]->GetCharacter();
			if(!pChr)
			{
				Dist[j].first = 1e9;
				continue;
			}
			if(!pChr->CanSnapCharacter(i))
				Dist[j].first = 1e8;
			else
				Dist[j].first = length_squared(GameServer()->m_apPlayers[i]->m_ViewPos - pChr->m_Pos);
		}

		// always send the player themselves, even if all in same position
		Dist[i].first = -1;

		std::nth_element(&Dist[0], &Dist[VANILLA_MAX_CLIENTS - 1], &Dist[MAX_CLIENTS], distCompare);

		int Index = 1; // exclude self client id
		for(int j = 0; j < VANILLA_MAX_CLIENTS - 1; j++)
		{
			pMap[j + 1] = -1; // also fill player with empty name to say chat msgs
			if(Dist[j].second == i || Dist[j].first > 5e9f)
				continue;
			pMap[Index++] = Dist[j].second;
		}

		// sort by real client ids, guarantee order on distance changes, O(Nlog(N)) worst case
		// sort just clients in game always except first (self client id) and last (fake client id) indexes
		std::sort(&pMap[1], &pMap[minimum(Index, VANILLA_MAX_CLIENTS - 1)]);
	}
}

void CGameWorld::Tick()
{
	if(m_ResetRequested)
		Reset();

	if(!m_Paused)
	{
		if(GameServer()->m_pController->IsForceBalanced())
			GameServer()->SendChat(-1, CGameContext::CHAT_ALL, "Teams have been balanced");

		// update all objects
		for(int i = 0; i < NUM_ENTTYPES; i++)
		{
			// It's important to call PreTick() and Tick() after each other.
			// If we call PreTick() before, and Tick() after other entities have been processed, it causes physics changes such as a stronger shotgun or grenade.
			if(g_Config.m_SvNoWeakHook && i == ENTTYPE_CHARACTER)
			{
				auto *pEnt = m_apFirstEntityTypes[i];
				for(; pEnt;)
				{
					m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
					((CCharacter *)pEnt)->PreTick();
					pEnt = m_pNextTraverseEntity;
				}
			}

			auto *pEnt = m_apFirstEntityTypes[i];
			for(; pEnt;)
			{
				m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
				pEnt->Tick();
				pEnt = m_pNextTraverseEntity;
			}
		}

		for(auto *pEnt : m_apFirstEntityTypes)
			for(; pEnt;)
			{
				m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
				pEnt->TickDeferred();
				pEnt = m_pNextTraverseEntity;
			}
	}
	else
	{
		// update all objects
		for(auto *pEnt : m_apFirstEntityTypes)
			for(; pEnt;)
			{
				m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
				pEnt->TickPaused();
				pEnt = m_pNextTraverseEntity;
			}
	}

	RemoveEntities();

	UpdatePlayerMaps();

	// find the characters' strong/weak id
	int StrongWeakID = 0;
	for(CCharacter *pChar = (CCharacter *)FindFirst(ENTTYPE_CHARACTER); pChar; pChar = (CCharacter *)pChar->TypeNext())
	{
		pChar->m_StrongWeakID = StrongWeakID;
		StrongWeakID++;
	}
}

void CGameWorld::SwapClients(int Client1, int Client2)
{
	// update all objects
	for(auto *pEnt : m_apFirstEntityTypes)
		for(; pEnt;)
		{
			m_pNextTraverseEntity = pEnt->m_pNextTypeEntity;
			pEnt->SwapClients(Client1, Client2);
			pEnt = m_pNextTraverseEntity;
		}
}

// TODO: should be more general
CCharacter *CGameWorld::IntersectCharacter(vec2 Pos0, vec2 Pos1, float Radius, vec2 &NewPos, const CCharacter *pNotThis, int CollideWith, const CCharacter *pThisOnly)
{
	// Find other players
	float ClosestLen = distance(Pos0, Pos1) * 100.0f;
	CCharacter *pClosest = 0;

	CCharacter *p = (CCharacter *)FindFirst(ENTTYPE_CHARACTER);
	for(; p; p = (CCharacter *)p->TypeNext())
	{
		if(p == pNotThis)
			continue;

		if(pThisOnly && p != pThisOnly)
			continue;

		if(CollideWith != -1 && !p->CanCollide(CollideWith))
			continue;

		vec2 IntersectPos;
		if(closest_point_on_line(Pos0, Pos1, p->m_Pos, IntersectPos))
		{
			float Len = distance(p->m_Pos, IntersectPos);
			if(Len < p->m_ProximityRadius + Radius)
			{
				Len = distance(Pos0, IntersectPos);
				if(Len < ClosestLen)
				{
					NewPos = IntersectPos;
					ClosestLen = Len;
					pClosest = p;
				}
			}
		}
	}

	return pClosest;
}

CCharacter *CGameWorld::ClosestCharacter(vec2 Pos, float Radius, const CEntity *pNotThis)
{
	// Find other players
	float ClosestRange = Radius * 2;
	CCharacter *pClosest = 0;

	CCharacter *p = (CCharacter *)GameServer()->m_World.FindFirst(ENTTYPE_CHARACTER);
	for(; p; p = (CCharacter *)p->TypeNext())
	{
		if(p == pNotThis)
			continue;

		float Len = distance(Pos, p->m_Pos);
		if(Len < p->m_ProximityRadius + Radius)
		{
			if(Len < ClosestRange)
			{
				ClosestRange = Len;
				pClosest = p;
			}
		}
	}

	return pClosest;
}

std::list<class CCharacter *> CGameWorld::IntersectedCharacters(vec2 Pos0, vec2 Pos1, float Radius, const CEntity *pNotThis)
{
	std::list<CCharacter *> listOfChars;

	CCharacter *pChr = (CCharacter *)FindFirst(CGameWorld::ENTTYPE_CHARACTER);
	for(; pChr; pChr = (CCharacter *)pChr->TypeNext())
	{
		if(pChr == pNotThis)
			continue;

		vec2 IntersectPos;
		if(closest_point_on_line(Pos0, Pos1, pChr->m_Pos, IntersectPos))
		{
			float Len = distance(pChr->m_Pos, IntersectPos);
			if(Len < pChr->m_ProximityRadius + Radius)
			{
				pChr->m_Intersection = IntersectPos;
				listOfChars.push_back(pChr);
			}
		}
	}
	return listOfChars;
}

void CGameWorld::ReleaseHooked(int ClientID)
{
	CCharacter *pChr = (CCharacter *)CGameWorld::FindFirst(CGameWorld::ENTTYPE_CHARACTER);
	for(; pChr; pChr = (CCharacter *)pChr->TypeNext())
	{
		CCharacterCore *pCore = pChr->Core();
		if(pCore->m_HookedPlayer == ClientID && !pChr->IsSuper())
		{
			pCore->SetHookedPlayer(-1);
			pCore->m_TriggeredEvents |= COREEVENT_HOOK_RETRACT;
			pCore->m_HookState = HOOK_RETRACTED;
		}
	}
}