// Copyright (c) 2004-present, Facebook, Inc.
// All Rights Reserved.
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

// datapackstore.h - c++ declarations for a data pack store
// no-check-code

#ifndef FBHGEXT_DATAPACKSTORE_H
#define FBHGEXT_DATAPACKSTORE_H

extern "C" {
#include "lib/cdatapack/cdatapack.h"
}

#include <ctime>
#include <memory>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include "hgext/extlib/cstore/datastore.h"
#include "hgext/extlib/cstore/key.h"
#include "lib/clib/portability/portability.h"

const clock_t PACK_REFRESH_RATE = 0.1 * CLOCKS_PER_SEC;

class DatapackStore;
class DatapackStoreKeyIterator : public KeyIterator
{
private:
  DatapackStore &_store;
  KeyIterator &_missing;

public:
  DatapackStoreKeyIterator(DatapackStore &store, KeyIterator &missing)
      : _store(store), _missing(missing)
  {
  }

  Key *next() override;
};

/* Manages access to a directory of datapack files. */
class DatapackStore : public DataStore
{
private:
  std::string path_;
  clock_t lastRefresh_;
  bool removeOnRefresh_;
  std::unordered_map<std::string, std::shared_ptr<datapack_handle_t>> packs_;

  std::shared_ptr<datapack_handle_t> addPack(const std::string &path);
  std::vector<std::shared_ptr<datapack_handle_t>> refresh();

public:
  ~DatapackStore();
  /** Initialize the store for the specified path.
   * If removeDeadPackFilesOnRefresh is set to true (NOT the default),
   * then the refresh() method can choose to unmap pack files that
   * have been deleted.  Since the DataStore API doesn't provide
   * for propagating ownership out through the DeltaChain and DeltaChain
   * iterator, it is not safe to removeDeadPackFilesOnRefresh if the calling
   * code is keeping longlived references to those values; it is the
   * responsibility of the calling code to ensure that the lifetime is
   * managed correctly as it cannot be enforced automatically without
   * restructing this API.
   */
  explicit DatapackStore(const std::string &path,
                         bool removeDeadPackFilesOnRefresh = false);

  DeltaChainIterator getDeltaChain(const Key &key);

  std::shared_ptr<KeyIterator> getMissing(KeyIterator &missing);

  std::shared_ptr<DeltaChain> getDeltaChainRaw(const Key &key);

  bool contains(const Key &key);

  void markForRefresh();
};

#endif // FBHGEXT_DATAPACKSTORE_H