/*
 * Copyright (c) 2016 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <vnet/ip/lookup.h>
#include <vnet/dpo/replicate_dpo.h>
#include <vnet/dpo/drop_dpo.h>
#include <vnet/adj/adj.h>

#undef REP_DEBUG

#ifdef REP_DEBUG
#define REP_DBG(_rep, _fmt, _args...)                                   \
{                                                                       \
    u8* _tmp =NULL;                                                     \
    clib_warning("rep:[%s]:" _fmt,                                      \
                 replicate_format(replicate_get_index((_rep)),          \
                                  0, _tmp),                             \
                 ##_args);                                              \
    vec_free(_tmp);                                                     \
}
#else
#define REP_DBG(_p, _fmt, _args...)
#endif

#define foreach_replicate_dpo_error                       \
_(BUFFER_ALLOCATION_FAILURE, "Buffer Allocation Failure")

typedef enum {
#define _(sym,str) REPLICATE_DPO_ERROR_##sym,
  foreach_replicate_dpo_error
#undef _
  REPLICATE_DPO_N_ERROR,
} replicate_dpo_error_t;

static char * replicate_dpo_error_strings[] = {
#define _(sym,string) string,
  foreach_replicate_dpo_error
#undef _
};

/**
 * Pool of all DPOs. It's not static so the DP can have fast access
 */
replicate_t *replicate_pool;

/**
 * The one instance of replicate main
 */
replicate_main_t replicate_main;

static inline index_t
replicate_get_index (const replicate_t *rep)
{
    return (rep - replicate_pool);
}

static inline dpo_id_t*
replicate_get_buckets (replicate_t *rep)
{
    if (REP_HAS_INLINE_BUCKETS(rep))
    {
        return (rep->rep_buckets_inline);
    }
    else
    {
        return (rep->rep_buckets);
    }
}

static replicate_t *
replicate_alloc_i (void)
{
    replicate_t *rep;

    pool_get_aligned(replicate_pool, rep, CLIB_CACHE_LINE_BYTES);
    memset(rep, 0, sizeof(*rep));

    vlib_validate_combined_counter(&(replicate_main.repm_counters),
                                   replicate_get_index(rep));
    vlib_zero_combined_counter(&(replicate_main.repm_counters),
                               replicate_get_index(rep));

    return (rep);
}

static u8*
replicate_format (index_t repi,
                  replicate_format_flags_t flags,
                  u32 indent,
                  u8 *s)
{
    vlib_counter_t to;
    replicate_t *rep;
    dpo_id_t *buckets;
    u32 i;

    rep = replicate_get(repi);
    vlib_get_combined_counter(&(replicate_main.repm_counters), repi, &to);
    buckets = replicate_get_buckets(rep);

    s = format(s, "%U: ", format_dpo_type, DPO_REPLICATE);
    s = format(s, "[index:%d buckets:%d ", repi, rep->rep_n_buckets);
    s = format(s, "to:[%Ld:%Ld]]", to.packets, to.bytes);

    for (i = 0; i < rep->rep_n_buckets; i++)
    {
        s = format(s, "\n%U", format_white_space, indent+2);
        s = format(s, "[%d]", i);
        s = format(s, " %U", format_dpo_id, &buckets[i], indent+6);
    }
    return (s);
}

u8*
format_replicate (u8 * s, va_list * args)
{
    index_t repi = va_arg(*args, index_t);
    replicate_format_flags_t flags = va_arg(*args, replicate_format_flags_t);

    return (replicate_format(repi, flags, 0, s));
}
static u8*
format_replicate_dpo (u8 * s, va_list * args)
{
    index_t repi = va_arg(*args, index_t);
    u32 indent = va_arg(*args, u32);

    return (replicate_format(repi, REPLICATE_FORMAT_DETAIL, indent, s));
}


static replicate_t *
replicate_create_i (u32 num_buckets,
                    dpo_proto_t rep_proto)
{
    replicate_t *rep;

    rep = replicate_alloc_i();
    rep->rep_n_buckets = num_buckets;
    rep->rep_proto = rep_proto;

    if (!REP_HAS_INLINE_BUCKETS(rep))
    {
        vec_validate_aligned(rep->rep_buckets,
                             rep->rep_n_buckets - 1,
                             CLIB_CACHE_LINE_BYTES);
    }

