/*
 * Copyright (C) 2015 Martine Lenders <mlenders@inf.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.
 */

/**
 * @{
 *
 * @file
 */

#include "kernel_types.h"
#include "net/ng_netbase.h"
#include "thread.h"
#include "utlist.h"

#include "net/ng_sixlowpan.h"
#include "net/ng_sixlowpan/frag.h"
#include "net/ng_sixlowpan/netif.h"

#define ENABLE_DEBUG    (0)
#include "debug.h"

static kernel_pid_t _pid = KERNEL_PID_UNDEF;
static char _stack[NG_SIXLOWPAN_STACK_SIZE];

/* handles NG_NETAPI_MSG_TYPE_RCV commands */
void _receive(ng_pktsnip_t *pkt);
/* handles NG_NETAPI_MSG_TYPE_SND commands */
void _send(ng_pktsnip_t *pkt);
/* Main event loop for 6LoWPAN */
static void *_event_loop(void *args);

kernel_pid_t ng_sixlowpan_init(void)
{
    if (_pid > KERNEL_PID_UNDEF) {
        return _pid;
    }

    _pid = thread_create(_stack, sizeof(_stack), NG_SIXLOWPAN_PRIO,
                         CREATE_STACKTEST, _event_loop, NULL, "6lo");

    return _pid;
}

void _receive(ng_pktsnip_t *pkt)
{
    ng_pktsnip_t *payload;
    uint8_t *dispatch;
    ng_netreg_entry_t *entry;

    LL_SEARCH_SCALAR(pkt, payload, type, NG_NETTYPE_SIXLOWPAN);

    if ((payload == NULL) || (payload->size < 1)) {
        DEBUG("6lo: Received packet has no 6LoWPAN payload\n");
        ng_pktbuf_release(pkt);
    }

    dispatch = payload->data;

    if (dispatch[0] == NG_SIXLOWPAN_UNCOMPRESSED) {
        ng_pktsnip_t *sixlowpan;
        DEBUG("6lo: received uncompressed IPv6 packet\n");
        payload = ng_pktbuf_start_write(payload);

        if (payload == NULL) {
            DEBUG("6lo: can not get write access on received packet\n");
#if defined(DEVELHELP) && defined(ENABLE_DEBUG)
            ng_pktbuf_stats();
#endif
            ng_pktbuf_release(pkt);
            return;
        }

        /* packet is uncompressed: just mark and remove the dispatch */
        sixlowpan = ng_pktbuf_add(payload, payload->data, sizeof(uint8_t),
                                  NG_NETTYPE_SIXLOWPAN);

        if (sixlowpan == NULL) {
            DEBUG("6lo: can not mark 6LoWPAN dispatch\n");
            ng_pktbuf_release(pkt);
            return;
        }

        pkt = ng_pktbuf_remove_snip(pkt, sixlowpan);
    }
#ifdef MODULE_NG_SIXLOWPAN_FRAG
    else if (ng_sixlowpan_frag_is((ng_sixlowpan_frag_t *)dispatch)) {
        DEBUG("6lo: received 6LoWPAN fragment\n");
        ng_sixlowpan_frag_handle_pkt(pkt);
        return;
    }
#endif
    else {
        DEBUG("6lo: dispatch %02x ... is not supported\n",
              dispatch[0]);
        ng_pktbuf_release(pkt);
        return;
    }

    payload->type = NG_NETTYPE_IPV6;

    entry = ng_netreg_lookup(NG_NETTYPE_IPV6, NG_NETREG_DEMUX_CTX_ALL);

    if (entry == NULL) {
        DEBUG("ipv6: No receivers for this packet found\n");
        ng_pktbuf_release(pkt);
        return;
    }

    ng_pktbuf_hold(pkt, ng_netreg_num(NG_NETTYPE_IPV6, NG_NETREG_DEMUX_CTX_ALL) - 1);

    while (entry) {
        DEBUG("6lo: Send receive command for %p to %" PRIu16 "\n",
              (void *)pkt, entry->pid);
        ng_netapi_receive(entry->pid, pkt);
        entry = ng_netreg_getnext(entry);
    }
}

void _send(ng_pktsnip_t *pkt)
{
    ng_netif_hdr_t *hdr;
    ng_pktsnip_t *ipv6, *sixlowpan;
    ng_sixlowpan_netif_t *iface;
    /* cppcheck: datagram_size will be read by frag */
    /* cppcheck-suppress unreadVariable */
    size_t payload_len, datagram_size;
    uint16_t max_frag_size;
    uint8_t *disp;

    if ((pkt == NULL) || (pkt->size < sizeof(ng_netif_hdr_t))) {
        DEBUG("6lo: Sending packet has no netif header\n");
        ng_pktbuf_release(pkt);
        return;
    }

    hdr = pkt->data;
    ipv6 = pkt->next;

    if ((ipv6 == NULL) || (ipv6->type != NG_NETTYPE_IPV6)) {
        DEBUG("6lo: Sending packet has no IPv6 header\n");
        ng_pktbuf_release(pkt);
        return;
    }

