// This file is distributed under the BSD License.
// See "license.txt" for details.
// Copyright 2009, Jonathan Turner (jturner@minnow-lang.org)
// and Jason Turner (lefticus@gmail.com)
// http://www.chaiscript.com

#ifndef __boxed_value_hpp__
#define __boxed_value_hpp__

#include "type_info.hpp"
#include "../chaiscript_threading.hpp"
#include <map>
#include <boost/shared_ptr.hpp>
#include <boost/any.hpp>
#include <boost/function.hpp>
#include <boost/ref.hpp>
#include <boost/bind.hpp>
#include <boost/cstdint.hpp>
#include <boost/type_traits/add_const.hpp>

namespace chaiscript 
{
  /**
   * Boxed_Value is the main tool of the dispatchkit. It allows
   * for boxed / untyped containment of any C++ object. It uses
   * boost::any internally but also provides user access the underlying
   * stored type information
   */
  class Boxed_Value
  {
    public:
      /**
       * used for explicitly creating a "void" object
       */
      struct Void_Type
      {
      };

    private:
      /**
       * structure which holds the internal state of a Boxed_Value
       */
      struct Data
      {
        template<typename T>
          static bool unique(boost::any *a)
          {
            boost::shared_ptr<T> *ptr = boost::any_cast<boost::shared_ptr<T> >(a);
            return ptr->unique();
          }

        template<typename T>
          static bool is_null(boost::any *a)
          {
            boost::shared_ptr<T> *ptr = boost::any_cast<boost::shared_ptr<T> >(a);
            return ptr->get() == 0;
          }

        Data(const Type_Info &ti,
            const boost::any &to,
            bool tr,
            const boost::function<bool (boost::any*)> &t_unique = boost::function<bool (boost::any*)>(),
            const boost::function<bool (boost::any*)> &t_is_null = boost::function<bool (boost::any*)>())
          : m_type_info(ti), m_obj(to), 
          m_is_ref(tr), m_unique(t_unique), m_is_null(t_is_null)
        {
        }

        Data &operator=(const Data &rhs)
        {
          m_type_info = rhs.m_type_info;
          m_obj = rhs.m_obj;
          m_is_ref = rhs.m_is_ref;
          m_unique = rhs.m_unique;
          m_is_null = rhs.m_is_null;

          return *this;
        }

        Type_Info m_type_info;
        boost::any m_obj;
        bool m_is_ref;
        boost::function<bool (boost::any*)> m_unique;
        boost::function<bool (boost::any*)> m_is_null;
      };

      /**
       * Cache of all created objects in the dispatch kit. Used to return the 
       * same shared_ptr if the same object is created more than once.
       * Also used for acquiring a shared_ptr of a reference object, if the 
       * value of the shared_ptr is known
       */
      struct Object_Cache
      {
        Object_Cache()
          : m_cullcount(0)
        {
        }

        boost::shared_ptr<Data> get(Boxed_Value::Void_Type)
        {
          return boost::shared_ptr<Data> (new Data(
                detail::Get_Type_Info<void>::get(),
                boost::any(), 
                false)
              );
        }

        template<typename T>
          boost::shared_ptr<Data> get(const boost::shared_ptr<T> *obj)
          {
            return get(*obj);
          }

        template<typename T>
          boost::shared_ptr<Data> get(const boost::shared_ptr<T> &obj)
          {
            bool b_const = boost::is_const<T>::value; 

            boost::shared_ptr<Data> data(new Data(
                  detail::Get_Type_Info<T>::get(), 
                  boost::any(obj), 
                  false,
                  &Data::unique<T>,
                  &Data::is_null<T>)
                );

            std::map<std::pair<const void *, bool>, Data>::iterator itr
              = m_ptrs.find(std::make_pair(obj.get(), b_const));

            if (itr != m_ptrs.end())
            {
              (*data) = (itr->second);
            } else {
              m_ptrs.insert(std::make_pair(std::make_pair(obj.get(), b_const), *data));
            }

            return data;
          }

        template<typename T>
          boost::shared_ptr<Data> get(T *t)
          {
            return get(boost::ref(*t));
          }

        template<typename T>
          boost::shared_ptr<Data> get(boost::reference_wrapper<T> obj)
          {
            bool b_const = boost::is_const<T>::value; 

            boost::shared_ptr<Data> data(new Data(
                  detail::Get_Type_Info<T>::get(),
                  boost::any(obj), 
                  true)
                );

            std::map<std::pair<const void *, bool>, Data >::iterator itr
              = m_ptrs.find(std::make_pair(obj.get_pointer(), b_const) );

