/*
* BuildingManager.cpp, 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
*
*/

#include "StdInc.h"
#include "ArmyManager.h"

#include "../../CCallback.h"
#include "../../lib/mapObjects/MapObjects.h"

void ArmyManager::init(CPlayerSpecificInfoCallback * CB)
{
	cb = CB;
}

void ArmyManager::setAI(VCAI * AI)
{
	ai = AI;
}

std::vector<SlotInfo> ArmyManager::getSortedSlots(const CCreatureSet * target, const CCreatureSet * source) const
{
	const CCreatureSet * armies[] = { target, source };

	//we calculate total strength for each creature type available in armies
	std::map<const CCreature *, SlotInfo> creToPower;
	std::vector<SlotInfo> resultingArmy;

	for(auto armyPtr : armies)
	{
		for(auto & i : armyPtr->Slots())
		{
			auto & slotInfp = creToPower[i.second->type];

			slotInfp.creature = i.second->type;
			slotInfp.power += i.second->getPower();
			slotInfp.count += i.second->count;
		}
	}

	for(auto pair : creToPower)
		resultingArmy.push_back(pair.second);

	boost::sort(resultingArmy, [](const SlotInfo & left, const SlotInfo & right) -> bool
	{
		return left.power > right.power;
	});

	return resultingArmy;
}

std::vector<SlotInfo>::iterator ArmyManager::getWeakestCreature(std::vector<SlotInfo> & army) const
{
	auto weakest = boost::min_element(army, [](const SlotInfo & left, const SlotInfo & right) -> bool
	{
		if(left.creature->level != right.creature->level)
			return left.creature->level < right.creature->level;
		
		return left.creature->Speed() > right.creature->Speed();
	});

	return weakest;
}

std::vector<SlotInfo> ArmyManager::getBestArmy(const CCreatureSet * target, const CCreatureSet * source) const
{
	auto resultingArmy = getSortedSlots(target, source);

	if(resultingArmy.size() > GameConstants::ARMY_SIZE)
	{
		resultingArmy.resize(GameConstants::ARMY_SIZE);
	}
	else if(source->needsLastStack())
	{
		auto weakest = getWeakestCreature(resultingArmy);

		if(weakest->count == 1)
		{
			resultingArmy.erase(weakest);
		}
		else
		{
			weakest->power -= weakest->power / weakest->count;
			weakest->count--;
		}
	}

	return resultingArmy;
}

bool ArmyManager::canGetArmy(const CArmedInstance * target, const CArmedInstance * source) const
{
	//TODO: merge with pickBestCreatures
	//if (ai->primaryHero().h == source)
	if(target->tempOwner != source->tempOwner)
	{
		logAi->error("Why are we even considering exchange between heroes from different players?");
		return false;
	}

	return 0 < howManyReinforcementsCanGet(target, source);
}

ui64 ArmyManager::howManyReinforcementsCanBuy(const CCreatureSet * h, const CGDwelling * t) const
{
	ui64 aivalue = 0;
	TResources availableRes = cb->getResourceAmount();
	int freeHeroSlots = GameConstants::ARMY_SIZE - h->stacksCount();

	for(auto const dc : t->creatures)
	{
		creInfo ci = infoFromDC(dc);

		if(!ci.count || ci.creID == -1)
			continue;

		vstd::amin(ci.count, availableRes / ci.cre->cost); //max count we can afford

		if(ci.count && ci.creID != -1) //valid creature at this level
		{
			//can be merged with another stack?
			SlotID dst = h->getSlotFor(ci.creID);
			if(!h->hasStackAtSlot(dst)) //need another new slot for this stack
			{
				if(!freeHeroSlots) //no more place for stacks
					continue;
				else
					freeHeroSlots--; //new slot will be occupied
			}

			//we found matching occupied or free slot
			aivalue += ci.count * ci.cre->AIValue;
			availableRes -= ci.cre->cost * ci.count;
		}
	}

	return aivalue;
}

ui64 ArmyManager::howManyReinforcementsCanGet(const CCreatureSet * target, const CCreatureSet * source) const
{
	auto bestArmy = getBestArmy(target, source);
	uint64_t newArmy = 0;
	uint64_t oldArmy = target->getArmyStrength();

	for(auto & slot : bestArmy)
	{
		newArmy += slot.power;
	}

	return newArmy > oldArmy ? newArmy - oldArmy : 0;
}