/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

/** @file ai_core.cpp Implementation of AI. */

#include "../stdafx.h"
#include "../core/backup_type.hpp"
#include "../core/bitmath_func.hpp"
#include "../company_base.h"
#include "../company_func.h"
#include "../network/network.h"
#include "../window_func.h"
#include "../framerate_type.h"
#include "ai_scanner.hpp"
#include "ai_instance.hpp"
#include "ai_config.hpp"
#include "ai_info.hpp"
#include "ai.hpp"

#include "../safeguards.h"

/* static */ uint AI::frame_counter = 0;
/* static */ std::unique_ptr<AIScannerInfo> AI::scanner_info = nullptr;
/* static */ std::unique_ptr<AIScannerLibrary> AI::scanner_library = nullptr;

/* static */ bool AI::CanStartNew()
{
	/* Only allow new AIs on the server and only when that is allowed in multiplayer */
	return !_networking || (_network_server && _settings_game.ai.ai_in_multiplayer);
}

/* static */ void AI::StartNew(CompanyID company)
{
	assert(Company::IsValidID(company));

	/* Clients shouldn't start AIs */
	if (_networking && !_network_server) return;

	Backup<CompanyID> cur_company(_current_company, company);
	Company *c = Company::Get(company);

	AIConfig *config = c->ai_config.get();
	if (config == nullptr) {
		c->ai_config = std::make_unique<AIConfig>(*AIConfig::GetConfig(company, AIConfig::SSS_FORCE_GAME));
		config = c->ai_config.get();
	}

	AIInfo *info = config->GetInfo();
	if (info == nullptr) {
		info = AI::scanner_info->SelectRandomAI();
		assert(info != nullptr);
		/* Load default data and store the name in the settings */
		config->Change(info->GetName(), -1, false);
	}
	config->AnchorUnchangeableSettings();

	c->ai_info = info;
	assert(c->ai_instance == nullptr);
	c->ai_instance = std::make_unique<AIInstance>();
	c->ai_instance->Initialize(info);
	c->ai_instance->LoadOnStack(config->GetToLoadData());
	config->SetToLoadData(nullptr);

	cur_company.Restore();

	InvalidateWindowClassesData(WC_SCRIPT_DEBUG, -1);
	return;
}

/* static */ void AI::GameLoop()
{
	/* If we are in networking, only servers run this function, and that only if it is allowed */
	if (_networking && (!_network_server || !_settings_game.ai.ai_in_multiplayer)) return;

	/* The speed with which AIs go, is limited by the 'competitor_speed' */
	AI::frame_counter++;
	assert(_settings_game.difficulty.competitor_speed <= 4);
	if ((AI::frame_counter & ((1 << (4 - _settings_game.difficulty.competitor_speed)) - 1)) != 0) return;

	Backup<CompanyID> cur_company(_current_company);
	for (const Company *c : Company::Iterate()) {
		if (c->is_ai) {
			PerformanceMeasurer framerate((PerformanceElement)(PFE_AI0 + c->index));
			cur_company.Change(c->index);
			c->ai_instance->GameLoop();
			/* Occasionally collect garbage; every 255 ticks do one company.
			 * Effectively collecting garbage once every two months per AI. */
			if ((AI::frame_counter & 255) == 0 && (CompanyID)GB(AI::frame_counter, 8, 4) == c->index) {
				c->ai_instance->CollectGarbage();
			}
		} else {
			PerformanceMeasurer::SetInactive((PerformanceElement)(PFE_AI0 + c->index));
		}
	}
	cur_company.Restore();
}

/* static */ uint AI::GetTick()
{
	return AI::frame_counter;
}

/* static */ void AI::Stop(CompanyID company)
{
	if (_networking && !_network_server) return;
	PerformanceMeasurer::SetInactive((PerformanceElement)(PFE_AI0 + company));

	Backup<CompanyID> cur_company(_current_company, company);
	Company *c = Company::Get(company);

	c->ai_instance.reset();
	c->ai_info = nullptr;
	c->ai_config.reset();

	cur_company.Restore();

