/*
 * Copyright (c) 2021-2022 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.
 */

/**
 * \file interfaces/hicn_light/hicn_light.c
 * \brief hICN light interface
 */
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>  // snprintf
#include <time.h>   // time

#include <hicn/ctrl.h>
#include <hicn/ctrl/socket.h>
#include <hicn/facemgr.h>
#include <hicn/util/ip_address.h>
#include <hicn/util/log.h>
#include <hicn/util/map.h>

#include "../../common.h"
#include "../../interface.h"

#define DEFAULT_ROUTE_COST 0

#define INTERVAL_MS 1000

#define WITH_POLL

typedef enum {
  HL_STATE_UNDEFINED,
  HL_STATE_IDLE,
  HL_STATE_ROUTES_SENT,
  HL_STATE_ROUTES_RECEIVED,
  HL_STATE_FACES_SENT,
  HL_STATE_FACES_RECEIVED,
  HL_STATE_N
} hl_state_t;

typedef struct {
  hc_sock_t *s; /* NULL means no active socket */

  /* Socket for polling, dependent on s */
  hc_sock_t *sp; /* NULL means no active socket */

  hl_state_t state;

  /* Timer used for forwarder reconnection */
  int reconnect_timer_fd; /* 0 means no active timer */

  /* Timer used to periodically poll the forwarder face and routing tables */
  int poll_timer_fd;
  hc_data_t *polled_routes;
} hl_data_t;

#ifdef WITH_POLL
int hl_process_state(interface_t *interface, int fd, void *unused);
#else
int hl_process_state(interface_t *interface);
#endif

void start_poll_timer(interface_t *interface) {
  hl_data_t *data = (hl_data_t *)interface->data;

  data->poll_timer_fd = interface_register_timer(interface, INTERVAL_MS,
                                                 hl_process_state, interface);
  if (data->poll_timer_fd < 0) {
    ERROR("[start_poll_timer) Could not start polling timer");
  }
}

void stop_poll_timer(interface_t *interface) {
  hl_data_t *data = (hl_data_t *)interface->data;

  if (data->poll_timer_fd > 0)
    if (interface_unregister_timer(interface, data->poll_timer_fd) < 0) {
      ERROR("[stop_poll_timer] Could not stop polling timer");
    }
}

#ifdef WITH_POLL
int hl_process_state(interface_t *interface, int fd, void *unused)
#else
int hl_process_state(interface_t *interface)
#endif
{
  hl_data_t *data = (hl_data_t *)interface->data;

  /*
   * Every tick we need to probe the forwarder for the list of faces and
   * associated routes.
   *
   * This is used to guess manually added faces and routes
   *
   * TODO ensure we are idle at tick time
   */

  switch (data->state) {
    case HL_STATE_IDLE:
      assert(!data->polled_routes);
      stop_poll_timer(interface);

      DEBUG("[hl_process_state] Querying route list");
      if (hc_route_list_async(data->sp) < 0) {
        DEBUG("[hl_process_state] Error querying route list");
        return -1;
      }
      data->state = HL_STATE_ROUTES_SENT;
      break;

    case HL_STATE_ROUTES_RECEIVED:
      DEBUG("[hl_process_state] Got route list");
      DEBUG("[hl_process_state] Querying face list");
      if (hc_face_list_async(data->sp) < 0) {
        DEBUG("[hl_process_state] Error querying face list");
        return -1;
      }
      data->state = HL_STATE_FACES_SENT;
      break;

    case HL_STATE_FACES_RECEIVED:
      DEBUG("[hl_process_state] Got face list");
      data->state = HL_STATE_IDLE;
      start_poll_timer(interface);
      break;

    case HL_STATE_ROUTES_SENT:
    case HL_STATE_FACES_SENT:
      WARN("[hl_process_state] Out of sync... resetting state");
      if (data->polled_routes) {
        hc_data_free(data->polled_routes);
        data->polled_routes = NULL;
      }
      data->state = HL_STATE_IDLE;
      start_poll_timer(interface);
      break;