            // If the ptr is found in the cache and it is the correct type,
            // return it. It may be the incorrect type when two variables share the
            // same memory location. Example:
            // struct test { int x; };
            // test t;
            // Both t and t.x share the same memory location, but do not represent
            // objects of the same type.
            if (itr != m_ptrs.end() 
                && itr->second.m_type_info.bare_equal(data->m_type_info))
            {
              (*data) = (itr->second);
            } 

            return data;
          }

        template<typename T>
          boost::shared_ptr<Data> get(const T& t)
          {
            boost::shared_ptr<Data> data(new Data(
                  detail::Get_Type_Info<T>::get(), 
                  boost::any(boost::shared_ptr<T>(new T(t))), 
                  false,
                  &Data::unique<T>,
                  &Data::is_null<T>)
                );

            boost::shared_ptr<T> *ptr = boost::any_cast<boost::shared_ptr<T> >(&data->m_obj);

            m_ptrs.insert(std::make_pair(std::make_pair(ptr->get(), false), *data));
            return data;
          }

        boost::shared_ptr<Data> get()
        {
          return boost::shared_ptr<Data> (new Data(
                Type_Info(),
                boost::any(),
                false)
              );
        }

        /**
         * Drop objects from the cache where there is only one (ie, our)
         * reference to it, so it may be destructed
         */
        void cull(bool force = false)
        {
          
          ++m_cullcount;
          if (force || m_cullcount % 20 != 0)
          {
            return;
          }


          std::map<std::pair<const void *, bool>, Data>::iterator itr = m_ptrs.begin();

          while (itr != m_ptrs.end())
          {
            if (itr->second.m_unique(&itr->second.m_obj))
            {
              std::map<std::pair<const void *, bool>, Data >::iterator todel = itr;
              ++itr;
              m_ptrs.erase(todel);
            } else {
              ++itr;
            }
          }
        }

        std::map<std::pair<const void *, bool>, Data> m_ptrs;
        int m_cullcount;
      };

    public:
      /**
       * Basic Boxed_Value constructor
       */
      template<typename T>
        explicit Boxed_Value(T t)
        : m_data(get_object_cache().get(t))
        {
          get_object_cache().cull();
        }

      /**
       * Copy constructor - each copy shares the same data pointer
       */
      Boxed_Value(const Boxed_Value &t_so)
        : m_data(t_so.m_data)
      {
      }

      /**
       * Unknown-type constructor
       */
      Boxed_Value()
        : m_data(get_object_cache().get())    
      {
      }

      ~Boxed_Value()
      {
      }

      /**
       * Return a reference to the static global Object_Cache
       */
      static Object_Cache &get_object_cache()
      {
        static chaiscript::threading::Thread_Storage<Object_Cache> oc;
        return *oc;
      }   

      static void clear_cache()
      {
        get_object_cache().m_ptrs.clear();
      }

      /**
       * copy the values stored in rhs.m_data to m_data
       * m_data pointers are not shared in this case
       */
      Boxed_Value assign(const Boxed_Value &rhs)
      {
        (*m_data) = (*rhs.m_data);
        return *this;
      }

      /**
       * shared data assignment, same as copy construction
       */
      Boxed_Value &operator=(const Boxed_Value &rhs)
      {
        m_data = rhs.m_data;
        return *this;
      }

      const Type_Info &get_type_info() const
      {
        return m_data->m_type_info;
      }

