/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright (c) 2017-2018 Fraunhofer IOSB (Author: Andreas Ebner)
 */

/* Enable POSIX features */
#if !defined(_XOPEN_SOURCE) && !defined(_WRS_KERNEL)
# define _XOPEN_SOURCE 600
#endif
#ifndef _DEFAULT_SOURCE
# define _DEFAULT_SOURCE
#endif

/* On older systems we need to define _BSD_SOURCE.
 * _DEFAULT_SOURCE is an alias for that. */
#ifndef _BSD_SOURCE
# define _BSD_SOURCE
#endif

 /* Disable some security warnings on MSVC */
#ifdef _MSC_VER
# define _CRT_SECURE_NO_WARNINGS
#endif

 /* Assume that Windows versions are newer than Windows XP */
#if defined(__MINGW32__) && (!defined(WINVER) || WINVER < 0x501)
# undef WINVER
# undef _WIN32_WINDOWS
# undef _WIN32_WINNT
# define WINVER 0x0501
# define _WIN32_WINDOWS 0x0501
# define _WIN32_WINNT 0x0501
#endif

#ifdef _WIN32
# include <winsock2.h>
# include <ws2tcpip.h>
# include <Iphlpapi.h>
# define CLOSESOCKET(S) closesocket((SOCKET)S)
# define ssize_t int
# define UA_fd_set(fd, fds) FD_SET((unsigned int)fd, fds)
# define UA_fd_isset(fd, fds) FD_ISSET((unsigned int)fd, fds)
#else /* _WIN32 */
#  define CLOSESOCKET(S) close(S)
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <net/if.h>
# define UA_fd_set(fd, fds) FD_SET(fd, fds)
# define UA_fd_isset(fd, fds) FD_ISSET(fd, fds)
# endif /* Not Windows */

#include <stdio.h>
#include "ua_plugin_network.h"
#include "ua_network_pubsub_udp.h"
#include "ua_log_stdout.h"

//UDP multicast network layer specific internal data
typedef struct {
    int ai_family;                        //Protocol family for socket.  IPv4/IPv6
    struct sockaddr_storage *ai_addr;     //https://msdn.microsoft.com/de-de/library/windows/desktop/ms740496(v=vs.85).aspx
    UA_UInt32 messageTTL;
    UA_Boolean enableLoopback;
    UA_Boolean enableReuse;
} UA_PubSubChannelDataUDPMC;

/**
 * Open communication socket based on the connectionConfig. Protocol specific parameters are
 * provided within the connectionConfig as KeyValuePair.
 * Currently supported options: "ttl" , "loopback", "reuse"
 *
 * @return ref to created channel, NULL on error
 */
static UA_PubSubChannel *
UA_PubSubChannelUDPMC_open(const UA_PubSubConnectionConfig *connectionConfig) {
    #ifdef _WIN32
        WSADATA wsaData;
        WSAStartup(MAKEWORD(2, 2), &wsaData);
    #endif /* Not Windows */

