alter.cpp

/* This file is part of the KDE project
   Copyright (C) 2006-2007 Jaroslaw Staniek <js@iidea.pl>
 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
 
   This library 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
   Library General Public License for more details.
 
   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
*/
 
#include "alter.h"
#include "utils.h"
#include <kexiutils/utils.h>
 
#include <tqmap.h>
 
#include <kstaticdeleter.h>
 
#include <stdlib.h>
 
namespace KexiDB {
class AlterTableHandler::Private
{
    public:
        Private()
        {}
        ~Private()
        {}
        ActionList actions;
        TQGuardedPtr<Connection> conn;
};
}
 
using namespace KexiDB;
 
AlterTableHandler::ChangeFieldPropertyAction nullChangeFieldPropertyAction(true);
AlterTableHandler::RemoveFieldAction nullRemoveFieldAction(true);
AlterTableHandler::InsertFieldAction nullInsertFieldAction(true);
AlterTableHandler::MoveFieldPositionAction nullMoveFieldPositionAction(true);
 
//--------------------------------------------------------
 
AlterTableHandler::ActionBase::ActionBase(bool null)
 : m_alteringRequirements(0)
 , m_order(-1)
 , m_null(null)
{
}
 
AlterTableHandler::ActionBase::~ActionBase()
{
}
 
AlterTableHandler::ChangeFieldPropertyAction& AlterTableHandler::ActionBase::toChangeFieldPropertyAction()
{
    if (dynamic_cast<ChangeFieldPropertyAction*>(this))
        return *dynamic_cast<ChangeFieldPropertyAction*>(this);
    return nullChangeFieldPropertyAction;
}
 
AlterTableHandler::RemoveFieldAction& AlterTableHandler::ActionBase::toRemoveFieldAction()
{
    if (dynamic_cast<RemoveFieldAction*>(this))
        return *dynamic_cast<RemoveFieldAction*>(this);
    return nullRemoveFieldAction;
}
 
AlterTableHandler::InsertFieldAction& AlterTableHandler::ActionBase::toInsertFieldAction()
{
    if (dynamic_cast<InsertFieldAction*>(this))
        return *dynamic_cast<InsertFieldAction*>(this);
    return nullInsertFieldAction;
}
 
AlterTableHandler::MoveFieldPositionAction& AlterTableHandler::ActionBase::toMoveFieldPositionAction()
{
    if (dynamic_cast<MoveFieldPositionAction*>(this))
        return *dynamic_cast<MoveFieldPositionAction*>(this);
    return nullMoveFieldPositionAction;
}
 
//--------------------------------------------------------
 
AlterTableHandler::FieldActionBase::FieldActionBase(const TQString& fieldName, int uid)
 : ActionBase()
 , m_fieldUID(uid)
 , m_fieldName(fieldName)
{
}
 
AlterTableHandler::FieldActionBase::FieldActionBase(bool)
 : ActionBase(true)
 , m_fieldUID(-1)
{
}
 
AlterTableHandler::FieldActionBase::~FieldActionBase()
{
}
 
//--------------------------------------------------------
 
static KStaticDeleter< TQMap<TQCString,int> > KexiDB_alteringTypeForProperty_deleter;
TQMap<TQCString,int> *KexiDB_alteringTypeForProperty = 0;
 
int AlterTableHandler::alteringTypeForProperty(const TQCString& propertyName)
{
    if (!KexiDB_alteringTypeForProperty) {
        KexiDB_alteringTypeForProperty_deleter.setObject( KexiDB_alteringTypeForProperty, 
            new TQMap<TQCString,int>() );
#define I(name, type) \
    KexiDB_alteringTypeForProperty->insert(TQCString(name).lower(), (int)AlterTableHandler::type)
#define I2(name, type1, type2) \
    flag = (int)AlterTableHandler::type1|(int)AlterTableHandler::type2; \
    if (flag & AlterTableHandler::PhysicalAlteringRequired) \
        flag |= AlterTableHandler::MainSchemaAlteringRequired; \
    KexiDB_alteringTypeForProperty->insert(TQCString(name).lower(), flag)
 
