/*
   This file is part of GNUnet.
   Copyright (C) 2020--2021 GNUnet e.V.

   GNUnet is free software: you can redistribute it and/or modify it
   under the terms of the GNU Affero General Public License as published
   by the Free Software Foundation, either version 3 of the License,
   or (at your option) any later version.

   GNUnet is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   SPDX-License-Identifier: AGPL3.0-or-later
 */
/**
 * @author Tobias Frisch
 * @file src/messenger/gnunet-service-messenger_member.c
 * @brief GNUnet MESSENGER service
 */

#include "gnunet-service-messenger_member.h"

#include "gnunet-service-messenger_member_session.h"

struct GNUNET_MESSENGER_Member*
create_member (struct GNUNET_MESSENGER_MemberStore *store, const struct GNUNET_ShortHashCode *id)
{
  GNUNET_assert (store);

  struct GNUNET_MESSENGER_Member *member = GNUNET_new(struct GNUNET_MESSENGER_Member);

  member->store = store;

  if (id)
    GNUNET_memcpy(&(member->id), id, sizeof(member->id));
  else if (GNUNET_YES != generate_free_member_id(&(member->id), store->members))
  {
    GNUNET_free (member);
    return NULL;
  }

  member->sessions = GNUNET_CONTAINER_multihashmap_create(2, GNUNET_NO);

  return member;
}

static int
iterate_destroy_session (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_MemberSession *session = value;
  destroy_member_session(session);
  return GNUNET_YES;
}

void
destroy_member (struct GNUNET_MESSENGER_Member *member)
{
  GNUNET_assert((member) && (member->sessions));

  GNUNET_CONTAINER_multihashmap_iterate (member->sessions, iterate_destroy_session, NULL);
  GNUNET_CONTAINER_multihashmap_destroy (member->sessions);

  GNUNET_free (member);
}

const struct GNUNET_ShortHashCode*
get_member_id (const struct GNUNET_MESSENGER_Member *member)
{
  GNUNET_assert (member);

  return &(member->id);
}

static int
callback_scan_for_sessions (void *cls, const char *filename)
{
  struct GNUNET_MESSENGER_Member *member = cls;

  if (GNUNET_YES == GNUNET_DISK_directory_test (filename, GNUNET_YES))
  {
    char *directory;

    GNUNET_asprintf (&directory, "%s%c", filename, DIR_SEPARATOR);

    load_member_session(member, directory);
  }

  return GNUNET_OK;
}

void
load_member (struct GNUNET_MESSENGER_MemberStore *store, const char *directory)
{
  GNUNET_assert ((store) && (directory));

  char *config_file;
  GNUNET_asprintf (&config_file, "%s%s", directory, "member.cfg");

  struct GNUNET_MESSENGER_Member *member = NULL;

  if (GNUNET_YES != GNUNET_DISK_file_test (config_file))
    goto free_config;

  struct GNUNET_CONFIGURATION_Handle *cfg = GNUNET_CONFIGURATION_create ();

  if (GNUNET_OK == GNUNET_CONFIGURATION_parse (cfg, config_file))
  {
    struct GNUNET_ShortHashCode id;

    if (GNUNET_OK != GNUNET_CONFIGURATION_get_data (cfg, "member", "id", &id, sizeof(id)))
      goto destroy_config;

    member = add_store_member(store, &id);
  }

destroy_config:

  GNUNET_CONFIGURATION_destroy (cfg);

free_config:
  GNUNET_free(config_file);

  if (!member)
    return;

  char *scan_dir;
  GNUNET_asprintf (&scan_dir, "%s%s%c", directory, "sessions", DIR_SEPARATOR);

  if (GNUNET_OK == GNUNET_DISK_directory_test (scan_dir, GNUNET_YES))
    GNUNET_DISK_directory_scan (scan_dir, callback_scan_for_sessions, member);

