#ifndef RFL_PARSING_PARSER_DEFAULT_HPP_
#define RFL_PARSING_PARSER_DEFAULT_HPP_

#include <map>
#include <stdexcept>
#include <type_traits>

#include "../Result.hpp"
#include "../always_false.hpp"
#include "../from_named_tuple.hpp"
#include "../internal/enums/StringConverter.hpp"
#include "../internal/has_reflection_method_v.hpp"
#include "../internal/has_reflection_type_v.hpp"
#include "../internal/is_basic_type.hpp"
#include "../internal/is_description.hpp"
#include "../internal/is_literal.hpp"
#include "../internal/is_validator.hpp"
#include "../internal/processed_t.hpp"
#include "../internal/to_ptr_named_tuple.hpp"
#include "../to_view.hpp"
#include "../type_name_t.hpp"
#include "AreReaderAndWriter.hpp"
#include "Parent.hpp"
#include "Parser_base.hpp"
#include "is_tagged_union_wrapper.hpp"
#include "schema/Type.hpp"

namespace rfl {
  namespace parsing {

    /// Default case - anything that cannot be explicitly matched.
    template <class R, class W, class T, class ProcessorsType>
      requires AreReaderAndWriter<R, W, T>
    struct Parser {
     public:
      using InputVarType  = typename R::InputVarType;
      using OutputVarType = typename W::OutputVarType;

      using ParentType = Parent<W>;

      /// Expresses the variables as type T.
      static Result<T> read(const R& _r, const InputVarType& _var) noexcept {
        if constexpr (R::template has_custom_constructor<T>) {
          return _r.template use_custom_constructor<T>(_var);
        } else {
          if constexpr (internal::has_reflection_type_v<T>) {
            using ReflectionType = std::remove_cvref_t<typename T::ReflectionType>;
            const auto wrap_in_t = [](auto _named_tuple) -> Result<T> {
              try {
                return T(_named_tuple);
              } catch (std::exception& e) { return Error(e.what()); }
            };
            return Parser<R, W, ReflectionType, ProcessorsType>::read(_r, _var).and_then(wrap_in_t);
          } else if constexpr (std::is_class_v<T> && std::is_aggregate_v<T>) {
            return read_struct(_r, _var);
          } else if constexpr (std::is_enum_v<T>) {
            using StringConverter = internal::enums::StringConverter<T>;
            return _r.template to_basic_type<std::string>(_var).and_then(
              StringConverter::string_to_enum
            );
          } else {
            return _r.template to_basic_type<std::remove_cvref_t<T>>(_var);
          }
        }
      }

      template <class P>
      static void write(const W& _w, const T& _var, const P& _parent) noexcept {
        if constexpr (internal::has_reflection_type_v<T>) {
          using ReflectionType = std::remove_cvref_t<typename T::ReflectionType>;
          if constexpr (internal::has_reflection_method_v<T>) {
            Parser<R, W, ReflectionType, ProcessorsType>::write(_w, _var.reflection(), _parent);
          } else {
            const auto& [r] = _var;
            Parser<R, W, ReflectionType, ProcessorsType>::write(_w, r, _parent);
          }
        } else if constexpr (std::is_class_v<T> && std::is_aggregate_v<T>) {
          const auto ptr_named_tuple =
            ProcessorsType::template process<T>(internal::to_ptr_named_tuple(_var));
          using PtrNamedTupleType = std::remove_cvref_t<decltype(ptr_named_tuple)>;
          Parser<R, W, PtrNamedTupleType, ProcessorsType>::write(_w, ptr_named_tuple, _parent);
        } else if constexpr (std::is_enum_v<T>) {
          using StringConverter = internal::enums::StringConverter<T>;
          const auto str        = StringConverter::enum_to_string(_var);
          ParentType::add_value(_w, str, _parent);
        } else {
          ParentType::add_value(_w, _var, _parent);
        }
      }

      /// Generates a schema for the underlying type.
      static schema::Type to_schema(std::map<std::string, schema::Type>* _definitions) {
        using U    = std::remove_cvref_t<T>;
        using Type = schema::Type;
        if constexpr (std::is_same<U, bool>()) {
          return Type { Type::Boolean {} };

        } else if constexpr (std::is_same<U, std::int32_t>()) {
          return Type { Type::Int32 {} };

        } else if constexpr (std::is_same<U, std::int64_t>()) {
          return Type { Type::Int64 {} };

        } else if constexpr (std::is_same<U, std::uint32_t>()) {
          return Type { Type::UInt32 {} };