	InvalidateWindowClassesData(WC_SCRIPT_DEBUG, -1);
}

/* static */ void AI::Pause(CompanyID company)
{
	/* The reason why dedicated servers are forbidden to execute this
	 * command is not because it is unsafe, but because there is no way
	 * for the server owner to unpause the script again. */
	if (_network_dedicated) return;

	Backup<CompanyID> cur_company(_current_company, company);
	Company::Get(company)->ai_instance->Pause();

	cur_company.Restore();
}

/* static */ void AI::Unpause(CompanyID company)
{
	Backup<CompanyID> cur_company(_current_company, company);
	Company::Get(company)->ai_instance->Unpause();

	cur_company.Restore();
}

/* static */ bool AI::IsPaused(CompanyID company)
{
	Backup<CompanyID> cur_company(_current_company, company);
	bool paused = Company::Get(company)->ai_instance->IsPaused();

	cur_company.Restore();

	return paused;
}

/* static */ void AI::KillAll()
{
	/* It might happen there are no companies .. than we have nothing to loop */
	if (Company::GetPoolSize() == 0) return;

	for (const Company *c : Company::Iterate()) {
		if (c->is_ai) AI::Stop(c->index);
	}
}

/* static */ void AI::Initialize()
{
	if (AI::scanner_info != nullptr) AI::Uninitialize(true);

	AI::frame_counter = 0;
	if (AI::scanner_info == nullptr) {
		TarScanner::DoScan(TarScanner::Mode::AI);
		AI::scanner_info = std::make_unique<AIScannerInfo>();
		AI::scanner_info->Initialize();
		AI::scanner_library = std::make_unique<AIScannerLibrary>();
		AI::scanner_library->Initialize();
	}
}

/* static */ void AI::Uninitialize(bool keepConfig)
{
	AI::KillAll();

	if (keepConfig) {
		/* Run a rescan, which indexes all AIInfos again, and check if we can
		 *  still load all the AIS, while keeping the configs in place */
		Rescan();
	} else {
		AI::scanner_info.reset();
		AI::scanner_library.reset();

		for (CompanyID c = CompanyID::Begin(); c < MAX_COMPANIES; ++c) {
			_settings_game.script_config.ai[c].reset();
			_settings_newgame.script_config.ai[c].reset();
		}
	}
}

/* static */ void AI::ResetConfig()
{
	/* Check for both newgame as current game if we can reload the AIInfo inside
	 *  the AIConfig. If not, remove the AI from the list (which will assign
	 *  a random new AI on reload). */
	for (CompanyID c = CompanyID::Begin(); c < MAX_COMPANIES; ++c) {
		if (_settings_game.script_config.ai[c] != nullptr && _settings_game.script_config.ai[c]->HasScript()) {
			if (!_settings_game.script_config.ai[c]->ResetInfo(true)) {
				Debug(script, 0, "After a reload, the AI by the name '{}' was no longer found, and removed from the list.", _settings_game.script_config.ai[c]->GetName());
				_settings_game.script_config.ai[c]->Change(std::nullopt);
			}
		}

		if (_settings_newgame.script_config.ai[c] != nullptr && _settings_newgame.script_config.ai[c]->HasScript()) {
			if (!_settings_newgame.script_config.ai[c]->ResetInfo(false)) {
				Debug(script, 0, "After a reload, the AI by the name '{}' was no longer found, and removed from the list.", _settings_newgame.script_config.ai[c]->GetName());
				_settings_newgame.script_config.ai[c]->Change(std::nullopt);
			}
		}

		if (Company::IsValidAiID(c) && Company::Get(c)->ai_config != nullptr) {
			AIConfig *config = Company::Get(c)->ai_config.get();
			if (!config->ResetInfo(true)) {
				/* The code belonging to an already running AI was deleted. We can only do
				 * one thing here to keep everything sane and that is kill the AI. After
				 * killing the offending AI we start a random other one in it's place, just
				 * like what would happen if the AI was missing during loading. */
				AI::Stop(c);
				AI::StartNew(c);
			} else {
				/* Update the reference in the Company struct. */
				Company::Get(c)->ai_info = config->GetInfo();
			}
		}
	}
}

