/**********************************************************************

  Audacity: A Digital Audio Editor

  @file ShuttleAutomation.h

  Paul Licameli split from SettingsVisitor.h

**********************************************************************/

#ifndef __AUDACITY_SHUTTLE_AUTOMATION__
#define __AUDACITY_SHUTTLE_AUTOMATION__

#include <type_traits>
#include "EffectInterface.h"
#include "SettingsVisitor.h"

class Effect;
//! Interface for manipulations of an Effect's settings
/*!
 It is meant to be stateless, so all member functions are const
 */
class COMMAND_PARAMETERS_API EffectParameterMethods {
public:
   virtual ~EffectParameterMethods();
   virtual void Reset(Effect &effect) const = 0;
   virtual void Visit(Effect &effect,
      SettingsVisitor &visitor, EffectSettings &settings) const = 0;
   virtual void Visit(const Effect &effect,
      ConstSettingsVisitor &visitor, const EffectSettings &settings) const = 0;
   virtual void Get(const Effect &effect, const EffectSettings &settings,
      CommandParameters & parms) const = 0;
   virtual bool Set(Effect &effect,
      const CommandParameters & parms, EffectSettings &settings) const = 0;
};

//! Generates EffectParameterMethods overrides from variadic template arguments.
/*!
For each effect parameter, the function...
   Reset resets it to a default
   Visit visits it with a SettingsVisitor object; there are overloads taking
      SettingsVisitor and ConstSettingsVisitor
   Get serializes it to a string
   Set deserializes it from a string and returns a success flag (if there is
      failure, parameters might not all be unchanged)

The constructor optionally takes an argument which is a function to be called at
the end of Reset or Set, and returning a value for Set.

 @tparam EffectType subclass of Effect,
    expected to define a public static member function FetchParameters,
    taking EffectType & and EffectSettings &,
    and returning a pointer to something that holds the parameters
 @tparam Parameters a pack of non-type template parameters, whose types are
    specializations of the class template EffectParameter

 TODO in C++20: could use simply `auto ...Parameters` if they are `constexpr`
*/
template <typename EffectType, const auto &...Parameters>
class CapturedParameters : public EffectParameterMethods {
public:
   using Params = std::remove_pointer_t< decltype(
      // When all effects become stateless, EffectType argument won't be needed
      EffectType::FetchParameters(
         std::declval<EffectType&>(), std::declval<EffectSettings &>())
   ) >;

   virtual ~CapturedParameters() = default;

   // Another helper type
   // boolean argument is true if updating (not resetting defaults)
   // Returns true if successful, but that is ignored when resetting
   // When all effects become stateless, EffectType argument won't be needed
   using PostSetFunction =
      std::function< bool(EffectType&, EffectSettings &, Params &, bool) >;

   // Constructors

   CapturedParameters() {}

   template< typename Fn,
      // Require that the argument be callable with appropriate arguments
      typename = decltype( std::declval<Fn>()(
         std::declval<EffectType &>(), std::declval<EffectSettings &>(),
         std::declval<Params &>(), true) )
   >
   // Like the previous, but with an argument,
   // which is called at the end of Reset or Set.  Its return value is
   // ignored in Reset() and passed as the result of Set.
   explicit CapturedParameters(Fn &&PostSet)
      : PostSetFn{ std::forward<Fn>(PostSet) }
   {}

