/*
 * Copyright (C) 2014 Freie Universität Berlin
 * Copyright (C) 2014 Lotte Steenbrink <lotte.steenbrink@fu-berlin.de>
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */

/**
 * @ingroup     aodvv2
 * @{
 *
 * @file        aodv.c
 * @brief       aodvv2 routing protocol
 *
 * @author      Lotte Steenbrink <lotte.steenbrink@fu-berlin.de>
 */

#include "debug.h"

#include "aodv.h"
#include "aodvv2/aodvv2.h"
#include "aodv_debug.h"

#define ENABLE_DEBUG (0)

#define UDP_BUFFER_SIZE     (128) /** with respect to IEEE 802.15.4's MTU */
#define RCV_MSG_Q_SIZE      (32)  /* TODO: check if smaller values work, too */

static void _init_addresses(void);
static void _init_sock_snd(void);
static void *_aodv_receiver_thread(void *arg);
static void *_aodv_sender_thread(void *arg);
static void _deep_free_msg_container(struct msg_container *msg_container);
static void _write_packet(struct rfc5444_writer *wr __attribute__ ((unused)),
                          struct rfc5444_writer_target *iface __attribute__((unused)),
                          void *buffer, size_t length);

#if ENABLE_DEBUG
char addr_str[IPV6_MAX_ADDR_STR_LEN];
static struct netaddr_str nbuf;
#endif

static char aodv_rcv_stack_buf[KERNEL_CONF_STACKSIZE_MAIN];
static char aodv_snd_stack_buf[KERNEL_CONF_STACKSIZE_MAIN];

static aodvv2_metric_t _metric_type;
static int sender_thread;
static int _sock_snd;
static struct autobuf _hexbuf;
static sockaddr6_t sa_wp;
static ipv6_addr_t _v6_addr_local, _v6_addr_mcast, _v6_addr_loopback;
static struct netaddr na_local; /* the same as _v6_addr_local, but to save us
                                 * constant calls to ipv6_addr_t_to_netaddr()... */
static struct writer_target *wt;
struct netaddr na_mcast = (struct netaddr){};

void aodv_init(void)
{
    AODV_DEBUG("%s()\n", __func__);

    /* TODO: set if_id properly */
    int if_id = 0;
    net_if_set_src_address_mode(if_id, NET_IF_TRANS_ADDR_M_SHORT);

    aodv_set_metric_type(AODVV2_DEFAULT_METRIC_TYPE);
    _init_addresses();
    _init_sock_snd();

    /* init ALL the things! \o, */
    seqnum_init();
    routingtable_init();
    clienttable_init();

    /* every node is its own client. */
    clienttable_add_client(&na_local);
    rreqtable_init();

    /* init reader and writer */
    aodv_packet_reader_init();
    aodv_packet_writer_init(_write_packet);

    /* start listening & enable sending */
    thread_create(aodv_rcv_stack_buf, sizeof(aodv_rcv_stack_buf), PRIORITY_MAIN,
                  CREATE_STACKTEST, _aodv_receiver_thread, NULL, "_aodv_receiver_thread");
    AODV_DEBUG("listening on port %d\n", HTONS(MANET_PORT));
    sender_thread = thread_create(aodv_snd_stack_buf, sizeof(aodv_snd_stack_buf),
                                  PRIORITY_MAIN, CREATE_STACKTEST, _aodv_sender_thread,
                                  NULL, "_aodv_sender_thread");

    /* register aodv for routing */
    ipv6_iface_set_routing_provider(aodv_get_next_hop);

}

void aodv_set_metric_type(aodvv2_metric_t metric_type)
{
    if (metric_type != AODVV2_DEFAULT_METRIC_TYPE) {
        return;
    }
    _metric_type = metric_type;
}

void aodv_send_rreq(struct aodvv2_packet_data *packet_data)
{
    AODV_DEBUG("%s()\n", __func__);

    struct aodvv2_packet_data *pd = malloc(sizeof(struct aodvv2_packet_data));
    memcpy(pd, packet_data, sizeof(struct aodvv2_packet_data));

    struct rreq_rrep_data *rd = malloc(sizeof(struct rreq_rrep_data));
    *rd = (struct rreq_rrep_data) {
        .next_hop = &na_mcast,
        .packet_data = pd,
    };

    struct msg_container *mc = malloc(sizeof(struct msg_container));
    *mc = (struct msg_container) {
        .type = RFC5444_MSGTYPE_RREQ,
        .data = rd
    };

    msg_t msg;
    msg.content.ptr = (char *) mc;

    msg_try_send(&msg, sender_thread);
}

void aodv_send_rrep(struct aodvv2_packet_data *packet_data, struct netaddr *next_hop)
{
    AODV_DEBUG("%s()\n", __func__);

