#pragma once

#include <forstio/common.hpp>
#include <forstio/error.hpp>
#include <forstio/templates.hpp>

#include <cassert>

#include <algorithm>
#include <array>
#include <concepts>
#include <variant>
#include <vector>

#include "schema.hpp"

namespace saw {
namespace encode {
struct Native {};
}
template<typename Schema, typename Encode>
class codec;
/*
 * Helper for the basic message container, so the class doesn't have to be
 * specialized 10 times.
 */
template <class T> struct native_data_type;

template <>
struct native_data_type<schema::Primitive<schema::SignedInteger, 1>> {
	using type = int8_t;
};

template <>
struct native_data_type<schema::Primitive<schema::SignedInteger, 2>> {
	using type = int16_t;
};

template <>
struct native_data_type<schema::Primitive<schema::SignedInteger, 4>> {
	using type = int32_t;
};

template <>
struct native_data_type<schema::Primitive<schema::SignedInteger, 8>> {
	using type = int64_t;
};

template <>
struct native_data_type<schema::Primitive<schema::UnsignedInteger, 1>> {
	using type = uint8_t;
};

template <>
struct native_data_type<schema::Primitive<schema::UnsignedInteger, 2>> {
	using type = uint16_t;
};

template <>
struct native_data_type<schema::Primitive<schema::UnsignedInteger, 4>> {
	using type = uint32_t;
};

template <>
struct native_data_type<schema::Primitive<schema::UnsignedInteger, 8>> {
	using type = uint64_t;
};

template <>
struct native_data_type<schema::Primitive<schema::FloatingPoint, 4>> {
	using type = float;
};

template <>
struct native_data_type<schema::Primitive<schema::FloatingPoint, 8>> {
	using type = double;
};

template<typename T, typename Encoding = encode::Native>
class data {
private:
	static_assert(always_false<T>, "Type not supported");
};

template<typename... T, string_literal... literals>
class data<schema::Union<schema::Member<T, literals>...>, encode::Native> {
private:
	std::variant<data<T,encode::Native>...> value_;
public:
	data() = default;

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	template<string_literal lit>
	void set(data<typename parameter_pack_type<parameter_key_pack_index<lit, literals...>::value, T...>::type, encode::Native> val){
		value_ = std::move(val);
	}

	template<string_literal lit>
	data<typename parameter_pack_type<parameter_key_pack_index<lit, literals...>::value, T...>::type, encode::Native>& init(){
		value_.template emplace<parameter_key_pack_index<lit, literals...>::value>();
		return get<lit>();
	}

	template<string_literal lit>
	bool holds_alternative() const {
		return (parameter_key_pack_index<lit, literals...>::value == value_.index());
	}

	template<string_literal lit>
	data<typename parameter_pack_type<parameter_key_pack_index<lit, literals...>::value, T...>::type, encode::Native>& get(){
		return std::get<parameter_key_pack_index<lit, literals...>::value>(value_);
	}
	
	template<string_literal lit>
	const data<typename parameter_pack_type<parameter_key_pack_index<lit, literals...>::value, T...>::type, encode::Native>& get() const{
		return std::get<parameter_key_pack_index<lit, literals...>::value>(value_);
	}
};

template<typename... T, string_literal... literals>
class data<schema::Struct<schema::Member<T, literals>...>, encode::Native> {
private:
	std::tuple<data<T,encode::Native>...> value_;
public:
	data() = default;
	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);
	
	template<string_literal literal>
	data<
		typename parameter_pack_type<
			parameter_key_pack_index<
				literal, literals...
			>::value
		, T...>::type
	, encode::Native>& get(){
		return std::get<parameter_key_pack_index<literal, literals...>::value>(value_);
	}
	
	template<string_literal literal>
	const data<
		typename parameter_pack_type<
			parameter_key_pack_index<
				literal, literals...
			>::value
		, T...>::type
	, encode::Native>& get() const {
		return std::get<parameter_key_pack_index<literal, literals...>::value>(value_);
	}

	constexpr size_t size() const {
		return sizeof...(T);
	}
};

template<typename... T>
class data<schema::Tuple<T...>, encode::Native> {
private:
	std::tuple<data<T,encode::Native>...> value_;
public:
	data() = default;
	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);
	
	template<size_t i>
	data<typename parameter_pack_type<i,T...>::type, encode::Native>& get(){
		return std::get<i>(value_);
	}
	