    case HL_STATE_UNDEFINED:
    case HL_STATE_N:
      ERROR("[hl_process_state] Unexpected state");
      return -1;
  }

  return 0;
}

/*
 * Called whenever a connection to both sockets succeeds.
 * Polling will be useful to detect when connection to the forwarder is lost,
 * and will allow to try reconnect both sockets (the control socket being UDP /
 * in blocking mode will not detect such loss of connection). Operations on the
 * control socket that will fail will be reattempted by higher layers.
 */
int hl_after_connect(interface_t *interface) {
  hl_data_t *data = interface->data;

  /* File descriptor for polling socket operations */
  if (interface_register_fd(interface, hc_sock_get_fd(data->sp), NULL) < 0) {
    ERROR("[hc_connect] Error registering fd");
    goto ERR_FD;
  }

  /* We always restart from the idle phase */
  data->state = HL_STATE_IDLE;

/* poll will replace the original get, ideally we would get notifications */
#ifdef WITH_POLL
  start_poll_timer(interface);
#else
  hl_process_state(interface);
#endif

  return 0;

  // interface_unregister_fd(interface, hc_sock_get_fd(data->sp));
ERR_FD:
  return -1;
}

int _hl_connect(interface_t *interface);

int hl_connect_timeout(interface_t *interface, int fd, void *unused) {
  hl_data_t *data = interface->data;
  assert(fd == data->reconnect_timer_fd);
  _unused(data);

  int rc = _hl_connect(interface);
  if (rc < 0) {
    DEBUG(
        "[hl_initialize] Error during connection reattempt; next attempt in "
        "%ds",
        INTERVAL_MS / 1000);
    return -1;
  }

  if (interface_unregister_timer(interface, fd) < 0) {
    ERROR(
        "[hl_connect_timeout] Could not cancel timer after successful connect");
  }

  /* Connect success */
  return hl_after_connect(interface);
}

/*
 * Connection without reattempt. Both control and polling sockets should be
 * connected to succeed.
 */
int _hl_connect(interface_t *interface) {
  hl_data_t *data = interface->data;
  assert(!data->s);
  assert(!data->sp);

  data->s = hc_sock_create(FORWARDER_TYPE_HICNLIGHT, NULL);
  if (data->s <= 0) {
    ERROR("[hc_connect] Could not create control socket");
    goto ERR_SOCK;
  }

  if (hc_sock_connect(data->s) < 0) {
    DEBUG("[hc_connect] Could not connect control socket");
    goto ERR_CONNECT;
  }

  data->sp = hc_sock_create(FORWARDER_TYPE_HICNLIGHT, NULL);
  if (data->sp <= 0) {
    ERROR("[hc_connect] Could not create polling socket");
    goto ERR_SOCK_POLL;
  }

  if (hc_sock_connect(data->sp) < 0) {
    DEBUG("[hc_connect] Could not connect polling socket");
    goto ERR_CONNECT_POLL;
  }

  return 0;

ERR_CONNECT_POLL:
  hc_sock_free(data->sp);
  data->sp = NULL;
ERR_SOCK_POLL:
ERR_CONNECT:
  hc_sock_free(data->s);
  data->s = NULL;
ERR_SOCK:
  return -1;
}

int hl_disconnect(interface_t *interface) {
  hl_data_t *data = (hl_data_t *)interface->data;
  if (data->reconnect_timer_fd > 0)
    interface_unregister_timer(interface, data->reconnect_timer_fd);

  stop_poll_timer(interface);

  if (data->polled_routes) hc_data_free(data->polled_routes);

  if (data->s) {
    hc_sock_free(data->s);
    data->s = NULL;
  }

  if (data->sp) {
    interface_unregister_fd(interface, hc_sock_get_fd(data->sp));
    hc_sock_free(data->sp);
    data->sp = NULL;
  }

  return 0;
}

/* Connection with reattempts */
int hl_connect(interface_t *interface) {
  hl_data_t *data = interface->data;

  if (_hl_connect(interface) >= 0) return hl_after_connect(interface);