    struct aodvv2_packet_data *pd = malloc(sizeof(struct aodvv2_packet_data));
    memcpy(pd, packet_data, sizeof(struct aodvv2_packet_data));

    struct netaddr *nh = malloc(sizeof(struct netaddr));
    memcpy(nh, next_hop, sizeof(struct netaddr));

    struct rreq_rrep_data *rd = malloc(sizeof(struct rreq_rrep_data));
    *rd = (struct rreq_rrep_data) {
        .next_hop = nh,
        .packet_data = pd,
    };

    struct msg_container *mc = malloc(sizeof(struct msg_container));
    *mc = (struct msg_container) {
        .type = RFC5444_MSGTYPE_RREP,
        .data = rd
    };

    msg_t msg;
    msg.content.ptr = (char *) mc;

    msg_try_send(&msg, sender_thread);
}

void aodv_send_rerr(struct unreachable_node unreachable_nodes[], size_t len, struct netaddr *next_hop)
{
    AODV_DEBUG("%s()\n", __func__);

    struct rerr_data *rerrd = malloc(sizeof(struct rerr_data));
    *rerrd = (struct rerr_data) {
        .unreachable_nodes = unreachable_nodes,
        .len = len,
        .hoplimit = AODVV2_MAX_HOPCOUNT,
        .next_hop = next_hop
    };

    struct msg_container *mc2 = malloc(sizeof(struct msg_container));
    *mc2 = (struct msg_container) {
        .type = RFC5444_MSGTYPE_RERR,
        .data = rerrd
    };

    msg_t msg2;
    msg2.content.ptr = (char *) mc2;

    msg_try_send(&msg2, sender_thread);
}

/*
 * init the multicast address all RREQ and RERRS are sent to
 * and the local address (source address) of this node
 */
static void _init_addresses(void)
{
    /* init multicast address: set to to a link-local all nodes multicast address */
    ipv6_addr_set_all_nodes_addr(&_v6_addr_mcast);
    AODV_DEBUG("my multicast address is: %s\n",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &_v6_addr_mcast));

    /* get best IP for sending */
    ipv6_net_if_get_best_src_addr(&_v6_addr_local, &_v6_addr_mcast);
    AODV_DEBUG("my src address is:       %s\n",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &_v6_addr_local));

    /* store src & multicast address as netaddr as well for easy interaction
     * with oonf based stuff */
    ipv6_addr_t_to_netaddr(&_v6_addr_local, &na_local);
    ipv6_addr_t_to_netaddr(&_v6_addr_mcast, &na_mcast);
    ipv6_addr_set_loopback_addr(&_v6_addr_loopback);

    /* init sockaddr that write_packet will use to send data */
    sa_wp.sin6_family = AF_INET6;
    sa_wp.sin6_port = HTONS(MANET_PORT);
}

/* init socket communication for sender */
static void _init_sock_snd(void)
{
    _sock_snd = socket_base_socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);

    if (-1 == _sock_snd) {
        AODV_DEBUG("Error Creating Socket!\n");
    }
}

/* Build RREQs, RREPs and RERRs from the information contained in the thread's
 * message queue and send them */
static void *_aodv_sender_thread(void *arg)
{
    (void) arg;

    msg_t msgq[RCV_MSG_Q_SIZE];
    msg_init_queue(msgq, sizeof msgq);
    AODV_DEBUG("_aodv_sender_thread initialized.\n");

    while (true) {
        AODV_DEBUG("%s()\n", __func__);
        msg_t msg;
        msg_receive(&msg);
        struct msg_container *mc = (struct msg_container *) msg.content.ptr;

        if (mc->type == RFC5444_MSGTYPE_RREQ) {
            struct rreq_rrep_data *rreq_data = (struct rreq_rrep_data *) mc->data;
            aodv_packet_writer_send_rreq(rreq_data->packet_data, rreq_data->next_hop);
        }
        else if (mc->type == RFC5444_MSGTYPE_RREP) {
            struct rreq_rrep_data *rrep_data = (struct rreq_rrep_data *) mc->data;
            aodv_packet_writer_send_rrep(rrep_data->packet_data, rrep_data->next_hop);
        }
        else if (mc->type == RFC5444_MSGTYPE_RERR) {
            struct rerr_data *rerr_data = (struct rerr_data *) mc->data;
            aodv_packet_writer_send_rerr(rerr_data->unreachable_nodes, rerr_data->len,
                             rerr_data->hoplimit, rerr_data->next_hop);
        }
        else {
            DEBUG("ERROR: Couldn't identify Message\n");
        }
        _deep_free_msg_container(mc);
    }

    return NULL;
}

/* receive RREQs, RREPs and RERRs and handle them */
static void *_aodv_receiver_thread(void *arg)
{
    (void) arg;

