#pragma once

#include "component.hpp"
#include "equilibrium.hpp"

namespace kel {
namespace lbm {
namespace cmpt {
struct BGK {};
struct BGKGuo {};
}

/**
 * Standard BGK collision operator for LBM
 */
template<typename T, typename Descriptor>
class component<T, Descriptor, cmpt::BGK> {
private:
	typename saw::native_data_type<T>::type relaxation_;
	saw::data<T> frequency_;
public:
	component(typename saw::native_data_type<T>::type relaxation__):
		relaxation_{relaxation__},
		frequency_{typename saw::native_data_type<T>::type(1) / relaxation_}
	{}

	using Component = cmpt::BGK;

	/**
	 * Thoughts regarding automating order setup
	 */
	using access = cmpt::access_tuple<
		cmpt::access<"dfs", 1, true, true, true>
	>;

	/**
	 * Thoughts regarding automating order setup
	 */
	static constexpr saw::string_literal name = "collision";
	static constexpr saw::string_literal after = "";
	static constexpr saw::string_literal before = "streaming";

	/**
	 * Raw setup
	 */
	template<typename CellFieldSchema>
	void apply(saw::data<CellFieldSchema>& field, saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> index, uint64_t time_step){
		bool is_even = ((time_step % 2) == 0);
		auto& cell = field(index);

		auto& dfs_old = (is_even) ? cell.template get<"dfs_old">() : cell.template get<"dfs">();
		// auto& dfs = (not is_even) ? cell.template get<"dfs_old">() : cell.template get<"dfs">();

		saw::data<T> rho;
		saw::data<sch::FixedArray<T,Descriptor::D>> vel;
		compute_rho_u<T,Descriptor>(dfs_old,rho,vel);
		auto eq = equilibrium<T,Descriptor>(rho,vel);

		for(uint64_t i = 0u; i < Descriptor::Q; ++i){
			dfs_old({i}) = dfs_old({i}) + frequency_ * (eq.at(i) - dfs_old({i}));
			// dfs_old({i}).set(dfs_old({i}).get() + (1.0 / relaxation_) * (eq.at(i).get() - dfs_old({i}).get()));
		}
	}
};

template<typename T, typename Descriptor>
class component<T, Descriptor, cmpt::BGKGuo> {
private:
	typename saw::native_data_type<T>::type relaxation_;
	saw::data<T> frequency_;
public:
	component(typename saw::native_data_type<T>::type relaxation__):
		relaxation_{relaxation__},
		frequency_{typename saw::native_data_type<T>::type(1) / relaxation_}
	{}

	using Component = cmpt::BGKGuo;

	using access = cmpt::access_tuple<
		cmpt::access<"dfs", 1, true, true, true>,
		cmpt::access<"force", 0, true, false>
	>;

	/**
	 * Thoughts regarding automating order setup
	 */
	static constexpr saw::string_literal name = "collision";
	static constexpr saw::string_literal after = "";
	static constexpr saw::string_literal before = "streaming";

	template<typename CellFieldSchema>
	void apply(saw::data<CellFieldSchema>& field, saw::data<sch::FixedArray<sch::UInt64, Descriptor::D>> index, uint64_t time_step){
		bool is_even = ((time_step % 2) == 0);
		auto& cell = field(index);

		auto& dfs_old = (is_even) ? cell.template get<"dfs_old">() : cell.template get<"dfs">();
		// auto& dfs = (not is_even) ? cell.template get<"dfs_old">() : cell.template get<"dfs">();

		saw::data<T> rho;
		saw::data<sch::FixedArray<T,Descriptor::D>> vel;
		compute_rho_u<T,Descriptor>(dfs_old,rho,vel);
		auto eq = equilibrium<T,Descriptor>(rho,vel);

		using dfi = df_info<T,Descriptor>;

		auto& force = cell.template get<"force">();

		for(uint64_t i = 0u; i < Descriptor::Q; ++i){
			// saw::data<T> ci_min_u{0};
			saw::data<T> ci_dot_u{0};
			for(uint64_t d = 0u; d < Descriptor::D; ++d){
				ci_dot_u = ci_dot_u + vel.at({d}) * saw::data<T>{static_cast<typename saw::native_data_type<T>::type>(dfi::directions[i][d])};
			}
			saw::data<T> F_i{0};// = saw::data<T>{dfi::weights[i]} * (ci_dot_F * dfi::inv_cs2 + ci_dot_u * ci_dot_F * (dfi::inv_cs2 * dfi::inv_cs2));

			for(uint64_t d = 0u; d < Descriptor::D; ++d){
				F_i = F_i +
					saw::data<T>{dfi::weights[i]} * ((saw::data<T>{static_cast<typename saw::native_data_type<T>::type>(dfi::directions[i][d])}
					- vel.at({d}) ) * dfi::inv_cs2 + ci_dot_u * saw::data<T>{static_cast<typename saw::native_data_type<T>::type>(dfi::directions[i][d])} * dfi::inv_cs2  * dfi::inv_cs2 ) * force({d});
			}


			dfs_old({i}) = dfs_old({i}) + frequency_ * (eq.at(i) - dfs_old({i}) ) + F_i * (saw::data<T>{1} - saw::data<T>{0.5f} * frequency_);
		}
	}
};
}
}