/*
 * 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 <http://www.gnu.org/licenses/>.
 */

/** @file dedicated_v.cpp Dedicated server video 'driver'. */

#include "../stdafx.h"

#include "../gfx_func.h"
#include "../network/network.h"
#include "../network/network_internal.h"
#include "../console_func.h"
#include "../genworld.h"
#include "../fileio_type.h"
#include "../fios.h"
#include "../blitter/factory.hpp"
#include "../company_func.h"
#include "../core/random_func.hpp"
#include "../saveload/saveload.h"
#include "../thread.h"
#include "../window_func.h"
#include "dedicated_v.h"

#ifdef __OS2__
#	include <sys/time.h> /* gettimeofday */
#	include <sys/types.h>
#	include <unistd.h>
#	include <conio.h>

#	define INCL_DOS
#	include <os2.h>

#	define STDIN 0  /* file descriptor for standard input */

/**
 * Switches OpenTTD to a console app at run-time, instead of a PM app
 * Necessary to see stdout, etc.
 */
static void OS2_SwitchToConsoleMode()
{
	PPIB pib;
	PTIB tib;

	DosGetInfoBlocks(&tib, &pib);

	/* Change flag from PM to VIO */
	pib->pib_ultype = 3;
}
#endif

#if defined(UNIX)
#	include <sys/time.h> /* gettimeofday */
#	include <sys/types.h>
#	include <unistd.h>
#	include <signal.h>
#	define STDIN 0  /* file descriptor for standard input */

/* Signal handlers */
static void DedicatedSignalHandler(int sig)
{
	if (_game_mode == GM_NORMAL && _settings_client.gui.autosave_on_exit) DoExitSave();
	_exit_game = true;
	signal(sig, DedicatedSignalHandler);
}
#endif

#if defined(_WIN32)
# include <windows.h> /* GetTickCount */
# include <conio.h>
# include <time.h>
# include <tchar.h>
# include "../os/windows/win32.h"

static HANDLE _hInputReady, _hWaitForInputHandling;
static HANDLE _hThread; // Thread to close
static char _win_console_thread_buffer[200];

/* Windows Console thread. Just loop and signal when input has been received */
static void WINAPI CheckForConsoleInput()
{
	SetCurrentThreadName("ottd:win-console");

	DWORD nb;
	HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
	for (;;) {
		ReadFile(hStdin, _win_console_thread_buffer, lengthof(_win_console_thread_buffer), &nb, nullptr);
		if (nb >= lengthof(_win_console_thread_buffer)) nb = lengthof(_win_console_thread_buffer) - 1;
		_win_console_thread_buffer[nb] = '\0';

		/* Signal input waiting that input is read and wait for it being handled
		 * SignalObjectAndWait() should be used here, but it's unsupported in Win98< */
		SetEvent(_hInputReady);
		WaitForSingleObject(_hWaitForInputHandling, INFINITE);
	}
}

static void CreateWindowsConsoleThread()
{
	DWORD dwThreadId;
	/* Create event to signal when console input is ready */
	_hInputReady = CreateEvent(nullptr, false, false, nullptr);
	_hWaitForInputHandling = CreateEvent(nullptr, false, false, nullptr);
	if (_hInputReady == nullptr || _hWaitForInputHandling == nullptr) usererror("Cannot create console event!");

	_hThread = CreateThread(nullptr, 0, (LPTHREAD_START_ROUTINE)CheckForConsoleInput, nullptr, 0, &dwThreadId);
	if (_hThread == nullptr) usererror("Cannot create console thread!");

	DEBUG(driver, 2, "Windows console thread started");
}

static void CloseWindowsConsoleThread()
{
	CloseHandle(_hThread);
	CloseHandle(_hInputReady);
	CloseHandle(_hWaitForInputHandling);
	DEBUG(driver, 2, "Windows console thread shut down");
}

#endif

#include "../safeguards.h"


static void *_dedicated_video_mem;

/* Whether a fork has been done. */
bool _dedicated_forks;

extern bool SafeLoad(const std::string &filename, SaveLoadOperation fop, DetailedFileType dft, GameMode newgm, Subdirectory subdir, struct LoadFilter *lf = nullptr);

static FVideoDriver_Dedicated iFVideoDriver_Dedicated;


const char *VideoDriver_Dedicated::Start(const StringList &parm)
{
	this->UpdateAutoResolution();

	int bpp = BlitterFactory::GetCurrentBlitter()->GetScreenDepth();
	_dedicated_video_mem = (bpp == 0) ? nullptr : MallocT<byte>(_cur_resolution.width * _cur_resolution.height * (bpp / 8));

	_screen.width  = _screen.pitch = _cur_resolution.width;
	_screen.height = _cur_resolution.height;
	_screen.dst_ptr = _dedicated_video_mem;
	ScreenSizeChanged();
	BlitterFactory::GetCurrentBlitter()->PostResize();

#if defined(_WIN32)
	/* For win32 we need to allocate a console (debug mode does the same) */
	CreateConsole();
	CreateWindowsConsoleThread();
	SetConsoleTitle(_T("OpenTTD Dedicated Server"));
#endif

#ifdef _MSC_VER
	/* Disable the MSVC assertion message box. */
	_set_error_mode(_OUT_TO_STDERR);
#endif

#ifdef __OS2__
	/* For OS/2 we also need to switch to console mode instead of PM mode */
	OS2_SwitchToConsoleMode();
#endif