  GNUNET_free(scan_dir);
}

static int
iterate_load_next_session (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  const char* sessions_directory = cls;

  char* load_dir;
  GNUNET_asprintf (&load_dir, "%s%s%c", sessions_directory, GNUNET_h2s(key), DIR_SEPARATOR);

  struct GNUNET_MESSENGER_MemberSession *session = value;

  if (GNUNET_YES == GNUNET_DISK_directory_test (load_dir, GNUNET_YES))
    load_member_session_next (session, load_dir);

  GNUNET_free (load_dir);
  return GNUNET_YES;
}

void
load_member_next_sessions (const struct GNUNET_MESSENGER_Member *member, const char *directory)
{
  GNUNET_assert ((member) && (directory));

  char* load_dir;
  GNUNET_asprintf (&load_dir, "%s%s%c", directory, "sessions", DIR_SEPARATOR);

  GNUNET_CONTAINER_multihashmap_iterate (member->sessions, iterate_load_next_session, load_dir);

  GNUNET_free(load_dir);
}

static int
iterate_save_session (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  const char* sessions_directory = cls;

  char* save_dir;
  GNUNET_asprintf (&save_dir, "%s%s%c", sessions_directory, GNUNET_h2s(key), DIR_SEPARATOR);

  struct GNUNET_MESSENGER_MemberSession *session = value;

  if ((GNUNET_YES == GNUNET_DISK_directory_test (save_dir, GNUNET_NO)) ||
      (GNUNET_OK == GNUNET_DISK_directory_create (save_dir)))
    save_member_session (session, save_dir);

  GNUNET_free (save_dir);
  return GNUNET_YES;
}

void
save_member (struct GNUNET_MESSENGER_Member *member, const char *directory)
{
  GNUNET_assert ((member) && (directory));

  char *config_file;
  GNUNET_asprintf (&config_file, "%s%s", directory, "member.cfg");

  struct GNUNET_CONFIGURATION_Handle *cfg = GNUNET_CONFIGURATION_create ();

  char *id_data = GNUNET_STRINGS_data_to_string_alloc (&(member->id), sizeof(member->id));

  if (id_data)
  {
    GNUNET_CONFIGURATION_set_value_string (cfg, "member", "id", id_data);

    GNUNET_free(id_data);
  }

  GNUNET_CONFIGURATION_write (cfg, config_file);
  GNUNET_CONFIGURATION_destroy (cfg);

  GNUNET_free(config_file);

  char* save_dir;
  GNUNET_asprintf (&save_dir, "%s%s%c", directory, "sessions", DIR_SEPARATOR);

  if ((GNUNET_YES == GNUNET_DISK_directory_test (save_dir, GNUNET_NO)) ||
      (GNUNET_OK == GNUNET_DISK_directory_create (save_dir)))
    GNUNET_CONTAINER_multihashmap_iterate (member->sessions, iterate_save_session, save_dir);

  GNUNET_free(save_dir);
}

static void
sync_session_contact_from_next (struct GNUNET_MESSENGER_MemberSession *session, struct GNUNET_MESSENGER_MemberSession *next)
{
  GNUNET_assert((session) && (next));

  if (session == next)
    return;

  if (next->next)
    sync_session_contact_from_next (session, next->next);
  else
    session->contact = next->contact;
}

static int
iterate_sync_session_contact (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_MemberSession *session = value;

  if (session->next)
    sync_session_contact_from_next (session, session->next);

  return GNUNET_YES;
}

void
sync_member_contacts (struct GNUNET_MESSENGER_Member *member)
{
  GNUNET_assert ((member) && (member->sessions));

  GNUNET_CONTAINER_multihashmap_iterate (member->sessions, iterate_sync_session_contact, NULL);
}

struct GNUNET_MESSENGER_MemberSession*
get_member_session (const struct GNUNET_MESSENGER_Member *member, const struct GNUNET_IDENTITY_PublicKey *public_key)
{
  GNUNET_assert ((member) && (public_key));

  struct GNUNET_HashCode hash;
  GNUNET_CRYPTO_hash(public_key, sizeof(*public_key), &hash);

