text: /**********************************************************************
  
    Audacity: A Digital Audio Editor
  
    Prefs.h
  
    Dominic Mazzoni
    Markus Meyer
  
    Audacity uses wxWidgets' wxFileConfig class to handle preferences.
    In Audacity versions prior to 1.3.1, it used wxConfig, which would
    store the prefs in a platform-dependent way (e.g. in the registry
    on Windows). Now it always stores the settings in a configuration file
    in the Audacity Data Directory.
  
    Every time we read a preference, we need to specify the default
    value for that preference, to be used if the preference hasn't
    been set before.
  
    So, to avoid code duplication, we provide functions in this file
    to read and write preferences which have a nonobvious default
    value, so that if we later want to change this value, we only
    have to change it in one place.
  
    See Prefs.cpp for a (complete?) list of preferences we keep
    track of...
  
  **********************************************************************/
  #ifndef __AUDACITY_PREFS__
  #define __AUDACITY_PREFS__
  
  
  
  // Increment this every time the prefs need to be reset
  // the first part (before the r) indicates the version the reset took place
  // the second part (after the r) indicates the number of times the prefs have been reset within the same version
  #define AUDACITY_PREFS_VERSION_STRING "1.1.1r1"
  
  #include <functional>
  
  #include "../include/audacity/ComponentInterface.h"
  #include "wxArrayStringEx.h"
  #include "widgets/FileConfig.h"
  
  #include <memory>
  #include <wx/event.h> // to declare custom event types
  
  class wxFileName;
  
  void InitPreferences( std::unique_ptr<FileConfig> uPrefs );
  void FinishPreferences();
  
  extern AUDACITY_DLL_API FileConfig *gPrefs;
  extern int gMenusDirty;
  
  
  struct ByColumns_t{};
  extern ByColumns_t ByColumns;
  
  //! Base class for settings objects.  It holds a configuration key path.
  /* The constructors are non-explicit for convenience */
  class AUDACITY_DLL_API SettingBase
  {
  public:
     SettingBase( const char *path ) : mPath{ path } {}
     SettingBase( const wxChar *path ) : mPath{ path } {}
     SettingBase( const wxString &path ) : mPath{ path } {}
  
     wxConfigBase *GetConfig() const;
  
     const wxString &GetPath() const { return mPath; }
  
     //! Delete the key if present, and return true iff it was.
     bool Delete();
  
  protected:
     SettingBase( const SettingBase& ) = default;
     const RegistryPath mPath;
  };
  
  //! Class template adds an in-memory cache of a value to SettingBase.
  template< typename T >
  class CachingSettingBase : public SettingBase
  {
  public:
     explicit CachingSettingBase( const SettingBase &path )
        : SettingBase{ path } {}
  protected:
     CachingSettingBase( const CachingSettingBase & ) = default;
     mutable T mCurrentValue{};
     mutable bool mValid{false};
  };
  
  //! Class template adds default value, read, and write methods to CachingSetingBase
  template< typename T >
  class Setting : public CachingSettingBase< T >
  {
  public:
     using CachingSettingBase< T >::CachingSettingBase;
  
     using DefaultValueFunction = std::function< T() >;
  
     //! Usual overload supplies a default value
     Setting( const SettingBase &path, const T &defaultValue )
        : CachingSettingBase< T >{ path }
        , mDefaultValue{ defaultValue }
     {}
  
     //! This overload causes recomputation of the default each time it is needed
     Setting( const SettingBase &path, DefaultValueFunction function )
        : CachingSettingBase< T >{ path }
        , mFunction{ function }
     {}
     
  
     const T& GetDefault() const
     {
        if ( mFunction )
           mDefaultValue = mFunction();
        return mDefaultValue;
     }
  
     //! overload of Read returning a boolean that is true if the value was previously defined  */
     bool Read( T *pVar ) const
     {
        return ReadWithDefault( pVar, GetDefault() );
     }
  
     //! overload of ReadWithDefault returning a boolean that is true if the value was previously defined  */
     bool ReadWithDefault( T *pVar, const T& defaultValue ) const
     {
        if ( pVar )
           *pVar = defaultValue;
        if ( pVar && this->mValid ) {
           *pVar = this->mCurrentValue;
           return true;
        }
        const auto config = this->GetConfig();
        if ( pVar && config ) {
           if ((this->mValid = config->Read( this->mPath, &this->mCurrentValue )))
              *pVar = this->mCurrentValue;
           return this->mValid;
        }
        return (this->mValid = false);
     }
  
