/*
 *  The Mana Server
 *  Copyright (C) 2004-2010  The Mana World Development Team
 *
 *  This file is part of The Mana Server.
 *
 *  The Mana Server 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
 *  any later version.
 *
 *  The Mana Server 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 The Mana Server.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "mysqldataprovider.h"

#include "dalexcept.h"

namespace dal
{

const std::string  MySqlDataProvider::CFGPARAM_MYSQL_HOST ="mysql_hostname";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_PORT ="mysql_port";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_DB   ="mysql_database";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_USER ="mysql_username";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_PWD  ="mysql_password";

const std::string  MySqlDataProvider::CFGPARAM_MYSQL_HOST_DEF = "localhost";
const unsigned     MySqlDataProvider::CFGPARAM_MYSQL_PORT_DEF = 3306;
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_DB_DEF   = "mana";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_USER_DEF = "mana";
const std::string  MySqlDataProvider::CFGPARAM_MYSQL_PWD_DEF  = "mana";

MySqlDataProvider::MySqlDataProvider()
    throw()
        : mDb(0),
          mStmt(0),
          mBind(0),
          mInTransaction(false)
{
}

MySqlDataProvider::~MySqlDataProvider()
    throw()
{
    // we are using the MySQL C API, there are no exceptions to catch.

    // make sure that the database is closed.
    // disconnect() calls mysql_close() which takes care of freeing
    // the memory allocated for the handle.
    if (mIsConnected)
        disconnect();
}

/**
 * Get the database backend name.
 */
DbBackends MySqlDataProvider::getDbBackend() const
    throw()
{
    return DB_BKEND_MYSQL;
}

/**
 * Create a connection to the database.
 */
void MySqlDataProvider::connect()
{
    if (mIsConnected)
        return;

    // retrieve configuration from config file
    const std::string hostname
        = Configuration::getValue(CFGPARAM_MYSQL_HOST, CFGPARAM_MYSQL_HOST_DEF);
    const std::string dbName
        = Configuration::getValue(CFGPARAM_MYSQL_DB, CFGPARAM_MYSQL_DB_DEF);
    const std::string username
        = Configuration::getValue(CFGPARAM_MYSQL_USER, CFGPARAM_MYSQL_USER_DEF);
    const std::string password
        = Configuration::getValue(CFGPARAM_MYSQL_PWD, CFGPARAM_MYSQL_PWD_DEF);
    const unsigned tcpPort
        = Configuration::getValue(CFGPARAM_MYSQL_PORT, CFGPARAM_MYSQL_PORT_DEF);

    // allocate and initialize a new MySQL object suitable
    // for mysql_real_connect().
    mDb = mysql_init(nullptr);

    if (!mDb)
    {
        throw DbConnectionFailure(
            "unable to initialize the MySQL library: no memory");
    }

    LOG_INFO("Trying to connect with mySQL database server '"
        << hostname << ":" << tcpPort << "' using '" << username
        << "' as user, and '" << dbName << "' as database.");

    // actually establish the connection.
    if (!mysql_real_connect(mDb,                // handle to the connection
                            hostname.c_str(),   // hostname
                            username.c_str(),   // username
                            password.c_str(),   // password
                            dbName.c_str(),     // database name
                            tcpPort,            // tcp port
                            nullptr,               // socket, currently not used
                            CLIENT_FOUND_ROWS)) // client flags
    {
        std::string msg(mysql_error(mDb));
        mysql_close(mDb);

        throw DbConnectionFailure(msg);
    }

    // Save the Db Name.
    mDbName = dbName;

    // Initialize statement structure
    mStmt = mysql_stmt_init(mDb);

    mIsConnected = true;
    LOG_INFO("Connection to mySQL was sucessfull.");
}

/**
 * Execute a SQL query.
 */
const RecordSet &MySqlDataProvider::execSql(const std::string& sql,
                                            const bool refresh)
{
    if (!mIsConnected)
        throw std::runtime_error("not connected to database");

    LOG_DEBUG("MySqlDataProvider::execSql Performing SQL query: " << sql);

    // do something only if the query is different from the previous
    // or if the cache must be refreshed
    // otherwise just return the recordset from cache.
    if (refresh || (sql != mSql))
    {
        mRecordSet.clear();

        // actually execute the query.
        if (mysql_query(mDb, sql.c_str()) != 0)
            throw DbSqlQueryExecFailure(mysql_error(mDb));

        if (mysql_field_count(mDb) > 0)
        {
            MYSQL_RES* res;

            // get the result of the query.
            if (!(res = mysql_store_result(mDb)))
                throw DbSqlQueryExecFailure(mysql_error(mDb));

