/*
 * LMDB Abstraction Layer.
 * Copyright (C) 2023  Yury Gubich <blue@macaw.me>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef LMDBAL_BASE_H
#define LMDBAL_BASE_H

#include <map>
#include <set>
#include <string>
#include <optional>
#include <limits>

#include <QString>
#include <QStandardPaths>
#include <QDir>

#include <lmdb.h>

#include "exceptions.h"

namespace LMDBAL {

class iStorage;

template<class T>
class Serializer;

template <class K, class V>
class Storage;

template <class K, class V>
class Cache;

typedef MDB_txn* TransactionID;

class Base {
    friend class iStorage;
public:

    Base(const QString& name, uint16_t mapSize = 10);
    ~Base();

    void open();
    void close();
    bool ready() const;
    bool removeDirectory();
    QString createDirectory();
    QString getName() const;
    void drop();

    TransactionID beginReadOnlyTransaction() const;
    TransactionID beginTransaction() const;
    void commitTransaction(TransactionID id) const;
    void abortTransaction(TransactionID id) const;

    template <class K, class V>
    LMDBAL::Storage<K, V>* addStorage(const std::string& name);

    template <class K, class V>
    LMDBAL::Cache<K, V>* addCache(const std::string& name);

    template <class K, class V>
    LMDBAL::Storage<K, V>* getStorage(const std::string& name);

    template <class K, class V>
    LMDBAL::Cache<K, V>* getCache(const std::string& name);

private:
    typedef std::map<std::string, LMDBAL::iStorage*> Storages;
    typedef std::set<TransactionID> Transactions;

    TransactionID beginReadOnlyTransaction(const std::string& storageName) const;
    TransactionID beginTransaction(const std::string& storageName) const;
    void commitTransaction(TransactionID id, const std::string& storageName) const;
    void abortTransaction(TransactionID id, const std::string& storageName) const;

    TransactionID beginPrivateReadOnlyTransaction(const std::string& storageName) const;
    TransactionID beginPrivateTransaction(const std::string& storageName) const;
    void commitPrivateTransaction(TransactionID id, const std::string& storageName) const;
    void abortPrivateTransaction(TransactionID id, const std::string& storageName) const;

private:
    std::string name;
    bool opened;
    uint16_t size;
    MDB_env* environment;
    Storages storages;
    Transactions* transactions;

    inline static const std::string emptyName = "";
};

}
#include "operators.hpp"

/**
 * Adds LMDBAL::Storage with the given name to the LMDBAL::Base, also returns it. The LMDBAL::Base must be closed
 */
template <class K, class V>
LMDBAL::Storage<K, V>* LMDBAL::Base::addStorage(const std::string& p_name) {
    if (opened) {
        throw Opened(name, "add storage " + p_name);
    }
    Storage<K, V>* storage = new Storage<K, V>(p_name, this);
    storages.insert(std::make_pair(p_name, (iStorage*)storage));
    return storage;
}

/**
 * Adds LMDBAL::Cache with given the name to the LMDBAL::Base, also returns it. The LMDBAL::Base must be closed
 */
template<class K, class V>
LMDBAL::Cache<K, V> * LMDBAL::Base::addCache(const std::string& p_name) {
    if (opened) {
        throw Opened(name, "add cache " + p_name);
    }
    Cache<K, V>* cache = new Cache<K, V>(p_name, this);
    storages.insert(std::make_pair(p_name, (iStorage*)cache));
    return cache;
}

/**
 * Returns LMDBAL::Storage with the given name
 */
template <class K, class V>
LMDBAL::Storage<K, V>* LMDBAL::Base::getStorage(const std::string& p_name) {
    return static_cast<Storage<K, V>*>(storages.at(p_name));
}

/**
 * Returns LMDBAL::Cache with the given name
 */
template <class K, class V>
LMDBAL::Cache<K, V>* LMDBAL::Base::getCache(const std::string& p_name) {
    return static_cast<Cache<K, V>*>(storages.at(p_name));
}

#endif //LMDBAL_BASE_H