    REP_DBG(rep, "create");

    return (rep);
}

index_t
replicate_create (u32 n_buckets,
                  dpo_proto_t rep_proto)
{
    return (replicate_get_index(replicate_create_i(n_buckets, rep_proto)));
}

static inline void
replicate_set_bucket_i (replicate_t *rep,
                        u32 bucket,
                        dpo_id_t *buckets,
                        const dpo_id_t *next)
{
    dpo_stack(DPO_REPLICATE, rep->rep_proto, &buckets[bucket], next);
}

void
replicate_set_bucket (index_t repi,
                      u32 bucket,
                      const dpo_id_t *next)
{
    replicate_t *rep;
    dpo_id_t *buckets;

    rep = replicate_get(repi);
    buckets = replicate_get_buckets(rep);

    ASSERT(bucket < rep->rep_n_buckets);

    replicate_set_bucket_i(rep, bucket, buckets, next);
}

int
replicate_is_drop (const dpo_id_t *dpo)
{
    replicate_t *rep;

    if (DPO_REPLICATE != dpo->dpoi_type)
        return (0);

    rep = replicate_get(dpo->dpoi_index);

    if (1 == rep->rep_n_buckets)
    {
        return (dpo_is_drop(replicate_get_bucket_i(rep, 0)));
    }
    return (0);
}

const dpo_id_t *
replicate_get_bucket (index_t repi,
                      u32 bucket)
{
    replicate_t *rep;

    rep = replicate_get(repi);

    return (replicate_get_bucket_i(rep, bucket));
}


static load_balance_path_t *
replicate_multipath_next_hop_fixup (load_balance_path_t *nhs,
                                    dpo_proto_t drop_proto)
{
    if (0 == vec_len(nhs))
    {
        load_balance_path_t *nh;

        /*
         * we need something for the replicate. so use the drop
         */
        vec_add2(nhs, nh, 1);

        nh->path_weight = 1;
        dpo_copy(&nh->path_dpo, drop_dpo_get(drop_proto));
    }

    return (nhs);
}

/*
 * Fill in adjacencies in block based on corresponding
 * next hop adjacencies.
 */
static void
replicate_fill_buckets (replicate_t *rep,
                        load_balance_path_t *nhs,
                        dpo_id_t *buckets,
                        u32 n_buckets)
{
    load_balance_path_t * nh;
    u16 ii, bucket;

    bucket = 0;

    /*
     * the next-hops have normalised weights. that means their sum is the number
     * of buckets we need to fill.
     */
    vec_foreach (nh, nhs)
    {
        for (ii = 0; ii < nh->path_weight; ii++)
        {
            ASSERT(bucket < n_buckets);
            replicate_set_bucket_i(rep, bucket++, buckets, &nh->path_dpo);
        }
    }
}

static inline void
replicate_set_n_buckets (replicate_t *rep,
                         u32 n_buckets)
{
    rep->rep_n_buckets = n_buckets;
}

void
replicate_multipath_update (const dpo_id_t *dpo,
                            load_balance_path_t * next_hops)
{
    load_balance_path_t * nh, * nhs;
    dpo_id_t *tmp_dpo;
    u32 ii, n_buckets;
    replicate_t *rep;

    ASSERT(DPO_REPLICATE == dpo->dpoi_type);
    rep = replicate_get(dpo->dpoi_index);
    nhs = replicate_multipath_next_hop_fixup(next_hops,
                                             rep->rep_proto);
    n_buckets = vec_len(nhs);

    if (0 == rep->rep_n_buckets)
    {
        /*
         * first time initialisation. no packets inflight, so we can write
         * at leisure.
         */
        replicate_set_n_buckets(rep, n_buckets);

        if (!REP_HAS_INLINE_BUCKETS(rep))
            vec_validate_aligned(rep->rep_buckets,
                                 rep->rep_n_buckets - 1,
                                 CLIB_CACHE_LINE_BYTES);

