#include "game_server/InternalGameServer.h"
#include "game_server/NetworkProtocol.h"
#if defined(NETWORK)
#include "game_server/WebsocketGameServer.h"
#endif
#include "Campaign.h"
#include "LocationState.h"
#include "utils/Utils.h"
#include <atomic>
#include <chrono>
#include <csignal>
#include <cstdlib>
#include <exception>
#include <iostream>
#include <limits>
#include <memory>
#include <string>
#include <thread>
#include <vector>

namespace {

std::atomic_bool stopRequested{false};

void requestStop(int)
{
	stopRequested.store(true);
}

std::int64_t parsePositiveNumber(const char* value, const char* option)
{
	try {
		const std::string text(value);
		std::size_t consumed = 0;
		const long long parsed = std::stoll(text, &consumed);
		if (consumed != text.size() || parsed <= 0)
			throw std::invalid_argument("not positive");
		return static_cast<std::int64_t>(parsed);
	} catch (const std::exception&) {
		throw std::runtime_error(
			std::string("Invalid value for ") + option + ": " + value);
	}
}

} // namespace

int main(int argc, char** argv)
{
	std::int64_t tickMs = FRG::kSimulationTickMs;
	std::int64_t maxTicks = (std::numeric_limits<std::int64_t>::max)();
	bool sleepBetweenTicks = true;
	std::string campaignId;
	std::string locationId;
	std::string campaignsPath = "resources/config/campaigns.json";
	std::string listenAddress = "0.0.0.0";
	std::int64_t listenPort = 8080;

	try {
		for (int index = 1; index < argc; ++index) {
			const std::string option(argv[index]);
			if (option == "--ticks" && index + 1 < argc) {
				maxTicks = parsePositiveNumber(argv[++index], "--ticks");
			} else if (option == "--tick-ms" && index + 1 < argc) {
				tickMs = parsePositiveNumber(argv[++index], "--tick-ms");
			} else if (option == "--no-sleep") {
				sleepBetweenTicks = false;
			} else if (option == "--campaign" && index + 1 < argc) {
				campaignId = argv[++index];
			} else if (option == "--location" && index + 1 < argc) {
				locationId = argv[++index];
			} else if (option == "--campaigns" && index + 1 < argc) {
				campaignsPath = argv[++index];
			} else if (option == "--address" && index + 1 < argc) {
				listenAddress = argv[++index];
			} else if (option == "--port" && index + 1 < argc) {
				listenPort = parsePositiveNumber(argv[++index], "--port");
				if (listenPort > 65535)
					throw std::runtime_error("Invalid value for --port");
			} else if (option == "--help") {
				std::cout
					<< "Usage: GameServer [--ticks N] [--tick-ms N] "
					   "[--no-sleep] [--campaign ID] [--location ID] "
					   "[--campaigns PATH] [--address IP] [--port N]\n";
				return EXIT_SUCCESS;
			} else {
				throw std::runtime_error("Unknown or incomplete option: " + option);
			}
		}
	} catch (const std::exception& error) {
		std::cerr << error.what() << '\n';
		return EXIT_FAILURE;
	}

	if (tickMs != FRG::kSimulationTickMs) {
		std::cerr << "Network lockstep requires --tick-ms "
			<< FRG::kSimulationTickMs << '\n';
		return EXIT_FAILURE;
	}

	std::signal(SIGINT, requestStop);
	std::signal(SIGTERM, requestStop);

	FRG::InternalGameServer server;
	std::vector<std::string> playerSlots;
	std::string compatibilityFingerprint = "lockstep-v2";
	if (!campaignId.empty()) {
		try {
			FRG::CampaignRegistry::instance().loadFromJson(campaignsPath);
			std::cout << "[server] Loading...\n" << std::flush;
			const FRG::CampaignConfig* campaign =
				FRG::CampaignRegistry::instance().find(campaignId);
			if (!campaign)
				throw std::runtime_error(
					"Unknown campaign '" + campaignId + "'");
			const std::string selectedLocation = locationId.empty()
				? campaign->startLocation : locationId;
			const FRG::LocationConfig* location =
				campaign->findLocation(selectedLocation);
			if (!location)
				throw std::runtime_error(
					"Campaign '" + campaignId +
					"' has no location '" + selectedLocation + "'");
			server.startCampaign(*campaign, std::string(), true, false);
			server.prepareLocation(*location);
			const std::string startState =
				FRG::readTextFile(campaign->startStatePath);
			if (!startState.empty()) {
				try {
					nlohmann::json persisted =
						nlohmann::json::parse(startState);
					nlohmann::json networkState;
					FRG::ClientLocationState ignoredLocalState;
					FRG::loadSinglePlayerPersistence(
						persisted, networkState, ignoredLocalState);
					networkState["campaignId"] = campaignId;
					networkState["currentLocationId"] = selectedLocation;
					server.load(networkState);
					std::cout << "Loaded initial state '"
						<< campaign->startStatePath << "'\n";
				} catch (const std::exception& error) {
					std::cerr << "Ignoring invalid initial state '"
						<< campaign->startStatePath << "': "
						<< error.what() << '\n';
				}
			}
			server.activateLocation(selectedLocation);
			playerSlots = campaign->networkPlayerSlots;
			for (const std::string& slot : playerSlots) {
				if (server.snapshot()->players.count(slot) == 0)
					throw std::runtime_error(
						"Multiplayer slot '" + slot +
						"' is missing from the initial state");
			}
			compatibilityFingerprint =
				campaign->networkCompatibility.empty()
					? "lockstep-v2:" + campaignId
					: campaign->networkCompatibility;
			if (!campaign->tutorial) {
				server.submit(FRG::SetTutorialStepCommand{
					FRG::TutorialStep::Completed});
			}
			std::cout << "Loaded campaign '" << campaignId
				<< "', location '" << selectedLocation
				<< "' with shared player '" << server.localPlayerId() << "'\n";
		} catch (const std::exception& error) {
			std::cerr << "Server content setup failed: "
				<< error.what() << '\n';
			return EXIT_FAILURE;
		}
	}
	const auto tickDuration = std::chrono::milliseconds(tickMs);
	auto nextTick = std::chrono::steady_clock::now();

#if defined(NETWORK)
	std::unique_ptr<FRG::WebsocketGameServer> websocketServer;
	try {
		websocketServer = std::make_unique<FRG::WebsocketGameServer>(
			server, playerSlots, compatibilityFingerprint,
			listenAddress, static_cast<std::uint16_t>(listenPort));
	} catch (const std::exception& error) {
		std::cerr << "WebSocket listener setup failed: "
			<< error.what() << '\n';
		return EXIT_FAILURE;
	}
	std::cout << "GameServer listening on ws://" << listenAddress << ':'
		<< websocketServer->port() << " (" << tickMs << " ms tick)\n";
#else
	std::cout << "GameServer started (network disabled, "
		<< tickMs << " ms tick)\n";
#endif
	for (std::int64_t tick = 0;
		tick < maxTicks && !stopRequested.load(); ++tick) {
		nextTick += tickDuration;
#if defined(NETWORK)
		websocketServer->update();
#else
		server.update(tickMs);
#endif
		if (sleepBetweenTicks) std::this_thread::sleep_until(nextTick);
	}
	std::cout << "GameServer stopped\n";
	return EXIT_SUCCESS;
}