/*************************************************************************/
/*  export_server.h                                                      */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/*************************************************************************/
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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/*************************************************************************/

#ifndef JAVASCRIPT_EXPORT_SERVER_H
#define JAVASCRIPT_EXPORT_SERVER_H

#include "core/io/image_loader.h"
#include "core/io/stream_peer_ssl.h"
#include "core/io/tcp_server.h"
#include "core/io/zip_io.h"
#include "editor/editor_paths.h"

class EditorHTTPServer : public RefCounted {
private:
	Ref<TCPServer> server;
	HashMap<String, String> mimes;
	Ref<StreamPeerTCP> tcp;
	Ref<StreamPeerSSL> ssl;
	Ref<StreamPeer> peer;
	Ref<CryptoKey> key;
	Ref<X509Certificate> cert;
	bool use_ssl = false;
	uint64_t time = 0;
	uint8_t req_buf[4096];
	int req_pos = 0;

	void _clear_client() {
		peer = Ref<StreamPeer>();
		ssl = Ref<StreamPeerSSL>();
		tcp = Ref<StreamPeerTCP>();
		memset(req_buf, 0, sizeof(req_buf));
		time = 0;
		req_pos = 0;
	}

	void _set_internal_certs(Ref<Crypto> p_crypto) {
		const String cache_path = EditorPaths::get_singleton()->get_cache_dir();
		const String key_path = cache_path.plus_file("html5_server.key");
		const String crt_path = cache_path.plus_file("html5_server.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=godot-debug.local,O=A Game Dev,C=XXA", "20140101000000", "20340101000000");
			cert->save(crt_path);
		}
	}

public:
	EditorHTTPServer() {
		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["wasm"] = "application/wasm";
		server.instantiate();
		stop();
	}

	void stop() {
		server->stop();
		_clear_client();
	}

	Error listen(int p_port, IPAddress p_address, bool p_use_ssl, String p_ssl_key, String p_ssl_cert) {
		use_ssl = p_use_ssl;
		if (use_ssl) {
			Ref<Crypto> crypto = Crypto::create();
			if (crypto.is_null()) {
				return ERR_UNAVAILABLE;
			}
			if (!p_ssl_key.is_empty() && !p_ssl_cert.is_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);
			}
		}
		return server->listen(p_port, p_address);
	}

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

	void _send_response() {
		Vector<String> psa = String((char *)req_buf).split("\r\n");
		int len = psa.size();
		ERR_FAIL_COND_MSG(len < 4, "Not enough response headers, got: " + itos(len) + ", expected >= 4.");

		Vector<String> req = psa[0].split(" ", false);
		ERR_FAIL_COND_MSG(req.size() < 2, "Invalid protocol or status code.");

		// Wrong protocol
		ERR_FAIL_COND_MSG(req[0] != "GET" || req[2] != "HTTP/1.1", "Invalid method or HTTP version.");

		const int query_index = req[1].find_char('?');
		const String path = (query_index == -1) ? req[1] : req[1].substr(0, query_index);

		const String req_file = path.get_file();
		const String req_ext = path.get_extension();
		const String cache_path = EditorPaths::get_singleton()->get_cache_dir().plus_file("web");
		const String filepath = cache_path.plus_file(req_file);

		if (!mimes.has(req_ext) || !FileAccess::exists(filepath)) {
			String s = "HTTP/1.1 404 Not Found\r\n";
			s += "Connection: Close\r\n";
			s += "\r\n";
			CharString cs = s.utf8();
			peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
			return;
		}
		const String ctype = mimes[req_ext];

		Ref<FileAccess> f = FileAccess::open(filepath, FileAccess::READ);
		ERR_FAIL_COND(f.is_null());
		String s = "HTTP/1.1 200 OK\r\n";
		s += "Connection: Close\r\n";
		s += "Content-Type: " + ctype + "\r\n";
		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";
		CharString cs = s.utf8();
		Error err = peer->put_data((const uint8_t *)cs.get_data(), cs.size() - 1);
		if (err != OK) {
			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) {
				ERR_FAIL();
			}
		}
	}

	void poll() {
		if (!server->is_listening()) {
			return;
		}
		if (tcp.is_null()) {
			if (!server->is_connection_available()) {
				return;
			}
			tcp = server->take_connection();
			peer = tcp;
			time = OS::get_singleton()->get_ticks_usec();
		}
		if (OS::get_singleton()->get_ticks_usec() - time > 1000000) {
			_clear_client();
			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);
				if (ssl->accept_stream(tcp, key, cert) != OK) {
					_clear_client();
					return;
				}
			}
			ssl->poll();
			if (ssl->get_status() == StreamPeerSSL::STATUS_HANDSHAKING) {
				// Still handshaking, keep waiting.
				return;
			}
			if (ssl->get_status() != StreamPeerSSL::STATUS_CONNECTED) {
				_clear_client();
				return;
			}
		}

		while (true) {
			char *r = (char *)req_buf;
			int l = req_pos - 1;
			if (l > 3 && r[l] == '\n' && r[l - 1] == '\r' && r[l - 2] == '\n' && r[l - 3] == '\r') {
				_send_response();
				_clear_client();
				return;
			}

			int read = 0;
			ERR_FAIL_COND(req_pos >= 4096);
			Error err = peer->get_partial_data(&req_buf[req_pos], 1, read);
			if (err != OK) {
				// Got an error
				_clear_client();
				return;
			} else if (read != 1) {
				// Busy, wait next poll
				return;
			}
			req_pos += read;
		}
	}
};

#endif // JAVASCRIPT_EXPORT_SERVER_H