/**
 * libzt API example
 */

#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <string>
#include <inttypes.h>

#if defined(_WIN32)
#include <WinSock2.h>
#include <stdint.h>
#else
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#endif

#include "ZeroTier.h"

bool nodeReady = false;
bool networkReady = false;

// Example callbacks
void myZeroTierEventCallback(struct zts_callback_msg *msg)
{
	// Node events
	if (msg->eventCode == ZTS_EVENT_NODE_ONLINE) {
		printf("ZTS_EVENT_NODE_ONLINE --- This node's ID is %llx\n", msg->node->address);
		nodeReady = true;
	}
	if (msg->eventCode == ZTS_EVENT_NODE_OFFLINE) {
		printf("ZTS_EVENT_NODE_OFFLINE --- Check your physical Internet connection, router, firewall, etc. What ports are you blocking?\n");
		nodeReady = false;
	}
	if (msg->eventCode == ZTS_EVENT_NODE_NORMAL_TERMINATION) {
		printf("ZTS_EVENT_NODE_NORMAL_TERMINATION\n");
	}

	// Virtual network events
	if (msg->eventCode == ZTS_EVENT_NETWORK_NOT_FOUND) {
		printf("ZTS_EVENT_NETWORK_NOT_FOUND --- Are you sure %llx is a valid network?\n",
			msg->network->nwid);
	}
	if (msg->eventCode == ZTS_EVENT_NETWORK_REQUESTING_CONFIG) {
		printf("ZTS_EVENT_NETWORK_REQUESTING_CONFIG --- Requesting config for network %llx, please wait a few seconds...\n", msg->network->nwid);
	} 
	if (msg->eventCode == ZTS_EVENT_NETWORK_ACCESS_DENIED) {
		printf("ZTS_EVENT_NETWORK_ACCESS_DENIED --- Access to virtual network %llx has been denied. Did you authorize the node yet?\n",
			msg->network->nwid);
	}
	if (msg->eventCode == ZTS_EVENT_NETWORK_READY_IP4) {
		printf("ZTS_EVENT_NETWORK_READY_IP4 --- Network config received. IPv4 traffic can now be sent over network %llx\n",
			msg->network->nwid);
		networkReady = true;
	}
	if (msg->eventCode == ZTS_EVENT_NETWORK_READY_IP6) {
		printf("ZTS_EVENT_NETWORK_READY_IP6 --- Network config received. IPv6 traffic can now be sent over network %llx\n",
			msg->network->nwid);
		networkReady = true;
	}
	if (msg->eventCode == ZTS_EVENT_NETWORK_DOWN) {
		printf("ZTS_EVENT_NETWORK_DOWN --- %llx\n", msg->network->nwid);
	}

	// Address events
	if (msg->eventCode == ZTS_EVENT_ADDR_ADDED_IP4) {
		char ipstr[INET_ADDRSTRLEN];
		struct zts_sockaddr_in *in4 = (struct zts_sockaddr_in*)&(msg->addr->addr);
		inet_ntop(ZTS_AF_INET, &(in4->sin_addr), ipstr, INET_ADDRSTRLEN);
		printf("ZTS_EVENT_ADDR_NEW_IP4 --- This node's virtual address on network %llx is %s\n", 
			msg->addr->nwid, ipstr);
	}
	if (msg->eventCode == ZTS_EVENT_ADDR_ADDED_IP6) {
		char ipstr[INET6_ADDRSTRLEN];
		struct zts_sockaddr_in6 *in6 = (struct zts_sockaddr_in6*)&(msg->addr->addr);
		inet_ntop(AF_INET6, &(in6->sin6_addr), ipstr, INET6_ADDRSTRLEN);
		printf("ZTS_EVENT_ADDR_NEW_IP6 --- This node's virtual address on network %llx is %s\n", 
			msg->addr->nwid, ipstr);
	}
	if (msg->eventCode == ZTS_EVENT_ADDR_REMOVED_IP4) {
		char ipstr[INET_ADDRSTRLEN];
		struct zts_sockaddr_in *in4 = (struct zts_sockaddr_in*)&(msg->addr->addr);
		inet_ntop(ZTS_AF_INET, &(in4->sin_addr), ipstr, INET_ADDRSTRLEN);
		printf("ZTS_EVENT_ADDR_REMOVED_IP4 --- The virtual address %s for this node on network %llx has been removed.\n", 
			ipstr, msg->addr->nwid);
	}
	if (msg->eventCode == ZTS_EVENT_ADDR_REMOVED_IP6) {
		char ipstr[INET6_ADDRSTRLEN];
		struct zts_sockaddr_in6 *in6 = (struct zts_sockaddr_in6*)&(msg->addr->addr);
		inet_ntop(ZTS_AF_INET6, &(in6->sin6_addr), ipstr, INET6_ADDRSTRLEN);
		printf("ZTS_EVENT_ADDR_REMOVED_IP6 --- The virtual address %s for this node on network %llx has been removed.\n", 
			ipstr, msg->addr->nwid);
	}
	// Peer events
	if (msg->eventCode == ZTS_EVENT_PEER_P2P) {
		printf("ZTS_EVENT_PEER_P2P --- node=%llx\n", msg->peer->address);
		// A direct path is known for nodeId
	}
	if (msg->eventCode == ZTS_EVENT_PEER_RELAY) {
		printf("ZTS_EVENT_PEER_RELAY --- node=%llx\n", msg->peer->address);
		// No direct path is known for nodeId
	}
}

