#ifndef LLARP_NODEDB_HPP
#define LLARP_NODEDB_HPP

#include <router_contact.hpp>
#include <router_id.hpp>
#include <util/common.hpp>
#include <util/fs.hpp>
#include <util/thread/threading.hpp>
#include <util/thread/annotations.hpp>
#include <dht/key.hpp>

#include <set>
#include <utility>

/**
 * nodedb.hpp
 *
 * persistent storage API for router contacts
 */
namespace llarp
{
  class Logic;
}  // namespace llarp

struct llarp_nodedb
{
  using DiskJob_t = std::function<void(void)>;
  using DiskCaller_t = std::function<void(DiskJob_t)>;
  using WorkJob_t = std::function<void(void)>;
  using WorkCaller_t = std::function<void(WorkJob_t)>;

  explicit llarp_nodedb(const std::string rootdir, DiskCaller_t diskCaller)
      : disk(std::move(diskCaller)), nodePath(rootdir)

  {}

  ~llarp_nodedb()
  {
    Clear();
  }

  const DiskCaller_t disk;
  mutable llarp::util::Mutex access;  // protects entries
  /// time for next save to disk event, 0 if never happened
  llarp_time_t m_NextSaveToDisk = 0s;
  /// how often to save to disk
  const llarp_time_t m_SaveInterval = 5min;

  struct NetDBEntry
  {
    const llarp::RouterContact rc;
    llarp_time_t inserted;

    NetDBEntry(llarp::RouterContact data);
  };

  using NetDBMap_t = std::unordered_map<llarp::RouterID, NetDBEntry, llarp::RouterID::Hash>;

  NetDBMap_t entries GUARDED_BY(access);
  fs::path nodePath;

  llarp::RouterContact
  FindClosestTo(const llarp::dht::Key_t& location);

  /// find the $numRouters closest routers to the given DHT key
  std::vector<llarp::RouterContact>
  FindClosestTo(const llarp::dht::Key_t& location, uint32_t numRouters);

  /// return true if we should save our nodedb to disk
  bool
  ShouldSaveToDisk(llarp_time_t now = 0s) const;

  bool
  Remove(const llarp::RouterID& pk) EXCLUDES(access);

  void
  RemoveIf(std::function<bool(const llarp::RouterContact&)> filter) EXCLUDES(access);

  void
  Clear() EXCLUDES(access);

  bool
  Get(const llarp::RouterID& pk, llarp::RouterContact& result) EXCLUDES(access);

  bool
  Has(const llarp::RouterID& pk) EXCLUDES(access);

  std::string
  getRCFilePath(const llarp::RouterID& pubkey) const;

  /// insert without writing to disk
  bool
  Insert(const llarp::RouterContact& rc) EXCLUDES(access);

  /// invokes Insert() asynchronously with an optional completion
  /// callback
  void
  InsertAsync(
      llarp::RouterContact rc,
      std::shared_ptr<llarp::Logic> l = nullptr,
      std::function<void(void)> completionHandler = nullptr);

  /// update rc if newer
  /// return true if we started to put this rc in the database
  /// retur false if not newer
  bool
  UpdateAsyncIfNewer(
      llarp::RouterContact rc,
      std::shared_ptr<llarp::Logic> l = nullptr,
      std::function<void(void)> completionHandler = nullptr) EXCLUDES(access);

  ssize_t
  Load(const fs::path& path);

  ssize_t
  loadSubdir(const fs::path& dir);
  /// save all entries to disk async
  void
  AsyncFlushToDisk();

  bool
  loadfile(const fs::path& fpath) EXCLUDES(access);

  void
  visit(std::function<bool(const llarp::RouterContact&)> visit) EXCLUDES(access);

  void
  set_dir(const char* dir);

  ssize_t
  LoadAll();

  ssize_t
  store_dir(const char* dir);

  /// visit all entries inserted into nodedb cache before a timestamp
  void
  VisitInsertedBefore(
      std::function<void(const llarp::RouterContact&)> visit, llarp_time_t insertedAfter)
      EXCLUDES(access);

  void
  RemoveStaleRCs(const std::set<llarp::RouterID>& keep, llarp_time_t cutoff);

  size_t
  num_loaded() const EXCLUDES(access);

  bool
  select_random_exit(llarp::RouterContact& rc) EXCLUDES(access);

  bool
  select_random_hop_excluding(
      llarp::RouterContact& result, const std::set<llarp::RouterID>& exclude) EXCLUDES(access);

  /// Ensures that the given nodedb 'dir' exists
  ///
  /// @param nodedbDir should be the desired nodedb directory
  /// @throws on any filesistem error or if `nodedbDir` exists and is not a directory
  static void
  ensure_dir(const fs::path& nodedbDir);

  void
  SaveAll() EXCLUDES(access);
};

/// struct for async rc verification
struct llarp_async_verify_rc;

using llarp_async_verify_rc_hook_func = std::function<void(struct llarp_async_verify_rc*)>;

/// verify rc request
struct llarp_async_verify_rc
{
  /// async_verify_context
  void* user;
  /// nodedb storage
  llarp_nodedb* nodedb;
  // llarp::Logic for queue_job
  std::shared_ptr<llarp::Logic> logic;
  llarp_nodedb::WorkCaller_t worker;
  llarp_nodedb::DiskCaller_t disk;

  /// router contact
  llarp::RouterContact rc;
  /// result
  bool valid;
  /// hook
  llarp_async_verify_rc_hook_func hook;
};

/**
    struct for async rc verification
    data is loaded in disk io threadpool
    crypto is done on the crypto worker threadpool
    result is called on the logic thread
*/
void
llarp_nodedb_async_verify(struct llarp_async_verify_rc* job);

struct llarp_async_load_rc;

using llarp_async_load_rc_hook_func = std::function<void(struct llarp_async_load_rc*)>;

struct llarp_async_load_rc
{
  /// async_verify_context
  void* user;
  /// nodedb storage
  llarp_nodedb* nodedb;
  /// llarp::Logic for calling hook
  llarp::Logic* logic;
  /// disk worker threadpool
  llarp_nodedb::DiskCaller_t disk;
  /// target pubkey
  llarp::PubKey pubkey;
  /// router contact result
  llarp::RouterContact result;
  /// set to true if we loaded the rc
  bool loaded;
  /// hook function called in logic thread
  llarp_async_load_rc_hook_func hook;
};

/// asynchronously load an rc from disk
void
llarp_nodedb_async_load_rc(struct llarp_async_load_rc* job);

#endif