    UA_NetworkAddressUrlDataType address;
    if(UA_Variant_hasScalarType(&connectionConfig->address, &UA_TYPES[UA_TYPES_NETWORKADDRESSURLDATATYPE])){
        address = *(UA_NetworkAddressUrlDataType *)connectionConfig->address.data;
    } else {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection creation failed. Invalid Address.");
        return NULL;
    }
    //allocate and init memory for the UDP multicast specific internal data
    UA_PubSubChannelDataUDPMC * channelDataUDPMC =
            (UA_PubSubChannelDataUDPMC *) UA_calloc(1, (sizeof(UA_PubSubChannelDataUDPMC)));
    if(!channelDataUDPMC){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection creation failed. Out of memory.");
        return NULL;
    }
    //set default values
    memcpy(channelDataUDPMC, &(UA_PubSubChannelDataUDPMC){0, NULL, 255, UA_TRUE, UA_TRUE}, sizeof(UA_PubSubChannelDataUDPMC));
    //iterate over the given KeyValuePair paramters
    UA_String ttlParam = UA_STRING("ttl"), loopbackParam = UA_STRING("loopback"), reuseParam = UA_STRING("reuse");
    for(size_t i = 0; i < connectionConfig->connectionPropertiesSize; i++){
        if(UA_String_equal(&connectionConfig->connectionProperties[i].key.name, &ttlParam)){
            if(UA_Variant_hasScalarType(&connectionConfig->connectionProperties[i].value, &UA_TYPES[UA_TYPES_UINT32])){
                channelDataUDPMC->messageTTL = *(UA_UInt32 *) connectionConfig->connectionProperties[i].value.data;
            }
        } else if(UA_String_equal(&connectionConfig->connectionProperties[i].key.name, &loopbackParam)){
            if(UA_Variant_hasScalarType(&connectionConfig->connectionProperties[i].value, &UA_TYPES[UA_TYPES_BOOLEAN])){
                channelDataUDPMC->enableLoopback = *(UA_Boolean *) connectionConfig->connectionProperties[i].value.data;
            }
        } else if(UA_String_equal(&connectionConfig->connectionProperties[i].key.name, &reuseParam)){
            if(UA_Variant_hasScalarType(&connectionConfig->connectionProperties[i].value, &UA_TYPES[UA_TYPES_BOOLEAN])){
                channelDataUDPMC->enableReuse = *(UA_Boolean *) connectionConfig->connectionProperties[i].value.data;
            }
        } else {
            UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection creation. Unknown connection parameter.");
        }
    }

    UA_PubSubChannel *newChannel = (UA_PubSubChannel *) UA_calloc(1, sizeof(UA_PubSubChannel));
    if(!newChannel){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection creation failed. Out of memory.");
        UA_free(channelDataUDPMC);
        return NULL;
    }
    struct addrinfo hints, *rp, *requestResult = NULL;
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_flags = 0;
    hints.ai_protocol = 0;

    UA_String hostname, path;
    UA_UInt16 networkPort;
    if(UA_parseEndpointUrl(&address.url, &hostname, &networkPort, &path) != UA_STATUSCODE_GOOD){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Invalid URL.");
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }
    if(hostname.length > 512) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. URL maximum length is 512.");
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }

    UA_STACKARRAY(char, addressAsChar, sizeof(char) * hostname.length +1);
    memcpy(addressAsChar, hostname.data, hostname.length);
    addressAsChar[hostname.length] = 0;
    char port[6];
    sprintf(port, "%u", networkPort);

    if(getaddrinfo(addressAsChar, port, &hints, &requestResult) != 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Internal error.");
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }

    //check if the ip address is a multicast address
    if(requestResult->ai_family == PF_INET){
        struct in_addr imr_interface;
        inet_pton(AF_INET, addressAsChar, &imr_interface);
        if((ntohl(imr_interface.s_addr) & 0xF0000000) != 0xE0000000){
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                         "PubSub Connection creation failed. No multicast address.");
            freeaddrinfo(requestResult);
            UA_free(channelDataUDPMC);
            UA_free(newChannel);
            return NULL;
        }
    } else {
        //TODO check if ipv6 addrr is multicast address.
    }

    for(rp = requestResult; rp != NULL; rp = rp->ai_next){
        newChannel->sockfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
        if(newChannel->sockfd != -1){
            break; /*success*/
        }
    }
    if(!rp){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Internal error.");
        freeaddrinfo(requestResult);
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }
    channelDataUDPMC->ai_family = rp->ai_family;
    channelDataUDPMC->ai_addr = (struct sockaddr_storage *) UA_calloc(1, sizeof(struct sockaddr_storage));
    if(!channelDataUDPMC->ai_addr){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Out of memory.");
        CLOSESOCKET(newChannel->sockfd);
        freeaddrinfo(requestResult);
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }
    memcpy(channelDataUDPMC->ai_addr, rp->ai_addr, sizeof(*rp->ai_addr));
    //link channel and internal channel data
    newChannel->handle = channelDataUDPMC;