    /* useful links: 
        http://dev.mysql.com/doc/refman/5.0/en/create-table.html
    */
        // ExtendedSchemaAlteringRequired is here because when the field is renamed, 
        // we need to do the same rename in extended table schema: <field name="...">
        int flag;
        I2("name", PhysicalAlteringRequired, MainSchemaAlteringRequired);
        I2("type", PhysicalAlteringRequired, DataConversionRequired);
        I("caption", MainSchemaAlteringRequired);
        I("description", MainSchemaAlteringRequired);
        I2("unsigned", PhysicalAlteringRequired, DataConversionRequired); // always?
        I2("length", PhysicalAlteringRequired, DataConversionRequired); // always?
        I2("precision", PhysicalAlteringRequired, DataConversionRequired); // always?
        I("width", MainSchemaAlteringRequired);
        // defaultValue: depends on backend, for mysql it can only by a constant or now()...
        // -- should we look at Driver here?
#ifdef KEXI_NO_UNFINISHED
        I("defaultValue", MainSchemaAlteringRequired);
#else
        I2("defaultValue", PhysicalAlteringRequired, MainSchemaAlteringRequired);
#endif
        I2("primaryKey", PhysicalAlteringRequired, DataConversionRequired);
        I2("unique", PhysicalAlteringRequired, DataConversionRequired); // we may want to add an Index here
        I2("notNull", PhysicalAlteringRequired, DataConversionRequired); // we may want to add an Index here
        // allowEmpty: only support it just at kexi level? maybe there is a backend that supports this?
        I2("allowEmpty", PhysicalAlteringRequired, MainSchemaAlteringRequired); 
        I2("autoIncrement", PhysicalAlteringRequired, DataConversionRequired); // data conversion may be hard here
        I2("indexed", PhysicalAlteringRequired, DataConversionRequired); // we may want to add an Index here
 
        // easier cases follow...
        I("visibleDecimalPlaces", ExtendedSchemaAlteringRequired);
 
        // lookup-field-related properties...
/*moved to KexiDB::isExtendedTableFieldProperty()
        I("boundColumn", ExtendedSchemaAlteringRequired);
        I("rowSource", ExtendedSchemaAlteringRequired);
        I("rowSourceType", ExtendedSchemaAlteringRequired);
        I("rowSourceValues", ExtendedSchemaAlteringRequired);
        I("visibleColumn", ExtendedSchemaAlteringRequired);
        I("columnWidths", ExtendedSchemaAlteringRequired);
        I("showColumnHeaders", ExtendedSchemaAlteringRequired);
        I("listRows", ExtendedSchemaAlteringRequired);
        I("limitToList", ExtendedSchemaAlteringRequired);
        I("displayWidget", ExtendedSchemaAlteringRequired);*/
 
        //more to come...
#undef I
#undef I2
    }
    const int res = (*KexiDB_alteringTypeForProperty)[propertyName.lower()];
    if (res == 0) {
        if (KexiDB::isExtendedTableFieldProperty(propertyName))
            return (int)ExtendedSchemaAlteringRequired;
        KexiDBWarn << TQString("AlterTableHandler::alteringTypeForProperty(): property \"%1\" not found!")
            .arg(propertyName.data()) << endl;
    }
    return res;
}
 
//---
 
AlterTableHandler::ChangeFieldPropertyAction::ChangeFieldPropertyAction(
    const TQString& fieldName, const TQString& propertyName, const TQVariant& newValue, int uid)
 : FieldActionBase(fieldName, uid)
 , m_propertyName(propertyName)
 , m_newValue(newValue)
{
}
 
AlterTableHandler::ChangeFieldPropertyAction::ChangeFieldPropertyAction(bool)
 : FieldActionBase(true)
{
}
 
AlterTableHandler::ChangeFieldPropertyAction::~ChangeFieldPropertyAction()
{
}
 
void AlterTableHandler::ChangeFieldPropertyAction::updateAlteringRequirements()
{
//  m_alteringRequirements = ???;
    setAlteringRequirements( alteringTypeForProperty( m_propertyName.latin1() ) );
}
 
TQString AlterTableHandler::ChangeFieldPropertyAction::debugString(const DebugOptions& debugOptions)
{
    TQString s = TQString("Set \"%1\" property for table field \"%2\" to \"%3\"")
        .arg(m_propertyName).arg(fieldName()).arg(m_newValue.toString());
    if (debugOptions.showUID)
        s.append(TQString(" (UID=%1)").arg(m_fieldUID));
    return s;
}
 
static AlterTableHandler::ActionDict* createActionDict( 
    AlterTableHandler::ActionDictDict &fieldActions, int forFieldUID )
{
    AlterTableHandler::ActionDict* dict = new AlterTableHandler::ActionDict(1009, false);
    dict->setAutoDelete(true);
    fieldActions.insert( forFieldUID, dict );
    return dict;
}
 
static void debugAction(AlterTableHandler::ActionBase *action, int nestingLevel, 
  bool simulate, const TQString& prependString = TQString(), TQString* debugTarget = 0)
{
    TQString debugString;
    if (!debugTarget)
        debugString = prependString;
    if (action) {
        AlterTableHandler::ActionBase::DebugOptions debugOptions;
        debugOptions.showUID = debugTarget==0;
        debugOptions.showFieldDebug = debugTarget!=0;
        debugString += action->debugString( debugOptions );
    }
    else {
        if (!debugTarget)
            debugString += "[No action]"; //hmm
    }
    if (debugTarget) {
        if (!debugString.isEmpty())
            *debugTarget += debugString + '\n';
    }
    else {
        KexiDBDbg << debugString << endl;
#ifdef KEXI_DEBUG_GUI
        if (simulate)
            KexiUtils::addAlterTableActionDebug(debugString, nestingLevel);
#endif
    }
}
 
