/*
   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_message_store.c
 * @brief GNUnet MESSENGER service
 */

#include "gnunet-service-messenger_message_store.h"
#include "messenger_api_message.h"

void
init_message_store (struct GNUNET_MESSENGER_MessageStore *store)
{
  GNUNET_assert(store);

  store->storage_messages = NULL;

  store->entries = GNUNET_CONTAINER_multihashmap_create (8, GNUNET_NO);
  store->messages = GNUNET_CONTAINER_multihashmap_create (8, GNUNET_NO);
  store->links = GNUNET_CONTAINER_multihashmap_create (8, GNUNET_NO);

  store->rewrite_entries = GNUNET_NO;
  store->write_links = GNUNET_NO;
}

static int
iterate_destroy_entries (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_MessageEntry *entry = value;

  GNUNET_free(entry);

  return GNUNET_YES;
}

static int
iterate_destroy_messages (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_Message *message = value;

  destroy_message (message);

  return GNUNET_YES;
}

static int
iterate_destroy_links (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_HashCode *previous = value;

  GNUNET_free(previous);

  return GNUNET_YES;
}

void
clear_message_store (struct GNUNET_MESSENGER_MessageStore *store)
{
  GNUNET_assert(store);

  if (store->storage_messages)
  {
    GNUNET_DISK_file_close (store->storage_messages);

    store->storage_messages = NULL;
  }

  GNUNET_CONTAINER_multihashmap_iterate (store->entries, iterate_destroy_entries, NULL);
  GNUNET_CONTAINER_multihashmap_iterate (store->messages, iterate_destroy_messages, NULL);
  GNUNET_CONTAINER_multihashmap_iterate (store->links, iterate_destroy_links, NULL);

  GNUNET_CONTAINER_multihashmap_destroy (store->entries);
  GNUNET_CONTAINER_multihashmap_destroy (store->messages);
  GNUNET_CONTAINER_multihashmap_destroy (store->links);
}

struct GNUNET_MESSENGER_MessageEntryStorage
{
  struct GNUNET_HashCode hash;
  struct GNUNET_MESSENGER_MessageEntry entry;
};

static void
load_message_store_entries (struct GNUNET_MESSENGER_MessageStore *store, const char *filename)
{
  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ);

  struct GNUNET_DISK_FileHandle *entries = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ, permission);

  if (!entries)
    return;

  struct GNUNET_MESSENGER_MessageEntryStorage storage;
  struct GNUNET_MESSENGER_MessageEntry *entry;

  do
  {
    entry = GNUNET_new(struct GNUNET_MESSENGER_MessageEntry);

    if (GNUNET_DISK_file_read (entries, &storage, sizeof(storage)) == sizeof(storage))
    {
      GNUNET_memcpy(entry, &(storage.entry), sizeof(*entry));

      if ((GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains (store->entries, &(storage.hash))) ||
          (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put (store->entries, &(storage.hash), entry,
                                                           GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST)))
      {
        store->rewrite_entries = GNUNET_YES;
        GNUNET_free(entry);
      }
    }
    else
    {
      GNUNET_free(entry);

      entry = NULL;
    }
  }
  while (entry);

  GNUNET_DISK_file_close (entries);
}

struct GNUNET_MESSENGER_MessageLinkStorage
{
  struct GNUNET_HashCode hash;
  struct GNUNET_MESSENGER_MessageLink link;
};

static void
load_message_store_links (struct GNUNET_MESSENGER_MessageStore *store, const char *filename)
{
  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ);

  struct GNUNET_DISK_FileHandle *entries = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ, permission);

  if (!entries)
    return;

  struct GNUNET_MESSENGER_MessageLinkStorage storage;
  struct GNUNET_MESSENGER_MessageLink *link = NULL;

  memset(&storage, 0, sizeof(storage));

  do
  {
    if ((sizeof(storage.hash) != GNUNET_DISK_file_read (entries, &(storage.hash), sizeof(storage.hash))) ||
        (sizeof(storage.link.multiple) != GNUNET_DISK_file_read (entries, &(storage.link.multiple), sizeof(storage.link.multiple))) ||
        (sizeof(storage.link.first) != GNUNET_DISK_file_read (entries, &(storage.link.first), sizeof(storage.link.first))) ||
        ((GNUNET_YES == storage.link.multiple) &&
         (sizeof(storage.link.second) != GNUNET_DISK_file_read (entries, &(storage.link.second), sizeof(storage.link.second)))))
      break;

    link = GNUNET_new(struct GNUNET_MESSENGER_MessageLink);