    //Set loop back data to your host
    if(setsockopt(newChannel->sockfd,
                     requestResult->ai_family == PF_INET6 ? IPPROTO_IPV6:IPPROTO_IP,
                     requestResult->ai_family == PF_INET6 ? IPV6_MULTICAST_LOOP : IP_MULTICAST_LOOP,
                     (const char *)&channelDataUDPMC->enableLoopback, sizeof (channelDataUDPMC->enableLoopback)) < 0) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation failed. Loopback setup failed.");
        CLOSESOCKET(newChannel->sockfd);
        freeaddrinfo(requestResult);
        UA_free(channelDataUDPMC);
        UA_free(newChannel);
        return NULL;
    }

    //Set Time to live (TTL). Value of 1 prevent forward beyond the local network.
    if(setsockopt(newChannel->sockfd,
                  requestResult->ai_family == PF_INET6 ? IPPROTO_IPV6:IPPROTO_IP,
                  requestResult->ai_family == PF_INET6 ? IPV6_MULTICAST_HOPS : IP_MULTICAST_TTL,
                  (const char *)&channelDataUDPMC->messageTTL, sizeof(channelDataUDPMC->messageTTL)) < 0) {
        UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                     "PubSub Connection creation problem. Time to live setup failed.");
    }

    //Set reuse address -> enables sharing of the same listening address on different sockets.
    if(channelDataUDPMC->enableReuse){
        int enableReuse = 1;
        if(setsockopt(newChannel->sockfd,
                      SOL_SOCKET, SO_REUSEADDR,
                      (const char*)&enableReuse, sizeof(enableReuse)) < 0){
            UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                           "PubSub Connection creation problem. Reuse address setup failed.");
        }
    }

    //Set the physical interface for outgoing traffic
    if(address.networkInterface.length > 0){
        UA_STACKARRAY(char, interfaceAsChar, sizeof(char) * address.networkInterface.length + 1);
        memcpy(interfaceAsChar, address.networkInterface.data, address.networkInterface.length);
        interfaceAsChar[address.networkInterface.length] = 0;
        enum{
            IPv4,
            IPv6,
            INVALID
        } ipVersion;
        union {
            struct ip_mreq ipv4;
            struct ipv6_mreq ipv6;
        } group;
        if(inet_pton(AF_INET, interfaceAsChar, &group.ipv4.imr_interface)){
            ipVersion = IPv4;
        } else if (inet_pton(AF_INET6, interfaceAsChar, &group.ipv6.ipv6mr_multiaddr)){
            group.ipv6.ipv6mr_interface = if_nametoindex(interfaceAsChar);
            ipVersion = IPv6;
        } else {
            ipVersion = INVALID;
        }
        if(ipVersion == INVALID ||
                setsockopt(newChannel->sockfd,
                           requestResult->ai_family == PF_INET6 ? IPPROTO_IPV6 : IPPROTO_IP,
                           requestResult->ai_family == PF_INET6 ? IPV6_MULTICAST_IF : IP_MULTICAST_IF,
                           ipVersion == IPv6 ? (void *) &group.ipv6.ipv6mr_interface : &group.ipv4.imr_interface,
                           ipVersion == IPv6 ? sizeof(group.ipv6.ipv6mr_interface) : sizeof(struct in_addr)) < 0){
            UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER,
                           "PubSub Connection creation problem. Interface selection failed.");
        };
    }
    freeaddrinfo(requestResult);
    newChannel->state = UA_PUBSUB_CHANNEL_PUB;
    return newChannel;
}

