vcmi/lib/CBattleCallback.h

#pragma once
#include "BattleHex.h"

class CGameState;
class CGTownInstance;
class CGHeroInstance;
class CStack;
class CSpell;
struct BattleInfo;
struct CObstacleInstance;

namespace boost
{class shared_mutex;}

namespace BattleSide
{
	enum {ATTACKER = 0, DEFENDER = 1};
}

typedef std::vector<const CStack*> TStacks;

class CBattleInfoEssentials;

//Basic class for various callbacks (interfaces called by players to get info about game and so forth)
class DLL_LINKAGE CCallbackBase
{
	const BattleInfo *battle; //battle to which the player is engaged, NULL if none or not applicable

	const BattleInfo * getBattle() const
	{
		return battle;
	}

protected:
	CGameState *gs;
	int player; // -1 gives access to all information, otherwise callback provides only information "visible" for player

	CCallbackBase(CGameState *GS, int Player)
		: battle(nullptr), gs(GS), player(Player)
	{}
	CCallbackBase()
		: battle(nullptr), gs(nullptr), player(-1)
	{}
	
	void setBattle(const BattleInfo *B);
	bool duringBattle() const;

public:
	boost::shared_mutex &getGsMutex(); //just return a reference to mutex, does not lock nor anything

	friend class CBattleInfoEssentials;
};


struct DLL_LINKAGE AttackableTiles
{
	std::set<BattleHex> hostileCreaturePositions;
	std::set<BattleHex> friendlyCreaturePositions; //for Dragon Breath
	template <typename Handler> void serialize(Handler &h, const int version)
	{
		h & hostileCreaturePositions & friendlyCreaturePositions;
	}
};

//Accessibility is property of hex in battle. It doesn't depend on stack, side's perspective and so on.
namespace EAccessibility
{
	enum EAccessibility
	{
		ACCESSIBLE, 
		ALIVE_STACK, 
		OBSTACLE,
		DESTRUCTIBLE_WALL,
		GATE, //sieges -> gate opens only for defender stacks
		UNAVAILABLE, //indestructible wall parts, special battlefields (like boat-to-boat)
		SIDE_COLUMN //used for first and last columns of hexes that are unavailable but wat machines can stand there
	};
}

typedef std::array<EAccessibility::EAccessibility, GameConstants::BFIELD_SIZE> TAccessibilityArray;

struct DLL_LINKAGE AccessibilityInfo : TAccessibilityArray
{
	bool occupiable(const CStack *stack, BattleHex tile) const;
	bool accessible(BattleHex tile, const CStack *stack) const; //checks for both tiles if stack is double wide
	bool accessible(BattleHex tile, bool doubleWide, bool attackerOwned) const; //checks for both tiles if stack is double wide
};

namespace BattlePerspective
{
	enum BattlePerspective
	{
		INVALID = -2,
		ALL_KNOWING = -1,
		LEFT_SIDE,
		RIGHT_SIDE
	};
}

// Reachability info is result of BFS calculation. It's dependant on stack (it's owner, whether it's flying),
// startPosition and perpective.
struct DLL_LINKAGE ReachabilityInfo
{
	typedef std::array<int, GameConstants::BFIELD_SIZE> TDistances;
	typedef std::array<BattleHex, GameConstants::BFIELD_SIZE> TPredecessors;

	enum { 	INFINITE_DIST = 1000000 };

	struct DLL_LINKAGE Parameters
	{
		const CStack *stack; //stack for which calculation is mage => not required (kept for debugging mostly), following variables are enough
		
		bool attackerOwned;
		bool doubleWide;
		bool flying;
		std::vector<BattleHex> knownAccessible; //hexes that will be treated as accessible, even if they're occupied by stack (by default - tiles occupied by stack we do reachability for, so it doesn't block itself)

		BattleHex startPosition; //assumed position of stack
		BattlePerspective::BattlePerspective perspective; //some obstacles (eg. quicksands) may be invisible for some side