    GNUNET_memcpy(link, &(storage.link), sizeof(*link));

    if ((GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains (store->links, &(storage.hash))) ||
        (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put (store->links, &(storage.hash), link,
                                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST)))
      break;
  }
  while (link);

  if (link)
    GNUNET_free(link);

  GNUNET_DISK_file_close (entries);
}

void
load_message_store (struct GNUNET_MESSENGER_MessageStore *store, const char *directory)
{
  GNUNET_assert((store) && (directory));

  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ | GNUNET_DISK_PERM_USER_WRITE);

  if (store->storage_messages)
    GNUNET_DISK_file_close (store->storage_messages);

  char *filename;
  GNUNET_asprintf (&filename, "%s%s", directory, "messages.store");

  if (GNUNET_YES == GNUNET_DISK_file_test (filename))
    store->storage_messages = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READWRITE, permission);
  else
    store->storage_messages = NULL;

  GNUNET_free(filename);

  if (!store->storage_messages)
    return;

  GNUNET_asprintf (&filename, "%s%s", directory, "entries.store");

  if (GNUNET_YES == GNUNET_DISK_file_test (filename))
    load_message_store_entries(store, filename);

  GNUNET_free(filename);

  GNUNET_asprintf (&filename, "%s%s", directory, "links.store");

  if (GNUNET_YES == GNUNET_DISK_file_test (filename))
    load_message_store_links(store, filename);

  GNUNET_free(filename);
}

struct GNUNET_MESSENGER_ClosureMessageSave
{
  struct GNUNET_MESSENGER_MessageStore *store;

  struct GNUNET_DISK_FileHandle *storage;
};

static int
iterate_save_entries (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_ClosureMessageSave *save = cls;
  struct GNUNET_MESSENGER_MessageEntry *entry = value;

  struct GNUNET_MESSENGER_MessageEntryStorage storage;

  GNUNET_memcpy(&(storage.hash), key, sizeof(storage.hash));
  GNUNET_memcpy(&(storage.entry), entry, sizeof(*entry));

  GNUNET_DISK_file_write (save->storage, &storage, sizeof(storage));

  return GNUNET_YES;
}

static int
iterate_save_messages (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_ClosureMessageSave *save = cls;

  if (GNUNET_NO != GNUNET_CONTAINER_multihashmap_contains (save->store->entries, key))
    return GNUNET_YES;

  struct GNUNET_MESSENGER_Message *message = value;
  struct GNUNET_MESSENGER_MessageEntryStorage storage;

  GNUNET_memcpy(&(storage.hash), key, sizeof(storage.hash));

  storage.entry.length = get_message_size (message, GNUNET_YES);
  storage.entry.offset = GNUNET_DISK_file_seek (save->store->storage_messages, 0, GNUNET_DISK_SEEK_END);

  if ((GNUNET_SYSERR == storage.entry.offset) || (sizeof(storage)
      != GNUNET_DISK_file_write (save->storage, &storage, sizeof(storage))))
    return GNUNET_YES;

  char *buffer = GNUNET_malloc(storage.entry.length);

  encode_message (message, storage.entry.length, buffer, GNUNET_YES);

  GNUNET_DISK_file_write (save->store->storage_messages, buffer, storage.entry.length);

  GNUNET_free(buffer);

  return GNUNET_YES;
}

static int
iterate_save_links (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_MESSENGER_ClosureMessageSave *save = cls;
  struct GNUNET_MESSENGER_MessageLink *link = value;