/**
 * Subscribe to a given address.
 *
 * @return UA_STATUSCODE_GOOD on success
 */
static UA_StatusCode
UA_PubSubChannelUDPMC_regist(UA_PubSubChannel *channel, UA_ExtensionObject *transportSettings) {
    if(!(channel->state == UA_PUBSUB_CHANNEL_PUB || channel->state == UA_PUBSUB_CHANNEL_RDY)){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    UA_PubSubChannelDataUDPMC * connectionConfig = (UA_PubSubChannelDataUDPMC *) channel->handle;
    if(connectionConfig->ai_family == PF_INET){//IPv4 handling
        struct sockaddr_in addr;
        memcpy(&addr, connectionConfig->ai_addr, sizeof(struct sockaddr_in));
        addr.sin_addr.s_addr = INADDR_ANY;
        if (bind(channel->sockfd, (const struct sockaddr *)&addr, sizeof(struct sockaddr_in)) != 0){
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed.");
            return UA_STATUSCODE_BADINTERNALERROR;
        }
        struct ip_mreq groupV4;
        memcpy(&groupV4.imr_multiaddr, &((const struct sockaddr_in *)connectionConfig->ai_addr)->sin_addr, sizeof(struct ip_mreq));
        groupV4.imr_interface.s_addr = htonl(INADDR_ANY);
        //multihomed hosts can join several groups on different IF, INADDR_ANY -> kernel decides

        if(setsockopt(channel->sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char *) &groupV4, sizeof(groupV4)) != 0){
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed.");
            return UA_STATUSCODE_BADINTERNALERROR;
        }

    } else if (connectionConfig->ai_family == PF_INET6) {//IPv6 handling
        //TODO implement regist for IPv6
    } else {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection regist failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    return UA_STATUSCODE_GOOD;
}

/**
 * Remove current subscription.
 *
 * @return UA_STATUSCODE_GOOD on success
 */
static UA_StatusCode
UA_PubSubChannelUDPMC_unregist(UA_PubSubChannel *channel, UA_ExtensionObject *transportSettings) {
    if(!(channel->state == UA_PUBSUB_CHANNEL_PUB_SUB || channel->state == UA_PUBSUB_CHANNEL_SUB)){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection unregist failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    UA_PubSubChannelDataUDPMC * connectionConfig = (UA_PubSubChannelDataUDPMC *) channel->handle;
    if(connectionConfig->ai_family == PF_INET){//IPv4 handling
        struct ip_mreq groupV4;
        memcpy(&groupV4.imr_multiaddr, &((const struct sockaddr_in *)connectionConfig->ai_addr)->sin_addr, sizeof(struct ip_mreq));
        groupV4.imr_interface.s_addr = htonl(INADDR_ANY);

        if(setsockopt(channel->sockfd, IPPROTO_IP, IP_DROP_MEMBERSHIP, (char *) &groupV4, sizeof(groupV4)) != 0){
            UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection unregist failed.");
            return UA_STATUSCODE_BADINTERNALERROR;
        }
    } else if (connectionConfig->ai_family == PF_INET6) {//IPv6 handling
        //TODO implement unregist for IPv6
    } else {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection unregist failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    return UA_STATUSCODE_GOOD;
}

/**
 * Send messages to the connection defined address
 *
 * @return UA_STATUSCODE_GOOD if success
 */
static UA_StatusCode
UA_PubSubChannelUDPMC_send(UA_PubSubChannel *channel, UA_ExtensionObject *transportSettigns, const UA_ByteString *buf) {
    UA_PubSubChannelDataUDPMC *channelConfigUDPMC = (UA_PubSubChannelDataUDPMC *) channel->handle;
    if(!(channel->state == UA_PUBSUB_CHANNEL_PUB || channel->state == UA_PUBSUB_CHANNEL_PUB_SUB)){
        UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection sending failed. Invalid state.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    //TODO evalute: chunk messages or check against MTU?
    long nWritten = 0;
    while (nWritten < (long)buf->length) {
        long n = sendto(channel->sockfd, buf->data, buf->length, 0,
                        (struct sockaddr *) channelConfigUDPMC->ai_addr, sizeof(struct sockaddr_storage));
        if(n == -1L) {
            UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection sending failed.");
            return UA_STATUSCODE_BADINTERNALERROR;
        }
        nWritten += n;
    }
    return UA_STATUSCODE_GOOD;
}

