/*************************************************************************/
/*  packet_peer_udp.cpp                                                  */
/*************************************************************************/
/*                         This file is part of:                         */
/*                          PANDEMONIUM ENGINE                           */
/*             https://github.com/Relintai/pandemonium_engine            */
/*************************************************************************/
/* Copyright (c) 2022-present Péter Magyar.                              */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
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/*************************************************************************/

#include "packet_peer_udp.h"

#include "core/io/ip.h"
#include "core/io/udp_server.h"

void PacketPeerUDP::set_blocking_mode(bool p_enable) {
	blocking = p_enable;
}

void PacketPeerUDP::set_broadcast_enabled(bool p_enabled) {
	ERR_FAIL_COND(udp_server);
	broadcast = p_enabled;
	if (_sock.is_valid() && _sock->is_open()) {
		_sock->set_broadcasting_enabled(p_enabled);
	}
}

Error PacketPeerUDP::join_multicast_group(IP_Address p_multi_address, String p_if_name) {
	ERR_FAIL_COND_V(udp_server, ERR_LOCKED);
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	ERR_FAIL_COND_V(!p_multi_address.is_valid(), ERR_INVALID_PARAMETER);

	if (!_sock->is_open()) {
		IP::Type ip_type = p_multi_address.is_ipv4() ? IP::TYPE_IPV4 : IP::TYPE_IPV6;
		Error err = _sock->open(NetSocket::TYPE_UDP, ip_type);
		ERR_FAIL_COND_V(err != OK, err);
		_sock->set_blocking_enabled(false);
		_sock->set_broadcasting_enabled(broadcast);
	}
	return _sock->join_multicast_group(p_multi_address, p_if_name);
}

Error PacketPeerUDP::leave_multicast_group(IP_Address p_multi_address, String p_if_name) {
	ERR_FAIL_COND_V(udp_server, ERR_LOCKED);
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	ERR_FAIL_COND_V(!_sock->is_open(), ERR_UNCONFIGURED);
	return _sock->leave_multicast_group(p_multi_address, p_if_name);
}

String PacketPeerUDP::_get_packet_ip() const {
	return get_packet_address();
}

Error PacketPeerUDP::_set_dest_address(const String &p_address, int p_port) {
	IP_Address ip;
	if (p_address.is_valid_ip_address()) {
		ip = p_address;
	} else {
		ip = IP::get_singleton()->resolve_hostname(p_address);
		if (!ip.is_valid()) {
			return ERR_CANT_RESOLVE;
		}
	}

	set_dest_address(ip, p_port);
	return OK;
}

int PacketPeerUDP::get_available_packet_count() const {
	// TODO we should deprecate this, and expose poll instead!
	Error err = const_cast<PacketPeerUDP *>(this)->_poll();
	if (err != OK) {
		return -1;
	}

	return queue_count;
}

Error PacketPeerUDP::get_packet(const uint8_t **r_buffer, int &r_buffer_size) {
	Error err = _poll();
	if (err != OK) {
		return err;
	}
	if (queue_count == 0) {
		return ERR_UNAVAILABLE;
	}

	uint32_t size = 0;
	uint8_t ipv6[16];
	rb.read(ipv6, 16, true);
	packet_ip.set_ipv6(ipv6);
	rb.read((uint8_t *)&packet_port, 4, true);
	rb.read((uint8_t *)&size, 4, true);
	rb.read(packet_buffer, size, true);
	--queue_count;
	*r_buffer = packet_buffer;
	r_buffer_size = size;
	return OK;
}

Error PacketPeerUDP::put_packet(const uint8_t *p_buffer, int p_buffer_size) {
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	ERR_FAIL_COND_V(!peer_addr.is_valid(), ERR_UNCONFIGURED);

