/**
 * @file   llviewmodel.h
 * @author Nat Goodspeed
 * @date   2008-08-08
 * @brief  Define "View Model" classes intended to store data values for use
 *         by LLUICtrl subclasses. The phrase is borrowed from Microsoft
 *         terminology, in which "View Model" means the storage object
 *         underlying a specific widget object -- as in our case -- rather
 *         than the business "model" object underlying the overall "view"
 *         presented by the collection of widgets.
 *
 * $LicenseInfo:firstyear=2008&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#if ! defined(LL_LLVIEWMODEL_H)
#define LL_LLVIEWMODEL_H

#include "llpointer.h"
#include "llsd.h"
#include "llrefcount.h"
#include "llstring.h"
#include "lltrace.h"
#include "llui.h"
#include <string>

class LLScrollListItem;

class LLViewModel;
class LLTextViewModel;
class LLListViewModel;
// Because LLViewModel is derived from LLRefCount, always pass, store
// and return LLViewModelPtr rather than plain LLViewModel*.
typedef LLPointer<LLViewModel> LLViewModelPtr;
typedef LLPointer<LLTextViewModel> LLTextViewModelPtr;
typedef LLPointer<LLListViewModel> LLListViewModelPtr;

/**
 * LLViewModel stores a scalar LLSD data item, the current display value of a
 * scalar LLUICtrl widget. LLViewModel subclasses are used to store data
 * collections used for aggregate widgets. LLViewModel is ref-counted because
 * -- for multiple skins -- we may have distinct widgets sharing the same
 * LLViewModel data. This way, the LLViewModel is quietly deleted when the
 * last referencing widget is destroyed.
 */
class LLViewModel
:   public LLRefCount
{
public:
    LLViewModel();
    /// Instantiate an LLViewModel with an existing data value
    LLViewModel(const LLSD& value);

    /// Update the stored value
    virtual void setValue(const LLSD& value);
    /// Get the stored value, in appropriate type.
    virtual LLSD getValue() const;

    /// Has the value been changed since last time we checked?
    bool isDirty() const { return mDirty; }
    /// Once the value has been saved to a file, or otherwise consumed by the
    /// app, we no longer need to enable the Save button
    void resetDirty() { mDirty = false; }
    //
    void setDirty() { mDirty = true; }

protected:
    LLSD mValue;
    bool mDirty;
};

/**
 * LLTextViewModel stores a value displayed as text.
 */
class LLTextViewModel: public LLViewModel
{
public:
    LLTextViewModel();
    /// Instantiate an LLViewModel with an existing data value
    LLTextViewModel(const LLSD& value);

    // LLViewModel functions
    virtual void setValue(const LLSD& value);
    virtual LLSD getValue() const;
    const std::string& getStringValue() const;

    // New functions
    /// Get the stored value in string form
    const LLWString& getDisplay() const { return mDisplay; }
    S32 getDisplayGeneration() const { return mDisplayGeneration; }
    LLWString& getEditableDisplay();

    /**
     * Set the display string directly (see LLTextEditor). What the user is
     * editing is actually the LLWString value rather than the underlying
     * UTF-8 value.
     */
    void setDisplay(const LLWString& value);

private:
    std::string mStringValue;

    /// To avoid converting every widget's stored value from LLSD to LLWString
    /// every frame, cache the converted value
    LLWString mDisplay;
    S32 mDisplayGeneration = -1;

    /// As the user edits individual characters (setDisplay()), defer
    /// LLWString-to-UTF8 conversions until s/he's done.
    bool mUpdateFromDisplay;

    friend void updateFromDisplayIfNeeded(const LLTextViewModel* model);
};

/**
 * LLListViewModel stores a list of data items. The semantics are borrowed
 * from LLScrollListCtrl.
 */
class LLListViewModel: public LLViewModel
{
public:
    LLListViewModel() {}
    LLListViewModel(const LLSD& values);

    virtual void addColumn(const LLSD& column, EAddPosition pos = ADD_BOTTOM);
    virtual void clearColumns();
    virtual void setColumnLabel(const std::string& column, const std::string& label);
    virtual LLScrollListItem* addElement(const LLSD& value, EAddPosition pos = ADD_BOTTOM,
                                         void* userdata = NULL);
    virtual LLScrollListItem* addSimpleElement(const std::string& value, EAddPosition pos,
                                               const LLSD& id);
    virtual void clearRows();
    virtual void sortByColumn(const std::string& name, bool ascending);
};

//namespace LLViewModel
//{
//  class Value
//  {
//  public:
//      Value(const LLSD& value = LLSD());
//
//      LLSD getValue() const { return mValue; }
//      void setValue(const LLSD& value) { mValue = value; }
//
//      bool isAvailable() const { return false; }
//      bool isReadOnly() const { return false; }
//
//      bool undo() { return false; }
//      bool redo() { return false; }
//
//      /// Has the value been changed since last time we checked?
//      bool isDirty() const { return mDirty; }
//      /// Once the value has been saved to a file, or otherwise consumed by the
//      /// app, we no longer need to enable the Save button
//      void resetDirty() { mDirty = false; }
//      //
//      void setDirty() { mDirty = true; }
//
//  protected:
//      LLSD    mValue;
//      bool mDirty;
//  };
//
//  class Numeric : public Value
//  {
//  public:
//      Numeric(S32 value = 0);
//      Numeric(F32 value);
//
//      F32 getPrecision();
//      F32 getMin();
//      F32 getMax();
//
//      void increment();
//      void decrement();
//  };
//
//  class MultipleValues : public Value
//  {
//      class Selector
//      {};
//
//      MultipleValues();
//      virtual S32 numElements();
//  };
//
//  class Tuple : public MultipleValues
//  {
//      Tuple(S32 size);
//      LLSD getValue(S32 which) const;
//      void setValue(S32 which, const LLSD& value);
//  };
//
//  class List : public MultipleValues
//  {
//      List();
//
//      void add(const ValueModel& value);
//      bool remove(const Selector& item);
//
//      void setSortElement(const Selector& element);
//      void sort();
//  };
//
//};
#endif /* ! defined(LL_LLVIEWMODEL_H) */