      /**
       * return true if the object is uninitialized
       */
      bool is_undef() const
      {
        return m_data->m_type_info.is_undef();
      }

      bool is_null() const
      {
        if (m_data->m_is_null)
        {
          return m_data->m_is_null(&m_data->m_obj);
        } else {
          return false;
        }
      }

      boost::any get() const
      {
        return m_data->m_obj;
      }

      bool is_ref() const
      {
        return m_data->m_is_ref;
      }

    private:
      boost::shared_ptr<Data> m_data;
  };


  namespace detail
  {
    // Cast_Helper helper classes

    /**
     * Generic Cast_Helper, for casting to any type
     */
    template<typename Result>
      struct Cast_Helper
      {
        typedef typename boost::reference_wrapper<typename boost::add_const<Result>::type > Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (ob.is_ref())
          {
            if (!ob.get_type_info().is_const())
            {
              return boost::cref((boost::any_cast<boost::reference_wrapper<Result> >(ob.get())).get());
            } else {
              return boost::any_cast<boost::reference_wrapper<const Result> >(ob.get());
            }
          } else {
            if (!ob.get_type_info().is_const())
            {
              return boost::cref(*(boost::any_cast<boost::shared_ptr<Result> >(ob.get())));   
            } else {
              return boost::cref(*(boost::any_cast<boost::shared_ptr<const Result> >(ob.get())));   
            }
          }
        }
      };

    /**
     * Cast_Helper for casting to a const & type
     */
    template<typename Result>
      struct Cast_Helper<const Result &>
      {
        typedef typename boost::reference_wrapper<typename boost::add_const<Result>::type > Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (ob.is_ref())
          {
            if (!ob.get_type_info().is_const())
            {
              return boost::cref((boost::any_cast<boost::reference_wrapper<Result> >(ob.get())).get());
            } else {
              return boost::any_cast<boost::reference_wrapper<const Result> >(ob.get());
            }
          } else {
            if (!ob.get_type_info().is_const())
            {
              return boost::cref(*(boost::any_cast<boost::shared_ptr<Result> >(ob.get())));   
            } else {
              return boost::cref(*(boost::any_cast<boost::shared_ptr<const Result> >(ob.get())));   
            }
          }
        }
      };

    /**
     * Cast_Helper for casting to a const * type
     */
    template<typename Result>
      struct Cast_Helper<const Result *>
      {
        typedef const Result * Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (ob.is_ref())
          {
            if (!ob.get_type_info().is_const())
            {
              return (boost::any_cast<boost::reference_wrapper<Result> >(ob.get())).get_pointer();
            } else {
              return (boost::any_cast<boost::reference_wrapper<const Result> >(ob.get())).get_pointer();
            }
          } else {
            if (!ob.get_type_info().is_const())
            {
              return (boost::any_cast<boost::shared_ptr<Result> >(ob.get())).get();
            } else {
              return (boost::any_cast<boost::shared_ptr<const Result> >(ob.get())).get();
            }
          }
        }
      };

    /**
     * Cast_Helper for casting to a * type
     */
    template<typename Result>
      struct Cast_Helper<Result *>
      {
        typedef Result * Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (ob.is_ref())
          {
            return (boost::any_cast<boost::reference_wrapper<Result> >(ob.get())).get_pointer();
          } else {
            return (boost::any_cast<boost::shared_ptr<Result> >(ob.get())).get();
          }
        }
      };

    /**
     * Cast_Helper for casting to a & type
     */
    template<typename Result>
      struct Cast_Helper<Result &>
      {
        typedef typename boost::reference_wrapper<Result> Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (ob.is_ref())
          {
            return boost::any_cast<boost::reference_wrapper<Result> >(ob.get());
          } else {
            return boost::ref(*(boost::any_cast<boost::shared_ptr<Result> >(ob.get())));
          }
        }
      };

    /**
     * Cast_Helper for casting to a boost::shared_ptr<> type
     */
    template<typename Result>
      struct Cast_Helper<typename boost::shared_ptr<Result> >
      {
        typedef typename boost::shared_ptr<Result> Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          return boost::any_cast<boost::shared_ptr<Result> >(ob.get());
        }
      };

    /**
     * Cast_Helper for casting to a boost::shared_ptr<const> type
     */
    template<typename Result>
      struct Cast_Helper<typename boost::shared_ptr<const Result> >
      {
        typedef typename boost::shared_ptr<const Result> Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (!ob.get_type_info().is_const())
          {
            return boost::const_pointer_cast<const Result>(boost::any_cast<boost::shared_ptr<Result> >(ob.get()));
          } else {
            return boost::any_cast<boost::shared_ptr<const Result> >(ob.get());
          }
        }
      };