    AODV_DEBUG("%s()\n", __func__);
    uint32_t fromlen;
    char buf_rcv[UDP_BUFFER_SIZE];
    msg_t msg_q[RCV_MSG_Q_SIZE];

    msg_init_queue(msg_q, RCV_MSG_Q_SIZE);

    sockaddr6_t sa_rcv = { .sin6_family = AF_INET6,
                           .sin6_port = HTONS(MANET_PORT)
                         };

    int sock_rcv = socket_base_socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);

    if (-1 == socket_base_bind(sock_rcv, &sa_rcv, sizeof(sa_rcv))) {
        DEBUG("Error: bind to receive socket failed!\n");
        socket_base_close(sock_rcv);
    }

    AODV_DEBUG("ready to receive data\n");
    while (true) {
        int32_t rcv_size = socket_base_recvfrom(sock_rcv, (void *)buf_rcv, UDP_BUFFER_SIZE, 0,
                                        &sa_rcv, &fromlen);

        if (rcv_size < 0) {
            AODV_DEBUG("ERROR receiving data!\n");
        }

        AODV_DEBUG("_aodv_receiver_thread() %s:",
              ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &_v6_addr_local));
        DEBUG(" UDP packet received from %s\n",
              ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &sa_rcv.sin6_addr));

        struct netaddr _sender;
        ipv6_addr_t_to_netaddr(&sa_rcv.sin6_addr, &_sender);

        /* For some reason we sometimes get passed our own packets. drop them. */
        if (netaddr_cmp(&_sender, &na_local) == 0) {
            AODV_DEBUG("received our own packet, dropping it.\n");
            aodv_packet_reader_handle_packet((void *) buf_rcv, rcv_size, &_sender);
        }
    }

    socket_base_close(sock_rcv);

    return NULL;
}

ipv6_addr_t *aodv_get_next_hop(ipv6_addr_t *dest)
{
    AODV_DEBUG("aodv_get_next_hop() %s:",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &_v6_addr_local));
    DEBUG(" getting next hop for %s\n",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, dest));

    struct netaddr _tmp_dest;
    ipv6_addr_t_to_netaddr(dest, &_tmp_dest);
    timex_t now;
    struct unreachable_node unreachable_nodes[AODVV2_MAX_UNREACHABLE_NODES];
    size_t len;

    /* The network stack sometimes asks us for the next hop towards our own IP */
    if (memcmp(dest, &_v6_addr_local, sizeof(ipv6_addr_t)) == 0) {
        AODV_DEBUG("That's me, returning loopback\n");
        return &_v6_addr_loopback;
    }

    /*
     * TODO use ndp_neighbor_get_ll_address() as soon as it's available.
     * note: delete check for active/stale/delayed entries, get_ll_address
     * does that for us then
    */
    ndp_neighbor_cache_t *ndp_nc_entry = ndp_neighbor_cache_search(dest);
    struct aodvv2_routing_entry_t *rt_entry = routingtable_get_entry(&_tmp_dest, _metric_type);

    if (ndp_nc_entry != NULL) {
        /* Case 2: Broken Link (detected by lower layer) */
        int link_broken = (ndp_nc_entry->state == NDP_NCE_STATUS_INCOMPLETE ||
                           ndp_nc_entry->state == NDP_NCE_STATUS_PROBE) &&
                          (rt_entry != NULL && rt_entry->state != ROUTE_STATE_BROKEN);

        if (link_broken) {
            DEBUG("\tNeighbor Cache entry found, but invalid (state: %i). Sending RERR.\n",
                  ndp_nc_entry->state);

            /* mark all routes (active, idle, expired) that use next_hop as broken
             * and add all *Active* routes to the list of unreachable nodes */
            routingtable_break_and_get_all_hopping_over(&_tmp_dest, unreachable_nodes, &len);

            aodv_send_rerr(unreachable_nodes, len, &na_mcast);
            return NULL;
        }

        DEBUG("[aodvv2][ndp] found NC entry. Returning dest addr.\n");
        return dest;
    }
    DEBUG("\t[ndp] no entry for addr %s found\n",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, dest));

    if (rt_entry) {
        /* Case 1: Undeliverable Packet */
        int packet_indeliverable = rt_entry->state == ROUTE_STATE_BROKEN ||
                                   rt_entry->state == ROUTE_STATE_EXPIRED;
        if (packet_indeliverable) {
            DEBUG("\tRouting table entry found, but invalid (state %i). Sending RERR.\n",
                  rt_entry->state);
            unreachable_nodes[0].addr = _tmp_dest;
            unreachable_nodes[0].seqnum = rt_entry->seqnum;
            aodv_send_rerr(unreachable_nodes, 1, &na_mcast);
            return NULL;
        }

