/*
 * 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_STORAGE_H
#define LMDBAL_STORAGE_H

#include <type_traits>
#include <cstring>

#include "base.h"
#include "serializer.h"
#include "cursor.h"
#include "transaction.h"

class BaseTest;
class DuplicatesTest;
class CacheCursorTest;
class StorageCursorTest;

namespace LMDBAL {

class iStorage {
    friend class Base;
public:
protected:
    iStorage(Base* parent, const std::string& name, bool duplicates = false);
    virtual ~iStorage();

    /**
    * \brief A private virtual function I need to open each storage in the database
    *
    * \param[in] transaction   - lmdb transaction to call <a class="el" href="http://www.lmdb.tech/doc/group__mdb.html#gac08cad5b096925642ca359a6d6f0562a">mdb_dbi_open</a>
    * \returns MDB_SUCCESS if everything went smooth or MDB_<error> -like error code
    */
    virtual int open(MDB_txn * transaction) = 0;
    virtual void close();
    virtual void handleDrop();

    bool isDBOpened() const;
    const std::string& dbName() const;

    void ensureOpened(const std::string& methodName) const;
    void throwDuplicateOrUnknown(int rc, const std::string& key) const;
    void throwDuplicateOrUnknown(int rc, TransactionID txn, const std::string& key) const;
    void throwNotFoundOrUnknown(int rc, const std::string& key) const;
    void throwNotFoundOrUnknown(int rc, TransactionID txn, const std::string& key) const;
    void throwUnknown(int rc, TransactionID txn) const;
    void throwUnknown(int rc) const;
    void throwUnknown(const std::string& message) const;
    void throwDuplicate(const std::string& key) const;
    void throwNotFound(const std::string& key) const;
    void throwCursorNotReady(const std::string& method) const;

    TransactionID extractTransactionId(const Transaction& txn, const std::string& action = "") const;
    TransactionID beginReadOnlyTransaction() const;
    TransactionID beginTransaction() const;
    void commitTransaction(TransactionID id);
    void abortTransaction(TransactionID id) const;
    virtual void transactionStarted(TransactionID txn, bool readOnly) const;
    virtual void transactionCommited(TransactionID txn);
    virtual void transactionAborted(TransactionID txn) const;
    virtual int drop(TransactionID transaction);
    virtual SizeType count(TransactionID txn) const;

public:
    virtual void drop();
    virtual int drop(const WriteTransaction& txn);
    virtual SizeType count() const;
    virtual SizeType count(const Transaction& txn) const;

protected:
    MDB_dbi dbi;                                                                /**<\brief lmdb storage handle*/
    Base* db;                                                                   /**<\brief parent database pointer (borrowed)*/
    const std::string name;                                                     /**<\brief this storage name*/
    const bool duplicates;                                                      /**<\brief true if storage supports duplicates*/

    inline static const std::string dropMethodName = "drop";                    /**<\brief member function name, just for exceptions*/
    inline static const std::string countMethodName = "count";                  /**<\brief member function name, just for exceptions*/
    inline static const std::string flagsMethodName = "flags";                  /**<\brief member function name, just for exceptions*/

    inline static const std::string addRecordMethodName = "addRecord";          /**<\brief member function name, just for exceptions*/
    inline static const std::string forceRecordMethodName = "forceRecord";      /**<\brief member function name, just for exceptions*/
    inline static const std::string changeRecordMethodName = "changeRecord";    /**<\brief member function name, just for exceptions*/
    inline static const std::string removeRecordMethodName = "removeRecord";    /**<\brief member function name, just for exceptions*/
    inline static const std::string checkRecordMethodName = "checkRecord";      /**<\brief member function name, just for exceptions*/
    inline static const std::string getRecordMethodName = "getRecord";          /**<\brief member function name, just for exceptions*/
    inline static const std::string readAllMethodName = "readAllRecord";        /**<\brief member function name, just for exceptions*/
    inline static const std::string replaceAllMethodName = "replaceAll";        /**<\brief member function name, just for exceptions*/
    inline static const std::string addRecordsMethodName = "addRecords";        /**<\brief member function name, just for exceptions*/