		Parameters();
		Parameters(const CStack *Stack);
	};

	Parameters params;
	AccessibilityInfo accessibility;
	TDistances distances;
	TPredecessors predecessors;

	ReachabilityInfo()
	{
		distances.fill(INFINITE_DIST);
		predecessors.fill(BattleHex::INVALID);
	}

	bool isReachable(BattleHex hex) const
	{
		return distances[hex] < INFINITE_DIST;
	}
};

class DLL_LINKAGE CBattleInfoEssentials : public virtual CCallbackBase
{
protected:
	bool battleDoWeKnowAbout(ui8 side) const;
public:
	enum EStackOwnership
	{
		ONLY_MINE, ONLY_ENEMY, MINE_AND_ENEMY
	};

	BattlePerspective::BattlePerspective battleGetMySide() const;

	ui8 battleTerrainType() const;
	int battleGetBattlefieldType() const; //   1. sand/shore   2. sand/mesas   3. dirt/birches   4. dirt/hills   5. dirt/pines   6. grass/hills   7. grass/pines   8. lava   9. magic plains   10. snow/mountains   11. snow/trees   12. subterranean   13. swamp/trees   14. fiery fields   15. rock lands   16. magic clouds   17. lucid pools   18. holy ground   19. clover field   20. evil fog   21. "favourable winds" text on magic plains background   22. cursed ground   23. rough   24. ship to ship   25. ship
	std::vector<shared_ptr<const CObstacleInstance> > battleGetAllObstacles(boost::optional<BattlePerspective::BattlePerspective> perspective = boost::none) const; //returns all obstacles on the battlefield
	TStacks battleGetAllStacks() const; //returns all stacks, alive or dead or undead or mechanical :)
	bool battleHasNativeStack(ui8 side) const;
	ui8 battleGetWallState(int partOfWall) const; //for determining state of a part of the wall; format: parameter [0] - keep, [1] - bottom tower, [2] - bottom wall, [3] - below gate, [4] - over gate, [5] - upper wall, [6] - uppert tower, [7] - gate; returned value: 1 - intact, 2 - damaged, 3 - destroyed; 0 - no battle
	int battleGetMoatDmg() const; //what dmg unit will suffer if ending turn in the moat
	const CGTownInstance * battleGetDefendedTown() const; //returns defended town if current battle is a siege, NULL instead
	const CStack *battleActiveStack() const;
	si8 battleTacticDist() const; //returns tactic distance in current tactics phase; 0 if not in tactics phase
	si8 battleGetTacticsSide() const; //returns which side is in tactics phase, undefined if none (?)
	bool battleCanFlee(int player) const;
	bool battleCanSurrender(int player) const;
	ui8 playerToSide(int player) const;
	ui8 battleGetSiegeLevel() const; //returns 0 when there is no siege, 1 if fort, 2 is citadel, 3 is castle
	bool battleHasHero(ui8 side) const;
	int battleCastSpells(ui8 side) const; //how many spells has given side casted
	const CGHeroInstance * battleGetFightingHero(ui8 side) const;

	//helpers
	TStacks battleAliveStacks() const;
	TStacks battleAliveStacks(ui8 side) const;
	const CStack * battleGetStackByID(int ID, bool onlyAlive = true) const; //returns stack info by given ID
	bool battleIsObstacleVisibleForSide(const CObstacleInstance & coi, BattlePerspective::BattlePerspective side) const;
	//ESpellCastProblem::ESpellCastProblem battleCanCastSpell(int player, ECastingMode::ECastingMode mode) const; //Checks if player is able to cast spells (at all) at the moment
};

class DLL_LINKAGE CBattleInfoCallback : public virtual CBattleInfoEssentials
{
public:
	enum ERandomSpell
	{
		RANDOM_GENIE, RANDOM_AIMED
	};

