#pragma once

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

#include <cassert>

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

#include "schema.hpp"
#include "schema_meta.hpp"

namespace saw {

namespace encode {
struct Native {
	static constexpr string_literal name = "encode::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<>
class data<schema::Void, encode::Native> {
public:
	using Schema = schema::Void;
	using MetaSchema = schema::Void;
};

template<>
class data<schema::Bool, encode::Native> {
public:
	using Schema = schema::Bool;
	using MetaSchema = schema::Void;
private:
	bool value_;
public:
	data():value_{false}{}
	data(data<MetaSchema, encode::Native>):value_{false}{}

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	void set(bool val){
		value_ = val;
	}

	bool get() const {
		return value_;
	}
};

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

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	data(typename native_data_type<Schema>::type value__):
		value_{std::move(value__)}{}

	void set(typename native_data_type<Schema>::type val){
		value_ = val;
	}

	typename native_data_type<Schema>::type get() const {return value_;}

	data<Schema, encode::Native> operator*(const data<Schema, encode::Native>& rhs)const{
		return {get() * rhs.get()};
	}
	
	data<Schema, encode::Native> operator/(const data<Schema, encode::Native>& rhs)const{
		return {get() / rhs.get()};
	}
	
	data<Schema, encode::Native> operator+(const data<Schema, encode::Native>& rhs)const{
		return {get() + rhs.get()};
	}
	
	data<Schema, encode::Native>& operator+=(const data<Schema, encode::Native>& rhs)const{
		value_ += rhs.get();
		return *this;
	}
	
	data<Schema, encode::Native>& operator-=(const data<Schema, encode::Native>& rhs)const{
		value_ -= rhs.get();
		return *this;
	}

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

	template<typename Enc>
	bool operator==(const data<Schema, Enc>& rhs)const{
		return get() == rhs.get();
	}

	template<typename Enc>
	bool operator<(const data<Schema, Enc>& rhs) const {
		return get() < rhs.get();
	}

	/**
	 * Casts 
	 */
	template<typename Target>
	data<Target, encode::Native> cast_to() const {
		auto raw_to = static_cast<typename saw::native_data_type<Target>::type>(value_);
		return {raw_to};
	}
};

/**
 * Mixed precision class for native formats
 */
template<typename TA, uint64_t NA, typename TB, uint64_t NB> 
class data<schema::MixedPrecision<schema::Primitive<TA,NA>, schema::Primitive<TB,NB>>, encode::Native>{
public:
	using Schema = schema::MixedPrecision<schema::Primitive<TA,NA>, schema::Primitive<TB,NB>>;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
	data<typename Schema::StorageSchema, encode::Native> value_;
public:
	data():value_{}{}
	data(data<MetaSchema, encode::Native>):value_{}{}

	data(typename saw::native_data_type<typename Schema::InterfaceSchema>::type val__):value_{static_cast<typename saw::native_data_type<typename Schema::StorageSchema>::type>(val__)}{}

	typename saw::native_data_type<typename Schema::InterfaceSchema>::type get() const {
		return value_.template cast_to<typename Schema::InterfaceSchema>().get();
	}

	data(const saw::data<typename Schema::InterfaceSchema, encode::Native>& val){
		value_ = val.template cast_to<typename Schema::StorageSchema>();
	}
	
	void set(typename saw::native_data_type<typename Schema::InterfaceSchema>::type val){
		value_.set(static_cast<typename Schema::StorageSchema>(val));
	}
	
	data<Schema, encode::Native> operator*(const data<Schema, encode::Native>& rhs) const {
		using CalcType = typename native_data_type<typename Schema::InterfaceSchema>::type;
		CalcType left = static_cast<CalcType>(value_.get());
		CalcType right = static_cast<CalcType>(rhs.get());
		return {left * right};
	}
	
	data<typename Schema::InterfaceSchema, encode::Native> operator*(const data<typename Schema::InterfaceSchema, encode::Native>& rhs) const {
		using CalcType = typename native_data_type<typename Schema::InterfaceSchema>::type;
		CalcType left = static_cast<CalcType>(value_.get());
		CalcType right = rhs.get();
		return {left * right};
	}
	
	data<typename Schema::InterfaceSchema, encode::Native> operator/(const data<Schema, encode::Native>& rhs)const{
		using CalcType = typename native_data_type<typename Schema::InterfaceSchema>::type;
		CalcType left = static_cast<CalcType>(value_.get());
		CalcType right = static_cast<CalcType>(rhs.get());
		return {left / right};
	}
	
	data<typename Schema::InterfaceSchema, encode::Native> operator+(const data<Schema, encode::Native>& rhs)const{
		using CalcType = typename native_data_type<typename Schema::InterfaceSchema>::type;
		CalcType left = static_cast<CalcType>(value_.get());
		CalcType right = static_cast<CalcType>(rhs.get());
		return {left + right};
	}
	
	data<Schema, encode::Native>& operator+=(const data<Schema, encode::Native>& rhs)const{
		*this = *this + rhs.get();
		return *this;
	}