            // set the field names.
            unsigned nFields = mysql_num_fields(res);
            MYSQL_FIELD* fields = mysql_fetch_fields(res);
            Row fieldNames;
            for (unsigned i = 0; i < nFields; ++i)
                fieldNames.push_back(fields[i].name);

            mRecordSet.setColumnHeaders(fieldNames);

            // populate the RecordSet.
            MYSQL_ROW row;
            while ((row = mysql_fetch_row(res)))
            {
                Row r;

                for (unsigned i = 0; i < nFields; ++i)
                    r.push_back(static_cast<char *>(row[i]));

                mRecordSet.add(r);
            }

            // free memory
            mysql_free_result(res);
        }
    }

    return mRecordSet;
}

/**
 * Close the connection to the database.
 */
void MySqlDataProvider::disconnect()
{
    if (!mIsConnected)
        return;

    // mysql_close() closes the connection and deallocates the connection
    // handle allocated by mysql_init().
    mysql_close(mDb);

    // Clean possible statement.
    mysql_stmt_close(mStmt);

    // deinitialize the MySQL client library.
    mysql_library_end();

    // Clean potential active binds
    cleanBinds();

    mDb = 0;
    mIsConnected = false;
}

void MySqlDataProvider::beginTransaction()
    throw (std::runtime_error)
{
    if (!mIsConnected)
    {
        const std::string error = "Trying to begin a transaction while not "
                                  "connected to the database!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (inTransaction())
    {
        const std::string error = "Trying to begin a transaction while another "
                                  "one is still open!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (mysql_autocommit(mDb, AUTOCOMMIT_OFF))
    {
        const std::string error = "Error while trying to disable autocommit";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    mInTransaction = true;
    execSql("BEGIN");
    LOG_DEBUG("SQL: started transaction");
}

void MySqlDataProvider::commitTransaction()
    throw (std::runtime_error)
{
    if (!mIsConnected)
    {
        const std::string error = "Trying to commit a transaction while not "
                                  "connected to the database!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (!inTransaction())
    {
        const std::string error = "Trying to commit a transaction while no "
                                  "one is open!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (mysql_commit(mDb) != 0)
    {
        LOG_ERROR("MySqlDataProvider::commitTransaction: " << mysql_error(mDb));
        throw DbSqlQueryExecFailure(mysql_error(mDb));
    }

    if (mysql_autocommit(mDb, AUTOCOMMIT_ON))
    {
        const std::string error = "Error while trying to enable autocommit";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    mInTransaction = false;
    LOG_DEBUG("SQL: commited transaction");
}

void MySqlDataProvider::rollbackTransaction()
    throw (std::runtime_error)
{
    if (!mIsConnected)
    {
        const std::string error = "Trying to rollback a transaction while not "
                                  "connected to the database!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (!inTransaction())
    {
        const std::string error = "Trying to rollback a transaction while no "
                                  "one is open!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    if (mysql_rollback(mDb) != 0)
    {
        LOG_ERROR("MySqlDataProvider::rollbackTransaction: "
                  << mysql_error(mDb));
        throw DbSqlQueryExecFailure(mysql_error(mDb));
    }

    mysql_autocommit(mDb, AUTOCOMMIT_ON);
    mInTransaction = false;
    LOG_DEBUG("SQL: transaction rolled back");
}

bool MySqlDataProvider::inTransaction() const
{
    return mInTransaction;
}

unsigned MySqlDataProvider::getModifiedRows() const
{
    if (!mIsConnected)
    {
        const std::string error = "Trying to getModifiedRows while not "
                                  "connected to the database!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    const my_ulonglong affected = mysql_affected_rows(mDb);

    if (affected > INT_MAX)
        throw std::runtime_error(
                               "MySqlDataProvider::getLastId exceeded INT_MAX");

    if (affected == (my_ulonglong)-1)
    {
        LOG_ERROR("MySqlDataProvider::getModifiedRows: " << mysql_error(mDb));
        throw DbSqlQueryExecFailure(mysql_error(mDb));
    }

    return (unsigned) affected;
}

unsigned MySqlDataProvider::getLastId() const
{
    if (!mIsConnected)
    {
        const std::string error = "not connected to the database!";
        LOG_ERROR(error);
        throw std::runtime_error(error);
    }

    const my_ulonglong lastId = mysql_insert_id(mDb);
    if (lastId > UINT_MAX)
        throw std::runtime_error(
                              "MySqlDataProvider::getLastId exceeded UINT_MAX");

    return (unsigned) lastId;
}

bool MySqlDataProvider::prepareSql(const std::string &sql)
{
    if (!mIsConnected)
        return false;