        replicate_fill_buckets(rep, nhs,
                               replicate_get_buckets(rep),
                               n_buckets);
    }
    else
    {
        /*
         * This is a modification of an existing replicate.
         * We need to ensure that packets in flight see a consistent state, that
         * is the number of reported buckets the REP has
         * is not more than it actually has. So if the
         * number of buckets is increasing, we must update the bucket array first,
         * then the reported number. vice-versa if the number of buckets goes down.
         */
        if (n_buckets == rep->rep_n_buckets)
        {
            /*
             * no change in the number of buckets. we can simply fill what
             * is new over what is old.
             */
            replicate_fill_buckets(rep, nhs,
                                   replicate_get_buckets(rep),
                                   n_buckets);
        }
        else if (n_buckets > rep->rep_n_buckets)
        {
            /*
             * we have more buckets. the old replicate map (if there is one)
             * will remain valid, i.e. mapping to indices within range, so we
             * update it last.
             */
            if (n_buckets > REP_NUM_INLINE_BUCKETS &&
                rep->rep_n_buckets <= REP_NUM_INLINE_BUCKETS)
            {
                /*
                 * the new increased number of buckets is crossing the threshold
                 * from the inline storage to out-line. Alloc the outline buckets
                 * first, then fixup the number. then reset the inlines.
                 */
                ASSERT(NULL == rep->rep_buckets);
                vec_validate_aligned(rep->rep_buckets,
                                     n_buckets - 1,
                                     CLIB_CACHE_LINE_BYTES);

                replicate_fill_buckets(rep, nhs,
                                       rep->rep_buckets,
                                       n_buckets);
                CLIB_MEMORY_BARRIER();
                replicate_set_n_buckets(rep, n_buckets);

                CLIB_MEMORY_BARRIER();

                for (ii = 0; ii < REP_NUM_INLINE_BUCKETS; ii++)
                {
                    dpo_reset(&rep->rep_buckets_inline[ii]);
                }
            }
            else
            {
                if (n_buckets <= REP_NUM_INLINE_BUCKETS)
                {
                    /*
                     * we are not crossing the threshold and it's still inline buckets.
                     * we can write the new on the old..
                     */
                    replicate_fill_buckets(rep, nhs,
                                           replicate_get_buckets(rep),
                                           n_buckets);
                    CLIB_MEMORY_BARRIER();
                    replicate_set_n_buckets(rep, n_buckets);
                }
                else
                {
                    /*
                     * we are not crossing the threshold. We need a new bucket array to
                     * hold the increased number of choices.
                     */
                    dpo_id_t *new_buckets, *old_buckets, *tmp_dpo;

                    new_buckets = NULL;
                    old_buckets = replicate_get_buckets(rep);

                    vec_validate_aligned(new_buckets,
                                         n_buckets - 1,
                                         CLIB_CACHE_LINE_BYTES);

                    replicate_fill_buckets(rep, nhs, new_buckets, n_buckets);
                    CLIB_MEMORY_BARRIER();
                    rep->rep_buckets = new_buckets;
                    CLIB_MEMORY_BARRIER();
                    replicate_set_n_buckets(rep, n_buckets);

                    vec_foreach(tmp_dpo, old_buckets)
                    {
                        dpo_reset(tmp_dpo);
                    }
                    vec_free(old_buckets);
                }
            }
        }
        else
        {
            /*
             * bucket size shrinkage.
             */
            if (n_buckets <= REP_NUM_INLINE_BUCKETS &&
                rep->rep_n_buckets > REP_NUM_INLINE_BUCKETS)
            {
                /*
                 * the new decreased number of buckets is crossing the threshold
                 * from out-line storage to inline:
                 *   1 - Fill the inline buckets,
                 *   2 - fixup the number (and this point the inline buckets are
                 *       used).
                 *   3 - free the outline buckets
                 */
                replicate_fill_buckets(rep, nhs,
                                       rep->rep_buckets_inline,
                                       n_buckets);
                CLIB_MEMORY_BARRIER();
                replicate_set_n_buckets(rep, n_buckets);
                CLIB_MEMORY_BARRIER();

                vec_foreach(tmp_dpo, rep->rep_buckets)
                {
                    dpo_reset(tmp_dpo);
                }
                vec_free(rep->rep_buckets);
            }
            else
            {
                /*
                 * not crossing the threshold.
                 *  1 - update the number to the smaller size
                 *  2 - write the new buckets
                 *  3 - reset those no longer used.
                 */
                dpo_id_t *buckets;
                u32 old_n_buckets;

                old_n_buckets = rep->rep_n_buckets;
                buckets = replicate_get_buckets(rep);

                replicate_set_n_buckets(rep, n_buckets);
                CLIB_MEMORY_BARRIER();

                replicate_fill_buckets(rep, nhs,
                                       buckets,
                                       n_buckets);

