/*************************************************************************/
/*  export.cpp                                                           */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           PANDEMONIUM ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
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/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
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/*************************************************************************/

#include "http_server_simple.h"

#include "core/os/dir_access.h"

#include "http_parser.h"
#include "modules/web/http/web_server_cookie.h"
#include "simple_web_server_request.h"
#include "web_server_simple.h"

#define CONNECTION_OPEN_CLOSE_DEBUG 0
#define CONNECTION_RESPOSE_DEBUG 0

void HTTPServerConnection::update() {
	ERR_FAIL_COND(closed());

	if (OS::get_singleton()->get_ticks_usec() - time > 1000000) {
		close();
		return;
	}

	if (tcp->get_status() != StreamPeerTCP::STATUS_CONNECTED) {
		return;
	}

	if (use_ssl) {
		if (ssl.is_null()) {
			ssl = Ref<StreamPeerSSL>(StreamPeerSSL::create());
			peer = ssl;
			ssl->set_blocking_handshake_enabled(false);

			Ref<CryptoKey> key = Ref<CryptoKey>(CryptoKey::create());
			Error err = key->load(_http_server->_ssl_key_file);
			if (err != OK) {
				close();
				ERR_FAIL_COND(err != OK);
			}

			Ref<X509Certificate> cert = Ref<X509Certificate>(X509Certificate::create());
			err = cert->load(_http_server->_ssl_cert_file);
			if (err != OK) {
				close();
				ERR_FAIL_COND(err != OK);
			}

			if (ssl->accept_stream(tcp, key, cert) != OK) {
				close();
				return;
			}
		}

		ssl->poll();

		if (ssl->get_status() == StreamPeerSSL::STATUS_HANDSHAKING) {
			// Still handshaking, keep waiting.
			return;
		}

		if (ssl->get_status() != StreamPeerSSL::STATUS_CONNECTED) {
			close();
			return;
		}
	}

	int read = 0;
	Error err = peer->get_partial_data(req_buf, 4096, read);

	if (err != OK) {
		// Got an error
		close();
		return;
	}

	if (read > 0) {
		int buffer_start_index = 0;
		while (true) {
			char *rb = reinterpret_cast<char *>(&req_buf[buffer_start_index]);
			buffer_start_index += _http_parser->read_from_buffer(rb, read);

			if (buffer_start_index >= read) {
				break;
			}

			// Stop processing if a protocol error happened
			if (_http_parser->has_error()) {
				break;
			}
		}
	}

	if (_http_parser->get_request_count() > 0) {
		Ref<SimpleWebServerRequest> request = _http_parser->get_next_request();

		request->_server = _http_server;
		request->_connection = Ref<HTTPServerConnection>(this);
		request->setup_url_stack();

		_web_server->server_handle_request(request);

		if (_http_parser->get_request_count() == 0 && _http_parser->is_finished()) {
			close();
		}
	}

	if (_http_parser->has_error()) {
		close();
	}
}

void HTTPServerConnection::send_redirect(Ref<WebServerRequest> request, const String &location, const HTTPServerEnums::HTTPStatusCode status_code) {
	//String s = "HTTP/1.1 " + itos(static_cast<int>(status_code)) + " Found\r\n";
	String s = "HTTP/1.1 " + HTTPServerEnums::get_status_code_header_string(status_code) + "\r\n";
	s += "Location: " + location + "\r\n";

	if (has_more_messages()) {
		s += "Connection: keep-alive\r\n";
	} else {
		s += "Connection: close\r\n";
	}

	for (int i = 0; i < request->response_get_cookie_count(); ++i) {
		Ref<WebServerCookie> cookie = request->response_get_cookie(i);

		ERR_CONTINUE(!cookie.is_valid());

		String cookie_str = cookie->get_response_header_string();

		if (cookie_str != "") {
			s += cookie_str;
		}
	}

	s += "\r\n";

#if CONNECTION_RESPOSE_DEBUG
	ERR_PRINT(s);
#endif

	CharString cs = s.utf8();
	peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
}

void HTTPServerConnection::send(Ref<WebServerRequest> request) {
	String body = request->get_compiled_body();

