// SPDX-License-Identifier: MIT
#pragma once

#include <memory>

namespace fedem
{
  namespace fson
  {
    class Null;
    class Boolean;
    class Number;
    class String;
    class Array;
    class Object;

    // ─────────────────────────────────────────────────────────────────────
    // Value
    //
    // Abstract base of every FSON value (docs/notation/00030-value.rrd):
    //   string | number | object | array | true | false | null
    //
    // Polymorphic class hierarchy; instances are owned through
    // std::unique_ptr< Value > and duplicated with clone().
    // The as<T>() helpers return nullptr when the dynamic type differs,
    // so callers can branch without dynamic_cast.
    // ─────────────────────────────────────────────────────────────────────
    class Value
    {
      public:
        enum class Type
        {
          Null,
          Boolean,
          Number,
          String,
          Array,
          Object
        };

        virtual ~Value( );

        virtual Type getType( ) const noexcept = 0;

        // Deep copy including all attached comments.
        virtual std::unique_ptr< Value > clone( ) const = 0;

        bool isNull   ( ) const noexcept;
        bool isBoolean( ) const noexcept;
        bool isNumber ( ) const noexcept;
        bool isString ( ) const noexcept;
        bool isArray  ( ) const noexcept;
        bool isObject ( ) const noexcept;

        virtual Null*           asNull   ( )       noexcept;
        virtual Null const*     asNull   ( ) const noexcept;
        virtual Boolean*        asBoolean( )       noexcept;
        virtual Boolean const*  asBoolean( ) const noexcept;
        virtual Number*         asNumber ( )       noexcept;
        virtual Number const*   asNumber ( ) const noexcept;
        virtual String*         asString ( )       noexcept;
        virtual String const*   asString ( ) const noexcept;
        virtual Array*          asArray  ( )       noexcept;
        virtual Array const*    asArray  ( ) const noexcept;
        virtual Object*         asObject ( )       noexcept;
        virtual Object const*   asObject ( ) const noexcept;

      protected:
        Value( ) = default;

      private:
        Value( Value const& ) = delete;
        Value( Value&&      ) = delete;
        Value& operator=( Value const& ) = delete;
        Value& operator=( Value&&      ) = delete;
    };

    inline bool Value::isNull( ) const noexcept
    {
      return getType( ) == Type::Null;
    }

    inline bool Value::isBoolean( ) const noexcept
    {
      return getType( ) == Type::Boolean;
    }

    inline bool Value::isNumber( ) const noexcept
    {
      return getType( ) == Type::Number;
    }

    inline bool Value::isString( ) const noexcept
    {
      return getType( ) == Type::String;
    }

    inline bool Value::isArray( ) const noexcept
    {
      return getType( ) == Type::Array;
    }

    inline bool Value::isObject( ) const noexcept
    {
      return getType( ) == Type::Object;
    }
  }  // end namespace fson
}  // end namespace fedem