/****************************************************************************
**
** Implementation of QSqlDriver class
**
** Created : 2000-11-03
**
** Copyright (C) 2000 Trolltech AS.  All rights reserved.
**
** This file is part of the sql module of the Qt GUI Toolkit.
**
** This file may be distributed under the terms of the Q Public License
** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** Licensees holding valid Qt Enterprise Edition licenses may use this
** file in accordance with the Qt Commercial License Agreement provided
** with the Software.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
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**   information about Qt Commercial License Agreements.
** See http://www.trolltech.com/qpl/ for QPL licensing information.
** See http://www.trolltech.com/gpl/ for GPL licensing information.
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**********************************************************************/

#include "qsqldriver.h"

#ifndef QT_NO_SQL

#include "qdatetime.h"
#include "qregexp.h"

// database states
#define DBState_Open		0x0001
#define DBState_OpenError	0x0002

/*!
  \class QSqlDriver qsqldriver.h
    \ingroup database

  \brief The QSqlDriver class is an abstract base class for accessing
  SQL databases.

  \module sql

  This class should not be used directly.
  Use QSqlDatabase instead.

*/

/*!  Default constructor. Creates a new driver with parent \a parent and
   name \a name.

*/

QSqlDriver::QSqlDriver( QObject * parent, const char * name )
: QObject(parent, name),
  dbState(0),
  error()
{
}

/*! Destroys the object and frees any allocated resources.

*/

QSqlDriver::~QSqlDriver()
{
}

/*! \fn bool QSqlDriver::open( const QString& db, const QString& user,
    const QString& password, const QString& host, int port )

    Derived classes must reimplement this abstract virtual function in
    order to open a database connection on database \a db, using user
    name \a user, password \a password, host \a host and port \a port.

    The function \e must return TRUE on success and FALSE on failure.

    \sa setOpen()

*/

/*! \fn bool QSqlDriver::close()
    Derived classes must reimplement this abstract virtual function in
    order to close the database connection. Return TRUE on success,
    FALSE on failure.

    \sa setOpen()

*/

/*! \fn QSqlQuery QSqlDriver::createQuery() const
    Creates an empty SQL result on the database.  Derived classes must
    reimplement this function and return a QSqlQuery object appropriate
    for their database to the caller.

*/

//void QSqlDriver::destroyResult( QSqlResult* r ) const
//{
//    if ( r )
//	delete r;
//}

/*!  Returns TRUE if the database connection is open, FALSE otherwise.

*/

bool QSqlDriver::isOpen() const
{
    return ((dbState & DBState_Open) == DBState_Open);
}

/*!  Returns TRUE if the there was an error opening the database
    connection, FALSE otherwise.

*/

bool QSqlDriver::isOpenError() const
{
    return ((dbState & DBState_OpenError) == DBState_OpenError);
}

/*! \enum QSqlDriver::DriverFeature

  This enum contains a list of features a driver may support. Use hasFeature()
  to query whether a feature is supported or not.

  The currently defined values are:

  \value Transactions  whether the driver supports SQL transactions
  \value QuerySize  whether the database is capable of reporting the size
  of a query. Note that some databases do not support returning the size
  (i.e. number of rows returned) of a query, in which case QSqlQuery::size() will return -1
  \value BLOB  whether the driver supports Binary Large Object fields

  \sa hasFeature()

*/

/*! \fn bool QSqlDriver::hasFeature( DriverFeature f ) const

  Returns TRUE if the driver supports feature \a f; otherwise returns FALSE.

  Note that some databases need to be open() before this can be
  determined.

  \sa DriverFeature

*/

/*! Protected function which sets the open state of the database to \a o.
    Derived classes can use this function to report the status of open().

    \sa open(), setOpenError()

*/

void QSqlDriver::setOpen( bool o )
{
    if ( o )
	dbState |= DBState_Open;
    else
	dbState &= ~DBState_Open;
}

/*! Protected function which sets the open error state of the database to \a e.
    Derived classes can use this function to report the status of open().
    Note that if \a e is TRUE the open state of the database is set to closed
    (i.e., isOpen() returns FALSE).

    \sa open(), setOpenError()

*/

void QSqlDriver::setOpenError( bool e )
{
    if ( e ) {
	dbState |= DBState_OpenError;
	dbState &= ~DBState_Open;
    }
    else
	dbState &= ~DBState_OpenError;
}

/*! Protected function which derived classes can reimplement to begin a
    transaction. If successful, return TRUE, otherwise return FALSE.
    The default implementation returns FALSE.

    \sa commitTransaction(), rollbackTransaction()

*/

bool QSqlDriver::beginTransaction()
{
    return FALSE;
}

/*! Protected function which derived classes can reimplement to commit a
    transaction. If successful, return TRUE, otherwise return FALSE. The
    default implementation returns FALSE.

    \sa beginTransaction(), rollbackTransaction()

*/

bool QSqlDriver::commitTransaction()
{
    return FALSE;
}

/*! Protected function which derived classes can reimplement to rollback a
    transaction. If successful, return TRUE, otherwise return FALSE.
    The default implementation returns FALSE.