  GNUNET_DISK_file_write (save->storage, key, sizeof(*key));
  GNUNET_DISK_file_write (save->storage, &(link->multiple), sizeof(link->multiple));
  GNUNET_DISK_file_write (save->storage, &(link->first), sizeof(link->first));

  if (GNUNET_YES == link->multiple)
    GNUNET_DISK_file_write (save->storage, &(link->second), sizeof(link->second));

  return GNUNET_YES;
}

void
save_message_store (struct GNUNET_MESSENGER_MessageStore *store, const char *directory)
{
  GNUNET_assert((store) && (directory));

  struct GNUNET_MESSENGER_ClosureMessageSave save;

  enum GNUNET_DISK_AccessPermissions permission = (GNUNET_DISK_PERM_USER_READ | GNUNET_DISK_PERM_USER_WRITE);

  char *filename;

  if (GNUNET_YES != store->write_links)
    goto save_entries;

  GNUNET_asprintf (&filename, "%s%s", directory, "links.store");

  save.store = store;
  save.storage = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_CREATE, permission);

  GNUNET_free(filename);

  if (!save.storage)
    goto save_entries;

  if (GNUNET_SYSERR == GNUNET_DISK_file_seek (save.storage, 0, GNUNET_DISK_SEEK_SET))
    goto close_links;

  GNUNET_CONTAINER_multihashmap_iterate (store->links, iterate_save_links, &save);
  store->write_links = GNUNET_NO;

close_links:
  GNUNET_DISK_file_close (save.storage);

save_entries:
  GNUNET_asprintf (&filename, "%s%s", directory, "entries.store");

  save.store = store;
  save.storage = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_CREATE, permission);

  GNUNET_free(filename);

  if (!save.storage)
    return;

  if (GNUNET_YES == store->rewrite_entries)
  {
    if (GNUNET_SYSERR == GNUNET_DISK_file_seek (save.storage, 0, GNUNET_DISK_SEEK_SET))
      goto close_entries;

    GNUNET_CONTAINER_multihashmap_iterate (store->entries, iterate_save_entries, &save);
    store->rewrite_entries = GNUNET_NO;
  }
  else if (GNUNET_SYSERR == GNUNET_DISK_file_seek (save.storage, 0, GNUNET_DISK_SEEK_END))
    goto close_entries;

  if (store->storage_messages)
    GNUNET_DISK_file_close (store->storage_messages);

  GNUNET_asprintf (&filename, "%s%s", directory, "messages.store");

  store->storage_messages = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READWRITE | GNUNET_DISK_OPEN_CREATE,
                                                   permission);

  GNUNET_free(filename);

  if (store->storage_messages)
  {
    GNUNET_CONTAINER_multihashmap_iterate (store->messages, iterate_save_messages, &save);

    GNUNET_DISK_file_sync (store->storage_messages);
    GNUNET_DISK_file_sync (save.storage);
  }

close_entries:
  GNUNET_DISK_file_close (save.storage);
}

int
contains_store_message (const struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash)
{
  GNUNET_assert((store) && (hash));

  if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains (store->messages, hash))
    return GNUNET_YES;

  return GNUNET_CONTAINER_multihashmap_contains (store->entries, hash);
}

const struct GNUNET_MESSENGER_Message*
get_store_message (struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash)
{
  GNUNET_assert((store) && (hash));

  struct GNUNET_MESSENGER_Message *message = GNUNET_CONTAINER_multihashmap_get (store->messages, hash);

  if (message)
    return message;

  if (!store->storage_messages)
    return NULL;

  const struct GNUNET_MESSENGER_MessageEntry *entry = GNUNET_CONTAINER_multihashmap_get (store->entries, hash);

  if (!entry)
    return NULL;

  if (entry->offset != GNUNET_DISK_file_seek (store->storage_messages, entry->offset, GNUNET_DISK_SEEK_SET))
    return message;

  char *buffer = GNUNET_malloc(entry->length);

  if (!buffer)
    return NULL;

  if ((GNUNET_DISK_file_read (store->storage_messages, buffer, entry->length) != entry->length) ||
      (entry->length < get_message_kind_size(GNUNET_MESSENGER_KIND_UNKNOWN)))
    goto free_buffer;

  message = create_message (GNUNET_MESSENGER_KIND_UNKNOWN);

  const int decoding = decode_message (message, entry->length, buffer, GNUNET_YES, NULL);

  struct GNUNET_HashCode check;
  hash_message (message, entry->length, buffer, &check);