	template<size_t i>
	const data<typename parameter_pack_type<i,T...>::type, encode::Native>& get() const{
		return std::get<i>(value_);
	}

	constexpr size_t size() const {
		return sizeof...(T);
	}
};

template<typename T, size_t Dim>
class data<schema::Array<T,Dim>, encode::Native> {
	private:
		std::array<uint64_t, Dim> dims_;
		std::vector<data<T, encode::Native>> value_;

		uint64_t get_full_size() const {
			uint64_t s = 1;

			for(uint64_t iter = 0; iter < Dim; ++iter){
				assert(dims_.at(iter) > 0);
				s *= dims_.at(iter);
			}

			return s;
		}
	public:
		data(){
			std::fill(dims_.begin(), dims_.end(), 0u);
			value_.resize(get_full_size());
		}

		SAW_DEFAULT_COPY(data);
		SAW_DEFAULT_MOVE(data);

		data(const std::array<uint64_t, Dim>& i):
			dims_{i},
			value_{}
		{
			value_.resize(get_full_size());
		}

		template<size_t i = 0>
		error_or<void> add(saw::data<T,encode::Native> data){
			/** @todo
			 * Generally the last dimension can always accept a element so to say.
			 * Changing the others would require moving data due to the stride changing.
			 * Since the last dimension doesn't affect the stride, we don't need reordering there.
			 * But I want a quick solution for one dimension so here we are.
			 *
			 * I can always ignore strides and use a stacked std::vector
			 * std::vector<std::vector<...>> and so on.
			 * But for now I'm keeping the strides. Smaller chunks of memory aren't to bad either
			 * though.
			 * I'll probably change it to the smaller chunks
			 */
			static_assert(Dim == 1, "Currently can't deal with higher dims");
			static_assert(i < Dim, "Can't add to dimension. Index i larger than dimension size");

			try {
				value_.emplace_back(std::move(data));
			}catch(const std::exception& e){
				(void) e;
				return make_error<err::out_of_memory>();
			}

			++dims_.at(i);

			return void_t{};
		}

		template<std::integral... Dims>
		data(Dims... size_):
			data{{static_cast<std::size_t>(size_)...}}
		{
			static_assert(sizeof...(Dims)==Dim, "Argument size must be equal to the Dimension");
		}

		data<T, encode::Native>& at(const std::array<std::size_t, Dim>& ind){
			return value_.at(this->get_flat_index(ind));
		}
		
		const data<T, encode::Native>& at(const std::array<std::size_t, Dim>& ind) const {
			return value_.at(this->get_flat_index(ind));
		}

		template<std::integral... Dims>
		data<T, encode::Native>& at(Dims... i){
			return value_.at(this->get_flat_index({static_cast<uint64_t>(i)...}));
		}
		
		template<std::integral... Dims>
		const data<T, encode::Native>& at(Dims... i) const {
			return value_.at(this->get_flat_index({static_cast<uint64_t>(i)...}));
		}

		data<T,encode::Native>& at(const data<schema::FixedArray<schema::UInt64,Dim>>& i){
			return value_.at(this->get_flat_index(i));
		}
		
		const data<T,encode::Native>& at(const data<schema::FixedArray<schema::UInt64,Dim>>& i)const{
			return value_.at(this->get_flat_index(i));
		}
		
		std::size_t get_dim_size(std::size_t i) const {
			return dims_.at(i);
		}

		size_t size() const { return value_.size();}

		data<schema::FixedArray<schema::UInt64, Dim>> get_dims() const {
			return {dims_};
		}

private:
		uint64_t get_flat_index(const std::array<uint64_t, Dim>& i) const {
			return get_flat_index(data<schema::FixedArray<schema::UInt64,Dim>>{i});
		}

		uint64_t get_flat_index(const data<schema::FixedArray<schema::UInt64,Dim>>& i) const {
			assert(value_.size() == get_full_size());
			uint64_t s = 0;

			uint64_t stride = 1;

			for(uint64_t iter = 0; iter < Dim; ++iter){
				assert(i.at(iter).get() < dims_.at(iter));
				s += i.at(iter).get() * stride;
				stride *= dims_.at(iter);
			}

			return s;
		}
};

template<typename T, uint64_t... D>
class data<schema::FixedArray<T,D...>, encode::Native> {
private:
	//using inner_type = std::array<data<T, encode::Native>, multiply_helper<Dims...>::value>;
	//std::unique_ptr<inner_type> value_;
	using ArrayT = std::array<data<T, encode::Native>, ct_multiply<uint64_t, D...>::value>;
	ArrayT value_;
	
