vcmi/AI/BattleAI/BattleExchangeVariant.h

/*
 * BattleExchangeVariant.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#pragma once

#include "../../lib/AI_Base.h"
#include "../../lib/battle/ReachabilityInfo.h"
#include "PotentialTargets.h"
#include "StackWithBonuses.h"

struct AttackerValue
{
	int64_t value;
	bool isRetalitated;
	BattleHex position;

	AttackerValue();
};

struct MoveTarget
{
	int64_t score;
	std::vector<BattleHex> positions;

	MoveTarget();
};

struct EvaluationResult
{
	static const int64_t INEFFECTIVE_SCORE = -1000000;

	AttackPossibility bestAttack;
	MoveTarget bestMove;
	bool wait;
	int64_t score;
	bool defend;

	EvaluationResult(const AttackPossibility & ap)
		:wait(false), score(0), bestAttack(ap), defend(false)
	{
	}
};

/// <summary>
/// The class represents evaluation of attack value
/// of exchanges between all stacks which can access particular hex
/// starting from initial attack represented by AttackPossibility and further according turn order.
/// Negative score value means we get more demage than deal
/// </summary>
class BattleExchangeVariant
{
public:
	BattleExchangeVariant()
		:dpsScore(0), attackerValue()
	{
	}

	int64_t trackAttack(const AttackPossibility & ap, HypotheticBattle & state);

	int64_t trackAttack(
		std::shared_ptr<StackWithBonuses> attacker,
		std::shared_ptr<StackWithBonuses> defender,
		bool shooting,
		bool isOurAttack,
		const CBattleInfoCallback & cb,
		bool evaluateOnly = false);

	int64_t getScore() const { return dpsScore; }

	void adjustPositions(
		std::vector<const battle::Unit *> attackers,
		const AttackPossibility & ap,
		std::map<BattleHex, battle::Units> & reachabilityMap);

private:
	int64_t dpsScore;
	std::map<uint32_t, AttackerValue> attackerValue;
};

class BattleExchangeEvaluator
{
private:
	std::shared_ptr<CBattleInfoCallback> cb;
	std::shared_ptr<Environment> env;
	std::map<BattleHex, std::vector<const battle::Unit *>> reachabilityMap;
	std::vector<battle::Units> turnOrder;

public:
	BattleExchangeEvaluator(std::shared_ptr<CBattleInfoCallback> cb, std::shared_ptr<Environment> env)
		:cb(cb), reachabilityMap(), env(env), turnOrder()
	{
	}

	EvaluationResult findBestTarget(const battle::Unit * activeStack, PotentialTargets & targets, HypotheticBattle & hb);
	int64_t calculateExchange(const AttackPossibility & ap, PotentialTargets & targets, HypotheticBattle & hb);
	void updateReachabilityMap(HypotheticBattle & hb);
	std::vector<const battle::Unit *> getExchangeUnits(const AttackPossibility & ap, PotentialTargets & targets, HypotheticBattle & hb);
	bool checkPositionBlocksOurStacks(HypotheticBattle & hb, const battle::Unit * unit, BattleHex position);
	MoveTarget findMoveTowardsUnreachable(const battle::Unit * activeStack, PotentialTargets & targets, HypotheticBattle & hb);
	std::vector<const battle::Unit *> getAdjacentUnits(const battle::Unit * unit);
};