static void debugActionDict(AlterTableHandler::ActionDict *dict, int fieldUID, bool simulate)
{
    TQString fieldName;
    AlterTableHandler::ActionDictIterator it(*dict);
    if (dynamic_cast<AlterTableHandler::FieldActionBase*>(it.current())) //retrieve field name from the 1st related action
        fieldName = dynamic_cast<AlterTableHandler::FieldActionBase*>(it.current())->fieldName();
    else
        fieldName = "??";
    TQString dbg = TQString("Action dict for field \"%1\" (%2, UID=%3):")
        .arg(fieldName).arg(dict->count()).arg(fieldUID);
    KexiDBDbg << dbg << endl;
#ifdef KEXI_DEBUG_GUI
    if (simulate)
        KexiUtils::addAlterTableActionDebug(dbg, 1);
#endif
    for (;it.current(); ++it) {
        debugAction(it.current(), 2, simulate);
    }
}
 
static void debugFieldActions(const AlterTableHandler::ActionDictDict &fieldActions, bool simulate)
{
#ifdef KEXI_DEBUG_GUI
    if (simulate)
        KexiUtils::addAlterTableActionDebug("** Simplified Field Actions:");
#endif
    for (AlterTableHandler::ActionDictDictIterator it(fieldActions); it.current(); ++it) {
        debugActionDict(it.current(), it.currentKey(), simulate);
    }
}
 
void AlterTableHandler::ChangeFieldPropertyAction::simplifyActions(ActionDictDict &fieldActions)
{
    ActionDict *actionsLikeThis = fieldActions[ uid() ];
    if (m_propertyName=="name") {
        // Case 1. special: name1 -> name2, i.e. rename action
        TQString newName( newValue().toString() );
        // try to find rename(newName, otherName) action
        ActionBase *renameActionLikeThis = actionsLikeThis ? actionsLikeThis->find( "name" ) : 0;
        if (dynamic_cast<ChangeFieldPropertyAction*>(renameActionLikeThis)) {
            // 1. instead of having rename(fieldName(), newValue()) action,
            // let's have rename(fieldName(), otherName) action
            dynamic_cast<ChangeFieldPropertyAction*>(renameActionLikeThis)->m_newValue 
                = dynamic_cast<ChangeFieldPropertyAction*>(renameActionLikeThis)->m_newValue;
/*          AlterTableHandler::ChangeFieldPropertyAction* newRenameAction 
                = new AlterTableHandler::ChangeFieldPropertyAction( *this );
            newRenameAction->m_newValue = dynamic_cast<ChangeFieldPropertyAction*>(renameActionLikeThis)->m_newValue;
            // (m_order is the same as in newAction)
            // replace prev. rename action (if any)
            actionsLikeThis->remove( "name" );
            ActionDict *adict = fieldActions[ fieldName().latin1() ];
            if (!adict)
                adict = createActionDict( fieldActions, fieldName() );
            adict->insert(m_propertyName.latin1(), newRenameAction);*/
        }
        else {
            ActionBase *removeActionForThisField = actionsLikeThis ? actionsLikeThis->find( ":remove:" ) : 0;
            if (removeActionForThisField) {
                //if this field is going to be removed, jsut change the action's field name 
                // and do not add a new action
            }
            else {
                //just insert a copy of the rename action
                if (!actionsLikeThis)
                    actionsLikeThis = createActionDict( fieldActions, uid() ); //fieldName() );
                AlterTableHandler::ChangeFieldPropertyAction* newRenameAction 
                    = new AlterTableHandler::ChangeFieldPropertyAction( *this );
                KexiDBDbg << "ChangeFieldPropertyAction::simplifyActions(): insert into '"
                    << fieldName() << "' dict:"  << newRenameAction->debugString() << endl;
                actionsLikeThis->insert( m_propertyName.latin1(), newRenameAction );
                return;
            }
        }
        if (actionsLikeThis) {
            // Case 1b. change "field name" information to fieldName() in any action that 
            //    is related to newName
            //    e.g. if there is setCaption("B", "captionA") action after rename("A","B"),
            //    replace setCaption action with setCaption("A", "captionA")
            foreach_dict (ActionDictIterator, it, *actionsLikeThis) {
                dynamic_cast<FieldActionBase*>(it.current())->setFieldName( fieldName() );
            }
        }
        return;
    }
    ActionBase *removeActionForThisField = actionsLikeThis ? actionsLikeThis->find( ":remove:" ) : 0;
    if (removeActionForThisField) {
        //if this field is going to be removed, do not add a new action
        return;
    }
    // Case 2. other cases: just give up with adding this "intermediate" action
    // so, e.g. [ setCaption(A, "captionA"), setCaption(A, "captionB") ]
    //  becomes: [ setCaption(A, "captionB") ]
    // because adding this action does nothing
    ActionDict *nextActionsLikeThis = fieldActions[ uid() ]; //fieldName().latin1() ];
    if (!nextActionsLikeThis || !nextActionsLikeThis->find( m_propertyName.latin1() )) { 
        //no such action, add this
        AlterTableHandler::ChangeFieldPropertyAction* newAction 
            = new AlterTableHandler::ChangeFieldPropertyAction( *this );
        if (!nextActionsLikeThis)
            nextActionsLikeThis = createActionDict( fieldActions, uid() );//fieldName() );
        nextActionsLikeThis->insert( m_propertyName.latin1(), newAction );
    }
}
 