public:
	data() = default;

	data(const std::array<typename native_data_type<T>::type, ct_multiply<uint64_t, D...>::value>& data) requires (is_primitive<T>::value)
	{
		for(uint64_t i = 0; i < ct_multiply<uint64_t, D...>::value; ++i){
			value_.at(i).set(data.at(i));
		}
	}

	data<T, encode::Native>& at(const std::array<uint64_t, sizeof...(D)>& ind){
		return value_.at(this->get_flat_index(ind));
	}
		
	const data<T, encode::Native>& at(const std::array<uint64_t, sizeof...(D)>& ind) const {
		return value_.at(this->get_flat_index(ind));
	}

	template<std::integral... Dims>
	data<T, encode::Native>& at(Dims... i) {
		return value_.at(this->get_flat_index({i...}));
	}

	template<std::integral... Dims>
	const data<T, encode::Native>& at(Dims... i) const {
		return value_.at(this->get_flat_index({i...}));
	}

	data<T, encode::Native>& at(const data<schema::FixedArray<schema::UInt64, sizeof...(D)>>& i){
		return value_.at(this->get_flat_index(i));
	}
	
	const data<T, encode::Native>& at(const data<schema::FixedArray<schema::UInt64, sizeof...(D)>>& i)const{
		return value_.at(this->get_flat_index(i));
	}

	template<uint64_t i>
	uint64_t get_dim_size() const {
		return parameter_pack_value<i, uint64_t, D...>::value;
	}

	data<schema::FixedArray<schema::UInt64, sizeof...(D)>> get_dims() const {
		return {std::array<uint64_t, sizeof...(D)>{D...}};
	}
private:
	uint64_t get_flat_index(const std::array<uint64_t, sizeof...(D)>& i) const {
		uint64_t s = 0;

		uint64_t stride = 1;

		constexpr static std::array<uint64_t, sizeof...(D)> dims_{D...};

		for(uint64_t iter = 0; iter < sizeof...(D); ++iter){
			assert(i.at(iter) < dims_.at(iter));
			s += i.at(iter) * stride;
			stride *= dims_.at(iter);
		}

		return s;
	}
};

template<>
class data<schema::String, encode::Native> {
private:
	std::string value_;
public:
	data() = default;
	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	data(std::string value__):value_{std::move(value__)}{}
	data(std::size_t size_){
		value_.resize(size_);
	}

	std::size_t size() const {
		return value_.size();
	}

	void set(std::string str){
		value_ = std::move(str);
	}

	char& at(size_t i) {
		return value_.at(i);
	}

	const char& at(size_t i) const {
		return value_.at(i);
	}

	char get_at(size_t i) const{
		return value_.at(i);
	}

	void set_at(size_t i, char val){
		value_.at(i) = val;
	}

	bool operator==(const std::string_view& val)const{
		return value_ == val;
	}
};

template<typename T, size_t N>
class data<schema::Primitive<T,N>, encode::Native> {
private:
	typename native_data_type<schema::Primitive<T,N>>::type value_;
public:
	data():value_{}{}

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	data(typename native_data_type<schema::Primitive<T,N>>::type value__):
		value_{std::move(value__)}{}

	void set(typename native_data_type<schema::Primitive<T,N>>::type val){
		value_ = val;
	}

	typename native_data_type<schema::Primitive<T,N>>::type get() const {return value_;}

	data<schema::Primitive<T,N>, encode::Native> operator*(const data<schema::Primitive<T,N>, encode::Native>& rhs)const{
		return {get() * rhs.get()};
	}
	
	data<schema::Primitive<T,N>, encode::Native> operator/(const data<schema::Primitive<T,N>, encode::Native>& rhs)const{
		return {get() / rhs.get()};
	}
	
	data<schema::Primitive<T,N>, encode::Native> operator+(const data<schema::Primitive<T,N>, encode::Native>& rhs)const{
		return {get() + rhs.get()};
	}

	data<schema::Primitive<T,N>, encode::Native> operator-(const data<schema::Primitive<T,N>, encode::Native>& rhs)const{
		return {get() - rhs.get()};
	}

	template<typename Enc>
	bool operator==(const data<schema::Primitive<T,N>, Enc>& rhs)const{
		return get() == rhs.get();
	}

	template<typename Enc>
	bool operator<(const data<schema::Primitive<T,N>, Enc>& rhs) const {
		return get() < rhs.get();
	}
};


}