     //! overload of Read, always returning a value
     /*! The value is the default stored in this in case the key is known to be absent from the config;
      but it returns type T's default value if there was failure to read the config */
     T Read() const
     {
        return ReadWithDefault( GetDefault() );
     }
  
     //! new direct use is discouraged but it may be needed in legacy code
     /*! Use the given default in case the preference is not defined, which may not be the
      default-default stored in this object. */
     T ReadWithDefault( const T &defaultValue ) const
     {
        const auto config = this->GetConfig();
        return config
           ? ( this->mValid = true, this->mCurrentValue =
                 config->ReadObject( this->mPath, defaultValue ) )
           : T{};
     }
  
     //! Write value to config and return true if successful
     bool Write( const T &value )
     {
        const auto config = this->GetConfig();
        if ( config ) {
           this->mCurrentValue = value;
           return DoWrite();
        }
        return false;
     }
  
     //! Reset to the default value
     bool Reset()
     {
        return Write( GetDefault() );
     }
  
  protected:
     //! Write cached value to config and return true if successful
     /*! (But the config object is not flushed) */
     bool DoWrite( )
     {
        const auto config = this->GetConfig();
        return this->mValid =
           config ? config->Write( this->mPath, this->mCurrentValue ) : false;
     }
  
     mutable T mDefaultValue{};
     const DefaultValueFunction mFunction;
  };
  
  //! This specialization of Setting for bool adds a Toggle method to negate the saved value
  class BoolSetting final : public Setting< bool >
  {
  public:
     using Setting::Setting;
  
     //! Write the negation of the previous value, and then return the current value.
     bool Toggle();
  };
  
  //! Specialization of Setting for int
  class IntSetting final : public Setting< int >
  {
  public:
     using Setting::Setting;
  };
  
  //! Specialization of Setting for double
  class DoubleSetting final : public Setting< double >
  {
  public:
     using Setting::Setting;
  };
  
  //! Specialization of Setting for strings
  class StringSetting final : public Setting< wxString >
  {
  public:
     using Setting::Setting;
  };
  
  /// A table of EnumValueSymbol that you can access by "row" with
  /// operator [] but also allowing access to the "columns" of internal or
  /// translated strings, and also allowing convenient column-wise construction
  class AUDACITY_DLL_API EnumValueSymbols : public std::vector< EnumValueSymbol >
  {
  public:
     EnumValueSymbols() = default;
     EnumValueSymbols( std::initializer_list<EnumValueSymbol> symbols )
       : vector( symbols )
     {}
  
     // columnwise constructor; arguments must have same size
     // (Implicit constructor takes initial tag argument to avoid unintended
     // overload resolution to the inherited constructor taking
     // initializer_list, in the case that each column has exactly two strings)
     EnumValueSymbols(
        ByColumns_t,
        const TranslatableStrings &msgids,
        wxArrayStringEx internals
     );
  
     const TranslatableStrings &GetMsgids() const;
     const wxArrayStringEx &GetInternals() const;
  
  private:
     mutable TranslatableStrings mMsgids;
     mutable wxArrayStringEx mInternals;
  };
  
  /// Packages a table of user-visible choices each with an internal code string,
  /// a preference key path, and a default choice
  class AUDACITY_DLL_API ChoiceSetting
  {
  public:
     ChoiceSetting(
        const SettingBase &key,
        EnumValueSymbols symbols,
        long defaultSymbol = -1
     )
        : mKey{ key.GetPath() }
  
        , mSymbols{ std::move( symbols ) }
  
        , mDefaultSymbol{ defaultSymbol }
     {
        wxASSERT( defaultSymbol < (long)mSymbols.size() );
     }
  
     const wxString &Key() const { return mKey; }
     const EnumValueSymbol &Default() const;
     const EnumValueSymbols &GetSymbols() const { return mSymbols; }
  
     wxString Read() const;
  