                for (ii = n_buckets; ii < old_n_buckets; ii++)
                {
                    dpo_reset(&buckets[ii]);
                }
            }
        }
    }

    vec_foreach (nh, nhs)
    {
        dpo_reset(&nh->path_dpo);
    }
    vec_free(nhs);
}

static void
replicate_lock (dpo_id_t *dpo)
{
    replicate_t *rep;

    rep = replicate_get(dpo->dpoi_index);

    rep->rep_locks++;
}

static void
replicate_destroy (replicate_t *rep)
{
    dpo_id_t *buckets;
    int i;

    buckets = replicate_get_buckets(rep);

    for (i = 0; i < rep->rep_n_buckets; i++)
    {
        dpo_reset(&buckets[i]);
    }

    REP_DBG(rep, "destroy");
    if (!REP_HAS_INLINE_BUCKETS(rep))
    {
        vec_free(rep->rep_buckets);
    }

    pool_put(replicate_pool, rep);
}

static void
replicate_unlock (dpo_id_t *dpo)
{
    replicate_t *rep;

    rep = replicate_get(dpo->dpoi_index);

    rep->rep_locks--;

    if (0 == rep->rep_locks)
    {
        replicate_destroy(rep);
    }
}

static void
replicate_mem_show (void)
{
    fib_show_memory_usage("replicate",
			  pool_elts(replicate_pool),
			  pool_len(replicate_pool),
			  sizeof(replicate_t));
}

const static dpo_vft_t rep_vft = {
    .dv_lock = replicate_lock,
    .dv_unlock = replicate_unlock,
    .dv_format = format_replicate_dpo,
    .dv_mem_show = replicate_mem_show,
};

/**
 * @brief The per-protocol VLIB graph nodes that are assigned to a replicate
 *        object.
 *
 * this means that these graph nodes are ones from which a replicate is the
 * parent object in the DPO-graph.
 */
const static char* const replicate_ip4_nodes[] =
{
    "ip4-replicate",
    NULL,
};
const static char* const replicate_ip6_nodes[] =
{
    "ip6-replicate",
    NULL,
};
const static char* const replicate_mpls_nodes[] =
{
    "mpls-replicate",
    NULL,
};

const static char* const * const replicate_nodes[DPO_PROTO_NUM] =
{
    [DPO_PROTO_IP4]  = replicate_ip4_nodes,
    [DPO_PROTO_IP6]  = replicate_ip6_nodes,
    [DPO_PROTO_MPLS] = replicate_mpls_nodes,
};

void
replicate_module_init (void)
{
    dpo_register(DPO_REPLICATE, &rep_vft, replicate_nodes);
}

static clib_error_t *
replicate_show (vlib_main_t * vm,
                unformat_input_t * input,
                vlib_cli_command_t * cmd)
{
    index_t repi = INDEX_INVALID;

    while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
        if (unformat (input, "%d", &repi))
            ;
        else
            break;
    }

    if (INDEX_INVALID != repi)
    {
        vlib_cli_output (vm, "%U", format_replicate, repi,
                         REPLICATE_FORMAT_DETAIL);
    }
    else
    {
        replicate_t *rep;

        pool_foreach(rep, replicate_pool,
        ({
            vlib_cli_output (vm, "%U", format_replicate,
                             replicate_get_index(rep),
                             REPLICATE_FORMAT_NONE);
        }));
    }

    return 0;
}

VLIB_CLI_COMMAND (replicate_show_command, static) = {
    .path = "show replicate",
    .short_help = "show replicate [<index>]",
    .function = replicate_show,
};

typedef struct replicate_trace_t_
{
    index_t rep_index;
    dpo_id_t dpo;
} replicate_trace_t;

static uword
replicate_inline (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame)
{
    vlib_combined_counter_main_t * cm = &replicate_main.repm_counters;
    u32 n_left_from, * from, * to_next, next_index;
    u32 cpu_index = os_get_cpu_number();

    from = vlib_frame_vector_args (frame);
    n_left_from = frame->n_vectors;
    next_index = node->cached_next_index;
  
    while (n_left_from > 0)
    {
        u32 n_left_to_next;

        vlib_get_next_frame (vm, node, next_index,
                             to_next, n_left_to_next);

        while (n_left_from > 0 && n_left_to_next > 0)
	{
            u32 next0, ci0, bi0, bucket, repi0;
            const replicate_t *rep0;
            vlib_buffer_t * b0, *c0;
            const dpo_id_t *dpo0;

            bi0 = from[0];
            to_next[0] = bi0;
            from += 1;
            to_next += 1;
            n_left_from -= 1;
            n_left_to_next -= 1;

            b0 = vlib_get_buffer (vm, bi0);
            repi0 = vnet_buffer (b0)->ip.adj_index[VLIB_TX];
            rep0 = replicate_get(repi0);

            vlib_increment_combined_counter(
                cm, cpu_index, repi0, 1,
                vlib_buffer_length_in_chain(vm, b0));