    /**
     * Cast_Helper for casting to a const boost::shared_ptr<> & type
     */
    template<typename Result>
      struct Cast_Helper<const boost::shared_ptr<Result> &>
      {
        typedef typename boost::shared_ptr<Result> Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          return boost::any_cast<boost::shared_ptr<Result> >(ob.get());
        }
      };

    /**
     * Cast_Helper for casting to a const boost::shared_ptr<const> & type
     */
    template<typename Result>
      struct Cast_Helper<const boost::shared_ptr<const Result> &>
      {
        typedef typename boost::shared_ptr<const Result> Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          if (!ob.get_type_info().is_const())
          {
            return boost::const_pointer_cast<const Result>(boost::any_cast<boost::shared_ptr<Result> >(ob.get()));
          } else {
            return boost::any_cast<boost::shared_ptr<const Result> >(ob.get());
          }
        }
      };



    /**
     * Cast_Helper for casting to a Boxed_Value type
     */
    template<>
      struct Cast_Helper<Boxed_Value>
      {
        typedef const Boxed_Value & Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          return ob;    
        }
      };

    /**
     * Cast_Helper for casting to a const Boxed_Value & type
     */
    template<>
      struct Cast_Helper<const Boxed_Value &>
      {
        typedef const Boxed_Value & Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          return ob;    
        }
      };
  }

  /**
   * class that is thrown in the event of a bad_boxed_cast. That is,
   * in the case that a Boxed_Value cannot be cast to the desired type
   */
  class bad_boxed_cast : public std::bad_cast
  {
    public:
      bad_boxed_cast(const Type_Info &t_from, const std::type_info &t_to) throw()
        : from(t_from), to(&t_to), m_what("Cannot perform boxed_cast")
      {
      }

      bad_boxed_cast(const std::string &w) throw()
        : m_what(w)
      {
      }

      virtual ~bad_boxed_cast() throw() {}

      virtual const char * what () throw()
      {
        return m_what.c_str();
      }

      Type_Info from;
      const std::type_info *to;

    private:
      std::string m_what;
  };

  /**
   * boxed_cast function for casting a Boxed_Value into a given type
   * example:
   * int &i = boxed_cast<int &>(boxedvalue);
   */
  template<typename Type>
  typename detail::Cast_Helper<Type>::Result_Type boxed_cast(const Boxed_Value &bv)
  {
    try {
      return detail::Cast_Helper<Type>::cast(bv);
    } catch (const boost::bad_any_cast &) {
      throw bad_boxed_cast(bv.get_type_info(), typeid(Type));
    }
  }

  /**
   * Object which attempts to convert a Boxed_Value into a generic
   * POD type and provide generic POD type operations
   */
  struct Boxed_POD_Value
  {
    Boxed_POD_Value(const Boxed_Value &v)
      : d(0), i(0), m_isfloat(false)
    {
      if (v.get_type_info().is_undef())
      {
        throw boost::bad_any_cast();
      }

      const Type_Info &inp_ = v.get_type_info();

      if (inp_ == typeid(double))
      {
        d = boxed_cast<double>(v);
        m_isfloat = true;
      } else if (inp_ == typeid(float)) {
        d = boxed_cast<float>(v);
        m_isfloat = true;
      } else if (inp_ == typeid(bool)) {
        i = boxed_cast<bool>(v);
      } else if (inp_ == typeid(char)) {
        i = boxed_cast<char>(v);
      } else if (inp_ == typeid(int)) {
        i = boxed_cast<int>(v);
      } else if (inp_ == typeid(unsigned int)) {
        i = boxed_cast<unsigned int>(v);
      } else if (inp_ == typeid(long)) {
        i = boxed_cast<long>(v);
      } else if (inp_ == typeid(unsigned long)) {
        i = boxed_cast<unsigned long>(v);
      } else if (inp_ == typeid(boost::int8_t)) {
        i = boxed_cast<boost::int8_t>(v);
      } else if (inp_ == typeid(boost::int16_t)) {
        i = boxed_cast<boost::int16_t>(v);
      } else if (inp_ == typeid(boost::int32_t)) {
        i = boxed_cast<boost::int32_t>(v);
      } else if (inp_ == typeid(boost::int64_t)) {
        i = boxed_cast<boost::int64_t>(v);
      } else if (inp_ == typeid(boost::uint8_t)) {
        i = boxed_cast<boost::uint8_t>(v);
      } else if (inp_ == typeid(boost::uint16_t)) {
        i = boxed_cast<boost::uint16_t>(v);
      } else if (inp_ == typeid(boost::uint32_t)) {
        i = boxed_cast<boost::uint32_t>(v);
      } else {
        throw boost::bad_any_cast();
      }
    }

