/*
 * Copyright (c) 2021 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/fib/fib.h>
#include <vnet/ip/ip.h>
#include <vnet/ip/lookup.h>

#include "mapper.h"
#include "netns.h"
#include <hicn/util/sstrncpy.h>

typedef struct
{
  int linux_ifindex;
  u32 sw_if_index;
} mapper_map_t;

typedef struct
{
  char nsname[RTNL_NETNS_NAMELEN + 1];
  mapper_map_t *mappings;
  u32 netns_handle; // Used to receive notifications
  u32 v4fib_index;  // One fib index for the namespace
  u32 v6fib_index;
} mapper_ns_t;

typedef struct
{
  mapper_ns_t *namespaces;
} mapper_main_t;

static mapper_main_t mapper_main;

mapper_map_t *
mapper_get_by_ifindex (mapper_ns_t *ns, int ifindex)
{
  mapper_map_t *map;
  pool_foreach (map, ns->mappings, {
    if (ifindex == map->linux_ifindex)
      return map;
  })
    ;
  return NULL;
}

int
mapper_add_del_route (mapper_ns_t *ns, ns_route_t *route, int del)
{
  mapper_main_t *mm = &mapper_main;
  clib_warning ("NS %d %s %U", ns - mm->namespaces, del ? "del" : "add",
		format_ns_route, route);

  mapper_map_t *map = mapper_get_by_ifindex (ns, route->oif);
  if (!map)
    return 0;

  if (route->rtm.rtm_family == AF_INET6)
    {

      // Filter-out multicast
      if (route->rtm.rtm_dst_len >= 8 && route->dst[0] == 0xff)
	return 0;

      fib_prefix_t prefix;
      ip_address_t nh;

      memset (&prefix, 0, sizeof (prefix));
      prefix.fp_len = route->rtm.rtm_dst_len;
      prefix.fp_proto = FIB_PROTOCOL_IP6;
      clib_memcpy (&prefix.fp_addr.ip6, route->dst,
		   sizeof (prefix.fp_addr.ip6));

      memset (&nh, 0, sizeof (nh));
      clib_memcpy (&nh.ip6, route->gateway, sizeof (nh.ip6));

      fib_table_entry_path_add (
	ns->v6fib_index, &prefix, FIB_SOURCE_API, FIB_ENTRY_FLAG_NONE,
	prefix.fp_proto, &nh, map->sw_if_index, ns->v6fib_index,
	0 /* weight */, (fib_mpls_label_t *) MPLS_LABEL_INVALID,
	FIB_ROUTE_PATH_FLAG_NONE);
    }
  else
    {
      fib_prefix_t prefix;
      ip_address_t nh;

      memset (&prefix, 0, sizeof (prefix));
      prefix.fp_len = route->rtm.rtm_dst_len;
      prefix.fp_proto = FIB_PROTOCOL_IP4;
      clib_memcpy (&prefix.fp_addr.ip4, route->dst,
		   sizeof (prefix.fp_addr.ip4));

      memset (&nh, 0, sizeof (nh));
      clib_memcpy (&nh.ip4, route->gateway, sizeof (nh.ip4));

      fib_table_entry_path_add (
	ns->v4fib_index, &prefix, FIB_SOURCE_API, FIB_ENTRY_FLAG_NONE,
	prefix.fp_proto, &nh, map->sw_if_index, ns->v4fib_index,
	0 /* weight */, (fib_mpls_label_t *) MPLS_LABEL_INVALID,
	FIB_ROUTE_PATH_FLAG_NONE);
    }

  return 0;
}

static void
mapper_netns_notify_cb (void *obj, netns_type_t type, u32 flags, uword opaque)
{
  mapper_main_t *mm = &mapper_main;
  mapper_ns_t *ns = &mm->namespaces[(u32) opaque];
  ASSERT (!pool_is_free_index (mm->namespaces, (u32) opaque));
  if (type != NETNS_TYPE_ROUTE)
    return; // For now...