	//battle
	shared_ptr<const CObstacleInstance> battleGetObstacleOnPos(BattleHex tile, bool onlyBlocking = true) const; //blocking obstacles makes tile inaccessible, others cause special effects (like Land Mines, Moat, Quicksands)
	const CStack * battleGetStackByPos(BattleHex pos, bool onlyAlive = true) const; //returns stack info by given pos
	void battleGetStackQueue(std::vector<const CStack *> &out, const int howMany, const int turn = 0, int lastMoved = -1) const;
	void battleGetStackCountOutsideHexes(bool *ac) const; // returns hexes which when in front of a stack cause us to move the amount box back


	std::vector<BattleHex> battleGetAvailableHexes(const CStack * stack, bool addOccupiable, std::vector<BattleHex> * attackable = NULL) const; //returns hexes reachable by creature with id ID (valid movement destinations), DOES contain stack current position

	int battleGetSurrenderCost(int Player) const; //returns cost of surrendering battle, -1 if surrendering is not possible
	ReachabilityInfo::TDistances battleGetDistances(const CStack * stack, BattleHex hex = BattleHex::INVALID, BattleHex * predecessors = NULL) const; //returns vector of distances to [dest hex number]
	std::set<BattleHex> battleGetAttackedHexes(const CStack* attacker, BattleHex destinationTile, BattleHex attackerPos = BattleHex::INVALID) const;
	bool battleCanShoot(const CStack * stack, BattleHex dest) const; //determines if stack with given ID shoot at the selected destination
	bool battleIsStackBlocked(const CStack * stack) const; //returns true if there is neighboring enemy stack
	std::set<const CStack*>  batteAdjacentCreatures (const CStack * stack) const;

	TDmgRange calculateDmgRange(const CStack* attacker, const CStack* defender, TQuantity attackerCount, bool shooting, ui8 charge, bool lucky, bool deathBlow, bool ballistaDoubleDmg) const; //charge - number of hexes travelled before attack (for champion's jousting); returns pair <min dmg, max dmg>
	TDmgRange calculateDmgRange(const CStack* attacker, const CStack* defender, bool shooting, ui8 charge, bool lucky, bool deathBlow, bool ballistaDoubleDmg) const; //charge - number of hexes travelled before attack (for champion's jousting); returns pair <min dmg, max dmg>

	//hextowallpart  //int battleGetWallUnderHex(BattleHex hex) const; //returns part of destructible wall / gate / keep under given hex or -1 if not found
	std::pair<ui32, ui32> battleEstimateDamage(const CStack * attacker, const CStack * defender, std::pair<ui32, ui32> * retaliationDmg = NULL) const; //estimates damage dealt by attacker to defender; it may be not precise especially when stack has randomly working bonuses; returns pair <min dmg, max dmg>
	si8 battleHasDistancePenalty( const CStack * stack, BattleHex destHex ) const;
	si8 battleHasWallPenalty(const CStack * stack, BattleHex destHex) const; //checks if given stack has wall penalty
	EWallParts::EWallParts battleHexToWallPart(BattleHex hex) const; //returns part of destructible wall / gate / keep under given hex or -1 if not found

	//*** MAGIC 
	si8 battleMaxSpellLevel() const; //calculates minimum spell level possible to be cast on battlefield - takes into account artifacts of both heroes; if no effects are set, 0 is returned
	ui32 battleGetSpellCost(const CSpell * sp, const CGHeroInstance * caster) const; //returns cost of given spell
	ESpellCastProblem::ESpellCastProblem battleCanCastSpell(int player, ECastingMode::ECastingMode mode) const; //returns true if there are no general issues preventing from casting a spell
	ESpellCastProblem::ESpellCastProblem battleCanCastThisSpell(int player, const CSpell * spell, ECastingMode::ECastingMode mode) const; //checks if given player can cast given spell
	ESpellCastProblem::ESpellCastProblem battleCanCastThisSpellHere(int player, const CSpell * spell, ECastingMode::ECastingMode mode, BattleHex dest) const; //checks if given player can cast given spell at given tile in given mode
	ESpellCastProblem::ESpellCastProblem battleCanCreatureCastThisSpell(const CSpell * spell, BattleHex destination) const; //determines if creature can cast a spell here

	si32 battleGetRandomStackSpell(const CStack * stack, ERandomSpell mode) const;
	TSpell getRandomBeneficialSpell(const CStack * subject) const;
	TSpell getRandomCastedSpell(const CStack * caster) const; //called at the beginning of turn for Faerie Dragon