            /* ship the original to the first bucket */
            dpo0 = replicate_get_bucket_i(rep0, 0);
            next0 = dpo0->dpoi_next_node;
            vnet_buffer (b0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

            if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
                replicate_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
                t->rep_index = repi0;
                t->dpo = *dpo0;
            }
            vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                             to_next, n_left_to_next,
                                             bi0, next0);

            /* ship copies to the rest of the buckets */
            for (bucket = 1; bucket < rep0->rep_n_buckets; bucket++)
            {
                /*
                 * After the enqueue of the first buffer, and of all subsequent
                 * buffers in this loop, it is possible that we over-flow the
                 * frame of the to-next node. When this happens we need to 'put'
                 * that full frame to the node and get a fresh empty one.
                 * Note that these are macros with side effects that change
                 * to_next & n_left_to_next
                 */
                if (PREDICT_FALSE(0 == n_left_to_next))
                {
                    vlib_put_next_frame (vm, node, next_index, n_left_to_next);
                    vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
                }

                /* Make a copy. This can fail, so deal with it. */
                c0 = vlib_buffer_copy(vm, b0);
                if (PREDICT_FALSE (c0 == 0))
                  {
                    vlib_node_increment_counter 
                      (vm, node->node_index, 
                       REPLICATE_DPO_ERROR_BUFFER_ALLOCATION_FAILURE,
                       1);
                    continue;
                  }
                
                ci0 = vlib_get_buffer_index(vm, c0);

                to_next[0] = ci0;
                to_next += 1;
                n_left_to_next -= 1;

                dpo0 = replicate_get_bucket_i(rep0, bucket);
                next0 = dpo0->dpoi_next_node;
                vnet_buffer (c0)->ip.adj_index[VLIB_TX] = dpo0->dpoi_index;

                if (PREDICT_FALSE(c0->flags & VLIB_BUFFER_IS_TRACED))
                {
                    replicate_trace_t *t = vlib_add_trace (vm, node, c0, sizeof (*t));
                    t->rep_index = repi0;
                    t->dpo = *dpo0;
                }

                vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                                 to_next, n_left_to_next,
                                                 ci0, next0);
            }
        }

        vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

    return frame->n_vectors;
}

static u8 *
format_replicate_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  replicate_trace_t *t = va_arg (*args, replicate_trace_t *);

  s = format (s, "replicate: %d via %U",
              t->rep_index,
              format_dpo_id, &t->dpo);
  return s;
}

static uword
ip4_replicate (vlib_main_t * vm,
               vlib_node_runtime_t * node,
               vlib_frame_t * frame)
{
    return (replicate_inline (vm, node, frame));
}

/**
 * @brief
 */
VLIB_REGISTER_NODE (ip4_replicate_node) = {
  .function = ip4_replicate,
  .name = "ip4-replicate",
  .vector_size = sizeof (u32),

  .n_errors = ARRAY_LEN(replicate_dpo_error_strings),
  .error_strings = replicate_dpo_error_strings,

  .format_trace = format_replicate_trace,
  .n_next_nodes = 1,
  .next_nodes = {
      [0] = "error-drop",
  },
};

static uword
ip6_replicate (vlib_main_t * vm,
               vlib_node_runtime_t * node,
               vlib_frame_t * frame)
{
    return (replicate_inline (vm, node, frame));
}

/**
 * @brief
 */
VLIB_REGISTER_NODE (ip6_replicate_node) = {
  .function = ip6_replicate,
  .name = "ip6-replicate",
  .vector_size = sizeof (u32),

  .n_errors = ARRAY_LEN(replicate_dpo_error_strings),
  .error_strings = replicate_dpo_error_strings,

  .format_trace = format_replicate_trace,
  .n_next_nodes = 1,
  .next_nodes = {
      [0] = "error-drop",
  },
};