bool AlterTableHandler::ChangeFieldPropertyAction::shouldBeRemoved(ActionDictDict &fieldActions)
{
    Q_UNUSED(fieldActions);
    return fieldName().lower() == m_newValue.toString().lower();
}
 
tristate AlterTableHandler::ChangeFieldPropertyAction::updateTableSchema(TableSchema &table, Field* field,
    TQMap<TQString, TQString>& fieldMap)
{
    //1. Simpler cases first: changes that do not affect table schema at all
    // "caption", "description", "width", "visibleDecimalPlaces"
    if (SchemaAlteringRequired & alteringTypeForProperty(m_propertyName.latin1())) {
        bool result = KexiDB::setFieldProperty(*field, m_propertyName.latin1(), newValue());
        return result;
    }
 
    if (m_propertyName=="name") {
        if (fieldMap[ field->name() ] == field->name())
            fieldMap.remove( field->name() );
        fieldMap.insert( newValue().toString(), field->name() );
        table.renameField(field, newValue().toString());
        return true;
    }
    return cancelled;
}
 
tristate AlterTableHandler::ChangeFieldPropertyAction::execute(Connection &conn, TableSchema &table)
{
    Q_UNUSED(conn);
    Field *field = table.field( fieldName() );
    if (!field) {
        return false;
    }
    bool result;
    //1. Simpler cases first: changes that do not affect table schema at all
    // "caption", "description", "width", "visibleDecimalPlaces"
    if (SchemaAlteringRequired & alteringTypeForProperty(m_propertyName.latin1())) {
        result = KexiDB::setFieldProperty(*field, m_propertyName.latin1(), newValue());
        return result;
    }
 
//todo
return true;
 
    //2. Harder cases, that often require special care
    if (m_propertyName=="name") {
        /*mysql:
         A. Get real field type (it's safer): 
            let <TYPE> be the 2nd "Type" column from result of "DESCRIBE tablename oldfieldname"
            ( http://dev.mysql.com/doc/refman/5.0/en/describe.html )
         B. Run "ALTER TABLE tablename CHANGE oldfieldname newfieldname <TYPE>";
            ( http://dev.mysql.com/doc/refman/5.0/en/alter-table.html )
        */
    }
    if (m_propertyName=="type") {
        /*mysql:
         A. Like A. for "name" property above
         B. Construct <TYPE> string, eg. "varchar(50)" using the driver
         C. Like B. for "name" property above
         (mysql then truncate the values for changes like varchar -> integer,
         and properly convert the values for changes like integer -> varchar)
 
         TODO: more cases to check
        */
    }
    if (m_propertyName=="length") {
        //use "select max( length(o_name) ) from kexi__Objects"
        
    }
    if (m_propertyName=="primaryKey") {
    }
 
/*
         "name", "unsigned", "precision", 
         "defaultValue", "primaryKey", "unique", "notNull", "allowEmpty",
         "autoIncrement", "indexed", 
 
 
    bool result = KexiDB::setFieldProperty(*field, m_propertyName.latin1(), newValue());
*/
    return result;
}
 
//--------------------------------------------------------
 
AlterTableHandler::RemoveFieldAction::RemoveFieldAction(const TQString& fieldName, int uid)
 : FieldActionBase(fieldName, uid)
{
}
 
AlterTableHandler::RemoveFieldAction::RemoveFieldAction(bool)
 : FieldActionBase(true)
{
}
 