	String s = "HTTP/1.1 " + HTTPServerEnums::get_status_code_header_string(request->get_status_code()) + "\r\n";
	s += "Content-Length: " + itos(body.utf8_byte_length()) + "\r\n";
	s += "Content-type: text/html\r\n";

	if (has_more_messages()) {
		s += "Connection: keep-alive\r\n";
	} else {
		s += "Connection: close\r\n";
	}

	for (int i = 0; i < request->response_get_cookie_count(); ++i) {
		Ref<WebServerCookie> cookie = request->response_get_cookie(i);

		ERR_CONTINUE(!cookie.is_valid());

		String cookie_str = cookie->get_response_header_string();

		if (cookie_str != "") {
			s += cookie_str;
		}
	}

	s += "\r\n";
	s += body;

#if CONNECTION_RESPOSE_DEBUG
	ERR_PRINT(s);
#endif

	CharString cs = s.utf8();
	peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
}
void HTTPServerConnection::send_file(Ref<WebServerRequest> request, const String &p_file_path) {
	if (!FileAccess::exists(p_file_path)) {
		String s = "HTTP/1.1 404 Not Found\r\n";

		if (has_more_messages()) {
			s += "Connection: keep-alive\r\n";
		} else {
			s += "Connection: close\r\n";
		}

		for (int i = 0; i < request->response_get_cookie_count(); ++i) {
			Ref<WebServerCookie> cookie = request->response_get_cookie(i);

			ERR_CONTINUE(!cookie.is_valid());

			String cookie_str = cookie->get_response_header_string();

			if (cookie_str != "") {
				s += cookie_str;
			}
		}

		s += "\r\n";

#if CONNECTION_RESPOSE_DEBUG
		ERR_PRINT(s);
#endif

		CharString cs = s.utf8();
		peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
		return;
	}

	String ctype;
	String req_ext = p_file_path.get_extension();

	if (_http_server->mimes.has(req_ext)) {
		ctype = _http_server->mimes[req_ext];
	} else {
		ctype = "text/plain";
	}

	FileAccess *f = FileAccess::open(p_file_path, FileAccess::READ);
	ERR_FAIL_COND(!f);
	String s = "HTTP/1.1 200 OK\r\n";

	if (has_more_messages()) {
		s += "Connection: keep-alive\r\n";
	} else {
		s += "Connection: close\r\n";
	}

	s += "Content-Type: " + ctype + "\r\n";

	for (int i = 0; i < request->response_get_cookie_count(); ++i) {
		Ref<WebServerCookie> cookie = request->response_get_cookie(i);

		ERR_CONTINUE(!cookie.is_valid());

		String cookie_str = cookie->get_response_header_string();

		if (cookie_str != "") {
			s += cookie_str;
		}
	}

	s += "Access-Control-Allow-Origin: *\r\n";
	s += "Cross-Origin-Opener-Policy: same-origin\r\n";
	s += "Cross-Origin-Embedder-Policy: require-corp\r\n";
	s += "Cache-Control: no-store, max-age=0\r\n";
	s += "\r\n";

#if CONNECTION_RESPOSE_DEBUG
	ERR_PRINT(s);
#endif

	CharString cs = s.utf8();

	Error err = peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
	if (err != OK) {
		memdelete(f);
		ERR_FAIL();
	}

	while (true) {
		uint8_t bytes[4096];
		uint64_t read = f->get_buffer(bytes, 4096);
		if (read == 0) {
			break;
		}
		err = peer->put_data(bytes, read);
		if (err != OK) {
			memdelete(f);
			ERR_FAIL();
		}
	}

	memdelete(f);
}

void HTTPServerConnection::close() {
#if CONNECTION_OPEN_CLOSE_DEBUG
	ERR_PRINT("CONN CLOSE");
#endif

	tcp.unref();
	ssl.unref();
	peer.unref();