	data<typename Schema::InterfaceSchema, encode::Native> operator-(const data<Schema, encode::Native>& rhs)const{
		using CalcType = typename native_data_type<typename Schema::InterfaceSchema>::type;
		CalcType left = static_cast<CalcType>(value_.get());
		CalcType right = static_cast<CalcType>(rhs.get());
		return {left - right};
	}
	
	data<Schema, encode::Native>& operator-=(const data<Schema, encode::Native>& rhs) const {
		*this = *this - rhs.get();
		return *this;
	}

	template<typename Enc>
	bool operator==(const data<Schema, Enc>& rhs)const{
		return get() == rhs.get();
	}

	template<typename Enc>
	bool operator<(const data<Schema, Enc>& rhs) const {
		return get() < rhs.get();
	}
};

/* 
template<typename T, typename N>
class data<schema::Ref<schema::Primitive<T,N>>, encode::Native {
public:
	using Schema = schema::Ref<schema::Primitive<T,N>>;
private:
	ref<typename native_data_type<schema::Primitive<T,N>>::type> orig_;
public:
	data(ref<typename native_data_type<schema::Primitive<T,N>>::type> orig__):
		orig_{orig__}
	{}

	/// @TODO what do we really want to return?
	data<schema::Primitive<T,N>, encode::Native> operator+(const data<Schema, encode::Native>& rhs) const {
		data<schema::Primitive<T,N>> prim;

		return prim;
	}
};
*/

/**
 * Union type for native data classes
 */
template<typename... T, string_literal... literals>
class data<schema::Union<schema::Member<T, literals>...>, encode::Native> {
public:
	using Schema = schema::Union<schema::Member<T,literals>...>;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
	std::variant<data<T,encode::Native>...> value_;
	
	template<uint64_t i = 0u>
	struct init_helper {
		static void apply(std::variant<data<T,encode::Native>...>& val, data<MetaSchema, encode::Native>&& init){
			if( init.index() == i ){
				auto& val_i = val.template init<i>();
				val_i = {std::move(init.template get<i>())};
				return;
			}

			if constexpr ( (i+1u) < sizeof...(T) ){
				init_helper<i+1u>::apply(val, init);
			}
		}
	};
public:
	data() = default;
	data(data<MetaSchema, encode::Native> init){
		if constexpr ( 0u < sizeof...(T) ){
			init_helper<0u>::apply(value_, std::move(init));
		}
	}

	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_);
	}
};

/**
 * Data class which represents a struct in the native format.
 */
template<typename... T, string_literal... literals>
class data<schema::Struct<schema::Member<T, literals>...>, encode::Native> {
public:
	using Schema = schema::Struct<schema::Member<T,literals>...>;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
	/**
	 * Tuple storing the member values.
	 */
	std::tuple<data<T,encode::Native>...> value_;
	
	template<uint64_t i = 0u>
	struct init_helper {
		static void apply(std::tuple<data<T,encode::Native>...>& val, data<Schema, encode::Native>&& init){
			auto& val_i = val.template get<i>();
			auto& init_i = init.template get<i>();

			val_i = {std::move(init_i)};

			if constexpr ( (i+1u) < sizeof...(T) ){
				init_helper<i+1u>::apply(val, init);
			}
		}
	};
public:
	/**
	 * Default constructor.
	 */
	data() = default;
	data(data<MetaSchema, encode::Native> init){
		if constexpr ( 0u < sizeof...(T) ){
			init_helper<0u>::apply(value_, std::move(init));
		}
	}

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);
	
	/**
	 * Get the member value based on the string_literal.
	 */
	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_);
	}
	
	/**
	 * Get the member value based on the string_literal.
	 */
	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_);
	}

	/**
	 * Return the amount of members.
	 */
	constexpr size_t size() const {
		return sizeof...(T);
	}
};

template<typename... T>
class data<schema::Tuple<T...>, encode::Native> {
public:
	using Schema = schema::Tuple<T...>;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
	std::tuple<data<T,encode::Native>...> value_;

	template<uint64_t i = 0u>
	struct init_helper {
		static void apply(std::tuple<data<T,encode::Native>...>& val, data<MetaSchema, encode::Native>&& init){
			auto& val_i = val.template get<i>();
			auto& init_i = init.template get<i>();

			val_i = {std::move(init_i)};

			if constexpr ( (i+1u) < sizeof...(T) ){
				init_helper<i+1u>::apply(val, init);
			}
		}
	};
public:
	data() = default;
	data(data<MetaSchema, encode::Native> init){
		if constexpr ( 0u < sizeof...(T) ){
			init_helper<0u>::apply(value_, std::move(init));
		}
	}

	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 Key, typename Value>
class data<schema::Map<Key,Value>, encode::Native> {
public:
		using Schema = schema::Map<Key,Value>;
		using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
		std::map<data<Key,encode::Native>, data<Value, encode::Native>> vals_;
public:
		data() = default;

