// PORT: in-client account registration. 40250 has no counterpart: its accounts were made on the web.
//
// net.RegisterAccount(host, port, login, password, socialId) starts one HTTP POST /register to the
// server's registration service (tools/40250/register_server.py) on a worker thread;
// net.GetRegisterAccountResult() polls it from the login window's OnUpdate. The reply is a single
// line, "OK" or "ERR <CODE>", returned to Python as-is.
#include "StdAfx.h"

#include <atomic>
#include <cerrno>
#include <cstring>
#include <mutex>
#include <string>
#include <thread>

#include <arpa/inet.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <poll.h>
#include <sys/socket.h>
#include <unistd.h>

namespace
{
enum ERegisterState
{
	REGISTER_IDLE,
	REGISTER_PENDING,
	REGISTER_DONE,
};

const int c_iRegisterTimeoutMs = 8000;

std::mutex gs_kRegisterMutex;
std::atomic<int> gs_iRegisterState(REGISTER_IDLE);
std::string gs_strRegisterResult;

std::string __UrlEncode(const std::string& c_rstText)
{
	static const char c_szHex[] = "0123456789ABCDEF";
	std::string stOut;
	for (unsigned char c : c_rstText)
	{
		if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '-' || c == '_' || c == '.' || c == '~')
		{
			stOut += char(c);
		}
		else
		{
			stOut += '%';
			stOut += c_szHex[c >> 4];
			stOut += c_szHex[c & 15];
		}
	}
	return stOut;
}

bool __WaitFor(int iSocket, short sEvents)
{
	pollfd kPoll = { iSocket, sEvents, 0 };
	return poll(&kPoll, 1, c_iRegisterTimeoutMs) == 1 && (kPoll.revents & sEvents);
}

std::string __Post(const std::string& c_rstHost, int iPort, const std::string& c_rstBody)
{
	addrinfo kHints;
	memset(&kHints, 0, sizeof(kHints));
	kHints.ai_family = AF_INET;
	kHints.ai_socktype = SOCK_STREAM;
	addrinfo* pkAddr = NULL;
	if (getaddrinfo(c_rstHost.c_str(), std::to_string(iPort).c_str(), &kHints, &pkAddr) != 0 || !pkAddr)
		return "ERR CONNECT";

	const int iSocket = socket(pkAddr->ai_family, pkAddr->ai_socktype, pkAddr->ai_protocol);
	if (iSocket < 0)
	{
		freeaddrinfo(pkAddr);
		return "ERR CONNECT";
	}
#ifdef SO_NOSIGPIPE
	const int iOne = 1;
	setsockopt(iSocket, SOL_SOCKET, SO_NOSIGPIPE, &iOne, sizeof(iOne));
#endif
	fcntl(iSocket, F_SETFL, fcntl(iSocket, F_GETFL, 0) | O_NONBLOCK);

	std::string stResult = "ERR CONNECT";
	int iError = 0;
	socklen_t iErrorLen = sizeof(iError);
	if (connect(iSocket, pkAddr->ai_addr, pkAddr->ai_addrlen) == 0 ||
		(errno == EINPROGRESS && __WaitFor(iSocket, POLLOUT) &&
		 getsockopt(iSocket, SOL_SOCKET, SO_ERROR, &iError, &iErrorLen) == 0 && iError == 0))
	{
		const std::string stRequest =
			"POST /register HTTP/1.0\r\n"
			"Host: " + c_rstHost + "\r\n"
			"Content-Type: application/x-www-form-urlencoded\r\n"
			"Content-Length: " + std::to_string(c_rstBody.size()) + "\r\n"
			"Connection: close\r\n\r\n" + c_rstBody;

		size_t uSent = 0;
		while (uSent < stRequest.size() && __WaitFor(iSocket, POLLOUT))
		{
#ifdef MSG_NOSIGNAL
			const ssize_t n = send(iSocket, stRequest.data() + uSent, stRequest.size() - uSent, MSG_NOSIGNAL);
#else
			const ssize_t n = send(iSocket, stRequest.data() + uSent, stRequest.size() - uSent, 0);
#endif
			if (n <= 0)
				break;
			uSent += size_t(n);
		}

		std::string stResponse;
		if (uSent == stRequest.size())
		{
			char acBuf[512];
			while (stResponse.size() < 4096 && __WaitFor(iSocket, POLLIN))
			{
				const ssize_t n = recv(iSocket, acBuf, sizeof(acBuf), 0);
				if (n <= 0)
					break;
				stResponse.append(acBuf, size_t(n));
			}
		}

		const size_t uBody = stResponse.find("\r\n\r\n");
		if (uBody == std::string::npos)
		{
			stResult = uSent == stRequest.size() ? "ERR TIMEOUT" : "ERR CONNECT";
		}
		else
		{
			stResult = stResponse.substr(uBody + 4);
			const size_t uEnd = stResult.find_first_of("\r\n");
			if (uEnd != std::string::npos)
				stResult.resize(uEnd);
			if (stResult.empty())
				stResult = "ERR SERVER";
		}
	}

	close(iSocket);
	freeaddrinfo(pkAddr);
	return stResult;
}
}

PyObject* netRegisterAccount(PyObject* poSelf, PyObject* poArgs)
{
	char* szHost;
	int iPort;
	char* szLogin;
	char* szPassword;
	char* szSocialID;
	if (!PyTuple_GetString(poArgs, 0, &szHost))
		return Py_BuildException();
	if (!PyTuple_GetInteger(poArgs, 1, &iPort))
		return Py_BuildException();
	if (!PyTuple_GetString(poArgs, 2, &szLogin))
		return Py_BuildException();
	if (!PyTuple_GetString(poArgs, 3, &szPassword))
		return Py_BuildException();
	if (!PyTuple_GetString(poArgs, 4, &szSocialID))
		return Py_BuildException();

	int iExpected = REGISTER_IDLE;
	if (!gs_iRegisterState.compare_exchange_strong(iExpected, REGISTER_PENDING))
	{
		iExpected = REGISTER_DONE;
		if (!gs_iRegisterState.compare_exchange_strong(iExpected, REGISTER_PENDING))
			return Py_BuildValue("i", 0); // one request at a time
	}

	const std::string stHost = szHost;
	const std::string stBody = "login=" + __UrlEncode(szLogin) + "&password=" + __UrlEncode(szPassword) +
		"&social_id=" + __UrlEncode(szSocialID);
	std::thread([stHost, iPort, stBody]()
	{
		const std::string stResult = __Post(stHost, iPort, stBody);
		{
			std::lock_guard<std::mutex> kLock(gs_kRegisterMutex);
			gs_strRegisterResult = stResult;
		}
		gs_iRegisterState = REGISTER_DONE;
	}).detach();
	return Py_BuildValue("i", 1);
}

// Returns "" while the request runs (or none was started), else its result once.
PyObject* netGetRegisterAccountResult(PyObject* poSelf, PyObject* poArgs)
{
	int iExpected = REGISTER_DONE;
	if (!gs_iRegisterState.compare_exchange_strong(iExpected, REGISTER_IDLE))
		return Py_BuildValue("s", "");
	std::lock_guard<std::mutex> kLock(gs_kRegisterMutex);
	return Py_BuildValue("s", gs_strRegisterResult.c_str());
}