    bool operator==(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) == ((r.m_isfloat)?r.d:r.i);
    }

    bool operator<(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) < ((r.m_isfloat)?r.d:r.i);
    }

    bool operator>(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) > ((r.m_isfloat)?r.d:r.i);
    }

    bool operator>=(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) >= ((r.m_isfloat)?r.d:r.i);
    }

    bool operator<=(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) <= ((r.m_isfloat)?r.d:r.i);
    }

    bool operator!=(const Boxed_POD_Value &r) const
    {
      return ((m_isfloat)?d:i) != ((r.m_isfloat)?r.d:r.i);
    }

    Boxed_Value operator+(const Boxed_POD_Value &r) const
    {
      if (!m_isfloat && !r.m_isfloat)
      {
        return Boxed_Value(i + r.i);
      }

      return Boxed_Value(((m_isfloat)?d:i) + ((r.m_isfloat)?r.d:r.i));
    }

    Boxed_Value operator*(const Boxed_POD_Value &r) const
    {
      if (!m_isfloat && !r.m_isfloat)
      {
        return Boxed_Value(i * r.i);
      }

      return Boxed_Value(((m_isfloat)?d:i) * ((r.m_isfloat)?r.d:r.i));
    }

    Boxed_Value operator/(const Boxed_POD_Value &r) const
    {
      if (!m_isfloat && !r.m_isfloat)
      {
        return Boxed_Value(i / r.i);
      }

      return Boxed_Value(((m_isfloat)?d:i) / ((r.m_isfloat)?r.d:r.i));
    }

    Boxed_Value operator-(const Boxed_POD_Value &r) const
    {
      if (!m_isfloat && !r.m_isfloat)
      {
        return Boxed_Value(i - r.i);
      }

      return Boxed_Value(((m_isfloat)?d:i) - ((r.m_isfloat)?r.d:r.i));
    }

    double d;
    boost::int64_t i;

    bool m_isfloat;
  };

  namespace detail
  {
    /**
     * Cast_Helper for converting from Boxed_Value to Boxed_POD_Value
     */
    template<>
      struct Cast_Helper<Boxed_POD_Value>
      {
        typedef Boxed_POD_Value Result_Type;

        static Result_Type cast(const Boxed_Value &ob)
        {
          return Boxed_POD_Value(ob);
        }
      };
  }

  template<typename T>
    Boxed_Value var(T t)
    {
      return Boxed_Value(t);
    }

  template<typename T>
    Boxed_Value const_var(T *t)
    {
      return Boxed_Value( const_cast<typename boost::add_const<T>::type>(t) );
    }

  template<typename T>
    Boxed_Value const_var(const boost::shared_ptr<T> &t)
    {
      return Boxed_Value( boost::const_pointer_cast<typename boost::add_const<T>::type>(t) );
    }

  template<typename T>
    Boxed_Value const_var(const boost::reference_wrapper<T> &t)
    {
      return Boxed_Value( boost::cref(t.get()) );
    }

  template<typename T>
    Boxed_Value const_var(const T &t)
    {
      return Boxed_Value(boost::shared_ptr<typename boost::add_const<T>::type >(new T(t)));
    }

  /**
   * Return true if the two Boxed_Values share the same internal type
   */
  static bool type_match(Boxed_Value l, Boxed_Value r)
  {
    return l.get_type_info() == r.get_type_info();
  }

}

#endif