/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#define FORBIDDEN_SYMBOL_ALLOW_ALL
#include <curl/curl.h>

#include "backends/networking/basic/curl/socket.h"
#include "backends/networking/basic/curl/cacert.h"

#include "common/debug.h"
#include "common/system.h"

// Auxiliary function that waits on the socket.
// From https://github.com/curl/curl/blob/master/docs/examples/sendrecv.c
static int waitOnSocket(curl_socket_t sockfd, int for_recv, long timeout_ms) {
	struct timeval tv {};
	fd_set infd {}, outfd {}, errfd {};
	int res;

	tv.tv_sec = timeout_ms / 1000;
	tv.tv_usec = (timeout_ms % 1000) * 1000;

	FD_ZERO(&infd);
	FD_ZERO(&outfd);
	FD_ZERO(&errfd);

	FD_SET(sockfd, &errfd); /* always check for error */

	if(for_recv) {
		FD_SET(sockfd, &infd);
	} else {
		FD_SET(sockfd, &outfd);
	}

	/* select() returns the number of signalled sockets or -1 */
	res = select((int)sockfd + 1, &infd, &outfd, &errfd, &tv);
	return res;
}

namespace Networking {

Socket *Socket::connect(const Common::String &url) {
	CURL *easy = curl_easy_init();
	if (!easy) {
		return nullptr;
	}

	curl_easy_setopt(easy, CURLOPT_URL, url.c_str());
	// Just connect to the host, do not do any transfers.
	curl_easy_setopt(easy, CURLOPT_CONNECT_ONLY, 1L);

	// libcurl won't connect to SSL connections
	// with VERIFYPEER enabled because we do not ship
	// with a CA bundle in these platforms.
	// So let's disable it.
#if defined NINTENDO_SWITCH || defined PSP2
	curl_easy_setopt(easy, CURLOPT_SSL_VERIFYPEER, 0);
#endif

	Common::String caCertPath = getCaCertPath();
	if (!caCertPath.empty()) {
		curl_easy_setopt(easy, CURLOPT_CAINFO, caCertPath.c_str());
	}

	CURLcode res = curl_easy_perform(easy);
	if (res != CURLE_OK) {
		warning("libcurl: Failed to connect: %s", curl_easy_strerror(res));
		curl_easy_cleanup(easy);
		return nullptr;
	}

	// Get the socket, we'll need it for waiting.
	// NB: Do not use CURL_AT_LEAST_VERSION(x,y,z) or CURL_VERSION_BITS(x,y,z) for version check
	//     These were only added around v7.45.0 release so break build with earlier libcurl versions
#if LIBCURL_VERSION_NUM >= 0x072d00 // 7.45.0
	// Use new CURLINFO_ACTIVESOCKET API for libcurl v7.45.0 or greater
	curl_socket_t socket;
	res = curl_easy_getinfo(easy, CURLINFO_ACTIVESOCKET, &socket);
	if (res == CURLE_OK) {
		return new CurlSocket(easy, socket);
	}
#else
	// Fallback on old deprecated CURLINFO_LASTSOCKET API for libcurl older than v7.45.0 (October 2015)
	long socket;
	res = curl_easy_getinfo(easy, CURLINFO_LASTSOCKET, &socket);
	if (res == CURLE_OK) {
		// curl_socket_t is an int or a SOCKET (Win32) which is a UINT_PTR
		// A cast should be safe enough as long fits in it
		return new CurlSocket(easy, (curl_socket_t)socket);
	}
#endif

	warning("libcurl: Failed to extract socket: %s", curl_easy_strerror(res));
	curl_easy_cleanup(easy);
	return nullptr;
}

CurlSocket::CurlSocket(CURL *easy, curl_socket_t socket) : _easy(easy), _socket(socket) {
}

CurlSocket::~CurlSocket() {
	// Always clean up.
	curl_easy_cleanup(_easy);
}

int CurlSocket::ready() {
	return waitOnSocket(_socket, 1, 0);
}

size_t CurlSocket::send(const char *data, int len) {
	size_t nsent_total = 0, left = len;
	CURLcode res = CURLE_AGAIN;

	// Keep looping until the whole thing is sent, errors,
	// or times out.
	while (((left > 0) && (len > 0))) {
		size_t nsent = 0;
		uint32 tickCount = g_system->getMillis() + 5000;
		while (res == CURLE_AGAIN) {
			res = curl_easy_send(_easy, data + nsent_total, left - nsent_total, &nsent);
			if (g_system->getMillis() >= tickCount) {
				warning("libcurl: Took too long attempting to send data to socket");
				return nsent;
			}
		}
		if (res == CURLE_OK) {
			nsent_total += nsent;
			left -= nsent;
		} else if (res != CURLE_AGAIN) {
			warning("libcurl: Error when sending to socket: %s", curl_easy_strerror(res));
			return nsent_total;
		}
	}

	return nsent_total;
}

size_t CurlSocket::recv(void *data, int maxLen) {
	size_t nread = 0;
	CURLcode res = CURLE_AGAIN;
	uint32 tickCount = g_system->getMillis() + 5000;
	while (res == CURLE_AGAIN) {
		res = curl_easy_recv(_easy, data, maxLen, &nread);
		if (g_system->getMillis() >= tickCount) {
			warning("libcurl: Took too long attempting to read data from socket");
			return nread;
		}
	}
	if(res != CURLE_OK) {
		warning("libcurl Error on receiving data: %s\n", curl_easy_strerror(res));
		return nread;
	}

	debug(3, "libcurl: Received %llu bytes", (unsigned long long)nread);
	return nread;
}

} // End of namespace Networking