AlterTableHandler::RemoveFieldAction::~RemoveFieldAction()
{
}
 
void AlterTableHandler::RemoveFieldAction::updateAlteringRequirements()
{
 
    setAlteringRequirements( PhysicalAlteringRequired );
}
 
TQString AlterTableHandler::RemoveFieldAction::debugString(const DebugOptions& debugOptions)
{
    TQString s = TQString("Remove table field \"%1\"").arg(fieldName());
    if (debugOptions.showUID)
        s.append(TQString(" (UID=%1)").arg(uid()));
    return s;
}
 
void AlterTableHandler::RemoveFieldAction::simplifyActions(ActionDictDict &fieldActions)
{
    AlterTableHandler::RemoveFieldAction* newAction 
            = new AlterTableHandler::RemoveFieldAction( *this );
    ActionDict *actionsLikeThis = fieldActions[ uid() ]; //fieldName().latin1() ];
    if (!actionsLikeThis)
        actionsLikeThis = createActionDict( fieldActions, uid() ); //fieldName() );
    actionsLikeThis->insert( ":remove:", newAction ); //special
}
 
tristate AlterTableHandler::RemoveFieldAction::updateTableSchema(TableSchema &table, Field* field,
    TQMap<TQString, TQString>& fieldMap)
{
    fieldMap.remove( field->name() );
    table.removeField(field);
    return true;
}
 
tristate AlterTableHandler::RemoveFieldAction::execute(Connection& conn, TableSchema& table)
{
    Q_UNUSED(conn);
    Q_UNUSED(table);
    return true;
}
 
//--------------------------------------------------------
 
AlterTableHandler::InsertFieldAction::InsertFieldAction(int fieldIndex, KexiDB::Field *field, int uid)
 : FieldActionBase(field->name(), uid)
 , m_index(fieldIndex)
 , m_field(0)
{
    Q_ASSERT(field);
    setField(field);
}
 
AlterTableHandler::InsertFieldAction::InsertFieldAction(const InsertFieldAction& action)
 : FieldActionBase(action) //action.fieldName(), action.uid())
 , m_index(action.index())
{
    m_field = new KexiDB::Field( action.field() );
}
 
AlterTableHandler::InsertFieldAction::InsertFieldAction(bool)
 : FieldActionBase(true)
 , m_index(0)
 , m_field(0)
{
}
 
AlterTableHandler::InsertFieldAction::~InsertFieldAction()
{
    delete m_field;
}
 
void AlterTableHandler::InsertFieldAction::setField(KexiDB::Field* field)
{
    if (m_field)
        delete m_field;
    m_field = field;
    setFieldName(m_field ? m_field->name() : TQString());
}
 
void AlterTableHandler::InsertFieldAction::updateAlteringRequirements()
{
 
    setAlteringRequirements( PhysicalAlteringRequired );
}
 
TQString AlterTableHandler::InsertFieldAction::debugString(const DebugOptions& debugOptions)
{
    TQString s = TQString("Insert table field \"%1\" at position %2")
        .arg(m_field->name()).arg(m_index);
    if (debugOptions.showUID)
        s.append(TQString(" (UID=%1)").arg(m_fieldUID));
    if (debugOptions.showFieldDebug)
        s.append(TQString(" (%1)").arg(m_field->debugString()));
    return s;
}
 
void AlterTableHandler::InsertFieldAction::simplifyActions(ActionDictDict &fieldActions)
{
    // Try to find actions related to this action
    ActionDict *actionsForThisField = fieldActions[ uid() ]; //m_field->name().latin1() ];
 
    ActionBase *removeActionForThisField = actionsForThisField ? actionsForThisField->find( ":remove:" ) : 0;
    if (removeActionForThisField) {
        //if this field is going to be removed, do not add a new action
        //and remove the "Remove" action
        actionsForThisField->remove(":remove:");
        return;
    }
    if (actionsForThisField) {
        //collect property values that have to be changed in this field
        TQMap<TQCString, TQVariant> values;
        for (ActionDictIterator it(*actionsForThisField); it.current();) {
            ChangeFieldPropertyAction* changePropertyAction = dynamic_cast<ChangeFieldPropertyAction*>(it.current());
            if (changePropertyAction) {
                //if this field is going to be renamed, also update fieldName()
                if (changePropertyAction->propertyName()=="name") {
                    setFieldName(changePropertyAction->newValue().toString());
                }
                values.insert( changePropertyAction->propertyName().latin1(), changePropertyAction->newValue() );
                //the subsequent "change property" action is no longer needed
                actionsForThisField->remove(changePropertyAction->propertyName().latin1());
            }
            else {
                ++it;
            }
        }
        if (!values.isEmpty()) {
            //update field, so it will be created as one step
            KexiDB::Field *f = new KexiDB::Field( field() );
            if (KexiDB::setFieldProperties( *f, values )) {
                //field() = f;
                setField( f );
                field().debug();
#ifdef KEXI_DEBUG_GUI
                KexiUtils::addAlterTableActionDebug(
                    TQString("** Property-set actions moved to field definition itself:\n")+field().debugString(), 0);
#endif
            }
            else {
#ifdef KEXI_DEBUG_GUI
                KexiUtils::addAlterTableActionDebug(
                    TQString("** Failed to set properties for field ")+field().debugString(), 0);
#endif
                KexiDBWarn << "AlterTableHandler::InsertFieldAction::simplifyActions(): KexiDB::setFieldProperties() failed!" << endl;
                delete f;
            }
        }
    }
    //ok, insert this action
    AlterTableHandler::InsertFieldAction* newAction 
            = new AlterTableHandler::InsertFieldAction( *this );
    if (!actionsForThisField)
        actionsForThisField = createActionDict( fieldActions, uid() );
    actionsForThisField->insert( ":insert:", newAction ); //special
}
 