  return GNUNET_CONTAINER_multihashmap_get(member->sessions, &hash);
}

struct GNUNET_MESSENGER_ClosureSearchSession {
  const struct GNUNET_MESSENGER_Message *message;
  const struct GNUNET_HashCode *hash;

  struct GNUNET_MESSENGER_MemberSession *match;
};

static int
iterate_search_session (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_ClosureSearchSession* search = cls;
  struct GNUNET_MESSENGER_MemberSession *session = value;

  if (GNUNET_OK != verify_member_session_as_sender(session, search->message, search->hash))
    return GNUNET_YES;

  search->match = session;
  return GNUNET_NO;
}

static struct GNUNET_MESSENGER_MemberSession*
try_member_session (struct GNUNET_MESSENGER_Member *member, const struct GNUNET_IDENTITY_PublicKey *public_key)
{
  struct GNUNET_MESSENGER_MemberSession* session = get_member_session(member, public_key);

  if (session)
    return session;

  session = create_member_session(member, public_key);

  if (session)
    add_member_session(member, session);

  return session;
}

struct GNUNET_MESSENGER_MemberSession*
get_member_session_of (struct GNUNET_MESSENGER_Member *member, const struct GNUNET_MESSENGER_Message *message,
                       const struct GNUNET_HashCode *hash)
{
  GNUNET_assert ((member) && (message) && (hash) &&
                 (0 == GNUNET_memcmp(&(member->id), &(message->header.sender_id))));

  if (GNUNET_MESSENGER_KIND_INFO == message->header.kind)
    return try_member_session(member, &(message->body.info.host_key));
  else if (GNUNET_MESSENGER_KIND_JOIN == message->header.kind)
    return try_member_session(member, &(message->body.join.key));

  struct GNUNET_MESSENGER_ClosureSearchSession search;

  search.message = message;
  search.hash = hash;

  search.match = NULL;
  GNUNET_CONTAINER_multihashmap_iterate(member->sessions, iterate_search_session, &search);

  return search.match;
}

void
add_member_session (struct GNUNET_MESSENGER_Member *member, struct GNUNET_MESSENGER_MemberSession *session)
{
  if (!session)
    return;

  GNUNET_assert((member) && (session->member == member));

  const struct GNUNET_IDENTITY_PublicKey *public_key = get_member_session_public_key(session);

  struct GNUNET_HashCode hash;
  GNUNET_CRYPTO_hash(public_key, sizeof(*public_key), &hash);

  if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put(
      member->sessions, &hash, session,
      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
    GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Adding a member session failed: %s\n",
               GNUNET_h2s(&hash));
}

void
remove_member_session (struct GNUNET_MESSENGER_Member *member, struct GNUNET_MESSENGER_MemberSession *session)
{
  GNUNET_assert ((member) && (session) && (session->member == member));

  const struct GNUNET_IDENTITY_PublicKey *public_key = get_member_session_public_key(session);

  struct GNUNET_HashCode hash;
  GNUNET_CRYPTO_hash(public_key, sizeof(*public_key), &hash);

  if (GNUNET_YES != GNUNET_CONTAINER_multihashmap_remove(member->sessions, &hash, session))
    GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Removing a member session failed: %s\n",
               GNUNET_h2s(&hash));
}

struct GNUNET_MESSENGER_ClosureIterateSessions {
  GNUNET_MESSENGER_MemberIteratorCallback it;
  void *cls;
};

static int
iterate_member_sessions_it (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_ClosureIterateSessions *iterate = cls;
  struct GNUNET_MESSENGER_MemberSession *session = value;

  return iterate->it (iterate->cls, get_member_session_public_key(session), session);
}

int
iterate_member_sessions (struct GNUNET_MESSENGER_Member *member, GNUNET_MESSENGER_MemberIteratorCallback it, void *cls)
{
  GNUNET_assert ((member) && (member->sessions) && (it));

  struct GNUNET_MESSENGER_ClosureIterateSessions iterate;

  iterate.it = it;
  iterate.cls = cls;

  return GNUNET_CONTAINER_multihashmap_iterate(member->sessions, iterate_member_sessions_it, &iterate);
}