/*
 * 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/>.
 */

#include "storage.h"

#define UNUSED(x) (void)(x)

/**
 * \class LMDBAL::iStorage
 *
 * This is a interface-like class, it's designed to be an inner database interface to
 * be used as a polymorphic entity, and provide protected interaction with the database
 * from the heirs code
 */

/**
 * \brief Constructs a storage interface
 */
LMDBAL::iStorage::iStorage(const std::string& p_name, Base* parent):
    dbi(),
    db(parent),
    name(p_name)
{}

/**
 * \brief Destroys a storage interface
 */
LMDBAL::iStorage::~iStorage() {}

/**
 * \brief A private virtual function I need to close each storage in the database
 */
void LMDBAL::iStorage::close() {
    mdb_dbi_close(db->environment, dbi);
}


/**
 * \brief Drops content of a storage interface
 *
 * Designed to drop storage content
 *
 * \exception LMDBAL::Closed    thrown if the database was closed
 * \exception LMDBAL::Unknown   thrown if something unexpected happened
 */
void LMDBAL::iStorage::drop() {
    ensureOpened(dropMethodName);

    TransactionID txn = db->beginTransaction();
    int rc = iStorage::drop(txn);
    if (rc != MDB_SUCCESS) {
        abortTransaction(txn);
        throw Unknown(db->name, mdb_strerror(rc), name);
    }

    db->commitTransaction(txn);
}

/**
 * \brief Drops content of a storage interface (transaction variant)
 *
 * Just performs content drop
 *
 * \param[in] transaction   - transaction ID, must be writable transaction!
 * \returns MDB_SUCCESS if everything went fine, MDB_<error> code otherwise
 */
int LMDBAL::iStorage::drop(TransactionID transaction) {
    return mdb_drop(transaction, dbi, 0);
}

/**
 * \brief Helper function, thows exception if the database is not opened
 *
 * \param[in] methodName    - name of the method this function is called from, just for display in std::exception::what() message
 *
 * \exception LMDBAL::Closed    thrown if the database was closed
 */
void LMDBAL::iStorage::ensureOpened(const std::string& methodName) const {
    if (!isDBOpened())
        throw Closed(methodName, db->name, name);
}

/**
 * \brief Storage size
 *
 * \returns amount of records in the storage
 *
 * \exception LMDBAL::Closed    thrown if the database was closed
 * \exception LMDBAL::Unknown   thrown if something unexpected happened
 */
LMDBAL::SizeType LMDBAL::iStorage::count() const {
    ensureOpened(countMethodName);

    TransactionID txn = beginReadOnlyTransaction();
    SizeType amount;
    try {
        amount = count(txn);
    } catch (...) {
        abortTransaction(txn);
        throw;
    }
    abortTransaction(txn);

    return amount;
}

/**
 * \brief Storage size (transaction variant)
 *
 * \param[in] txn   - transaction ID, can be read-only transaction
 * \returns amount of records in the storage
 *
 * \exception LMDBAL::Unknown   thrown if something unexpected happened
 */
LMDBAL::SizeType LMDBAL::iStorage::count(TransactionID txn) const {
    MDB_stat stat;
    int rc = mdb_stat(txn, dbi, &stat);
    if (rc != MDB_SUCCESS)
        throw Unknown(db->name, mdb_strerror(rc), name);

    return stat.ms_entries;
}

/**
 * \brief Throws LMDBAL::Exist or LMDBAL::Unknown (transaction vairiant)
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 * \param[in] txn   - transaction ID to be aborted, any transaction
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::Exist     thrown if rc == MDB_KEYEXIST
 * \exception LMDBAL::Unknown   thrown if rc != MDB_KEYEXIST
 */
void LMDBAL::iStorage::throwDuplicateOrUnknown(int rc, TransactionID txn, const std::string& key) const {
    abortTransaction(txn);
    throwDuplicateOrUnknown(rc, key);
}

/**
 * \brief Throws LMDBAL::NotFound or LMDBAL::Unknown (transaction vairiant)
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 * \param[in] txn   - transaction ID to be aborted, any transaction
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::NotFound  thrown if rc == MDB_NOTFOUND
 * \exception LMDBAL::Unknown   thrown if rc != MDB_NOTFOUND
 */
void LMDBAL::iStorage::throwNotFoundOrUnknown(int rc, LMDBAL::TransactionID txn, const std::string& key) const {
    abortTransaction(txn);
    throwNotFoundOrUnknown(rc, key);
}

/**
 * \brief Throws LMDBAL::Exist or LMDBAL::Unknown
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::Exist     thrown if rc == MDB_KEYEXIST
 * \exception LMDBAL::Unknown   thrown if rc != MDB_KEYEXIST
 */
void LMDBAL::iStorage::throwDuplicateOrUnknown(int rc, const std::string& key) const {
    if (rc == MDB_KEYEXIST)
        throwDuplicate(key);
    else
        throwUnknown(rc);
}

/**
 * \brief Throws LMDBAL::NotFound or LMDBAL::Unknown (transaction variant)
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::NotFound  thrown if rc == MDB_NOTFOUND
 * \exception LMDBAL::Unknown   thrown if rc != MDB_NOTFOUND
 */
void LMDBAL::iStorage::throwNotFoundOrUnknown(int rc, const std::string& key) const {
    if (rc == MDB_NOTFOUND)
        throwNotFound(key);
    else
        throwUnknown(rc);
}