tristate AlterTableHandler::InsertFieldAction::updateTableSchema(TableSchema &table, Field* field,
    TQMap<TQString, TQString>& fieldMap)
{
    //in most cases we won't add the field to fieldMap
    Q_UNUSED(field);
    fieldMap.remove( this->field().name() );
    table.insertField(index(), new Field(this->field()));
    return true;
}
 
tristate AlterTableHandler::InsertFieldAction::execute(Connection& conn, TableSchema& table)
{
    Q_UNUSED(conn);
    Q_UNUSED(table);
    return true;
}
 
//--------------------------------------------------------
 
AlterTableHandler::MoveFieldPositionAction::MoveFieldPositionAction(
    int fieldIndex, const TQString& fieldName, int uid)
 : FieldActionBase(fieldName, uid)
 , m_index(fieldIndex)
{
}
 
AlterTableHandler::MoveFieldPositionAction::MoveFieldPositionAction(bool)
 : FieldActionBase(true)
{
}
 
AlterTableHandler::MoveFieldPositionAction::~MoveFieldPositionAction()
{
}
 
void AlterTableHandler::MoveFieldPositionAction::updateAlteringRequirements()
{
    setAlteringRequirements( MainSchemaAlteringRequired );
}
 
TQString AlterTableHandler::MoveFieldPositionAction::debugString(const DebugOptions& debugOptions)
{
    TQString s = TQString("Move table field \"%1\" to position %2")
        .arg(fieldName()).arg(m_index);
    if (debugOptions.showUID)
        s.append(TQString(" (UID=%1)").arg(uid()));
    return s;
}
 
void AlterTableHandler::MoveFieldPositionAction::simplifyActions(ActionDictDict &fieldActions)
{
    Q_UNUSED(fieldActions);
}
 
tristate AlterTableHandler::MoveFieldPositionAction::execute(Connection& conn, TableSchema& table)
{
    Q_UNUSED(conn);
    Q_UNUSED(table);
    return true;
}
 
//--------------------------------------------------------
 
AlterTableHandler::AlterTableHandler(Connection &conn)
 : Object()
 , d( new Private() )
{
    d->conn = &conn;
}
 
AlterTableHandler::~AlterTableHandler()
{
    delete d;
}
 
void AlterTableHandler::addAction(ActionBase* action)
{
    d->actions.append(action);
}
 
AlterTableHandler& AlterTableHandler::operator<< ( ActionBase* action )
{
    d->actions.append(action);
    return *this;
}
 
const AlterTableHandler::ActionList& AlterTableHandler::actions() const
{
    return d->actions;
}
 
void AlterTableHandler::removeAction(int index)
{
    d->actions.remove( d->actions.at(index) );
}
 
void AlterTableHandler::clear()
{
    d->actions.clear();
}
 
void AlterTableHandler::setActions(const ActionList& actions)
{
    d->actions = actions;
}
 
void AlterTableHandler::debug()
{
    KexiDBDbg << "AlterTableHandler's actions:" << endl;
    foreach_list (ActionListIterator, it, d->actions)
        it.current()->debug();
}
 
TableSchema* AlterTableHandler::execute(const TQString& tableName, ExecutionArguments& args)
{
    args.result = false;
    if (!d->conn) {
        return 0;
    }
    if (d->conn->isReadOnly()) {
        return 0;
    }
    if (!d->conn->isDatabaseUsed()) {
        return 0;
    }
    TableSchema *oldTable = d->conn->tableSchema(tableName);
    if (!oldTable) {
        return 0;
    }
 
    if (!args.debugString)
        debug();
 
    // Find a sum of requirements...
    int allActionsCount = 0;
    for(ActionListIterator it(d->actions); it.current(); ++it, allActionsCount++) {
        it.current()->updateAlteringRequirements();
        it.current()->m_order = allActionsCount;
    }
 
    /* Simplify actions list if possible and check for errors
 
    How to do it?
    - track property changes/deletions in reversed order
    - reduce intermediate actions
 
    Trivial example 1:
     *action1: "rename field a to b"
     *action2: "rename field b to c"
     *action3: "rename field c to d"
 
     After reduction:
     *action1: "rename field a to d" 
     Summing up: we have tracked what happens to field curently named "d"
     and eventually discovered that it was originally named "a".
 