  /* Timer for managing the connection to the forwarder */
  DEBUG("Connection to forwarder failed... next retry in %ds",
        INTERVAL_MS / 1000);
  data->reconnect_timer_fd = interface_register_timer(interface, INTERVAL_MS,
                                                      hl_connect_timeout, NULL);
  if (data->reconnect_timer_fd < 0) {
    ERROR("[hc_connect] Could not initialize reattempt timer");
    return -1;
  }

  return 0;
}

int hl_initialize(interface_t *interface, void *cfg) {
  hl_data_t *data = malloc(sizeof(hl_data_t));
  if (!data) {
    ERROR("[hicn_light] Out of memory!");
    goto ERR_MALLOC;
  }

  data->s = NULL;
  data->sp = NULL;
  data->reconnect_timer_fd = 0;
  data->poll_timer_fd = 0;
  data->polled_routes = NULL;
  data->state = HL_STATE_UNDEFINED;

  interface->data = data;

  /* Connect both control and polling sockets */
  if (hl_connect(interface) < 0) {
    ERROR("[hl_initialize] Error during connection to forwarder");
    goto ERR_CONNECT;
  }

  return 0;

ERR_CONNECT:
  free(data);
ERR_MALLOC:
  return -1;
}

int hl_finalize(interface_t *interface) {
  hl_data_t *data = (hl_data_t *)interface->data;

  hl_disconnect(interface);

  if (data->polled_routes) hc_data_free(data->polled_routes);

  free(data);

  return 0;
}

int hl_on_event(interface_t *interface, facelet_t *facelet) {
  hc_route_t route;
  int rc;
  int ret = 0;
  hl_data_t *data = (hl_data_t *)interface->data;
  face_t *face = NULL;

  /* NOTE
   *  - One example where this fails (and it is normal) is when we delete a
   *  face that was not completely created, because for instance bonjour did
   *  not give any data
   */
  if (facelet_get_face(facelet, &face) < 0) {
    ERROR("Could not retrieve face from facelet");
    ret = -FACELET_ERROR_REASON_INTERNAL_ERROR;
    goto ERR_FACE;
  }

  if (!data->s) {
    /* We are not connected to the forwarder */
    ret = -FACELET_ERROR_REASON_FORWARDER_OFFLINE;
    goto ERR;
  }

  switch (facelet_get_event(facelet)) {
    case FACELET_EVENT_CREATE: {
      /* Create face */
      char buf[MAXSZ_FACELET];
      facelet_snprintf(buf, MAXSZ_FACELET, facelet);
      DEBUG("Create facelet %s", buf);

      rc = hc_face_create(data->s, face);
      if (rc < 0) {
        ERROR("Failed to create face\n");
        ret = -FACELET_ERROR_REASON_UNSPECIFIED_ERROR;
        goto ERR;
      }
      INFO("Created face id=%d - %s", face->id, buf);
    }

      hicn_route_t **route_array;
      int n = facelet_get_route_array(facelet, &route_array);
      if (n < 0) {
        ERROR("Failed to create default hICN/IPv4 route");
        ret = -FACELET_ERROR_REASON_UNSPECIFIED_ERROR;
        goto ERR;
      }
      if (n == 0) {
        /* Adding default routes */
        route = (hc_route_t){
            .face_id = face->id,
            .family = AF_INET,
            .remote_addr = IPV4_ANY,
            .len = 0,
            .cost = DEFAULT_ROUTE_COST,

        };
        if (hc_route_create(data->s, &route) < 0) {
          ERROR("Failed to create default hICN/IPv4 route");
          ret = -1;
        }

        route = (hc_route_t){
            .face_id = face->id,
            .family = AF_INET6,
            .remote_addr = IPV6_ANY,
            .len = 0,
            .cost = DEFAULT_ROUTE_COST,
        };
        if (hc_route_create(data->s, &route) < 0) {
          ERROR("Failed to create default hICN/IPv6 route");
          ret = -1;
        }