     // new direct use is discouraged but it may be needed in legacy code:
     // use a default in case the preference is not defined, which may not be
     // the default-default stored in this object.
     wxString ReadWithDefault( const wxString & ) const;
  
     bool Write( const wxString &value ); // you flush gPrefs afterward
  
     void SetDefault( long value );
  
  protected:
     size_t Find( const wxString &value ) const;
     virtual void Migrate( wxString& );
  
     const wxString mKey;
  
     const EnumValueSymbols mSymbols;
  
     // stores an internal value
     mutable bool mMigrated { false };
  
     long mDefaultSymbol;
  };
  
  /// Extends ChoiceSetting with a corresponding table of integer codes
  /// (generally not equal to their table positions),
  /// and optionally an old preference key path that stored integer codes, to be
  /// migrated into one that stores internal string values instead
  class AUDACITY_DLL_API EnumSettingBase : public ChoiceSetting
  {
  public:
     EnumSettingBase(
        const SettingBase &key,
        EnumValueSymbols symbols,
        long defaultSymbol,
  
        std::vector<int> intValues, // must have same size as symbols
        const wxString &oldKey = {}
     );
  
  protected:
  
     // Read and write the encoded values
     int ReadInt() const;
  
     // new direct use is discouraged but it may be needed in legacy code:
     // use a default in case the preference is not defined, which may not be
     // the default-default stored in this object.
     int ReadIntWithDefault( int defaultValue ) const;
  
     bool WriteInt( int code ); // you flush gPrefs afterward
  
     size_t FindInt( int code ) const;
     void Migrate( wxString& ) override;
  
  private:
     std::vector<int> mIntValues;
     const wxString mOldKey;
  };
  
  /// Adapts EnumSettingBase to a particular enumeration type
  template< typename Enum >
  class EnumSetting : public EnumSettingBase
  {
  public:
  
     EnumSetting(
        const SettingBase &key,
        EnumValueSymbols symbols,
        long defaultSymbol,
  
        std::vector< Enum > values, // must have same size as symbols
        const wxString &oldKey = {}
     )
        : EnumSettingBase{
           key, symbols, defaultSymbol,
           { values.begin(), values.end() },
           oldKey
        }
     {}
  
     // Wrap ReadInt() and ReadIntWithDefault() and WriteInt()
     Enum ReadEnum() const
     { return static_cast<Enum>( ReadInt() ); }
  
     // new direct use is discouraged but it may be needed in legacy code:
     // use a default in case the preference is not defined, which may not be
     // the default-default stored in this object.
     Enum ReadEnumWithDefault( Enum defaultValue ) const
     {
        auto integer = static_cast<int>(defaultValue);
        return static_cast<Enum>( ReadIntWithDefault( integer ) );
     }
  
     bool WriteEnum( Enum value )
     { return WriteInt( static_cast<int>( value ) ); }
  
  };
  
  // An event emitted by the application when the Preference dialog commits
  // changes
  wxDECLARE_EXPORTED_EVENT(AUDACITY_DLL_API,
     EVT_PREFS_UPDATE, wxCommandEvent);
  
  // Invoke UpdatePrefs() when Preference dialog commits changes.
  class AUDACITY_DLL_API PrefsListener
  {
  public:
     PrefsListener();
     virtual ~PrefsListener();
  
     // Called when all preferences should be updated.
     virtual void UpdatePrefs() = 0;
  
  protected:
     // Called when only selected preferences are to be updated.
     // id is some value generated by wxNewId() that identifies the portion
     // of preferences.
     // Default function does nothing.
     virtual void UpdateSelectedPrefs( int id );
  
  private:
     struct Impl;
     std::unique_ptr<Impl> mpImpl;
  };
  
  /// Return the config file key associated with a warning dialog identified
  /// by internalDialogName.  When the box is checked, the value at the key
  /// becomes false.
  AUDACITY_DLL_API
  wxString WarningDialogKey(const wxString &internalDialogName);
  
  /*
   Meant to be statically constructed.  A callback to repopulate configuration
   files after a reset.
   */
  struct AUDACITY_DLL_API PreferenceInitializer {
     PreferenceInitializer();
     virtual ~PreferenceInitializer();
     virtual void operator () () = 0;
  
     static void ReinitializeAll();
  };
  
  #endif
  