    LOG_DEBUG("MySqlDataProvider::prepareSql Preparing SQL statement: " << sql);

    cleanBinds();

    if (mysql_stmt_prepare(mStmt, sql.c_str(), sql.size()) != 0)
        return false;

    // Allocate bind memory now that the prepared state is done.
    mBind = new MYSQL_BIND[(int)mysql_stmt_param_count(mStmt)];

    return true;
}

const RecordSet &MySqlDataProvider::processSql()
{
    if (!mIsConnected)
        throw std::runtime_error("not connected to database");

    // Since we'll have to return something in all cases,
    // we clear the result member first.
    mRecordSet.clear();

    if (!mBind)
    {
        LOG_ERROR("MySqlDataProvider::processSql: "
                  "No bind done before processing.");
        return mRecordSet;
    }

    if (mysql_stmt_bind_param(mStmt, mBind))
    {
        LOG_ERROR("MySqlDataProvider::processSql Bind params failed: "
                  << mysql_stmt_error(mStmt));
        return mRecordSet;
    }

    if (mysql_stmt_field_count(mStmt) > 0)
    {
        MYSQL_BIND* resultBind;
        MYSQL_RES* res;

        if (mysql_stmt_execute(mStmt))
        {
            LOG_ERROR("MySqlDataProvider::processSql Execute failed: "
                      << mysql_stmt_error(mStmt));
        }

        res = mysql_stmt_result_metadata(mStmt);

        // set the field names.
        unsigned nFields = mysql_num_fields(res);
        MYSQL_FIELD* fields = mysql_fetch_fields(res);
        Row fieldNames;

        resultBind = new MYSQL_BIND[mysql_num_fields(res)];

        unsigned i = 0;
        for (i = 0; i < mysql_num_fields(res); ++i)
        {
            resultBind[i].buffer_type = MYSQL_TYPE_STRING;
            resultBind[i].buffer = (void*) new char[255];
            resultBind[i].buffer_length = 255;
            resultBind[i].is_null = new my_bool;
            resultBind[i].length = new unsigned long;
            resultBind[i].error = new my_bool;
        }

        if (mysql_stmt_bind_result(mStmt, resultBind))
        {
            LOG_ERROR("MySqlDataProvider::processSql Bind result failed: "
                      << mysql_stmt_error(mStmt));
        }

        for (i = 0; i < nFields; ++i)
            fieldNames.push_back(fields[i].name);

        mRecordSet.setColumnHeaders(fieldNames);

        // store the result of the query.
        if (mysql_stmt_store_result(mStmt))
            throw DbSqlQueryExecFailure(mysql_stmt_error(mStmt));

        // populate the RecordSet.
        while (!mysql_stmt_fetch(mStmt))
        {
            Row r;

            for (i = 0; i < nFields; ++i)
                r.push_back(static_cast<char *>(resultBind[i].buffer));

            mRecordSet.add(r);
        }

        delete[] resultBind;
    }
    else
    {
        if (mysql_stmt_execute(mStmt))
        {
            LOG_ERROR("MySqlDataProvider::processSql Execute failed: "
                      << mysql_stmt_error(mStmt));
        }
    }

    // Free memory
    mysql_stmt_free_result(mStmt);

    return mRecordSet;
}

void MySqlDataProvider::bindValue(int place, const std::string &value)
{
    unsigned long* size = new unsigned long;
    *size = value.size();
    MYSQL_BIND* bind = new MYSQL_BIND;
    bind->buffer_type= MYSQL_TYPE_STRING;
    bind->buffer= (void*) value.c_str();
    bind->buffer_length= value.size();
    bind->length = size;
    bind->is_null = 0;

    bindValue(place, bind);
}

void MySqlDataProvider::bindValue(int place, int value)
{
    MYSQL_BIND* bind = new MYSQL_BIND;
    bind->buffer_type= MYSQL_TYPE_LONG;
    bind->buffer= &value;
    bind->is_null = 0;

    bindValue(place, bind);
}

void MySqlDataProvider::bindValue(int place, MYSQL_BIND* bind)
{
    if (!mBind)
        LOG_ERROR("MySqlDataProvider::bindValue: "
                  "Attempted to use an unprepared bind!");
    else if (place > 0 && place <= (int)mysql_stmt_param_count(mStmt))
        mBind[place - 1] = *bind;
    else
        LOG_ERROR("MySqlDataProvider::bindValue: "
                  "Attempted bind index out of range");
}

void MySqlDataProvider::cleanBinds()
{
    if (mBind)
    {
        delete[] mBind;
        mBind = 0;
    }
}

} // namespace dal