  ns_route_t *route = obj;
  if (flags & NETNS_F_DEL)
    {
      mapper_add_del_route (ns, route, 1);
    }
  else if (flags & NETNS_F_ADD)
    {
      mapper_add_del_route (ns, route, 0);
    }
}

void
mapper_delmap (mapper_ns_t *ns, mapper_map_t *map)
{
  ns_route_t *route;
  netns_t *netns = netns_getns (ns->netns_handle);
  pool_foreach (route, netns->routes, {
    if (route->oif == map->linux_ifindex)
      mapper_add_del_route (ns, route, 1);
  })
    ;
  pool_put (ns->mappings, map);
}

mapper_map_t *
mapper_getmap (mapper_ns_t *ns, u32 sw_if_index, int linux_ifindex, int create)
{
  mapper_map_t *map;
  pool_foreach (map, ns->mappings, {
    if (linux_ifindex == map->linux_ifindex)
      {
	if (sw_if_index != map->sw_if_index)
	  return NULL; // Cannot have multiple mapping with the same ifindex
	else
	  return map;
      }
  })
    ;

  if (!create)
    return NULL;

  pool_get (ns->mappings, map);
  map->linux_ifindex = linux_ifindex;
  map->sw_if_index = sw_if_index;
  ip6_main.fib_index_by_sw_if_index[sw_if_index] = ns->v6fib_index;
  ip4_main.fib_index_by_sw_if_index[sw_if_index] = ns->v4fib_index;

  // Load available routes
  ns_route_t *route;
  netns_t *netns = netns_getns (ns->netns_handle);
  pool_foreach (route, netns->routes, {
    if (route->oif == map->linux_ifindex)
      mapper_add_del_route (ns, route, 0);
  })
    ;
  return map;
}

u32
mapper_get_ns (char *nsname)
{
  mapper_main_t *mm = &mapper_main;
  mapper_ns_t *ns;
  pool_foreach (ns, mm->namespaces, {
    if (!strcmp (nsname, ns->nsname))
      return ns - mm->namespaces;
  })
    ;
  return ~0;
}

int
mapper_add_del (u32 nsindex, int linux_ifindex, u32 sw_if_index, int del)
{
  mapper_main_t *mm = &mapper_main;
  // ip6_main_t *im6 = &ip6_main;
  mapper_ns_t *ns = &mm->namespaces[nsindex];
  mapper_map_t *map;
  // vnet_sw_interface_t *iface = vnet_get_sw_interface(vnet_get_main(),
  // sw_if_index);

  if (pool_is_free (mm->namespaces, ns))
    return -1;

  /*if (!del) {
    if ((iface->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP) &&
	im6->fib_index_by_sw_if_index[sw_if_index] != ~0) {
      //A custom fib index will be used...
      clib_warning("Cannot add interface with a custom fib index (current is
  %d)", im6->fib_index_by_sw_if_index[sw_if_index]); return -1;
    }
  }*/

  if (!(map = mapper_getmap (ns, sw_if_index, linux_ifindex, !del)))
    return -1;

  if (del)
    mapper_delmap (ns, map);

  return 0;
}

int
mapper_add_ns (char *nsname, u32 v4fib_index, u32 v6fib_index, u32 *nsindex)
{
  mapper_main_t *mm = &mapper_main;
  mapper_ns_t *ns;
  if (mapper_get_ns (nsname) != ~0)
    return -1; // Already exists

  pool_get (mm->namespaces, ns);
  int rc = strcpy_s (ns->nsname, sizeof (ns->nsname), nsname);
  if (rc != EOK)
    return -1;
  ns->v4fib_index = v4fib_index;
  ns->v6fib_index = v6fib_index;
  ns->mappings = 0;

  netns_sub_t sub;
  sub.notify = mapper_netns_notify_cb;
  sub.opaque = (uword) (ns - mm->namespaces);
  if ((ns->netns_handle = netns_open (ns->nsname, &sub)) == ~0)
    {
      pool_put (mm->namespaces, ns);
      return -1;
    }
  *nsindex = ns - mm->namespaces;
  return 0;
}

int
mapper_del_ns (u32 nsindex)
{
  mapper_main_t *mm = &mapper_main;
  mapper_ns_t *ns = &mm->namespaces[nsindex];
  if (pool_is_free (mm->namespaces, ns))
    return -1;

  // Remove all existing mappings
  int i, *indexes = 0;
  pool_foreach_index (i, ns->mappings, { vec_add1 (indexes, i); })
    ;
  vec_foreach_index (i, indexes)
    {
      mapper_delmap (ns, &ns->mappings[indexes[i]]);
    }
  vec_free (indexes);

  netns_close (ns->netns_handle);
  pool_put (mm->namespaces, ns);
  return 0;
}

clib_error_t *
mapper_init (vlib_main_t *vm)
{
  mapper_main_t *mm = &mapper_main;
  mm->namespaces = 0;
  return 0;
}

VLIB_INIT_FUNCTION (mapper_init);