    Trivial example 2:
     *action1: "rename field a to b"
     *action2: "rename field b to c"
     *action3: "remove field b"
     After reduction:
     *action3: "remove field b"
     Summing up: we have noticed that field "b" has beed eventually removed
     so we needed to find all actions related to this field and remove them.
     This is good optimization, as some of the eventually removed actions would 
     be difficult to perform and/or costly, what would be a waste of resources
     and a source of unwanted questions sent to the user.
    */
 
    ActionListIterator it(d->actions);
 
    // Fields-related actions. 
    ActionDictDict fieldActions(3001);
    fieldActions.setAutoDelete(true);
    ActionBase* action;
    for(it.toLast(); (action = it.current()); --it) {
        action->simplifyActions( fieldActions );
    }
 
    if (!args.debugString)
        debugFieldActions(fieldActions, args.simulate);
 
    // Prepare actions for execution ----
    // - Sort actions by order
    ActionVector actionsVector(allActionsCount);
    int currentActionsCount = 0; //some actions may be removed
    args.requirements = 0;
    TQDict<char> fieldsWithChangedMainSchema(997); // Used to collect fields with changed main schema.
                                                  // This will be used when recreateTable is false to update kexi__fields
    for (ActionDictDictIterator it(fieldActions); it.current(); ++it) {
        for (AlterTableHandler::ActionDictIterator it2(*it.current());it2.current(); ++it2, currentActionsCount++) {
            if (it2.current()->shouldBeRemoved(fieldActions))
                continue;
            actionsVector.insert( it2.current()->m_order, it2.current() );
            // a sum of requirements...
            const int r = it2.current()->alteringRequirements();
            args.requirements |= r;
            if (r & MainSchemaAlteringRequired && dynamic_cast<ChangeFieldPropertyAction*>(it2.current())) {
                // Remember, this will be used when recreateTable is false to update kexi__fields, below.
                fieldsWithChangedMainSchema.insert( 
                    dynamic_cast<ChangeFieldPropertyAction*>(it2.current())->fieldName(), (char*)1 );
            }
        }
    }
    // - Debug
    TQString dbg = TQString("** Overall altering requirements: %1").arg(args.requirements);
    KexiDBDbg << dbg << endl;
 
    if (args.onlyComputeRequirements) {
        args.result = true;
        return 0;
    }
 
    const bool recreateTable = (args.requirements & PhysicalAlteringRequired);
 
#ifdef KEXI_DEBUG_GUI
    if (args.simulate)
        KexiUtils::addAlterTableActionDebug(dbg, 0);
#endif
    dbg = TQString("** Ordered, simplified actions (%1, was %2):").arg(currentActionsCount).arg(allActionsCount);
    KexiDBDbg << dbg << endl;
#ifdef KEXI_DEBUG_GUI
    if (args.simulate)
        KexiUtils::addAlterTableActionDebug(dbg, 0);
#endif
    for (int i=0; i<allActionsCount; i++) {
        debugAction(actionsVector[i], 1, args.simulate, TQString("%1: ").arg(i+1), args.debugString);
    }
 
    if (args.requirements == 0) {//nothing to do
        args.result = true;
        return oldTable;
    }
    if (args.simulate) {//do not execute
        args.result = true;
        return oldTable;
    }
// @todo transaction!
 
    // Create new TableSchema
    TableSchema *newTable = recreateTable ? new TableSchema(*oldTable, false) : oldTable;
    // find nonexisting temp name for new table schema
    if (recreateTable) {
        TQString tempDestTableName;
        while (true) {
            tempDestTableName = TQString("%1_temp%2%3").arg(newTable->name()).arg(TQString::number(rand(), 16)).arg(TQString::number(rand(), 16));
            if (!d->conn->tableSchema(tempDestTableName))
                break;
        }
        newTable->setName( tempDestTableName );
    }
    oldTable->debug();
    if (recreateTable && !args.debugString)
        newTable->debug();
 
    // Update table schema in memory ----
    int lastUID = -1;
    Field *currentField = 0;
    TQMap<TQString, TQString> fieldMap; // a map from new value to old value
    foreach_list( Field::ListIterator, it, newTable->fieldsIterator() ) {
        fieldMap.insert( it.current()->name(), it.current()->name() );
    }
    for (int i=0; i<allActionsCount; i++) {
        action = actionsVector[i];
        if (!action)
            continue;
        //remember the current Field object because soon we may be unable to find it by name:
        FieldActionBase *fieldAction = dynamic_cast<FieldActionBase*>(action);
        if (!fieldAction) {
            currentField = 0;
        }
        else {
            if (lastUID != fieldAction->uid()) {
                currentField = newTable->field( fieldAction->fieldName() );
                lastUID = currentField ? fieldAction->uid() : -1;
            }
            InsertFieldAction *insertFieldAction = dynamic_cast<InsertFieldAction*>(action);
            if (insertFieldAction && insertFieldAction->index()>(int)newTable->fieldCount()) {
                //update index: there can be empty rows
                insertFieldAction->setIndex(newTable->fieldCount());
            }
        }
        //if (!currentField)
        //  continue;
        args.result = action->updateTableSchema(*newTable, currentField, fieldMap);
        if (args.result!=true) {
            if (recreateTable)
                delete newTable;
            return 0;
        }
    }
 
    if (recreateTable) {
        // Create the destination table with temporary name
        if (!d->conn->createTable( newTable, false )) {
            setError(d->conn);
            delete newTable;
            args.result = false;
            return 0;
        }
    }
 