        INFO("Successfully created default route(s).");
      } else {
        for (unsigned i = 0; i < n; i++) {
          hicn_route_t *hicn_route = route_array[i];
          hicn_ip_prefix_t prefix;
          int cost;
          if (hicn_route_get_prefix(hicn_route, &prefix) < 0) {
            ERROR("Failed to get route prefix");
            ret = -1;
            continue;
          }
          if (hicn_route_get_cost(hicn_route, &cost) < 0) {
            ERROR("Failed to get route cost");
            ret = -1;
            continue;
          }
          route = (hc_route_t){
              .face_id = face->id,
              .face_name = "", /* take face_id into account */
              .family = prefix.family,
              .remote_addr = prefix.address,
              .len = prefix.len,
              .cost = cost,
          };
          if (hc_route_create(data->s, &route) < 0) {
            ERROR("Failed to create static route route");
            ret = -1;
            continue;
          }
        }
      }
      free(route_array);

      break;

    case FACELET_EVENT_DELETE:
      /* Removing a face should also remove associated routes */
      rc = hc_face_delete(data->s, face);  // delete_listener= */ 1);
      if (rc < 0) {
        ERROR("Failed to delete face\n");
        ret = -FACELET_ERROR_REASON_UNSPECIFIED_ERROR;
        goto ERR;
      }

      char buf[MAXSZ_FACELET];
      facelet_snprintf(buf, MAXSZ_FACELET, facelet);
      INFO("Deleted face id=%d", face->id);

      break;

    case FACELET_EVENT_UPDATE:
      /* Currently, only admin_state & priority are supported */
      if (facelet_get_admin_state_status(facelet) ==
          FACELET_ATTR_STATUS_DIRTY) {
        hc_data_t *face_found;

        rc = hc_face_get(data->s, face, &face_found);
        if (rc < 0) {
          ERROR("Failed to find face\n");
          ret = -FACELET_ERROR_REASON_INTERNAL_ERROR;
          goto ERR;
        }
        if (!face_found) {
          ERROR("Face to update has not been found");
          ret = -FACELET_ERROR_REASON_UNSPECIFIED_ERROR;
          goto ERR;
        }
        char conn_id_or_name[SYMBOLIC_NAME_LEN];

        const hc_object_t *object = hc_data_get_object(face_found, 0);
        snprintf(conn_id_or_name, SYMBOLIC_NAME_LEN, "%d", object->face.id);
        hc_data_free(face_found);

        face_state_t admin_state;
        if (facelet_get_admin_state(facelet, &admin_state) < 0) {
          ERROR("Failed to retrieve facelet admin state");
          ret = -FACELET_ERROR_REASON_INTERNAL_ERROR;
          goto ERR;
        }

        if (hc_connection_set_admin_state(data->s, conn_id_or_name,
                                          admin_state) < 0) {
          ERROR("Failed to update admin state");
          ret = -FACELET_ERROR_REASON_UNSPECIFIED_ERROR;
          goto ERR;
        }
        facelet_set_admin_state_status(facelet, FACELET_ATTR_STATUS_CLEAN);
        INFO("Updated face id=%d - admin_state=%s", face->id,
             face_state_str(admin_state));
      }
      if (facelet_get_netdevice_type_status(facelet) ==
          FACELET_ATTR_STATUS_DIRTY) {
        hc_data_t *face_found;

        rc = hc_face_get(data->s, face, &face_found);
        if (rc < 0) {
          ERROR("Failed to find face\n");
          goto ERR;
        }
        if (!face_found) {
          ERROR("Face to update has not been found");
          goto ERR;
        }
        char conn_id_or_name[SYMBOLIC_NAME_LEN];
        const hc_object_t *object = hc_data_get_object(face_found, 0);
        snprintf(conn_id_or_name, SYMBOLIC_NAME_LEN, "%d", object->face.id);
        hc_data_free(face_found);

        netdevice_type_t netdevice_type;
        if (facelet_get_netdevice_type(facelet, &netdevice_type) < 0) {
          ERROR("Failed to retrieve facelet netdevice_type");
          goto ERR;
        }