    \sa beginTransaction(), commitTransaction()

*/

bool QSqlDriver::rollbackTransaction()
{
    return FALSE;
}

/*! Protected function which allows derived classes to set the value of
    the last error, \a e, that occurred on the database.

    \sa lastError()

*/

void QSqlDriver::setLastError( const QSqlError& e )
{
    error = e;
}

/*! Returns a QSqlError object which contains information about the last
    error that occurred on the database.

*/

QSqlError QSqlDriver::lastError() const
{
    return error;
}

/*!
  Returns a list of tables in the database.  The default
  implementation returns an empty list.

  Currently the \a user argument is unused.
*/

QStringList QSqlDriver::tables( const QString&	) const
{
    return QStringList();
}

/*!
  Returns the primary index for table \a tableName.  Returns an empty
  QSqlIndex if the table doesn't have a primary index. The default
  implementation returns an empty index.

*/

QSqlIndex QSqlDriver::primaryIndex( const QString& ) const
{
    return QSqlIndex();
}


/*!
  Returns a QSqlRecord populated with the names of the fields in table
  \a tableName.	 If no such table exists, an empty list is returned.
  The default implementation returns an empty record.

*/

QSqlRecord QSqlDriver::record( const QString&  ) const
{
    return QSqlRecord();
}

/*! \overload

  Returns a QSqlRecord populated with the names of the fields in the
  SQL \a query. The default implementation returns an empty record.

*/

QSqlRecord QSqlDriver::record( const QSqlQuery& ) const
{
   return QSqlRecord();
}

/*! Returns a QSqlRecordInfo object with meta data on the table \a tablename.
*/
QSqlRecordInfo QSqlDriver::recordInfo( const QString& tablename ) const
{
    return QSqlRecordInfo( record( tablename ) );
}

/*! \overload

    Returns a QSqlRecordInfo object with meta data for the QSqlQuery \a query.
    Note that this overloaded function may return not as much information as
    the recordInfo function which takes the name of a table as parameter.

*/
QSqlRecordInfo QSqlDriver::recordInfo( const QSqlQuery& query ) const
{
    return QSqlRecordInfo( record( query ) );
}


/*!  Returns a string representation of the 'NULL' value for the
  database.  This is used, for example, when constructing INSERT and
  UPDATE statements.  The default implementation returns the string 'NULL'.

*/

QString QSqlDriver::nullText() const
{
    return "NULL";
}

/*!  Returns a string representation of the \a field value for the
  database.  This is used, for example, when constructing INSERT and
  UPDATE statements.

  The default implementation returns the value formatted as a string
  according to the following rules:

  <ul>

  <li> If \a field is null, nullText() is returned.

  <li> If \a field is character data, the value is returned enclosed
  in single quotation marks, which is appropriate for many SQL
  databases. Any embedded single-quote characters are escaped
  (replaced with two single-quote characters). If \a trimStrings is
  TRUE (the default is FALSE), all trailing whitespace is trimmed from
  the field.

  <li> If \a field is date/time data, the value is formatted in ISO
  format and enclosed in single quotation marks.  If the date/time
  data is invalid, nullText() is returned.

  <li> If \a field is bytearray data, and the driver can edit binary
  fields, the value is formatted as a hexadecimal string.

  <li> For any other field type toString() will be called on its value
  and the result returned.

  </ul>

  \sa QVariant::toString().

*/
QString QSqlDriver::formatValue( const QSqlField* field, bool trimStrings ) const
{
    QString r;
    if ( field->isNull() )
	r = nullText();
    else {
	switch ( field->type() ) {
	case QVariant::Date:
	    if ( field->value().toDate().isValid() )
		r = "'" + field->value().toDate().toString( Qt::ISODate ) + "'";
	    else
		r = nullText();
	    break;
	case QVariant::Time:
	    if ( field->value().toTime().isValid() )
		r = "'" + field->value().toTime().toString( Qt::ISODate ) + "'";
	    else
		r = nullText();
	    break;
	case QVariant::DateTime:
	    if ( field->value().toDateTime().isValid() )
		r = "'" +
		    field->value().toDateTime().toString( Qt::ISODate ) + "'";
	    else
		r = nullText();
	    break;
	case QVariant::String:
	case QVariant::CString: {
	    QString result = field->value().toString();
	    if ( trimStrings ) {
		int end = result.length() - 1;
		while ( end && result[end].isSpace() ) /* skip white space from end */
		    end--;
		result.truncate( end );
	    }
	    /* escape the "'" character */
	    result.replace( QRegExp( "'" ), "''" );
	    r = "'" + result + "'";
	    break;
	}
	case QVariant::ByteArray : {
	    if ( hasFeature( BLOB ) ) {
		QByteArray ba = field->value().toByteArray();
		QString res;
		static const char hexchars[] = "0123456789abcdef";
		for ( uint i = 0; i < ba.size(); ++i ) {
		    uchar s = (uchar) ba[(int)i];
		    res += hexchars[s >> 4];
		    res += hexchars[s & 0x0f];
		}
		r = "'" + res + "'";
		break;
	    }
	}
	default:
	    r = field->value().toString();
	    break;
	}
    }
    return r;
}

#endif // QT_NO_SQL