		SAW_DEFAULT_COPY(data);
		SAW_DEFAULT_MOVE(data);

		data(data<MetaSchema, encode::Native> init){}

		error_or<void> emplace(ref<data<Key, encode::Native>> key, ref<data<Value,encode::Native>> value){
			auto insert = vals_.emplace(std::make_pair(std::move(key()), std::move(value())));
			if(!insert.second){
				return make_error<err::already_exists>();
			}
			return make_void();
		}

		error_or<void> erase(ref<data<Key,encode::Native>> key){
			auto erase = vals_.erase(key());
			if(erase == 0u){
				return make_error<err::not_found>();
			}
			return make_void();
		}

		error_or<ptr<data<Value,encode::Native>>> find(ref<data<Value,encode::Native>> key){
			auto find = vals_.find(key());
			if(find == vals_.end()){
				return make_error<err::not_found>();
			}

			return ptr<data<Value,encode::Native>>{find->second};
		}
};

template<typename T, size_t Dim>
class data<schema::Array<T,Dim>, encode::Native> {
	public:
		using Schema = schema::Array<T,Dim>;
		using MetaSchema = typename meta_schema<Schema>::MetaSchema;
	private:
		// data<schema::FixedArray<schema::UInt64, Dim>> dims_;
		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){
				s *= dims_.at(iter);
			}

			return s;
		}
	public:
		data():
			value_{}
		{
			for(auto& iter : dims_){
				iter = 0u;
			}
		}

		SAW_DEFAULT_COPY(data);
		SAW_DEFAULT_MOVE(data);

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

		data(data<MetaSchema, encode::Native> init)
		{
			for(uint64_t i = 0; i < Dim; ++i){
				dims_.at(i) = init.at(i).get();
			}
			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<uint64_t>(size_)...}}
		{
			static_assert(sizeof...(Dims)==Dim, "Argument size must be equal to the Dimension");
		}

		data<T, encode::Native>& at(const std::array<uint64_t, Dim>& ind){
			return value_.at(this->get_flat_index(ind));
		}
		
		const data<T, encode::Native>& at(const std::array<uint64_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(std::array<uint64_t, Dim>{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(std::array<uint64_t, Dim>{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(uint64_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:
		template<typename U>
		uint64_t get_flat_index(const U& i) const {
			static_assert(
					std::is_same_v<U,data<schema::FixedArray<schema::UInt64,Dim>>> or
					std::is_same_v<U,std::array<uint64_t,Dim>>,
					"Unsupported type"
			);
			assert(value_.size() == get_full_size());
			uint64_t s = 0;

			uint64_t stride = 1;

			for(uint64_t iter = 0; iter < Dim; ++iter){
				uint64_t ind = [](auto val) -> uint64_t {
					using V = std::decay_t<decltype(val)>;
					if constexpr (std::is_same_v<V,data<schema::UInt64>>){
						return val.get();
					}else if constexpr (std::is_same_v<V, uint64_t>){
						return val;
					}else{
						static_assert(always_false<V>, "Cases exhausted");
					}
				}(i.at(iter));
				assert(ind < dims_.at(iter));
				s += ind * stride;
				stride *= dims_.at(iter);
			}

			return s;
		}
};

template<typename T, uint64_t... D>
class data<schema::FixedArray<T,D...>, encode::Native> {
public:
	using Schema = schema::FixedArray<T,D...>;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
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(data<MetaSchema, encode::Native>){}
	data(const std::array<data<T, encode::Native>, ct_multiply<uint64_t,D...>::value>& value__):
		value_{value__}
	{}

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

	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;
	}
};

/**
 * Data type representing string.
 */
template<>
class data<schema::String, encode::Native> {
public:
	using Schema = schema::String;
	using MetaSchema = typename meta_schema<Schema>::MetaSchema;
private:
	/**
	 * The native way to represent strings.
	 */
	std::string value_;
public:
	data() = default;
	data(uint64_t size__){
		value_.resize(size__);
	}
	data(data<MetaSchema, encode::Native> init){
		value_.resize(init.get());
	}

	SAW_DEFAULT_COPY(data);
	SAW_DEFAULT_MOVE(data);

	data(std::string value__):value_{std::move(value__)}{}

	/**
	 * Return the length of the string.
	 */
	std::size_t size() const {
		return value_.size();
	}

	/**
	 * set the inner string to str.
	 */
	void set(std::string str){
		value_ = std::move(str);
	}

	/**
	 * Get a char reference at position i.
	 */
	char& at(size_t i) {
		return value_.at(i);
	}

	/**
	 * Get a char reference at position 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;
	}

	std::string_view stl_view() {
		return value_;
	}

	std::string stl_string() const {
		return value_;
	}

	template<typename Enc2>
	bool operator==(const data<schema::String, Enc2>& rhs) const {
		if(size() != rhs.size()){
			return false;
		}
		bool eq = true;
		for(uint64_t i = 0; i < size(); ++i){
			eq = eq && (get_at(i) == rhs.get_at(i));
		}
		return eq;
	}

	/**
	 * Check if a string_view is equal to this type.
	 */
	bool operator==(const std::string_view& val)const{
		return value_ == val;
	}
};


}