	_closed = true;
}
bool HTTPServerConnection::closed() {
	return _closed;
}

bool HTTPServerConnection::has_more_messages() {
	if (_closed) {
		return false;
	}

	if (_http_parser->has_error()) {
		return false;
	}

	if (_http_parser->get_request_count() == 0 && _http_parser->is_finished()) {
		return false;
	}

	return true;
}

HTTPServerConnection::HTTPServerConnection() {
	_web_server = nullptr;
	_http_server = nullptr;

	_http_parser.instance();
	_http_parser->max_request_size = max_request_size;
	time = 0;

	memset(req_buf, 0, sizeof(req_buf));

	_closed = false;
}
HTTPServerConnection::~HTTPServerConnection() {
}

void HTTPServerSimple::stop() {
	server->stop();

	_clear_clients();
}

Error HTTPServerSimple::listen(int p_port, IP_Address p_address, bool p_use_ssl, String p_ssl_key, String p_ssl_cert) {
	use_ssl = p_use_ssl;
	_ssl_key_file = p_ssl_key;
	_ssl_cert_file = p_ssl_cert;

	if (use_ssl) {
		Ref<Crypto> crypto = Crypto::create();
		if (crypto.is_null()) {
			return ERR_UNAVAILABLE;
		}

		if (!p_ssl_key.empty() && !p_ssl_cert.empty()) {
			key = Ref<CryptoKey>(CryptoKey::create());
			Error err = key->load(p_ssl_key);
			ERR_FAIL_COND_V(err != OK, err);
			cert = Ref<X509Certificate>(X509Certificate::create());
			err = cert->load(p_ssl_cert);
			ERR_FAIL_COND_V(err != OK, err);
		} else {
			_set_internal_certs(crypto);
		}
	}

	Error err = server->listen(p_port, p_address);

	if (err != OK) {
		return err;
	}

	if (_use_worker_threads) {
		for (int i = 0; i < _thread_count; ++i) {
			ServerWorkerThread *t = memnew(ServerWorkerThread);
			t->running = true;
			t->server.reference_ptr(this);
			t->semaphore = memnew(Semaphore);

			t->thread = memnew(Thread());
			t->thread->start(HTTPServerSimple::_worker_thread_func, t);

			_threads.push_back(t);
		}
	}

	return OK;
}

bool HTTPServerSimple::is_listening() const {
	return server->is_listening();
}

void HTTPServerSimple::poll() {
	if (!server->is_listening()) {
		return;
	}

	//todo add connection limit
	while (server->is_connection_available()) {
		_connections_lock.write_lock();

		Ref<StreamPeerTCP> tcp = server->take_connection();

		ERR_CONTINUE(!tcp.is_valid());

#if CONNECTION_OPEN_CLOSE_DEBUG
		ERR_PRINT("NEW CONN");
#endif

		Ref<HTTPServerConnection> connection;
		connection.instance();

		connection->_web_server = _web_server;
		connection->_http_server = this;

		connection->max_request_size = max_request_size;
		connection->_http_parser->max_request_size = max_request_size;

		connection->use_ssl = use_ssl;
		connection->key = key;

		connection->tcp = tcp;
		connection->peer = connection->tcp;
		connection->time = OS::get_singleton()->get_ticks_usec();

		_connections.push_back(connection);
		_connections_lock.write_unlock();
	}

	if (!_use_worker_threads) {
		_connections_lock.write_lock();

		List<Ref<HTTPServerConnection>>::Element *e = _connections.front();

		while (e) {
			Ref<HTTPServerConnection> c = e->get();

			if (c->closed()) {
				List<Ref<HTTPServerConnection>>::Element *etmp = e->next();
				_connections.erase(e);
				e = etmp;
				continue;
			}

			c->update();

			if (c->closed()) {
				List<Ref<HTTPServerConnection>>::Element *etmp = e->next();
				_connections.erase(e);
				e = etmp;
				continue;
			}

			e = e->next();
		}

		_connections_lock.write_unlock();
	} else {
		if (_connections.size() > 0) {
			_wake_workers();
		}
	}
}

