/*
 * Copyright (C) 2008-2015 TrinityCore <http://www.trinitycore.org/>
 *
 * 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 2 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 "DatabaseLoader.h"
#include "DBUpdater.h"
#include "Config.h"

#include <mysqld_error.h>

DatabaseLoader::DatabaseLoader(std::string const& logger, uint32 const defaultUpdateMask)
    : _logger(logger), _autoSetup(sConfigMgr->GetBoolDefault("Updates.AutoSetup", true)),
    _updateFlags(sConfigMgr->GetIntDefault("Updates.EnableDatabases", defaultUpdateMask))
{
}

template <class T>
DatabaseLoader& DatabaseLoader::AddDatabase(DatabaseWorkerPool<T>& pool, std::string const& name)
{
    bool const updatesEnabledForThis = DBUpdater<T>::IsEnabled(_updateFlags);

    _open.push(std::make_pair([this, name, updatesEnabledForThis, &pool]() -> bool
    {
        std::string const dbString = sConfigMgr->GetStringDefault(name + "DatabaseInfo", "");
        if (dbString.empty())
        {
            TC_LOG_ERROR(_logger.c_str(), "Database %s not specified in configuration file!", name.c_str());
            return false;
        }

        uint8 const asyncThreads = uint8(sConfigMgr->GetIntDefault(name + "Database.WorkerThreads", 1));
        if (asyncThreads < 1 || asyncThreads > 32)
        {
            TC_LOG_ERROR(_logger.c_str(), "%s database: invalid number of worker threads specified. "
                "Please pick a value between 1 and 32.", name.c_str());
            return false;
        }

        uint8 const synchThreads = uint8(sConfigMgr->GetIntDefault(name + "Database.SynchThreads", 1));

        pool.SetConnectionInfo(dbString, asyncThreads, synchThreads);
        if (uint32 error = pool.Open())
        {
            // Database does not exist
            if ((error == ER_BAD_DB_ERROR) && updatesEnabledForThis && _autoSetup)
            {
                // Try to create the database and connect again if auto setup is enabled
                if (DBUpdater<T>::Create(pool) && (!pool.Open()))
                    error = 0;
            }

            // If the error wasn't handled quit
            if (error)
            {
                TC_LOG_ERROR("sql.driver", "\nDatabasePool %s NOT opened. There were errors opening the MySQL connections. Check your SQLDriverLogFile "
                    "for specific errors. Read wiki at http://www.trinitycore.info/display/tc/TrinityCore+Home", name.c_str());

                return false;
            }
        }
        return true;
    },
    [&pool]()
    {
        pool.Close();
    }));

    // Populate and update only if updates are enabled for this pool
    if (updatesEnabledForThis)
    {
        _populate.push([this, name, &pool]() -> bool
        {
            if (!DBUpdater<T>::Populate(pool))
            {
                TC_LOG_ERROR(_logger.c_str(), "Could not populate the %s database, see log for details.", name.c_str());
                return false;
            }
            return true;
        });

        _update.push([this, name, &pool]() -> bool
        {
            if (!DBUpdater<T>::Update(pool))
            {
                TC_LOG_ERROR(_logger.c_str(), "Could not update the %s database, see log for details.", name.c_str());
                return false;
            }
            return true;
        });
    }

    _prepare.push([this, name, &pool]() -> bool
    {
        if (!pool.PrepareStatements())
        {
            TC_LOG_ERROR(_logger.c_str(), "Could not prepare statements of the %s database, see log for details.", name.c_str());
            return false;
        }
        return true;
    });

    return *this;
}

bool DatabaseLoader::Load()
{
    if (!_updateFlags)
        TC_LOG_INFO("sql.updates", "Automatic database updates are disabled for all databases!");

    if (!OpenDatabases())
        return false;

    if (!PopulateDatabases())
        return false;

    if (!UpdateDatabases())
        return false;

    if (!PrepareStatements())
        return false;

    return true;
}

bool DatabaseLoader::OpenDatabases()
{
    while (!_open.empty())
    {
        std::pair<Predicate, std::function<void()>> const load = _open.top();
        if (load.first())
            _close.push(load.second);
        else
        {
            // Close all loaded databases
            while (!_close.empty())
            {
                _close.top()();
                _close.pop();
            }
            return false;
        }

        _open.pop();
    }
    return true;
}

// Processes the elements of the given stack until a predicate returned false.
bool DatabaseLoader::Process(std::stack<Predicate>& stack)
{
    while (!stack.empty())
    {
        if (!stack.top()())
            return false;

        stack.pop();
    }
    return true;
}

bool DatabaseLoader::PopulateDatabases()
{
    return Process(_populate);
}

bool DatabaseLoader::UpdateDatabases()
{
    return Process(_update);
}

bool DatabaseLoader::PrepareStatements()
{
    return Process(_prepare);
}

template
DatabaseLoader& DatabaseLoader::AddDatabase<LoginDatabaseConnection>(DatabaseWorkerPool<LoginDatabaseConnection>& pool, std::string const& name);
template
DatabaseLoader& DatabaseLoader::AddDatabase<WorldDatabaseConnection>(DatabaseWorkerPool<WorldDatabaseConnection>& pool, std::string const& name);
template
DatabaseLoader& DatabaseLoader::AddDatabase<CharacterDatabaseConnection>(DatabaseWorkerPool<CharacterDatabaseConnection>& pool, std::string const& name);
template
DatabaseLoader& DatabaseLoader::AddDatabase<HotfixDatabaseConnection>(DatabaseWorkerPool<HotfixDatabaseConnection>& pool, std::string const& name);