    /* payload length and datagram size are different in that the payload
     * length is the length of the IPv6 datagram + 6LoWPAN dispatches,
     * while the datagram size is the size of only the IPv6 datagram */
    payload_len = ng_pkt_len(ipv6);
    datagram_size = (uint16_t)payload_len;

    /* use sixlowpan packet snip as temporary one */
    sixlowpan = ng_pktbuf_start_write(pkt);

    if (sixlowpan == NULL) {
        DEBUG("6lo: no space left in packet buffer\n");
        ng_pktbuf_release(pkt);
        return;
    }

    pkt = sixlowpan;

    DEBUG("6lo: Send uncompressed\n");

    sixlowpan = ng_pktbuf_add(NULL, NULL, sizeof(uint8_t), NG_NETTYPE_SIXLOWPAN);

    if (sixlowpan == NULL) {
        DEBUG("6lo: no space left in packet buffer\n");
        ng_pktbuf_release(pkt);
        return;
    }

    sixlowpan->next = ipv6;
    pkt->next = sixlowpan;
    disp = sixlowpan->data;
    disp[0] = NG_SIXLOWPAN_UNCOMPRESSED;
    payload_len++;

    iface = ng_sixlowpan_netif_get(hdr->if_pid);

    if (iface == NULL) {
        if (ng_netapi_get(hdr->if_pid, NETCONF_OPT_MAX_PACKET_SIZE,
                          0, &max_frag_size, sizeof(max_frag_size)) < 0) {
            /* if error we assume it works */
            DEBUG("6lo: can not get max packet size from interface %"
                  PRIkernel_pid "\n", hdr->if_pid);
            max_frag_size = UINT16_MAX;
        }

        ng_sixlowpan_netif_add(hdr->if_pid, max_frag_size);
    }
    else {
        max_frag_size = iface->max_frag_size;
    }

    DEBUG("6lo: max_frag_size = %" PRIu16 " for interface %"
          PRIkernel_pid "\n", max_frag_size, hdr->if_pid);

    /* IP should not send anything here if it is not a 6LoWPAN interface,
     * so we don't need to check for NULL pointers */
    if (payload_len <= max_frag_size) {
        DEBUG("6lo: Send SND command for %p to %" PRIu16 "\n",
              (void *)pkt, hdr->if_pid);
        ng_netapi_send(hdr->if_pid, pkt);

        return;
    }
#ifdef MODULE_NG_SIXLOWPAN_FRAG
    else {
        DEBUG("6lo: Send fragmented (%u > %" PRIu16 ")\n",
              (unsigned int)payload_len, max_frag_size);
        ng_sixlowpan_frag_send(hdr->if_pid, pkt, payload_len, datagram_size);
    }
#else
    (void)datagram_size;
    DEBUG("6lo: packet too big (%u> %" PRIu16 ")\n",
          (unsigned int)payload_len, max_frag_size);
#endif
}

static void *_event_loop(void *args)
{
    msg_t msg, reply, msg_q[NG_SIXLOWPAN_MSG_QUEUE_SIZE];
    ng_netreg_entry_t me_reg;

    (void)args;
    msg_init_queue(msg_q, NG_SIXLOWPAN_MSG_QUEUE_SIZE);

    me_reg.demux_ctx = NG_NETREG_DEMUX_CTX_ALL;
    me_reg.pid = thread_getpid();

    /* register interest in all 6LoWPAN packets */
    ng_netreg_register(NG_NETTYPE_SIXLOWPAN, &me_reg);

    /* preinitialize ACK */
    reply.type = NG_NETAPI_MSG_TYPE_ACK;

    /* start event loop */
    while (1) {
        DEBUG("6lo: waiting for incoming message.\n");
        msg_receive(&msg);

        switch (msg.type) {
            case NG_NETAPI_MSG_TYPE_RCV:
                DEBUG("6lo: NG_NETDEV_MSG_TYPE_RCV received\n");
                _receive((ng_pktsnip_t *)msg.content.ptr);
                break;

            case NG_NETAPI_MSG_TYPE_SND:
                DEBUG("6lo: NG_NETDEV_MSG_TYPE_SND received\n");
                _send((ng_pktsnip_t *)msg.content.ptr);
                break;

            case NG_NETAPI_MSG_TYPE_GET:
            case NG_NETAPI_MSG_TYPE_SET:
                DEBUG("6lo: reply to unsupported get/set\n");
                reply.content.value = -ENOTSUP;
                msg_reply(&msg, &reply);
                break;

            default:
                DEBUG("6lo: operation not supported\n");
                break;
        }
    }

    return NULL;
}

/** @} */