#pragma once

namespace saw {
namespace impl {
template<typename Schema>
struct netcdf_primitive_id {
		static_assert(always_false<Schema>, "Not a primitive id");
};

template<>
struct netcdf_primitive_id<schema::Int32> {
		static constexpr nc_type value = NC_INT;
};

template<>
struct netcdf_primitive_id<schema::UInt32> {
		static constexpr nc_type value = NC_UINT;
};

template<>
struct netcdf_primitive_id<schema::Int64> {
		static constexpr nc_type value = NC_INT64;
};

template<>
struct netcdf_primitive_id<schema::UInt64> {
		static constexpr nc_type value = NC_UINT64;
};

template<>
struct netcdf_primitive_id<schema::Float32> {
		static constexpr nc_type value = NC_FLOAT;
};

template<>
struct netcdf_primitive_id<schema::Float64> {
		static constexpr nc_type value = NC_DOUBLE;
};

template<typename Schema>
struct netcdf_is_group {
		static constexpr bool value = false;
};

template<typename... T, string_literal... Lits>
struct netcdf_is_group<schema::Struct<schema::Member<T,Lits>...>> {
		static constexpr bool value = true;
};

template<typename Schema, typename ToEncode>
struct netcdf_decode;

template<typename T, size_t N, typename ToDecode>
struct netcdf_decode<schema::Primitive<T,N>, ToDecode> {
		using Schema = schema::Primitive<T,N>;

		static error_or<void> decode(data<Schema, ToDecode>& to, int from, int nc_varid){
				int rc{};
				
				nc_type nc_vartype{};
				int nc_dimnum{};
				std::array<int,NC_MAX_VAR_DIMS> nc_dimids;

				rc = nc_inq_var(from, nc_varid, nullptr, &nc_vartype, &nc_dimnum, &nc_dimids[0], nullptr);
				if(rc != NC_NOERR){
						return make_error<err::critical>();
				}
				if(nc_vartype != netcdf_primitive_id<schema::Primitive<T,N>>::value){
						return make_error<err::critical>();
				}
				if(nc_dimnum != 0){
						return make_error<err::critical>();
				}
				
				typename native_data_type<schema::Primitive<T,N>>::type val{};
				rc = nc_get_var(from, nc_varid, &val);
				if(rc != NC_NOERR){
						return make_error<err::critical>();
				}

				to.set(val);

				return void_t {};
		}
};

template<typename T, size_t Dim, typename ToDecode>
struct netcdf_decode<schema::Array<T,Dim>, ToDecode> {
		using Schema = schema::Array<T,Dim>;

		template<std::size_t Level>
		static error_or<void> decode_level(data<Schema, ToDecode>& to, int from, int nc_varid, std::array<std::size_t, Dim>& index, const std::array<size_t,Dim>& count){
				if constexpr ( Level == Dim ){
						int rc{};
						typename native_data_type<T>::type val;
						rc = nc_get_vara(from, nc_varid, index.data(), count.data(), &val);
						if(rc != NC_NOERR){
								return make_error<err::critical>();
						}
						to.at(index).set(val);
				}else{
						const std::size_t dim_size = to.get_dim_size(Level);
						for(index[Level] = 0; index[Level] < dim_size; ++index[Level]){
								auto eov = decode_level<Level+1>(to, from, nc_varid, index, count);
								if(eov.is_error()){
										return eov;
								}
						}
				}

				return void_t{};
		}

		static error_or<void> decode(data<Schema, ToDecode>& to, int from, int nc_varid){
				int rc{};

				nc_type nc_vartype{};

				int nc_dimnum{};
				std::array<int, NC_MAX_VAR_DIMS> nc_dimids;

				rc = nc_inq_var(from, nc_varid, nullptr, &nc_vartype, &nc_dimnum, &nc_dimids[0], nullptr);
				if(rc != NC_NOERR){
						return make_error<err::critical>();
				}
				if(nc_vartype != netcdf_primitive_id<T>::value){
						return make_error<err::critical>();
				}
				if(nc_dimnum != Dim){
						return make_error<err::critical>();
				}

				std::array<std::size_t, Dim> dims;
				std::array<size_t, Dim> count;
				for(std::size_t i = 0; i < Dim; ++i){
						rc = nc_inq_dim(from, nc_dimids[i], nullptr, &dims[i]);
						if(rc != NC_NOERR){
								return make_error<err::critical>();
						}
						count[i] = 1;
				}

				to = {dims};
				std::array<std::size_t, Dim> index;

				return decode_level<0>(to, from, nc_varid, index, count);
		}
};

template<typename... T, string_literal... Lits, typename ToDecode>
struct netcdf_decode<schema::Struct<schema::Member<T,Lits>...>, ToDecode> {
	using Schema = schema::Struct<schema::Member<T,Lits>...>;

	template<std::size_t i>
	static error_or<void> decode_member(data<Schema,ToDecode>& to, int from){
			using Type = typename parameter_pack_type<i,T...>::type;
			constexpr string_literal Literal = parameter_key_pack_type<i, Lits...>::literal;
			{
				/**
				 * We have to ask for the internal id of the netcdf structure
				 */
				if constexpr (netcdf_is_group<Type>::value){
						int nc_group_id{};
						int rc {};
						rc = nc_inq_ncid(from, Literal.data.data(), &nc_group_id);
						if(rc != NC_NOERR) {
								return make_error<err::critical>();
						}
						auto eov = netcdf_decode<Type, ToDecode>::decode(to.template get<Literal>(), nc_group_id);
						if(eov.is_error()){
								return eov;
						}
				}else{
						int nc_varid{};
						int rc {};
						rc = nc_inq_varid(from, Literal.data.data(), &nc_varid);
						if(rc != NC_NOERR) {
								return make_error<err::critical>();
						}
						auto eov = netcdf_decode<Type, ToDecode>::decode(to.template get<Literal>(), from, nc_varid); 
				}

			}
			if constexpr ((i+1) < sizeof...(T)){
				auto eov = decode_member<i+1>(to, from);
				if(eov.is_error()){
						return eov;
				}
			}

			return void_t{};
	}


	static error_or<void> decode(data<Schema, ToDecode>& to, int from){
		if constexpr (sizeof...(T) > 0){
				auto eov = decode_member<0>(to, from);
				return eov;
		}
		
		return void_t{};
	}
};
}
}