        } else if constexpr (std::is_same<U, std::uint64_t>()) {
          return Type { Type::UInt64 {} };

        } else if constexpr (std::is_integral<U>()) {
          return Type { Type::Integer {} };

        } else if constexpr (std::is_same<U, float>()) {
          return Type { Type::Float {} };

        } else if constexpr (std::is_floating_point_v<U>) {
          return Type { Type::Double {} };

        } else if constexpr (std::is_same<U, std::string>()) {
          return Type { Type::String {} };

        } else if constexpr (rfl::internal::is_description_v<U>) {
          return make_description<U>(_definitions);

        } else if constexpr (std::is_enum_v<U>) {
          return make_enum<U>(_definitions);

        } else if constexpr (std::is_class_v<U> && std::is_aggregate_v<U>) {
          return make_reference<U>(_definitions);

        } else if constexpr (internal::is_literal_v<U>) {
          return Type { Type::Literal { .values_ = U::strings() } };

        } else if constexpr (internal::is_validator_v<U>) {
          return make_validated<U>(_definitions);

        } else if constexpr (internal::has_reflection_type_v<U>) {
          return Parser<R, W, typename U::ReflectionType, ProcessorsType>::to_schema(_definitions);

        } else {
          static_assert(rfl::always_false_v<U>, "Unsupported type.");
        }
      }

     private:
      template <class U>
      static schema::Type make_description(std::map<std::string, schema::Type>* _definitions) {
        using Type = schema::Type;
        return Type {
          Type::Description {
                             .description_ = typename U::Content().str(),
                             .type_        = Ref<Type>::make(
              Parser<R, W, std::remove_cvref_t<typename U::Type>, ProcessorsType>::to_schema(
                _definitions
              )
            ) }
        };
      }

      template <class U>
      static schema::Type make_enum(std::map<std::string, schema::Type>* _definitions) {
        using Type = schema::Type;
        using S    = internal::enums::StringConverter<U>;
        if constexpr (S::is_flag_enum_) {
          return Type { Type::String {} };
        } else {
          return Parser<R, W, typename S::NamesLiteral, ProcessorsType>::to_schema(_definitions);
        }
      }

      template <class U>
      static schema::Type make_reference(std::map<std::string, schema::Type>* _definitions) {
        using Type      = schema::Type;
        const auto name = make_type_name<U>();
        if (_definitions->find(name) == _definitions->end()) {
          (*_definitions)[name] = Type { Type::Integer {} }; // Placeholder to avoid infinite loop.
          using NamedTupleType  = internal::processed_t<U, ProcessorsType>;
          (*_definitions)[name] =
            Parser<R, W, NamedTupleType, ProcessorsType>::to_schema(_definitions);
        }
        return Type { Type::Reference { name } };
      }

      template <class U>
      static schema::Type make_validated(std::map<std::string, schema::Type>* _definitions) {
        using Type           = schema::Type;
        using ReflectionType = std::remove_cvref_t<typename U::ReflectionType>;
        using ValidationType = std::remove_cvref_t<typename U::ValidationType>;
        return Type {
          Type::Validated { .type_ = Ref<Type>::make(
                              Parser<R, W, ReflectionType, ProcessorsType>::to_schema(_definitions)
                            ), .validation_ = ValidationType::template to_schema<ReflectionType>() }
        };
      }

      template <class U>
      static std::string make_type_name() {
        if constexpr (is_tagged_union_wrapper_v<U>) {
          return replace_non_alphanumeric(type_name_t<typename U::Type>().str() + "__tagged");
        } else {
          return replace_non_alphanumeric(type_name_t<U>().str());
        }
      }

      /// The way this works is that we allocate space on the stack in this size
      /// of the struct in which we then write the individual fields using views
      /// and placement new. This is how we deal with the fact that some fields
      /// might not be default-constructible.
      static Result<T> read_struct(const R& _r, const InputVarType& _var) {
        alignas(T) unsigned char buf[sizeof(T)];
        auto                     ptr  = reinterpret_cast<T*>(buf);
        auto                     view = ProcessorsType::template process<T>(to_view(*ptr));
        using ViewType                = std::remove_cvref_t<decltype(view)>;
        const auto err = Parser<R, W, ViewType, ProcessorsType>::read_view(_r, _var, &view);
        if (err) [[unlikely]] {
          return *err;
        }
        return std::move(*ptr);
      }

      static std::string replace_non_alphanumeric(std::string _str) {
        for (auto& ch : _str) { ch = std::isalnum(ch) ? ch : '_'; }
        return _str;
      }
    };

  } // namespace parsing
} // namespace rfl

#endif