/**
 * Receive messages. The regist function should be called before.
 *
 * @param timeout in usec | on windows platforms are only multiples of 1000usec possible
 * @return
 */
static UA_StatusCode
UA_PubSubChannelUDPMC_receive(UA_PubSubChannel *channel, UA_ByteString *message, UA_ExtensionObject *transportSettigns, UA_UInt32 timeout){
    if(!(channel->state == UA_PUBSUB_CHANNEL_PUB || channel->state == UA_PUBSUB_CHANNEL_PUB_SUB)) {
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection receive failed. Invalid state.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    UA_PubSubChannelDataUDPMC *channelConfigUDPMC = (UA_PubSubChannelDataUDPMC *) channel->handle;

    if(timeout > 0) {
        fd_set fdset;
        FD_ZERO(&fdset);
        UA_fd_set(channel->sockfd, &fdset);
        struct timeval tmptv = {(long int)(timeout / 1000000),
                                (long int)(timeout % 1000000)};
        int resultsize = select(channel->sockfd+1, &fdset, NULL,
                                NULL, &tmptv);
        if(resultsize == 0) {
            message->length = 0;
            return UA_STATUSCODE_GOODNONCRITICALTIMEOUT;
        }
        if (resultsize == -1) {
            message->length = 0;
            return UA_STATUSCODE_BADINTERNALERROR;
        }
    }

    if(channelConfigUDPMC->ai_family == PF_INET){
        ssize_t messageLength;
        messageLength = recvfrom(channel->sockfd, message->data, message->length, 0, NULL, NULL);
        if(messageLength > 0){
            message->length = (size_t) messageLength;
        } else {
            message->length = 0;
        }
    } else {
        //TODO implement recieve for IPv6
    }
    return UA_STATUSCODE_GOOD;
}

/**
 * Close channel and free the channel data.
 *
 * @return UA_STATUSCODE_GOOD if success
 */
static UA_StatusCode
UA_PubSubChannelUDPMC_close(UA_PubSubChannel *channel) {
#ifdef _WIN32
    WSACleanup();
#endif /* Not Windows */
    if(CLOSESOCKET(channel->sockfd) != 0){
        UA_LOG_ERROR(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "PubSub Connection delete failed.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }
    //cleanup the internal NetworkLayer data
    UA_PubSubChannelDataUDPMC *networkLayerData = (UA_PubSubChannelDataUDPMC *) channel->handle;
    UA_free(networkLayerData->ai_addr);
    UA_free(networkLayerData);
    UA_free(channel);
    return UA_STATUSCODE_GOOD;
}

/**
 * Generate a new channel. based on the given configuration.
 *
 * @param connectionConfig connection configuration
 * @return  ref to created channel, NULL on error
 */
static UA_PubSubChannel *
TransportLayerUDPMC_addChannel(UA_PubSubConnectionConfig *connectionConfig) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "PubSub channel requested");
    UA_PubSubChannel * pubSubChannel = UA_PubSubChannelUDPMC_open(connectionConfig);
    if(pubSubChannel){
        pubSubChannel->regist = UA_PubSubChannelUDPMC_regist;
        pubSubChannel->unregist = UA_PubSubChannelUDPMC_unregist;
        pubSubChannel->send = UA_PubSubChannelUDPMC_send;
        pubSubChannel->receive = UA_PubSubChannelUDPMC_receive;
        pubSubChannel->close = UA_PubSubChannelUDPMC_close;
        pubSubChannel->connectionConfig = connectionConfig;
    }
    return pubSubChannel;
}

//UDPMC channel factory
UA_PubSubTransportLayer
UA_PubSubTransportLayerUDPMP() {
    UA_PubSubTransportLayer pubSubTransportLayer;
    pubSubTransportLayer.transportProfileUri = UA_STRING("http://opcfoundation.org/UA-Profile/Transport/pubsub-udp-uadp");
    pubSubTransportLayer.createPubSubChannel = &TransportLayerUDPMC_addChannel;
    return pubSubTransportLayer;
}

#undef _POSIX_C_SOURCE