HTTPServerSimple::HTTPServerSimple() {
	_web_server = nullptr;

	mimes["html"] = "text/html";
	mimes["js"] = "application/javascript";
	mimes["json"] = "application/json";
	mimes["pck"] = "application/octet-stream";
	mimes["png"] = "image/png";
	mimes["svg"] = "image/svg";
	mimes["jpg"] = "image/jpeg";
	mimes["jpeg"] = "image/jpeg";
	mimes["wasm"] = "application/wasm";
	mimes["css"] = "text/css";

	server.instance();
	stop();
}

HTTPServerSimple::~HTTPServerSimple() {
}

void HTTPServerSimple::_clear_clients() {
	//stop worker threads first!
	_stop_workers();

	_connections_lock.write_lock();
	for (List<Ref<HTTPServerConnection>>::Element *e = _connections.front(); e; e = e->next()) {
		e->get()->close();
	}

	_connections.clear();
	_connections_lock.write_unlock();
}

void HTTPServerSimple::_stop_workers() {
	for (int i = 0; i < _threads.size(); ++i) {
		_threads.write[i]->running = false;
		_threads.write[i]->semaphore->post();
	}

	for (int i = 0; i < _threads.size(); ++i) {
		_threads.write[i]->thread->wait_to_finish();
		memdelete(_threads.write[i]->thread);
		memdelete(_threads.write[i]->semaphore);
	}

	_threads.clear();
}

void HTTPServerSimple::_set_internal_certs(Ref<Crypto> p_crypto) {
	const String cache_path = "user://cache/web/";

	DirAccess *dir = DirAccess::create(DirAccess::ACCESS_USERDATA);
	ERR_FAIL_COND(!dir);
	dir->make_dir_recursive(cache_path);
	memdelete(dir);

	const String key_path = cache_path.plus_file("http_server_simple_cert.key");
	const String crt_path = cache_path.plus_file("http_server_simple_cert.crt");
	bool regen = !FileAccess::exists(key_path) || !FileAccess::exists(crt_path);

	if (!regen) {
		key = Ref<CryptoKey>(CryptoKey::create());
		cert = Ref<X509Certificate>(X509Certificate::create());
		if (key->load(key_path) != OK || cert->load(crt_path) != OK) {
			regen = true;
		}
	}

	if (regen) {
		key = p_crypto->generate_rsa(2048);
		key->save(key_path);
		cert = p_crypto->generate_self_signed_certificate(key, "CN=pandemonium-debug.local,O=A Game Dev,C=XXA", "20140101000000", "20340101000000");
		cert->save(crt_path);
	}

	_ssl_key_file = key_path;
	_ssl_cert_file = crt_path;
}

void HTTPServerSimple::_wake_workers() {
	for (int i = 0; i < _threads.size(); ++i) {
		if (_connections.size() == 0) {
			return;
		}

		ServerWorkerThread *t = _threads[i];

		if (!t->working) {
			t->semaphore->post();
		}
	}
}

void HTTPServerSimple::_worker_thread_func(void *data) {
	ServerWorkerThread *context = reinterpret_cast<ServerWorkerThread *>(data);

	Ref<HTTPServerSimple> server = context->server;

	context->working = true;

	while (context->running) {
		//THis will only work well in a worker thread
		while (!server->_connections.empty()) {
			server->_connections_lock.write_lock();
			List<Ref<HTTPServerConnection>>::Element *e = server->_connections.front();

			if (!e) {
				server->_connections_lock.write_unlock();
				break;
			}

			Ref<HTTPServerConnection> c = e->get();

			server->_connections.pop_front();
			server->_connections_lock.write_unlock();

			if (c->closed()) {
				continue;
			}

			c->update();

			if (c->closed()) {
				continue;
			}

			server->_connections_lock.write_lock();
			server->_connections.push_back(c);
			server->_connections_lock.write_unlock();
		}

		context->working = false;
		context->semaphore->wait();
		context->working = true;
	}
}