/**
 * \brief Throws LMDBAL::Unknown (transaction vairiant)
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 * \param[in] txn   - transaction ID to be aborted, any transaction
 *
 * \exception LMDBAL::Unknown   thrown everytime
 */
void LMDBAL::iStorage::throwUnknown(int rc, LMDBAL::TransactionID txn) const {
    abortTransaction(txn);
    throwUnknown(rc);
}

/**
 * \brief Database name
 *
 * Ment to be used in heirs, to provide some sort of interface to acces to some of the database information
 *
 * \returns database name
 */
const std::string & LMDBAL::iStorage::dbName() const {
    return db->name;}

/**
 * \brief Is database opened
 *
 * Ment to be used in heirs, to provide some sort of interface to acces to some of the database information
 *
 * \returns true if database is ipened, false otherwise
 */
bool LMDBAL::iStorage::isDBOpened() const {
    return db->opened;}

/**
 * \brief Throws LMDBAL::Unknown
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] rc    - result of lmdb low level operation
 *
 * \exception LMDBAL::Unknown   thrown everytime
 */
void LMDBAL::iStorage::throwUnknown(int rc) const {
    throw Unknown(db->name, mdb_strerror(rc), name);}

/**
 * \brief Throws LMDBAL::Exist
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::Exist   thrown everytime
 */
void LMDBAL::iStorage::throwDuplicate(const std::string& key) const {
    throw Exist(key, db->name, name);}

/**
 * \brief Throws LMDBAL::NotFound
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] key   - requested key string representation, just to show in std::exception::what() message
 *
 * \exception LMDBAL::NotFound   thrown everytime
 */
void LMDBAL::iStorage::throwNotFound(const std::string& key) const {
    throw NotFound(key, db->name, name);}

/**
 * \brief Throws LMDBAL::CursorNotReady
 *
 * Helper function ment to be used in heirs and reduce the code a bit
 *
 * \param[in] method   - called cursor method name, just to show in std::exception::what() message
 *
 * \exception LMDBAL::CursorNotReady   thrown everytime
 */
void LMDBAL::iStorage::throwCursorNotReady(const std::string& method) const {
    throw CursorNotReady(method, db->name, name);}

/**
 * \brief Begins read-only transaction
 *
 * Ment to be called from heirs, name is reported to the database just to be displayed in std::exception::what() message
 *
 * \returns read only transaction
 */
LMDBAL::TransactionID LMDBAL::iStorage::beginReadOnlyTransaction() const {
    return db->beginPrivateReadOnlyTransaction(name);}

/**
 * \brief Begins writable transaction
 *
 * Ment to be called from heirs, name is reported to the database just to be displayed in std::exception::what() message
 *
 * \returns read only transaction
 */
LMDBAL::TransactionID LMDBAL::iStorage::beginTransaction() const {
    return db->beginPrivateTransaction(name);}

/**
 * \brief Aborts transaction
 *
 * Ment to be called from heirs, name is reported to the database just to be displayed in std::exception::what() message
 */
void LMDBAL::iStorage::abortTransaction(LMDBAL::TransactionID id) const {
    db->abortPrivateTransaction(id, name);}

/**
 * \brief Commits transaction
 *
 * Ment to be called from heirs, name is reported to the database just to be displayed in std::exception::what() message
 *
 * \exception LMDBAL::Unknown   thrown if something unexpected happened
 */
void LMDBAL::iStorage::commitTransaction(LMDBAL::TransactionID id) {
    db->commitPrivateTransaction(id, name);}

/**
 * \brief called on beginning of public transaction
 *
 * This function is called on every storage of the database
 * when user calls LMDBAL::Base::beginTransaction() or LMDBAL::Base::beginReadOnlyTransaction()
 *
 * This function is met to be reimplemented in heirs
 * if the heir code requires some transaction custom handling
 *
 * \param[in] txn       - ID of started transaction
 * \param[in] readOnly  - true if transaction is read-only, false otherwise
 */
void LMDBAL::iStorage::transactionStarted(LMDBAL::TransactionID txn, bool readOnly) const {
    UNUSED(txn);
    UNUSED(readOnly);
}

/**
 * \brief called on commitment of public transaction
 *
 * This function is called on every storage of the database
 * when user calls LMDBAL::Base::commitTransaction(LMDBAL::TransactionID)
 *
 * This function is met to be reimplemented in heirs
 * if the heir code requires some transaction custom handling
 *
 * \param[in] txn       - ID of started transaction
 */
void LMDBAL::iStorage::transactionCommited(LMDBAL::TransactionID txn) {
    UNUSED(txn);}

/**
 * \brief called on abortion of public transaction
 *
 * This function is called on every storage of the database
 * when user calls LMDBAL::Base::abortTransaction(LMDBAL::TransactionID)
 *
 * This function is met to be reimplemented in heirs
 * if the heir code requires some transaction custom handling
 *
 * \param[in] txn       - ID of started transaction
 */
void LMDBAL::iStorage::transactionAborted(LMDBAL::TransactionID txn) const {
    UNUSED(txn);}