	//checks for creature immunity / anything that prevent casting *at given hex* - doesn't take into acount general problems such as not having spellbook or mana points etc.
	ESpellCastProblem::ESpellCastProblem battleIsImmune(const CGHeroInstance * caster, const CSpell * spell, ECastingMode::ECastingMode mode, BattleHex dest) const; 


	const CStack * getStackIf(boost::function<bool(const CStack*)> pred) const;

	si8 battleHasShootingPenalty(const CStack * stack, BattleHex destHex)
	{
		return battleHasDistancePenalty(stack, destHex) || battleHasWallPenalty(stack, destHex);
	}
	si8 battleCanTeleportTo(const CStack * stack, BattleHex destHex, int telportLevel) const; //checks if teleportation of given stack to given position can take place


	//convenience methods using the ones above
	bool isInTacticRange( BattleHex dest ) const;
	si8 battleGetTacticDist() const; //returns tactic distance for calling player or 0 if this player is not in tactic phase (for ALL_KNOWING actual distance for tactic side)

	AttackableTiles getPotentiallyAttackableHexes(const CStack* attacker, BattleHex destinationTile, BattleHex attackerPos) const;
	std::set<const CStack*> getAttackedCreatures(const CStack* attacker, BattleHex destinationTile, BattleHex attackerPos = BattleHex::INVALID) const; //calculates range of multi-hex attacks

	ReachabilityInfo getReachability(const CStack *stack) const;
	ReachabilityInfo getReachability(const ReachabilityInfo::Parameters &params) const;
	AccessibilityInfo getAccesibility() const;
	AccessibilityInfo getAccesibility(const CStack *stack) const; //Hexes ocupied by stack will be marked as accessible.
	AccessibilityInfo getAccesibility(const std::vector<BattleHex> &accessibleHexes) const; //given hexes will be marked as accessible
	std::pair<const CStack *, BattleHex> getNearestStack(const CStack * closest, boost::logic::tribool attackerOwned) const;
protected:
	ReachabilityInfo getFlyingReachability(const ReachabilityInfo::Parameters params) const;
	ReachabilityInfo makeBFS(const AccessibilityInfo &accessibility, const ReachabilityInfo::Parameters params) const;
	ReachabilityInfo makeBFS(const CStack *stack) const; //uses default parameters -> stack position and owner's perspective
	std::set<BattleHex> getStoppers(BattlePerspective::BattlePerspective whichSidePerspective) const; //get hexes with stopping obstacles (quicksands)


};

class DLL_LINKAGE CPlayerBattleCallback : public CBattleInfoCallback
{
public:
	bool battleCanFlee() const; //returns true if caller can flee from the battle
	TStacks battleGetStacks(EStackOwnership whose = MINE_AND_ENEMY, bool onlyAlive = true) const; //returns stacks on battlefield
	ESpellCastProblem::ESpellCastProblem battleCanCastThisSpell(const CSpell * spell) const; //determines if given spell can be casted (and returns problem description)
	ESpellCastProblem::ESpellCastProblem battleCanCastThisSpell(const CSpell * spell, BattleHex destination) const; //if hero can cast spell here
	ESpellCastProblem::ESpellCastProblem battleCanCreatureCastThisSpell(const CSpell * spell, BattleHex destination) const; //determines if creature can cast a spell here
	int battleGetSurrenderCost() const; //returns cost of surrendering battle, -1 if surrendering is not possible

	bool battleCanCastSpell(ESpellCastProblem::ESpellCastProblem *outProblem = nullptr) const; //returns true, if caller can cast a spell. If not, if pointer is given via arg, the reason will be written.
};