// Squawk messenger. 
// Copyright (C) 2019  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 "database.h"
#include "exceptions.h"
#include "storage.h"

LMDBDataBase::DataBase::DataBase(const QString& p_name, uint16_t mapSize):
    name(p_name.toStdString()),
    opened(false),
    size(mapSize),
    environment(),
    tables(),
    transactions(new Transactions())
{}

LMDBDataBase::DataBase::~DataBase() {
    close();

    delete transactions;

    for (const std::pair<const std::string, StorageBase*>& pair : tables)
        delete pair.second;
}

void LMDBDataBase::DataBase::close() {
    if (opened) {
        for (const std::pair<const std::string, StorageBase*>& pair : tables) {
            StorageBase* table = pair.second;
            mdb_dbi_close(environment, table->dbi);
        }
        mdb_env_close(environment);
        opened = false;
    }
}

void LMDBDataBase::DataBase::open() {
    if (!opened) {
        mdb_env_create(&environment);
        QString path = createDirectory();

        mdb_env_set_maxdbs(environment, tables.size());
        mdb_env_set_mapsize(environment, size * 1024UL * 1024UL);
        mdb_env_open(environment, path.toStdString().c_str(), 0, 0664);

        MDB_txn *txn;
        mdb_txn_begin(environment, NULL, 0, &txn);

        for (const std::pair<const std::string, StorageBase*>& pair : tables) {
            StorageBase* table = pair.second;
            int rc = table->createTable(txn);
            if (rc)
                throw Unknown(name, mdb_strerror(rc));
        }
        mdb_txn_commit(txn);
        opened = true;
    }
}

bool LMDBDataBase::DataBase::removeDirectory() {
    if (opened)
        throw Opened(name, "remove database directory");

    QString path(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
    path += "/" + getName();
    QDir cache(path);

    if (cache.exists())
        return cache.removeRecursively();
    else
        return true;
}

QString LMDBDataBase::DataBase::createDirectory() {
    if (opened)
        throw Opened(name, "create database directory");

    QString path(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
    path += "/" + getName();
    QDir cache(path);

    if (!cache.exists()) {
        bool res = cache.mkpath(path);
        if (!res)
            throw Directory(path.toStdString());
    }

    return path;
}

QString LMDBDataBase::DataBase::getName() const {
    return QString::fromStdString(name);}

bool LMDBDataBase::DataBase::ready() const {
    return opened;}

void LMDBDataBase::DataBase::drop() {
    if (!opened)
        throw Closed("drop", name);

    MDB_txn *txn;
    int rc = mdb_txn_begin(environment, NULL, 0, &txn);
    if (rc)
        throw Unknown(name, mdb_strerror(rc));

    for (const std::pair<const std::string, StorageBase*>& pair : tables) {
        rc = pair.second->drop(txn);
        if (rc)
            throw Unknown(name, mdb_strerror(rc), pair.first);
    }

    mdb_txn_commit(txn);
}

LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginReadOnlyTransaction() const {
    return beginReadOnlyTransaction(emptyName);}

LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginTransaction() const {
    return beginTransaction(emptyName);}

void LMDBDataBase::DataBase::abortTransaction(LMDBDataBase::TransactionID id) const {
    return abortTransaction(id, emptyName);}

void LMDBDataBase::DataBase::commitTransaction(LMDBDataBase::TransactionID id) const {
    return commitTransaction(id, emptyName);}


LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginReadOnlyTransaction(const std::string& storageName) const {
    if (!opened)
        throw Closed("beginReadOnlyTransaction", name, storageName);

    MDB_txn* txn;
    int rc = mdb_txn_begin(environment, NULL, MDB_RDONLY, &txn);
    if (rc) {
        mdb_txn_abort(txn);
        throw Unknown(name, mdb_strerror(rc), storageName);
    }
    transactions->emplace(txn);
    return txn;
}

LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginTransaction(const std::string& storageName) const {
    if (!opened)
        throw Closed("beginTransaction", name, storageName);

    MDB_txn* txn;
    int rc = mdb_txn_begin(environment, NULL, 0, &txn);
    if (rc) {
        mdb_txn_abort(txn);
        throw Unknown(name, mdb_strerror(rc), storageName);
    }
    transactions->emplace(txn);
    return txn;
}

void LMDBDataBase::DataBase::abortTransaction(LMDBDataBase::TransactionID id, const std::string& storageName) const {
    if (!opened)
        throw Closed("abortTransaction", name, storageName);

    Transactions::iterator itr = transactions->find(id);
    if (itr == transactions->end())     //TODO may be it's a good idea to make an exception class for this
        throw Unknown(name, "unable to abort transaction: transaction was not found", storageName);

    mdb_txn_abort(id);
    transactions->erase(itr);
}

void LMDBDataBase::DataBase::commitTransaction(LMDBDataBase::TransactionID id, const std::string& storageName) const {
    if (!opened)
        throw Closed("abortTransaction", name, storageName);

    Transactions::iterator itr = transactions->find(id);
    if (itr == transactions->end())     //TODO may be it's a good idea to make an exception class for this
        throw Unknown(name, "unable to commit transaction: transaction was not found", storageName);

    int rc = mdb_txn_commit(id);
    transactions->erase(itr);
    if (rc != MDB_SUCCESS)
        throw Unknown(name, mdb_strerror(rc), storageName);
}