/*
* ResourceTrader.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 "ResourceTrader.h"

namespace NK2AI
{
bool ResourceTrader::trade(const std::unique_ptr<BuildAnalyzer> & buildAnalyzer, std::shared_ptr<CCallback> cc, TResources freeResources)
{
	// TODO: Mircea: Maybe include based on how close danger is: X as default + proportion of close danger or something around that
	constexpr float ARMY_GOLD_RATIO_PER_MAKE_TURN_PASS = 0.1f;
	constexpr float EXPENDABLE_BULK_RATIO = 0.3f;
	bool haveTraded = false;
	ObjectInstanceID marketId;

	// TODO: Mircea: What about outside town markets that have better rates than a single town for example?
	// Are those used anywhere? To inspect.
	for (const auto * const town : cc->getTownsInfo())
	{
		if (town->hasBuiltSomeTradeBuilding())
		{
			marketId = town->id;
			break;
		}
	}

	if (!marketId.hasValue())
		return false;

	const CGObjectInstance * obj = cc->getObj(marketId, false);
	assert(obj);
	// if (!obj)
	// return false;

	const auto * market = dynamic_cast<const IMarket *>(obj);
	assert(market);
	// if (!market)
	// return false;

	bool shouldTryToTrade = true;
	while(shouldTryToTrade)
	{
		shouldTryToTrade = false;
		buildAnalyzer->update();

		// if we favor getResourcesRequiredNow is better on short term, if we favor getTotalResourcesRequired is better on long term
		TResources missingNow = buildAnalyzer->getMissingResourcesNow(ARMY_GOLD_RATIO_PER_MAKE_TURN_PASS);
		if(missingNow.empty())
			break;

		TResources income = buildAnalyzer->getDailyIncome();
		// We don't want to sell something that's necessary later on, though that could make short term a bit harder sometimes
		TResources freeAfterMissingTotal = buildAnalyzer->getFreeResourcesAfterMissingTotal(ARMY_GOLD_RATIO_PER_MAKE_TURN_PASS);

#if NK2AI_TRACE_LEVEL >= 2
		logAi->info("ResourceTrader: Free %s. FreeAfterMissingTotal %s. MissingNow  %s", freeResources.toString(), freeAfterMissingTotal.toString(), missingNow.toString());
#endif

		if(ResourceTrader::tradeHelper(EXPENDABLE_BULK_RATIO, market, missingNow, income, freeAfterMissingTotal, buildAnalyzer, cc))
		{
			haveTraded = true;
			shouldTryToTrade = true;
		}
	}
	return haveTraded;
}

bool ResourceTrader::tradeHelper(
	float EXPENDABLE_BULK_RATIO,
	const IMarket * market,
	TResources missingNow,
	TResources income,
	TResources freeAfterMissingTotal,
	const std::unique_ptr<BuildAnalyzer> & buildAnalyzer,
	std::shared_ptr<CCallback> cc
)
{
	constexpr int EMPTY = -1;
	int mostWanted = EMPTY;
	TResource mostWantedScoreNeg = std::numeric_limits<TResource>::max();
	int mostExpendable = EMPTY;
	TResource mostExpendableAmountPos = 0;

	// Find the most wanted resource
	for(int i = 0; i < missingNow.size(); ++i)
	{
		if(missingNow[i] == 0)
			continue;

		const TResource score = income[i] - missingNow[i];
		if(score < mostWantedScoreNeg)
		{
			mostWanted = i;
			mostWantedScoreNeg = score;
		}
	}

	// Find the most expendable resource
	for(int i = 0; i < missingNow.size(); ++i)
	{
		const TResource amountToSell = freeAfterMissingTotal[i];
		if(amountToSell == 0)
			continue;

		bool okToSell = false;
		if(i == GameResID::GOLD)
		{
			// TODO: Mircea: Check if we should negate isGoldPressureOverMax() instead
			if(income[GameResID::GOLD] > 0 && !buildAnalyzer->isGoldPressureOverMax())
				okToSell = true;
		}
		else
		{
			okToSell = true;
		}

		if(amountToSell > mostExpendableAmountPos && okToSell)
		{
			mostExpendable = i;
			mostExpendableAmountPos = amountToSell;
		}
	}

#if NK2AI_TRACE_LEVEL >= 2
	logAi->trace(
		"ResourceTrader: mostWanted: %d, mostWantedScoreNeg %d, mostExpendable: %d, mostExpendableAmountPos %d",
		mostWanted,
		mostWantedScoreNeg,
		mostExpendable,
		mostExpendableAmountPos
	);
#endif

	if(mostExpendable == mostWanted || mostWanted == EMPTY || mostExpendable == EMPTY)
		return false;

	int givenPerUnit;
	int receivedPerUnit;
	market->getOffer(mostExpendable, mostWanted, givenPerUnit, receivedPerUnit, EMarketMode::RESOURCE_RESOURCE);
	if(!givenPerUnit || !receivedPerUnit)
	{
		logGlobal->error(
			"ResourceTrader: No offer for %d of %d, given %d, received %d. Should never happen",
			mostExpendable,
			mostWanted,
			givenPerUnit,
			receivedPerUnit
		);
		return false;
	}

	// TODO: Mircea: if 15 wood and 14 gems, gems can be used a lot more for buying other things
	if(givenPerUnit > mostExpendableAmountPos)
		return false;

	TResource multiplier = std::min(
		static_cast<int>(mostExpendableAmountPos * EXPENDABLE_BULK_RATIO / givenPerUnit),
		missingNow[mostWanted] / receivedPerUnit
	); // for gold we have to / receivedUnits, because 1 ore gives many gold units
	if(multiplier == 0) // could happen for very small values due to EXPENDABLE_BULK_RATIO
		multiplier = 1;

	const TResource givenMultiplied = givenPerUnit * multiplier;
	if(givenMultiplied > freeAfterMissingTotal[mostExpendable])
	{
		logGlobal->error("ResourceTrader: Something went wrong with the multiplier %d", multiplier);
		return false;
	}

	cc->trade(market->getObjInstanceID(), EMarketMode::RESOURCE_RESOURCE, GameResID(mostExpendable), GameResID(mostWanted), givenMultiplied);
#if NK2AI_TRACE_LEVEL >= 2
	logAi->info("ResourceTrader: Traded %d of %s for %d receivedPerUnit of %s", givenMultiplied, mostExpendable, receivedPerUnit, mostWanted);
#endif
	return true;
}
}