        /* Encode netdevice type into tags */
        policy_tags_t tags = POLICY_TAGS_EMPTY;
        if (facelet_has_netdevice_type(facelet)) {
          netdevice_type_t netdevice_type;
          if (facelet_get_netdevice_type(facelet, &netdevice_type) < 0) {
            ERROR("error getting netdevice_type");
            goto ERR;
          }

          switch (netdevice_type) {
            case NETDEVICE_TYPE_UNDEFINED:
            case NETDEVICE_TYPE_LOOPBACK:
              break;
            case NETDEVICE_TYPE_WIRED:
              policy_tags_add(&tags, POLICY_TAG_WIRED);
              break;
            case NETDEVICE_TYPE_WIFI:
              policy_tags_add(&tags, POLICY_TAG_WIFI);
              break;
            case NETDEVICE_TYPE_CELLULAR:
              policy_tags_add(&tags, POLICY_TAG_CELLULAR);
              break;
            default:
              goto ERR;
          }
        }
        // face->tags = tags;

        if (hc_connection_set_tags(data->s, conn_id_or_name, tags) < 0) {
          ERROR("Failed to update tags");
          goto ERR;
        }
        facelet_set_netdevice_type_status(facelet, FACELET_ATTR_STATUS_CLEAN);
        INFO("Updated face id=%d - netdevice_type=%s", face->id,
             netdevice_type_str(netdevice_type));
      }
      if (facelet_get_priority_status(facelet) == FACELET_ATTR_STATUS_DIRTY) {
        INFO("Updating priority...");
        hc_data_t *face_found;

        rc = hc_face_get(data->s, face, &face_found);
        if (rc < 0) {
          ERROR("Failed to find face\n");
          goto ERR;
        }
        if (!face_found) {
          ERROR("Face to update has not been found");
          goto ERR;
        }
        char conn_id_or_name[SYMBOLIC_NAME_LEN];
        const hc_object_t *object = hc_data_get_object(face_found, 0);
        snprintf(conn_id_or_name, SYMBOLIC_NAME_LEN, "%d", object->face.id);
        hc_data_free(face_found);

        uint32_t priority;
        if (facelet_get_priority(facelet, &priority) < 0) {
          ERROR("Failed to retrieve facelet priority");
          goto ERR;
        }

        INFO("Changing connection %s priority to %d", conn_id_or_name,
             priority);
        if (hc_connection_set_priority(data->s, conn_id_or_name, priority) <
            0) {
          ERROR("Failed to update priority");
          goto ERR;
        }
        facelet_set_priority_status(facelet, FACELET_ATTR_STATUS_CLEAN);

        INFO("Updated face id=%d - priority=%d", face->id, priority);
      }
      break;

    default:
      ERROR("Unknown event %s\n",
            facelet_event_str[facelet_get_event(facelet)]);
      /* Unsupported events */
      ret = -FACELET_ERROR_REASON_INTERNAL_ERROR;
      goto ERR;
  }

ERR:
  face_free(face);
ERR_FACE:
  return ret;
}

/*
 * This should only receive data from the polling socket which is asynchronous,
 * while all face creation, etc. operations are done synchronously in this
 * version.
 */
int hl_callback(interface_t *interface, int fd, void *unused) {
  hl_data_t *data = (hl_data_t *)interface->data;
  hc_data_t *results;
  int ret = 0;

  /* Workaround: sometimes this is called with data = NULL */
  if (!data) {
    INFO("[hl_callback] no data");
    return 0;
  }

  /* In case of error, reconnect to forwarder */
  if (hc_sock_receive_all(data->sp, &results) < 0) {
    INFO("Closing socket... reconnecting...");
    if (interface_unregister_fd(interface, hc_sock_get_fd(data->sp)) < 0) {
      ERROR("[hl_callback] Error unregistering fd");
    }