	Error err;
	int sent = -1;

	if (!_sock->is_open()) {
		IP::Type ip_type = peer_addr.is_ipv4() ? IP::TYPE_IPV4 : IP::TYPE_IPV6;
		err = _sock->open(NetSocket::TYPE_UDP, ip_type);
		ERR_FAIL_COND_V(err != OK, err);
		_sock->set_blocking_enabled(false);
		_sock->set_broadcasting_enabled(broadcast);
	}

	do {
		if (connected && !udp_server) {
			err = _sock->send(p_buffer, p_buffer_size, sent);
		} else {
			err = _sock->sendto(p_buffer, p_buffer_size, sent, peer_addr, peer_port);
		}
		if (err != OK) {
			if (err != ERR_BUSY) {
				return FAILED;
			} else if (!blocking) {
				return ERR_BUSY;
			}
			// Keep trying to send full packet
			continue;
		}
		return OK;

	} while (sent != p_buffer_size);

	return OK;
}

int PacketPeerUDP::get_max_packet_size() const {
	return 512; // uhm maybe not
}

Error PacketPeerUDP::listen(int p_port, const IP_Address &p_bind_address, int p_recv_buffer_size) {
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	ERR_FAIL_COND_V(_sock->is_open(), ERR_ALREADY_IN_USE);
	ERR_FAIL_COND_V(!p_bind_address.is_valid() && !p_bind_address.is_wildcard(), ERR_INVALID_PARAMETER);

	Error err;
	IP::Type ip_type = IP::TYPE_ANY;

	if (p_bind_address.is_valid()) {
		ip_type = p_bind_address.is_ipv4() ? IP::TYPE_IPV4 : IP::TYPE_IPV6;
	}

	err = _sock->open(NetSocket::TYPE_UDP, ip_type);

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

	_sock->set_blocking_enabled(false);
	_sock->set_broadcasting_enabled(broadcast);
	err = _sock->bind(p_bind_address, p_port);

	if (err != OK) {
		_sock->close();
		return err;
	}
	rb.resize(nearest_shift(p_recv_buffer_size));
	return OK;
}

Error PacketPeerUDP::connect_shared_socket(Ref<NetSocket> p_sock, IP_Address p_ip, uint16_t p_port, UDPServer *p_server) {
	udp_server = p_server;
	connected = true;
	_sock = p_sock;
	peer_addr = p_ip;
	peer_port = p_port;
	packet_ip = peer_addr;
	packet_port = peer_port;
	return OK;
}

void PacketPeerUDP::disconnect_shared_socket() {
	udp_server = nullptr;
	_sock = Ref<NetSocket>(NetSocket::create());
	close();
}

Error PacketPeerUDP::connect_to_host(const IP_Address &p_host, int p_port) {
	ERR_FAIL_COND_V(udp_server, ERR_LOCKED);
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	ERR_FAIL_COND_V(!p_host.is_valid(), ERR_INVALID_PARAMETER);

	Error err;

	if (!_sock->is_open()) {
		IP::Type ip_type = p_host.is_ipv4() ? IP::TYPE_IPV4 : IP::TYPE_IPV6;
		err = _sock->open(NetSocket::TYPE_UDP, ip_type);
		ERR_FAIL_COND_V(err != OK, ERR_CANT_OPEN);
		_sock->set_blocking_enabled(false);
	}

	err = _sock->connect_to_host(p_host, p_port);

	// I see no reason why we should get ERR_BUSY (wouldblock/eagain) here.
	// This is UDP, so connect is only used to tell the OS to which socket
	// it shuold deliver packets when multiple are bound on the same address/port.
	if (err != OK) {
		close();
		ERR_FAIL_V_MSG(FAILED, "Unable to connect");
	}

	connected = true;

	peer_addr = p_host;
	peer_port = p_port;

	// Flush any packet we might still have in queue.
	rb.clear();
	return OK;
}

bool PacketPeerUDP::is_connected_to_host() const {
	return connected;
}

void PacketPeerUDP::close() {
	if (udp_server) {
		udp_server->remove_peer(peer_addr, peer_port);
		udp_server = nullptr;
		_sock = Ref<NetSocket>(NetSocket::create());
	} else if (_sock.is_valid()) {
		_sock->close();
	}
	rb.resize(16);
	queue_count = 0;
	connected = false;
}

Error PacketPeerUDP::wait() {
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);
	return _sock->poll(NetSocket::POLL_TYPE_IN, -1);
}