	DEBUG(driver, 1, "Loading dedicated server");
	return nullptr;
}

void VideoDriver_Dedicated::Stop()
{
#ifdef _WIN32
	CloseWindowsConsoleThread();
#endif
	free(_dedicated_video_mem);
}

void VideoDriver_Dedicated::MakeDirty(int left, int top, int width, int height) {}
bool VideoDriver_Dedicated::ChangeResolution(int w, int h) { return false; }
bool VideoDriver_Dedicated::ToggleFullscreen(bool fs) { return false; }

#if defined(UNIX) || defined(__OS2__)
static bool InputWaiting()
{
	struct timeval tv;
	fd_set readfds;

	tv.tv_sec = 0;
	tv.tv_usec = 1;

	FD_ZERO(&readfds);
	FD_SET(STDIN, &readfds);

	/* don't care about writefds and exceptfds: */
	return select(STDIN + 1, &readfds, nullptr, nullptr, &tv) > 0;
}

#else

static bool InputWaiting()
{
	return WaitForSingleObject(_hInputReady, 1) == WAIT_OBJECT_0;
}

#endif

static void DedicatedHandleKeyInput()
{
	static char input_line[1024] = "";

	if (!InputWaiting()) return;

	if (_exit_game) return;

#if defined(UNIX) || defined(__OS2__)
	if (fgets(input_line, lengthof(input_line), stdin) == nullptr) return;
#else
	/* Handle console input, and signal console thread, it can accept input again */
	static_assert(lengthof(_win_console_thread_buffer) <= lengthof(input_line));
	strecpy(input_line, _win_console_thread_buffer, lastof(input_line));
	SetEvent(_hWaitForInputHandling);
#endif

	/* Remove trailing \r or \n */
	for (char *c = input_line; *c != '\0'; c++) {
		if (*c == '\n' || *c == '\r' || c == lastof(input_line)) {
			*c = '\0';
			break;
		}
	}
	str_validate(input_line, lastof(input_line));

	IConsoleCmdExec(input_line); // execute command
}

void VideoDriver_Dedicated::MainLoop()
{
	auto cur_ticks = std::chrono::steady_clock::now();
	auto last_realtime_tick = cur_ticks;
	auto next_game_tick = cur_ticks;

	/* Signal handlers */
#if defined(UNIX)
	signal(SIGTERM, DedicatedSignalHandler);
	signal(SIGINT, DedicatedSignalHandler);
	signal(SIGQUIT, DedicatedSignalHandler);
#endif

	/* Load the dedicated server stuff */
	_is_network_server = true;
	_network_dedicated = true;
	_current_company = _local_company = COMPANY_SPECTATOR;

	/* If SwitchMode is SM_LOAD_GAME, it means that the user used the '-g' options */
	if (_switch_mode != SM_LOAD_GAME) {
		StartNewGameWithoutGUI(GENERATE_NEW_SEED);
		SwitchToMode(_switch_mode);
		_switch_mode = SM_NONE;
	} else {
		_switch_mode = SM_NONE;
		/* First we need to test if the savegame can be loaded, else we will end up playing the
		 *  intro game... */
		if (!SafeLoad(_file_to_saveload.name, _file_to_saveload.file_op, _file_to_saveload.detail_ftype, GM_NORMAL, BASE_DIR)) {
			/* Loading failed, pop out.. */
			DEBUG(net, 0, "Loading requested map failed, aborting");
			_networking = false;
		} else {
			/* We can load this game, so go ahead */
			SwitchToMode(SM_LOAD_GAME);
		}
	}

	/* Done loading, start game! */

	if (!_networking) {
		DEBUG(net, 0, "Dedicated server could not be started, aborting");
		return;
	}

	while (!_exit_game) {
		InteractiveRandom(); // randomness

		if (!_dedicated_forks) DedicatedHandleKeyInput();

		cur_ticks = std::chrono::steady_clock::now();

		/* If more than a millisecond has passed, increase the _realtime_tick. */
		if (cur_ticks - last_realtime_tick > std::chrono::milliseconds(1)) {
			auto delta = std::chrono::duration_cast<std::chrono::milliseconds>(cur_ticks - last_realtime_tick);
			_realtime_tick += delta.count();
			last_realtime_tick += delta;
		}

		if (cur_ticks >= next_game_tick || _ddc_fastforward) {
			if (_ddc_fastforward) {
				next_game_tick = cur_ticks + std::chrono::milliseconds(MILLISECONDS_PER_TICK);
			} else {
				next_game_tick += std::chrono::milliseconds(MILLISECONDS_PER_TICK);
				/* Avoid next_game_tick getting behind more and more if it cannot keep up. */
				if (next_game_tick < cur_ticks - std::chrono::milliseconds(ALLOWED_DRIFT * MILLISECONDS_PER_TICK)) next_game_tick = cur_ticks;
			}

			GameLoop();
			InputLoop();
			UpdateWindows();
		}

		/* Don't sleep when fast forwarding (for desync debugging) */
		if (!_ddc_fastforward) {
			/* Sleep longer on a dedicated server, if the game is paused and no clients connected.
			 * That can allow the CPU to better use deep sleep states. */
			if (_pause_mode != 0 && !HasClients()) {
				std::this_thread::sleep_for(std::chrono::milliseconds(100));
			} else {
				/* See how much time there is till we have to process the next event, and try to hit that as close as possible. */
				auto now = std::chrono::steady_clock::now();

				if (next_game_tick > now) {
					std::this_thread::sleep_for(next_game_tick - now);
				}
			}
		}
	}
}