   void Reset(Effect &effect) const override {
      EffectSettings dummy;
      if (auto pStruct = EffectType::FetchParameters(
         static_cast<EffectType&>(effect), dummy))
         DoReset(effect, dummy, *pStruct, *this);
   }
   void Visit(Effect &effect,
      SettingsVisitor &visitor, EffectSettings &settings)
      const override {
      if (auto pStruct = EffectType::FetchParameters(
         static_cast<EffectType&>(effect), settings))
         DoVisit<false>(*pStruct, visitor);
   }
   void Visit(const Effect &effect,
      ConstSettingsVisitor &visitor, const EffectSettings &settings)
      const override {
      // const_cast the effect...
      auto &nonconstEffect = const_cast<Effect&>(effect);
      // ... and the settings ...
      auto &nonconstSettings = const_cast<EffectSettings&>(settings);
      // ... but only to fetch the structure and pass it as const &
      if (auto pStruct = EffectType::FetchParameters(
         static_cast<EffectType&>(nonconstEffect), nonconstSettings))
         DoVisit(*pStruct, visitor);
   }
   void Get(const Effect &effect, const EffectSettings &settings,
      CommandParameters & parms) const override {
      // const_cast the effect...
      auto &nonconstEffect = const_cast<Effect &>(effect);
      // ... and the settings ...
      auto &nonconstSettings = const_cast<EffectSettings&>(settings);
      // ... but only to fetch the structure and pass it as const &
      if (auto pStruct = EffectType::FetchParameters(
         static_cast<EffectType&>(nonconstEffect), nonconstSettings))
         DoGet(*pStruct, parms);
   }
   bool Set(Effect &effect, const CommandParameters & parms,
      EffectSettings &settings) const override {
      if (auto pStruct = EffectType::FetchParameters(
         static_cast<EffectType&>(effect), settings))
         return DoSet(effect, settings, *pStruct, *this, parms);
      else
         return false;
   }

private:
   PostSetFunction PostSetFn;

   // Function templates.  There are functions to treat individual parameters,
   // sometimes with two overloads, and variadic functions that use
   // fold expressions that apply to the sequence of parameters.

   template< typename Member, typename Type, typename Value >
   static void ResetOne(Params &structure,
      const EffectParameter< Params, Member, Type, Value > &param) {
      // Do one assignment of the default value
      structure.*(param.mem) = param.def;
   }
   static void DoReset(Effect &effect, EffectSettings settings,
      Params &structure,
      const CapturedParameters &This) {
      (ResetOne(structure, Parameters), ...);
      // Call the post-set function after all other assignments
      if (This.PostSetFn)
         This.PostSetFn(
            static_cast<EffectType&>(effect), settings, structure, false);
   }

   template< bool Const, typename Member, typename Type, typename Value >
   static void VisitOne(Params &structure, SettingsVisitorBase<Const> &visitor,
      const EffectParameter< Params, Member, Type, Value > &param) {
      // Visit one variable
      visitor.Define( structure.*(param.mem), param.key,
         static_cast<Member>(param.def),
         static_cast<Member>(param.min),
         static_cast<Member>(param.max),
         static_cast<Member>(param.scale) );
   }
   // More specific overload for enumeration parameters
   template< bool Const, typename Member >
   static void VisitOne(Params &structure, SettingsVisitorBase<Const> &visitor,
      const EnumParameter<Params, Member> &param) {
      // Visit one enumeration variable, passing the table of names
      visitor.DefineEnum( structure.*(param.mem),
         param.key, param.def, param.symbols, param.nSymbols );
   }
   template<bool Const>
   static void DoVisit(Params &structure, SettingsVisitorBase<Const> &visitor) {
      (VisitOne<Const>(structure, visitor, Parameters), ...);
   }

   template< typename Member, typename Type, typename Value >
   static void GetOne(const Params &structure, CommandParameters & parms,
      const EffectParameter< Params, Member, Type, Value > &param) {
      // Serialize one variable
      parms.Write( param.key, static_cast<Value>(structure.*(param.mem)) );
   }
   // More specific overload for enumeration parameters
   template< typename Member >
   static void GetOne(const Params &structure, CommandParameters & parms,
      const EnumParameter<Params, Member> &param) {
      // Serialize one enumeration variable as a string identifier, not a number
      parms.Write(
         param.key, param.symbols[ structure.*(param.mem) ].Internal() );
   }
   static void DoGet(const Params &structure, CommandParameters &parms) {
      (GetOne(structure, parms, Parameters), ...);
   }