/**
 *
 *   IDENTITIES and AUTHORIZATION:
 *
 * - Upon the first execution of this code, a new identity will be generated and placed in
 *   the location given in the first argument to zts_start(path, ...). If you accidentally
 *   duplicate the identity files and use them simultaneously in a different node instance
 *   you will experience undefined behavior and it is likely nothing will work.
 * 
 * - You must authorize the node ID provided by the ZTS_EVENT_NODE_ONLINE callback to join
 *   your network, otherwise nothing will happen. This can be done manually or via
 *   our web API: https://my.zerotier.com/help/api
 *
 * - An exception to the above rule is if you are using an Ad-hoc network, it has no 
 *   controller and therefore requires no authorization.
 *
 *
 *   ESTABLISHING A CONNECTION:
 *
 * - Creating a standard socket connection generally works the same as it would using
 *   an ordinary socket interface, however with libzt there is a subtle difference in
 *   how connections are established which may cause confusion:
 *
 *   The underlying virtual ZT layer creates what are called "transport-triggered links"
 *   between nodes. That is, links are not established until an attempt to communicate
 *   with a peer has taken place. The side effect is that the first few packets sent from
 *   a libzt instance are usually relayed via our free infrastructure and it isn't until a
 *   root server has passed contact information to both peers that a direct connection will be
 *   established. Therefore, it is required that multiple connection attempts be undertaken
 *   when initially communicating with a peer. After a transport-triggered link is
 *   established libzt will inform you via ZTS_EVENT_PEER_P2P for a specific peer ID. No
 *   action is required on your part for this callback event.
 *
 *   Note: In these initial moments before ZTS_EVENT_PEER_P2P has been received for a
 *         specific peer, traffic may be slow, jittery and there may be high packet loss.
 *         This will subside within a couple of seconds.
 *
 *
 *   ERROR HANDLING:
 *
 * - libzt's API is actually composed of two categories of functions with slightly
 *   different error reporting mechanisms.
 *
 *   Category 1: Control functions (zts_start, zts_join, zts_get_peer_status, etc). Errors
 *                returned by these functions can be any of the following:
 *
 *      [ 0] ZTS_ERR_OK          - No error.
 *      [-1] ZTS_ERR             - Error (see zts_errno for more information).
 *      [-2] ZTS_ERR_INVALID_ARG - An argument provided is invalid.
 *      [-3] ZTS_ERR_SERVICE     - ZT is not yet initialized. Try again.
 *      [-4] ZTS_ERR_INVALID_OP  - Operation is not permitted (Doesn't make sense in this state).
 *      [-5] ZTS_ERR_NO_RESULT   - Call succeeded but no result was available. Not always an error.
 *      [-6] ZTS_ERR_GENERAL     - General internal failure. Consider filing a bug report.
 *
 *   Category 2: Sockets (zts_socket, zts_bind, zts_connect, zts_listen, etc).
 *               Errors returned by these functions can be the same as the above. With
 *               the added possibility of zts_errno being set. Much like standard
 *               errno this will provide a more specific reason for an error's occurrence.
 *               These error values are defined in: libzt/ext/lwip/src/include/lwip/errno.h
 *               and closely map to standard Linux error values.
 *
 *
 *   API COMPATIBILITY WITH HOST OS:
 *
 * - Since libzt re-implements a socket API probably very similar to your host OS's own
 *   API it may be tempting to mix and match host OS structures and functions with those
 *   of libzt. This may work on occasion, but you are tempting fate, so here are a few
 *   guidelines:
 *
 *   If you are calling a zts_* function, use the appropriate ZTS_* constants:
 *             
 *          zts_socket(ZTS_AF_INET6, ZTS_SOCK_DGRAM, 0); (CORRECT)
 *          zts_socket(AF_INET6, SOCK_DGRAM, 0);         (INCORRECT)
 *
 *   If you are calling a zts_* function, use the appropriate zts_* structure:
 *
 *          struct zts_sockaddr_in in4;  <------ Note the zts_* prefix
 *             ...
 *          zts_bind(fd, (struct sockaddr *)&in4, sizeof(struct zts_sockaddr_in)) < 0)
 *
 *   If you are calling a host OS function, use your host OS's constants (and structures!):
 *       
 *          inet_ntop(AF_INET6, &(in6->sin6_addr), ...);     (CORRECT)
 *          inet_ntop(ZTS_AF_INET6, &(in6->sin6_addr), ...); (INCORRECT)
 *
 *   If you are calling a host OS function but passing a zts_* structure, this can
 *       work sometimes but you should take care to pass the correct host OS constants:
 *
 *          struct zts_sockaddr_in6 in6;
 *             ...
 *          inet_ntop(AF_INET6, &(in6->sin6_addr), dstStr, INET6_ADDRSTRLEN);
 */