Error PacketPeerUDP::_poll() {
	ERR_FAIL_COND_V(!_sock.is_valid(), ERR_UNAVAILABLE);

	if (!_sock->is_open()) {
		return FAILED;
	}
	if (udp_server) {
		return OK; // Handled by UDPServer.
	}

	Error err;
	int read;
	IP_Address ip;
	uint16_t port;

	while (true) {
		if (connected) {
			err = _sock->recv(recv_buffer, sizeof(recv_buffer), read);
			ip = peer_addr;
			port = peer_port;
		} else {
			err = _sock->recvfrom(recv_buffer, sizeof(recv_buffer), read, ip, port);
		}

		if (err != OK) {
			if (err == ERR_BUSY) {
				break;
			}
			return FAILED;
		}

		err = store_packet(ip, port, recv_buffer, read);
#ifdef TOOLS_ENABLED
		if (err != OK) {
			WARN_PRINT("Buffer full, dropping packets!");
		}
#endif
	}

	return OK;
}

Error PacketPeerUDP::store_packet(IP_Address p_ip, uint32_t p_port, uint8_t *p_buf, int p_buf_size) {
	if (rb.space_left() < p_buf_size + 24) {
		return ERR_OUT_OF_MEMORY;
	}
	rb.write(p_ip.get_ipv6(), 16);
	rb.write((uint8_t *)&p_port, 4);
	rb.write((uint8_t *)&p_buf_size, 4);
	rb.write(p_buf, p_buf_size);
	++queue_count;
	return OK;
}

bool PacketPeerUDP::is_listening() const {
	return _sock.is_valid() && _sock->is_open();
}

IP_Address PacketPeerUDP::get_packet_address() const {
	return packet_ip;
}

int PacketPeerUDP::get_packet_port() const {
	return packet_port;
}

void PacketPeerUDP::set_dest_address(const IP_Address &p_address, int p_port) {
	ERR_FAIL_COND_MSG(connected, "Destination address cannot be set for connected sockets");
	peer_addr = p_address;
	peer_port = p_port;
}

void PacketPeerUDP::_bind_methods() {
	ClassDB::bind_method(D_METHOD("listen", "port", "bind_address", "recv_buf_size"), &PacketPeerUDP::listen, DEFVAL("*"), DEFVAL(65536));
	ClassDB::bind_method(D_METHOD("close"), &PacketPeerUDP::close);
	ClassDB::bind_method(D_METHOD("wait"), &PacketPeerUDP::wait);
	ClassDB::bind_method(D_METHOD("is_listening"), &PacketPeerUDP::is_listening);
	ClassDB::bind_method(D_METHOD("connect_to_host", "host", "port"), &PacketPeerUDP::connect_to_host);
	ClassDB::bind_method(D_METHOD("is_connected_to_host"), &PacketPeerUDP::is_connected_to_host);
	ClassDB::bind_method(D_METHOD("get_packet_ip"), &PacketPeerUDP::_get_packet_ip);
	ClassDB::bind_method(D_METHOD("get_packet_port"), &PacketPeerUDP::get_packet_port);
	ClassDB::bind_method(D_METHOD("set_dest_address", "host", "port"), &PacketPeerUDP::_set_dest_address);
	ClassDB::bind_method(D_METHOD("set_broadcast_enabled", "enabled"), &PacketPeerUDP::set_broadcast_enabled);
	ClassDB::bind_method(D_METHOD("join_multicast_group", "multicast_address", "interface_name"), &PacketPeerUDP::join_multicast_group);
	ClassDB::bind_method(D_METHOD("leave_multicast_group", "multicast_address", "interface_name"), &PacketPeerUDP::leave_multicast_group);
}

PacketPeerUDP::PacketPeerUDP() :
		packet_port(0),
		queue_count(0),
		peer_port(0),
		connected(false),
		blocking(true),
		broadcast(false),
		udp_server(nullptr),
		_sock(Ref<NetSocket>(NetSocket::create())) {
	rb.resize(16);
}

PacketPeerUDP::~PacketPeerUDP() {
	close();
}