   template< typename Member, typename Type, typename Value >
   static bool SetOne(Params &structure,
      const CommandParameters &parms,
      const EffectParameter< Params, Member, Type, Value > &param) {
      // Deserialize and assign one variable (or fail)
      Value temp;
      if (!parms.ReadAndVerify(param.key, &temp, param.def,
         param.min, param.max))
         return false;
      structure.*(param.mem) = temp;
      return true;
   }
   // More specific overload for enumeration parameters
   template< typename Member >
   static bool SetOne(Params &structure,
      const CommandParameters &parms,
      const EnumParameter<Params, Member> &param) {
      // Deserialize and assign one enumeration variable (or fail)
      int temp;
      if (!parms.ReadAndVerify(param.key, &temp, param.def,
         param.symbols, param.nSymbols))
         return false;
      structure.*(param.mem) = temp;
      return true;
   }
   static bool DoSet(Effect &effect,
      EffectSettings &settings, Params &structure,
      const CapturedParameters &This, const CommandParameters &parms) {
      if (!(SetOne(structure, parms, Parameters) && ...))
         return false;
      // Call the post-set function after all other assignments, or return
      // true if no function was given
      return !This.PostSetFn ||
         This.PostSetFn(
            static_cast<EffectType&>(effect), settings, structure, true);
   }
};

/**************************************************************************//**
\brief SettingsVisitor that gets parameter values into a string.
********************************************************************************/
class COMMAND_PARAMETERS_API ShuttleGetAutomation final
   : public ConstSettingsVisitor
{
public:
   ConstSettingsVisitor & Optional(const bool & var) override;
   void Define(bool var, const wxChar * key, bool vdefault,
      bool vmin, bool vmax, bool vscl) override;
   void Define(int var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl) override;
   void Define(size_t var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl) override;
   void Define(float var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl) override;
   void Define(double var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl) override;
   void Define(double var, const wxChar * key, double vdefault,
      double vmin, double vmax, double vscl) override;
   void Define(const wxString &var,  const wxChar * key, wxString vdefault,
      wxString vmin, wxString vmax, wxString vscl) override;
   void DefineEnum(int var, const wxChar * key, int vdefault,
      const EnumValueSymbol strings[], size_t nStrings) override;
};

/**************************************************************************//**
\brief SettingsVisitor that sets parameters to a value (from a string)
********************************************************************************/
class COMMAND_PARAMETERS_API ShuttleSetAutomation final : public SettingsVisitor
{
public:
   ShuttleSetAutomation() {}
   bool bOK{ false };
   bool bWrite{ false };

   bool CouldGet(const wxString &key);
   void SetForValidating( CommandParameters * pEap) {
      mpEap = pEap;
      bOK = true;
      bWrite = false;
   }
   void SetForWriting(CommandParameters * pEap) {
      mpEap = pEap;
      bOK = true;
      bWrite = true;
   }

   SettingsVisitor & Optional( bool & var ) override;
   void Define( bool & var, const wxChar * key, bool vdefault,
      bool vmin, bool vmax, bool vscl ) override;
   void Define( int & var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl ) override;
   void Define( size_t & var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl ) override;
   void Define( float & var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl ) override;
   void Define( double & var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl ) override;
   void Define( double & var, const wxChar * key, double vdefault,
      double vmin, double vmax, double vscl ) override;
   void Define( wxString &var,  const wxChar * key, wxString vdefault,
      wxString vmin, wxString vmax, wxString vscl ) override;
   void DefineEnum( int &var, const wxChar * key, int vdefault,
      const EnumValueSymbol strings[], size_t nStrings ) override;
};

/**************************************************************************//**
\brief SettingsVisitor that sets parameters to their default values.
********************************************************************************/
class COMMAND_PARAMETERS_API ShuttleDefaults final : public SettingsVisitor
{
public:
   wxString Result;
   
   SettingsVisitor & Optional( bool & var ) override;
   SettingsVisitor & OptionalY( bool & var ) override;
   SettingsVisitor & OptionalN( bool & var ) override;
   void Define( bool & var, const wxChar * key, bool vdefault,
      bool vmin, bool vmax, bool vscl ) override;
   void Define( int & var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl ) override;
   void Define( size_t & var, const wxChar * key, int vdefault,
      int vmin, int vmax, int vscl ) override;
   void Define( float & var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl ) override;
   void Define( double & var, const wxChar * key, float vdefault,
      float vmin, float vmax, float vscl ) override;
   void Define( double & var, const wxChar * key, double vdefault,
      double vmin, double vmax, double vscl ) override;
   void Define( wxString &var,  const wxChar * key, wxString vdefault,
      wxString vmin, wxString vmax, wxString vscl ) override;
   void DefineEnum( int &var, const wxChar * key, int vdefault,
      const EnumValueSymbol strings[], size_t nStrings ) override;
};

#endif