protected:
    template <class K, class V>
    int makeStorage(MDB_txn* transaction, bool duplicates = false);

    template <class T>
    static std::string toString(const T& value);
};

template <class K, class V>
class Storage : public iStorage {
    friend class ::BaseTest;
    friend class ::DuplicatesTest;
    friend class ::CacheCursorTest;
    friend class ::StorageCursorTest;
    friend class Base;
    friend class Cursor<K, V>;
protected:
    Storage(Base* parent, const std::string& name, bool duplicates = false);
    ~Storage() override;

    virtual void discoveredRecord(const K& key, const V& value) const;
    virtual void discoveredRecord(const K& key, const V& value, TransactionID txn) const;
    uint32_t flags() const;

    virtual void addRecord(const K& key, const V& value, TransactionID txn);
    virtual bool forceRecord(const K& key, const V& value, TransactionID txn);
    virtual void changeRecord(const K& key, const V& value, TransactionID txn);
    virtual void removeRecord(const K& key, TransactionID txn);
    virtual bool checkRecord(const K& key, TransactionID txn) const;
    virtual void getRecord(const K& key, V& value, TransactionID txn) const;
    virtual V getRecord(const K& key, TransactionID txn) const;
    virtual std::map<K, V> readAll(TransactionID txn) const;
    virtual void readAll(std::map<K, V>& result, TransactionID txn) const;
    virtual void replaceAll(const std::map<K, V>& data, TransactionID txn);
    virtual uint32_t addRecords(const std::map<K, V>& data, TransactionID txn, bool overwrite = false);

public:
    using iStorage::drop;
    virtual void addRecord(const K& key, const V& value);
    virtual void addRecord(const K& key, const V& value, const WriteTransaction& txn);
    virtual bool forceRecord(const K& key, const V& value);     //returns true if there was addition, false if change
    virtual bool forceRecord(const K& key, const V& value, const WriteTransaction& txn);
    virtual void changeRecord(const K& key, const V& value);
    virtual void changeRecord(const K& key, const V& value, const WriteTransaction& txn);
    virtual void removeRecord(const K& key);
    virtual void removeRecord(const K& key, const WriteTransaction& txn);
    virtual bool checkRecord(const K& key) const;               //checks if there is a record with given key
    virtual bool checkRecord(const K& key, const Transaction& txn) const;
    virtual void getRecord(const K& key, V& value) const;
    virtual void getRecord(const K& key, V& value, const Transaction& txn) const;
    virtual V getRecord(const K& key) const;
    virtual V getRecord(const K& key, const Transaction& txn) const;
    virtual std::map<K, V> readAll() const;
    virtual std::map<K, V> readAll(const Transaction& txn) const;
    virtual void readAll(std::map<K, V>& result) const;
    virtual void readAll(std::map<K, V>& result, const Transaction& txn) const;
    virtual void replaceAll(const std::map<K, V>& data);
    virtual void replaceAll(const std::map<K, V>& data, const WriteTransaction& txn);
    virtual uint32_t addRecords(const std::map<K, V>& data, bool overwrite = false);
    virtual uint32_t addRecords(const std::map<K, V>& data, const WriteTransaction& txn, bool overwrite = false);

    Cursor<K, V> createCursor();
    void destroyCursor(Cursor<K, V>& cursor);

protected:
    mutable Serializer<K> keySerializer;        /**<\brief internal object that would serialize and deserialize keys*/
    mutable Serializer<V> valueSerializer;      /**<\brief internal object that would serialize and deserialize values*/
    std::map<uint32_t, Cursor<K, V>*> cursors;  /**<\brief a set of cursors that has been created under this storage*/

    int open(MDB_txn* transaction) override;
    void close() override;
};

}

#include "storage.hpp"

#endif //LMDBAL_STORAGE_H