#include "stdafx.h"
#include "SessionAuthModule.h"
#include "HttpClient.h"
#include "StringHelpers.h"
#include "Common/vendor/nlohmann/json.hpp"
#include <random>
#include <fstream>
#include <algorithm>

static wstring generateServerId()
{
	static constexpr wchar_t hex[] = L"0123456789abcdef";
	static std::mt19937 rng(std::random_device{}());
	wstring id(16, L'0');
	for (auto &c : id) c = hex[rng() & 0xF];
	return id;
}

static vector<YggdrasilProviderConfig> s_registryProviders;
static bool s_registryLoaded = false;

void YggdrasilRegistry::load()
{
	s_registryProviders.clear();

	std::ifstream file("yggdrasil.json");
	if (file.is_open())
	{
		auto j = nlohmann::json::parse(file, nullptr, false);
		if (j.is_array())
		{
			for (const auto &entry : j)
			{
				if (!entry.is_object()) continue;
				YggdrasilProviderConfig cfg;
				cfg.name = convStringToWstring(entry.value("name", ""));
				cfg.displayName = convStringToWstring(entry.value("displayName", ""));
				cfg.authUrl = entry.value("authUrl", "");
				cfg.sessionUrl = entry.value("sessionUrl", "");
				if (!cfg.name.empty() && !cfg.sessionUrl.empty())
					s_registryProviders.push_back(std::move(cfg));
			}
		}
	}

	if (std::none_of(s_registryProviders.begin(), s_registryProviders.end(),
		[](const auto &p) { return p.name == L"elyby"; }))
		s_registryProviders.insert(s_registryProviders.begin(),
			{L"elyby", L"Ely.by", "https://authserver.ely.by/auth", "https://authserver.ely.by/session"});

	s_registryProviders.push_back(
		{L"mojang", L"Mojang", "", "https://sessionserver.mojang.com/session/minecraft"});

	s_registryLoaded = true;
}

const vector<YggdrasilProviderConfig> &YggdrasilRegistry::providers()
{
	if (!s_registryLoaded) load();
	return s_registryProviders;
}

const YggdrasilProviderConfig *YggdrasilRegistry::find(const wstring &name)
{
	for (const auto &p : providers())
		if (p.name == name) return &p;
	return nullptr;
}

const YggdrasilProviderConfig &YggdrasilRegistry::defaultProvider()
{
	const auto &list = providers();
	for (const auto &p : list)
		if (p.name != L"mojang") return p;
	return list[0];
}

const wchar_t *SessionAuthModule::schemeName() { return L"mcconsoles:session"; }

vector<wstring> SessionAuthModule::supportedVariations()
{
	vector<wstring> result;
	for (const auto &p : YggdrasilRegistry::providers())
		result.push_back(p.name);
	return result;
}

vector<pair<wstring, wstring>> SessionAuthModule::getSettings(const wstring &variation)
{
	auto *p = YggdrasilRegistry::find(variation);
	if (!p) return {};

	activeProvider = p;
	activeServerId = generateServerId();
	return {
		{L"joinUrl", convStringToWstring(p->joinUrl())},
		{L"serverId", activeServerId}
	};
}

bool SessionAuthModule::serverVerify(const YggdrasilProviderConfig &provider, const wstring &username, const wstring &serverId, wstring &outUid, wstring &outUsername)
{
	string url = provider.hasJoinedUrl() + "?username=" + narrowStr(username) + "&serverId=" + narrowStr(serverId);

	app.DebugPrintf("AUTH SERVER [%ls]: hasJoined GET %s\n", provider.name.c_str(), url.c_str());
	auto response = HttpClient::get(url);
	app.DebugPrintf("AUTH SERVER [%ls]: hasJoined status=%d\n", provider.name.c_str(), response.statusCode);

	if (response.statusCode != 200)
		return false;

	auto json = nlohmann::json::parse(response.body, nullptr, false);
	if (json.is_discarded())
		return false;

	string id = json.value("id", "");
	string name = json.value("name", "");
	if (id.empty() || name.empty())
		return false;

	outUid = convStringToWstring(id);
	outUsername = convStringToWstring(name);
	return true;
}

bool SessionAuthModule::onAuthData(const vector<pair<wstring, wstring>> &fields, wstring &outUid, wstring &outUsername)
{
	wstring username;
	for (const auto &[k, v] : fields)
		if (k == L"username") username = v;

	if (username.empty() || activeServerId.empty() || !activeProvider)
		return false;

	if (!serverVerify(*activeProvider, username, activeServerId, outUid, outUsername))
		return false;

	return validate(outUid, outUsername);
}