/* Copyright (c) 2018 Albert S.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include <atomic>
#include <mutex>
#include <openssl/evp.h>
#include "handlerlogin.h"
#include "../logger.h"
struct LoginFail
{
	std::mutex mutex;
	std::atomic<unsigned int> count;
	time_t lastfail;
};
static std::map<std::string, LoginFail> loginFails;

// TODO: make configurable
bool HandlerLogin::isBanned(std::string ip)
{
	if(utils::hasKey(loginFails, ip))
	{
		LoginFail &fl = loginFails[ip];
		std::lock_guard<std::mutex> lock(fl.mutex);
		return fl.count > 5 && (time(nullptr) - fl.lastfail) < 1200;
	}
	return false;
}

void HandlerLogin::incFailureCount(std::string ip)
{
	LoginFail &fl = loginFails[ip];
	fl.count += 1;
	fl.lastfail = time(nullptr);
}

std::vector<char> HandlerLogin::pbkdf5(std::string password, const std::vector<char> &salt)
{
	unsigned char hash[32];
	const EVP_MD *sha256 = EVP_sha256();
	const unsigned char *rawsalt = reinterpret_cast<const unsigned char *>(salt.data());
	PKCS5_PBKDF2_HMAC(password.c_str(), password.size(), rawsalt, salt.size(), 300000, sha256, sizeof(hash), hash);

	std::vector<char> result;

	for(size_t i = 0; i < sizeof(hash); i++)
	{

		result.push_back(static_cast<char>(hash[i]));
	}

	return result;
}

Response HandlerLogin::handleRequest(const Request &r)
{
	auto createErrorReesponse = [&]() {
		return errorResponse("Login error", "The supplied credenetials are incorrect");
	};

	if(isBanned(r.getIp()))
	{
		return errorResponse("Banned", "You have been banned for too many login attempts. Try again later");
	}
	if(r.param("submit") == "1")
	{
		std::string password = r.post("password");
		std::string username = r.post("user");

		auto userDao = this->database->createUserDao();
		std::optional<User> user = userDao->find(username);
		if(!user)
		{
			return createErrorReesponse();
		}
		if(!user->enabled)
		{
			return errorResponse("Login failed", "The user account has been disabled");
		}

		auto hashresult = pbkdf5(password, user.value().salt);
		// TODO: timing attack
		if(hashresult == user.value().password)
		{
			loginFails.erase(r.getIp());
			Response r = Response::redirectTemporarily(urlProvider->index());
			*(this->userSession) = Session(user.value());
			return r;
		}
		else
		{
			// TODO: only if wanted by config
			incFailureCount(r.getIp());
			return createErrorReesponse();
		}

		// auto pbkdf5 = pbkdf5(password, user->)
	}
	std::string page = r.get("page");
	if(page.empty())
		page = "index";

	TemplatePage &loginTemplatePage = this->templ->getPage("login");
	setGeneralVars(loginTemplatePage);
	loginTemplatePage.setVar("loginurl", urlProvider->login(page));
	loginTemplatePage.setVar("title", createPageTitle("Login"));
	Response result;
	result.setStatus(200);
	result.setBody(loginTemplatePage.render());
	return result;
}

bool HandlerLogin::canAccess(const Permissions &perms)
{
	return true;
}