  if ((GNUNET_YES != decoding) || (GNUNET_CRYPTO_hash_cmp (hash, &check) != 0))
  {
    if (GNUNET_YES != GNUNET_CONTAINER_multihashmap_remove (store->entries, hash, entry))
      GNUNET_log(GNUNET_ERROR_TYPE_WARNING, "Corrupted entry could not be removed from store: %s\n",
                 GNUNET_h2s(hash));

    store->rewrite_entries = GNUNET_YES;

    goto free_message;
  }

  if (GNUNET_OK == GNUNET_CONTAINER_multihashmap_put (store->messages, hash, message,
                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
    goto free_buffer;

free_message: destroy_message (message);
  message = NULL;

free_buffer:
  GNUNET_free(buffer);

  return message;
}

const struct GNUNET_MESSENGER_MessageLink*
get_store_message_link (struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash,
                        int deleted_only)
{
  if (deleted_only)
    goto get_link;

  const struct GNUNET_MESSENGER_Message *message = get_store_message(store, hash);

  if (!message)
    goto get_link;

  static struct GNUNET_MESSENGER_MessageLink link;

  GNUNET_memcpy(&(link.first), &(message->header.previous), sizeof(link.first));

  link.multiple = GNUNET_MESSENGER_KIND_MERGE == message->header.kind? GNUNET_YES : GNUNET_NO;

  if (GNUNET_YES == link.multiple)
    GNUNET_memcpy(&(link.second), &(message->body.merge.previous), sizeof(link.second));
  else
    GNUNET_memcpy(&(link.second), &(message->header.previous), sizeof(link.second));

  return &link;

get_link:
  return GNUNET_CONTAINER_multihashmap_get (store->links, hash);
}

int
put_store_message (struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash,
                   struct GNUNET_MESSENGER_Message *message)
{
  GNUNET_assert((store) && (hash) && (message));

  return GNUNET_CONTAINER_multihashmap_put (store->messages, hash, message,
                                            GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST);
}

static void
add_link (struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash,
          const struct GNUNET_MESSENGER_Message *message)
{
  struct GNUNET_MESSENGER_MessageLink *link = GNUNET_new(struct GNUNET_MESSENGER_MessageLink);

  GNUNET_memcpy(&(link->first), &(message->header.previous), sizeof(link->first));

  link->multiple = GNUNET_MESSENGER_KIND_MERGE == message->header.kind? GNUNET_YES : GNUNET_NO;

  if (GNUNET_YES == link->multiple)
    GNUNET_memcpy(&(link->second), &(message->body.merge.previous), sizeof(link->second));
  else
    GNUNET_memcpy(&(link->second), &(message->header.previous), sizeof(link->second));

  if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put(store->links, hash, link,
                                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
    GNUNET_free(link);
}

int
delete_store_message (struct GNUNET_MESSENGER_MessageStore *store, const struct GNUNET_HashCode *hash)
{
  GNUNET_assert((store) && (hash));

  const struct GNUNET_MESSENGER_MessageEntry *entry = GNUNET_CONTAINER_multihashmap_get (store->entries, hash);

  if (!entry)
    goto clear_memory;

  const struct GNUNET_MESSENGER_Message *message = get_store_message(store, hash);

  if (message)
    add_link (store, hash, message);

  if (!store->storage_messages)
    goto clear_entry;

  if (entry->offset != GNUNET_DISK_file_seek (store->storage_messages, entry->offset, GNUNET_DISK_SEEK_SET))
    return GNUNET_SYSERR;

  char *clear_buffer = GNUNET_malloc(entry->length);

  if (!clear_buffer)
    return GNUNET_SYSERR;

  GNUNET_CRYPTO_zero_keys (clear_buffer, entry->length);

  if ((entry->length != GNUNET_DISK_file_write (store->storage_messages, clear_buffer, entry->length)) || (GNUNET_OK
      != GNUNET_DISK_file_sync (store->storage_messages)))
  {
    GNUNET_free(clear_buffer);
    return GNUNET_SYSERR;
  }

  GNUNET_free(clear_buffer);

clear_entry:
  if (GNUNET_YES == GNUNET_CONTAINER_multihashmap_remove (store->entries, hash, entry))
    store->rewrite_entries = GNUNET_YES;

clear_memory:
  GNUNET_CONTAINER_multihashmap_remove_all (store->messages, hash);
  return GNUNET_OK;
}