/* static */ void AI::NewEvent(CompanyID company, ScriptEvent *event)
{
	ScriptObjectRef counter(event);

	/* Clients should ignore events */
	if (_networking && !_network_server) {
		return;
	}

	/* Only AIs can have an event-queue */
	if (!Company::IsValidAiID(company)) {
		return;
	}

	/* Queue the event */
	Backup<CompanyID> cur_company(_current_company, company);
	Company::Get(_current_company)->ai_instance->InsertEvent(event);
	cur_company.Restore();
}

/* static */ void AI::BroadcastNewEvent(ScriptEvent *event, CompanyID skip_company)
{
	ScriptObjectRef counter(event);

	/* Clients should ignore events */
	if (_networking && !_network_server) {
		return;
	}

	/* Try to send the event to all AIs */
	for (CompanyID c = CompanyID::Begin(); c < MAX_COMPANIES; ++c) {
		if (c != skip_company) AI::NewEvent(c, event);
	}
}

/* static */ void AI::Save(CompanyID company)
{
	if (!_networking || _network_server) {
		Company *c = Company::GetIfValid(company);
		assert(c != nullptr);

		/* When doing emergency saving, an AI can be not fully initialised. */
		if (c->ai_instance != nullptr) {
			Backup<CompanyID> cur_company(_current_company, company);
			c->ai_instance->Save();
			cur_company.Restore();
			return;
		}
	}

	AIInstance::SaveEmpty();
}

/* static */ void AI::GetConsoleList(std::back_insert_iterator<std::string> &output_iterator, bool newest_only)
{
	AI::scanner_info->GetConsoleList(output_iterator, newest_only);
}

/* static */ void AI::GetConsoleLibraryList(std::back_insert_iterator<std::string> &output_iterator)
{
	 AI::scanner_library->GetConsoleList(output_iterator, true);
}

/* static */ const ScriptInfoList *AI::GetInfoList()
{
	return AI::scanner_info->GetInfoList();
}

/* static */ const ScriptInfoList *AI::GetUniqueInfoList()
{
	return AI::scanner_info->GetUniqueInfoList();
}

/* static */ AIInfo *AI::FindInfo(const std::string &name, int version, bool force_exact_match)
{
	return AI::scanner_info->FindInfo(name, version, force_exact_match);
}

/* static */ AILibrary *AI::FindLibrary(const std::string &library, int version)
{
	return AI::scanner_library->FindLibrary(library, version);
}

/* static */ void AI::Rescan()
{
	TarScanner::DoScan(TarScanner::Mode::AI);

	AI::scanner_info->RescanDir();
	AI::scanner_library->RescanDir();
	ResetConfig();

	InvalidateWindowData(WC_SCRIPT_LIST, 0, 1);
	SetWindowClassesDirty(WC_SCRIPT_DEBUG);
	InvalidateWindowClassesData(WC_SCRIPT_SETTINGS);
}

/**
 * Check whether we have an AI (library) with the exact characteristics as ci.
 * @param ci the characteristics to search on (shortname and md5sum)
 * @param md5sum whether to check the MD5 checksum
 * @return true iff we have an AI (library) matching.
 */
/* static */ bool AI::HasAI(const ContentInfo &ci, bool md5sum)
{
	return AI::scanner_info->HasScript(ci, md5sum);
}

/* static */ bool AI::HasAILibrary(const ContentInfo &ci, bool md5sum)
{
	return AI::scanner_library->HasScript(ci, md5sum);
}

/* static */ AIScannerInfo *AI::GetScannerInfo()
{
	return AI::scanner_info.get();
}

/* static */ AIScannerLibrary *AI::GetScannerLibrary()
{
	return AI::scanner_library.get();
}