int main(int argc, char **argv) 
{
	if (argc != 5) {
		printf("\nlibzt example server\n");
		printf("server <config_file_path> <nwid> <4|6> <bind port>\n");
		exit(0);
	}
	uint64_t nwid = strtoull(argv[2],NULL,16);
	int ipVersion = atoi(argv[3]);
	int bindPort = atoi(argv[4]);
	int defaultServicePort = 9998;
	
	struct zts_sockaddr_in in4, acc_in4;
	if (ipVersion == 4) {
		in4.sin_port = htons(bindPort);
		in4.sin_addr.s_addr = INADDR_ANY;
		in4.sin_family = ZTS_AF_INET;
	}

	// Bring up ZeroTier service and join network

	int fd, accfd;
	int err = ZTS_ERR_OK;

	if((err = zts_start(argv[1], &myZeroTierEventCallback, defaultServicePort)) != ZTS_ERR_OK) {
		printf("Unable to start service, error = %d. Exiting.\n", err);
		exit(1);
	}
	printf("Waiting for node to come online...\n");
	while (!nodeReady) { usleep(50000); }
	printf("This node's identity is stored in %s\n", argv[1]);

	if((err = zts_join(nwid)) != ZTS_ERR_OK) {
		printf("Unable to join network, error = %d. Exiting.\n", err);
		exit(1);
	}
	printf("Joining network %llx\n", nwid);
	printf("Don't forget to authorize this device in my.zerotier.com or the web API!\n");
	while (!networkReady) { usleep(50000); }

	// Socket-like API example

	printf("Creating socket...\n");
	if ((fd = zts_socket(ZTS_AF_INET, ZTS_SOCK_STREAM, 0)) < 0) {
		printf("Error creating ZeroTier socket (fd=%d, ret=%d, zts_errno=%d). Exiting.\n",fd, err, zts_errno);
		exit(1);
	}
	printf("Binding...\n");
	if ((err = zts_bind(fd, (struct sockaddr *)&in4, sizeof(struct zts_sockaddr_in)) < 0)) {
		printf("Error binding to interface (fd=%d, ret=%d, zts_errno=%d). Exiting.\n", fd, err, zts_errno);
		exit(1);
	}
	printf("Listening...\n");
	int backlog = 100;
	if ((err = zts_listen(fd, backlog)) < 0) {
		printf("Error placing socket in LISTENING state (fd=%d, ret=%d, zts_errno=%d). Exiting.\n", fd, err, zts_errno);
		exit(1);
	}
	
	int bytes=0;
	char recvBuf[128];
	memset(recvBuf, 0, sizeof(recvBuf));

	while (true) {
		socklen_t client_addrlen = sizeof(zts_sockaddr_in);
		if ((accfd = zts_accept(fd, (struct sockaddr *)&acc_in4, &client_addrlen)) < 0) {
			printf("Error accepting connection (fd=%d, ret=%d, zts_errno=%d). Exiting.\n", fd, err, zts_errno);
		}
		socklen_t peer_addrlen = sizeof(struct zts_sockaddr_storage);
		zts_getpeername(accfd, (struct sockaddr*)&acc_in4, &peer_addrlen);

		char ipstr[INET_ADDRSTRLEN];
		memset(ipstr, 0, sizeof(ipstr));
		inet_ntop(AF_INET, &(acc_in4.sin_addr), ipstr, INET_ADDRSTRLEN);
		printf("Accepted connection from %s:%d\n", ipstr, ntohs(acc_in4.sin_port));

		printf("Reading message string from client...\n");
		if((bytes = zts_read(accfd, recvBuf, sizeof(recvBuf))) < 0) {
			printf("Error writing to socket (fd=%d, ret=%d, zts_errno=%d). Exiting.\n", fd, bytes, zts_errno);
			exit(1);
		}
		printf("Read %d bytes: %s\n", bytes, recvBuf);
		printf("Sending message string to client...\n");
		if((bytes = zts_write(accfd, recvBuf, bytes)) < 0) {
			printf("Error writing to socket (fd=%d, ret=%d, zts_errno=%d). Exiting.\n", fd, bytes, zts_errno);
			exit(1);
		}
		printf("Sent %d bytes: %s\n", bytes, recvBuf);
		printf("Closing connection socket\n");
		err = zts_close(accfd);
	}
	printf("Closing listen socket\n");
	err = zts_close(fd);
	printf("Shutting down service\n");
	zts_stop();
	return 0;
}