    /* Stopping poll timer */
    stop_poll_timer(interface);
    if (data->polled_routes) hc_data_free(data->polled_routes);

    hc_sock_free(data->s);
    data->s = NULL;
    hc_sock_free(data->sp);
    data->sp = NULL;

    hl_connect(interface);
    return ret;
  }

  /* Shall we wait for more data ? */
  if (!hc_data_is_complete(results)) {
    INFO("[hl_callback] results incomplete");
    return ret;
  }

  /* Process returned data */
  // DEBUG("Processing data");
  switch (data->state) {
    case HL_STATE_ROUTES_SENT:
      // DEBUG("[hl_callback] Processing routes");
      data->polled_routes = results;

#if 0
            foreach_route(r, results) {
                char buf[MAXSZ_FACE];
                int rc = hc_route_snprintf(route_s, MAXSZ_HC_ROUTE, r);
                if (rc >= MAXSZ_HC_ROUTE)
                    ERROR("[hl_callback] Unexpected truncation of route string");
                if (rc < 0)
                    ERROR("[hl_callback] Error during route string formatting");
                DEBUG("Route: %s", buf);
            }
#endif
      data->state = HL_STATE_ROUTES_RECEIVED;
      if (hl_process_state(interface, fd, unused) < 0) {
        ERROR("[hl_callback] Error processing state after routes received");
        ret = -1;
      }
      break;

    case HL_STATE_FACES_SENT:
      // DEBUG("[hl_callback] Processing faces");
      assert(data->polled_routes);
      foreach_face(f, results) {
#if 0
                char buf[MAXSZ_FACE];
                int rc = hc_face_snprintf(buf, MAXSZ_FACE, f);
                if (rc >= MAXSZ_HC_FACE)
                    ERROR("[hl_callback] Unexpected truncation of face string");
                if (rc < 0)
                    ERROR("[hl_callback] Error during face string formatting");

                DEBUG("Face: %s", buf);
#endif

        /* We can ignore faces on localhost */

        facelet_t *facelet = facelet_create_from_face(f);
        if (!facelet) {
          ERROR("[hl_callback] Could not create facelet... skipping");
          continue;
        }

        foreach_route(r, data->polled_routes) {
          if (r->face_id != f->id) continue;

#if 0
                    char route_s[MAXSZ_HC_ROUTE];
                    int rc = hc_route_snprintf(route_s, MAXSZ_HC_ROUTE, r);
                    if (rc >= MAXSZ_HC_ROUTE)
                        ERROR("[hl_callback] Unexpected truncation of route string");
                    if (rc < 0)
                        ERROR("[hl_callback] Error during route string formatting");
                    DEBUG("Associated route: %s", route_s);
#endif

          if (r->len == 0) continue;

          hicn_ip_prefix_t prefix = {
              .family = r->family,
              .address = r->remote_addr,
              .len = r->len,
          };
          hicn_route_t *route = hicn_route_create(&prefix, r->face_id, r->cost);
          facelet_add_route(facelet, route);
        }

        facelet_set_event(facelet, FACELET_EVENT_GET);
        interface_raise_event(interface, facelet);
      }
      hc_data_free(results);
      hc_data_free(data->polled_routes);
      data->polled_routes = NULL;
      data->state = HL_STATE_FACES_RECEIVED;
      if (hl_process_state(interface, fd, unused) < 0) {
        ERROR("[hl_callback] Error processing state after faces received");
        ret = -1;
      }
      break;

    case HL_STATE_IDLE:
    case HL_STATE_FACES_RECEIVED:
    case HL_STATE_ROUTES_RECEIVED:
    case HL_STATE_UNDEFINED:
    case HL_STATE_N:
      ERROR("[hl_callback] Unexpected state");
      ret = -1;
  }

  return ret;
}

const interface_ops_t hicn_light_ops = {
    .type = "hicn_light",
    .initialize = hl_initialize,
    .finalize = hl_finalize,
    .on_event = hl_on_event,
    .callback = hl_callback,
};