#if 0//todo
    // Execute actions ----
    for (int i=0; i<allActionsCount; i++) {
        action = actionsVector[i];
        if (!action)
            continue;
        args.result = action->execute(*d->conn, *newTable);
        if (!args.result || ~args.result) {
            args.result = false;
            return 0;
        }
    }
#endif
 
    // update extended table schema after executing the actions
    if (!d->conn->storeExtendedTableSchemaData(*newTable)) {
        setError(d->conn);
        args.result = false;
        return 0;
    }
 
    if (recreateTable) {
        // Copy the data:
        // Build "INSERT INTO ... SELECT FROM ..." SQL statement
        // The order is based on the order of the source table fields.
        // Notes:
        // -Some source fields can be skipped in case when there are deleted fields.
        // -Some destination fields can be skipped in case when there 
        //  are new empty fields without fixed/default value.
        TQString sql = TQString("INSERT INTO %1 (").arg(d->conn->escapeIdentifier(newTable->name()));
        //insert list of dest. fields
        bool first = true;
        TQString sourceFields;
        foreach_list( Field::ListIterator, it, newTable->fieldsIterator() ) {
            Field * const f = it.current();
            TQString renamedFieldName( fieldMap[ f->name() ] );
            TQString sourceSQLString;
            if (!renamedFieldName.isEmpty()) {
                //this field should be renamed
                sourceSQLString = d->conn->escapeIdentifier(renamedFieldName);
            }
            else if (!f->defaultValue().isNull()) {
                //this field has a default value defined
                sourceSQLString = d->conn->driver()->valueToSQL( f->type(), f->defaultValue() );
            }
            else if (f->isNotNull()) {
                //this field cannot be null
                sourceSQLString = d->conn->driver()->valueToSQL( 
                    f->type(), KexiDB::emptyValueForType( f->type() ) );
            }
            else if (f->isNotEmpty()) {
                //this field cannot be empty - use any nonempty value..., e.g. " " for text or 0 for number
                sourceSQLString = d->conn->driver()->valueToSQL( 
                    f->type(), KexiDB::notEmptyValueForType( f->type() ) );
            }
 
            if (!sourceSQLString.isEmpty()) {
                if (first) {
                    first = false;
                }
                else {
                    sql.append( ", " );
                    sourceFields.append( ", " );
                }
                sql.append( d->conn->escapeIdentifier( f->name() ) );
                sourceFields.append( sourceSQLString );
            }
        }
        sql.append(TQString(") SELECT ") + sourceFields + " FROM " + oldTable->name());
        KexiDBDbg << " ** " << sql << endl;
        if (!d->conn->executeSQL( sql )) {
            setError(d->conn);
            args.result = false;
            return 0;
        }
 
        const TQString oldTableName = oldTable->name();
/*      args.result = d->conn->dropTable( oldTable );
        if (!args.result || ~args.result) {
            setError(d->conn);
            return 0;
        }
        oldTable = 0;*/
 
        // Replace the old table with the new one (oldTable will be destroyed)
        if (!d->conn->alterTableName(*newTable, oldTableName, true /*replace*/)) {
            setError(d->conn);
            args.result = false;
            return 0;
        }
        oldTable = 0;
    }
 
    if (!recreateTable) {
        if ((MainSchemaAlteringRequired & args.requirements) && !fieldsWithChangedMainSchema.isEmpty()) {
            //update main schema (kexi__fields) for changed fields
            foreach_list(TQDictIterator<char>, it, fieldsWithChangedMainSchema) {
                Field *f = newTable->field( it.currentKey() );
                if (f) {
                    if (!d->conn->storeMainFieldSchema(f)) {
                        setError(d->conn);
                        args.result = false;
                        return 0;
                    }
                }
            }
        }
    }
 
    args.result = true;
    return newTable;
}
 
/*TableSchema* AlterTableHandler::execute(const TQString& tableName, tristate &result, bool simulate)
{
    return executeInternal( tableName, result, simulate, 0 );
}
 
tristate AlterTableHandler::simulateExecution(const TQString& tableName, TQString& debugString)
{
    tristate result;
    (void)executeInternal( tableName, result, true//simulate
    , &debugString );
    return result;
}
*/