        DEBUG("\tfound dest %s in routing table\n",
              ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, dest));

        vtimer_now(&now);
        rt_entry->lastUsed = now;
        if (rt_entry->state == ROUTE_STATE_IDLE) {
            rt_entry->state = ROUTE_STATE_ACTIVE;
        }

        /* Currently, there is no way to do this, so I'm doing it the worst
         * possible, but safe way: I can't make sure that the current call to
         * aodv_get_next_hop() is overridden by another call to aodv_get_next_hop()
         * by a thread with higher priority, thus messing up return values if I just
         * use a static ipv6_addr_t.
         * The following malloc will never be free()'d. TODO: FIX THIS ASAP.
        */
        ipv6_addr_t *next_hop = (ipv6_addr_t *) malloc(sizeof(ipv6_addr_t));
        netaddr_to_ipv6_addr_t(&rt_entry->nextHopAddr, next_hop);

        return next_hop;
    }

    aodvv2_seqnum_t seqnum = seqnum_get();
    seqnum_inc();

    struct aodvv2_packet_data rreq_data = (struct aodvv2_packet_data) {
        .hoplimit = AODVV2_MAX_HOPCOUNT,
        .metricType = _metric_type,
        .origNode = (struct node_data) {
            .addr = na_local,
            .metric = 0,
            .seqnum = seqnum,
        },
        .targNode = (struct node_data) {
            .addr = _tmp_dest,
        },
        .timestamp = (timex_t) {0,0} /* this timestamp is never used, it exists
                                      * merely to make the compiler shut up */
    };

    DEBUG("\tNo route found towards %s, starting route discovery... \n",
          ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, dest));
    aodv_send_rreq(&rreq_data);

    return NULL;
}

/**
 * Handle the output of the RFC5444 packet creation process. This callback is
 * called by every writer_send_* function.
 */
static void _write_packet(struct rfc5444_writer *wr __attribute__ ((unused)),
                          struct rfc5444_writer_target *iface __attribute__((unused)),
                          void *buffer, size_t length)
{
    AODV_DEBUG("%s()\n", __func__);
    /* generate hexdump and human readable representation of packet
     * and print to console */
    abuf_hexdump(&_hexbuf, "\t", buffer, length);
    rfc5444_print_direct(&_hexbuf, buffer, length);
    DEBUG("%s", abuf_getptr(&_hexbuf));
    abuf_clear(&_hexbuf);

    /* fetch the address the packet is supposed to be sent to (i.e. to a
     * specific node or the multicast address) from the writer_target struct
     * iface* is stored in. This is a bit hacky, but it does the trick. */
    wt = container_of(iface, struct writer_target, interface);
    netaddr_to_ipv6_addr_t(&wt->target_addr, &sa_wp.sin6_addr);

    /* When originating a RREQ, add it to our RREQ table/update its predecessor */
    if (wt->type == RFC5444_MSGTYPE_RREQ
        && netaddr_cmp(&wt->packet_data.origNode.addr, &na_local) == 0) {
        AODV_DEBUG("originating RREQ with SeqNum %d towards %s via %s; updating RREQ table...\n",
              wt->packet_data.origNode.seqnum,
              netaddr_to_string(&nbuf, &wt->packet_data.targNode.addr),
              ipv6_addr_to_str(addr_str, IPV6_MAX_ADDR_STR_LEN, &sa_wp.sin6_addr));
        rreqtable_is_redundant(&wt->packet_data);
    }

    int bytes_sent = socket_base_sendto(_sock_snd, buffer, length,
                                        0, &sa_wp, sizeof sa_wp);

    (void) bytes_sent;
    AODV_DEBUG("%d bytes sent.\n", bytes_sent);
}

/* free the matryoshka doll of cobbled-together structs that the sender_thread receives */
static void _deep_free_msg_container(struct msg_container *mc)
{
    int type = mc->type;
    if ((type == RFC5444_MSGTYPE_RREQ) || (type == RFC5444_MSGTYPE_RREP)) {
        struct rreq_rrep_data *rreq_rrep_data = (struct rreq_rrep_data *) mc->data;
        free(rreq_rrep_data->packet_data);
        if (netaddr_cmp(rreq_rrep_data->next_hop, &na_mcast) != 0) {
            free(rreq_rrep_data->next_hop);
        }
    }
    else if (type == RFC5444_MSGTYPE_RERR) {
        struct rerr_data *rerr_data = (struct rerr_data *) mc->data;
        if (netaddr_cmp(rerr_data->next_hop, &na_mcast) != 0) {
            free(rerr_data->next_hop);
        }
    }
    free(mc->data);
    free(mc);
}