#include <forstio/error.h>
#include <forstio/templates.h>
#include <forstio/codec/schema.h>

#include <string>
#include <sstream>
#include <map>

#include <iostream>

#include <forstio/codec/schema_stringify.h>

namespace saw {

namespace impl {
/**
 * Type meant to provide future help if I decide to introduce more maps
 */
struct c_types {
		struct c_member {
				std::string key;
				std::string name;
				bool is_primitive;
		};
		
		struct c_struct {
				std::string kind;
				std::string type;
				std::string cpp_schema;
				std::vector<c_member> members;
		};

		struct c_response {
				std::string key;
				bool is_primitive;
		};

		struct c_func {
				std::string cpp_schema;
				std::string cpp_name;
				c_response response;
				std::vector<c_member> requests;
		};

		using c_struct_map = std::map<std::string, c_struct>;
		using c_func_map = std::map<std::string, c_func>;

		struct state {
				std::string interface_schema;
				c_struct_map struct_map;
				c_func_map func_map;
				std::string prefix;
				std::string postfix;
				std::string encoding;
		};
};

namespace schema {
using namespace saw::schema;
/**
Pseudo flattened
using Foo = Struct<
		Member<Array<Int32>, "a">
		Member<Array<Float32>, "b">
>;

Needs to be flattened to

template<typename InnerSchema>
using FlattenedSchemaElement = Struct<
		Member<Array<String>, "path">,
		Member<InnerSchema, "inner_schema">
>;

// Illegal, but doable with more lines of code
// Just use typename... T and 
// "T..." for
// "Member<FlattenedSchemaElement<Ele>,Names>...>"
// and specialize somewhere else
template<typename... Ele, string_literal... Names>
using FlattenedSchema = Struct<
		Member<String, "top_schema">,
		Member<FlattenedSchemaElement<Ele>, Names>...
>;
 */
template<typename T, typename Res>
struct schema_flattener {
		static_assert(always_false<T>, "Not supported");
};

template<typename T0, string_literal Name0, typename... T, string_literal... Names, typename Res>
struct schema_flattener<schema::Struct<schema::Member<T0,Name0>,schema::Member<T,Names>...>, Res> {
};

using StructBindingSchema = Struct<
		Member<String, "kind">,
		Member<String, "key">,
		Member<String, "cpp_schema">,
		Member<Array<String>, "members">
>;

using FunctionBindingSchema = Struct<
		Member<String, "cpp_schema">,
		Member<String, "name">,
		Member<String, "foo">
>;

using BindingSchema = Struct<
		Member<String, "interface_schema">,
		Member<String, "prefix">,
		Member<String, "postfix">,
		Member<String, "encoding">,
		Member<Array<StructBindingSchema>, "structs">,
		Member<Array<FunctionBindingSchema>, "functions">
>;
}

/**
 * Helper to determine if we are dealing with primitive types
 */
template<typename Schema>
struct c_is_primitive {
		static constexpr bool value = false;
};

template<typename T, size_t N>
struct c_is_primitive<schema::Primitive<T,N>> {
		static constexpr bool value = true;
};

template<typename Schema>
struct c_primitive_string {
	static_assert(always_false<Schema>, "Not supported");
};

template<>
struct c_primitive_string<schema::Int8> {
	static constexpr std::string_view value = "int8_t";
};

template<>
struct c_primitive_string<schema::Int16> {
	static constexpr std::string_view value = "int16_t";
};

template<>
struct c_primitive_string<schema::Int32> {
	static constexpr std::string_view value = "int32_t";
};

template<>
struct c_primitive_string<schema::Int64> {
	static constexpr std::string_view value = "int64_t";
};

template<>
struct c_primitive_string<schema::UInt8> {
	static constexpr std::string_view value = "uint8_t";
};

template<>
struct c_primitive_string<schema::UInt16> {
	static constexpr std::string_view value = "uint16_t";
};

template<>
struct c_primitive_string<schema::UInt32> {
	static constexpr std::string_view value = "uint32_t";
};

template<>
struct c_primitive_string<schema::UInt64> {
	static constexpr std::string_view value = "uint64_t";
};

template<>
struct c_primitive_string<schema::Float32> {
	static constexpr std::string_view value = "float";
};

template<>
struct c_primitive_string<schema::Float64> {
	static constexpr std::string_view value = "double";
};

template<typename Schema>
struct c_data_translater {
	static_assert(always_false<Schema>, "Not supported");
};

template<typename T, size_t N>
struct c_data_translater<schema::Primitive<T,N>> {
    using StructMap = typename c_types::c_struct_map;
	using Schema = schema::Primitive<T,N>;

	static error_or<void> generate(c_types::state& c_state, std::string& str){
		(void) c_state;
		str += c_primitive_string<Schema>::value;
		return void_t{};
	}
};

template<typename T, size_t Dim>
struct c_data_translater<schema::Array<T,Dim>> {
		using Schema = schema::Array<T,Dim>;
		using StructMap = typename c_types::c_struct_map;

	static error_or<void> generate(c_types::state& c_state, std::string& type_str){
		type_str = "array_";

		std::string inner_type_str;
		auto eov = impl::c_data_translater<T>::generate(c_state, inner_type_str);
		if(eov.is_error()){
			return eov;
		}

		type_str += inner_type_str;

		if(Dim > 1){
			type_str += "_";
			type_str += std::to_string(Dim);
			type_str += "d";
		}

		if(c_state.struct_map.find(type_str) != c_state.struct_map.end()){
			return void_t{};
		}

		c_types::c_struct str;

		try {
				std::stringstream iss;
				schema_stringify<Schema>::apply(iss);
				str.cpp_schema = iss.str();
		}catch(const std::exception& e){
				return make_error<err::critical>();
		}

		/**
		 * Adding heap alloc data ptr
		 */
		{
				c_types::c_member memb;
				memb.key = inner_type_str;
				memb.name = "data";
				memb.is_primitive = c_is_primitive<T>::value;
				// fn.members.emplace_back(std::move(memb));

				str.members.emplace_back(std::move(memb));
		}
		{
				c_types::c_member memb;
				memb.key
		}


		str.def = "struct ";
		str.def += type_str;

		str.def += " {\n";

		str.def += "\t" + inner_type_str + "* data;\n";
		str.def += "\tsize_t size;\n";
		if( Dim > 1 ){
			str.def += "\tsize_t dims["+std::to_string(Dim)+"];\n";
		}

		str.def += "};\n";

		c_state.struct_map.emplace(std::make_pair(type_str, std::move(str)));
		return void_t{};
	}
};

template<typename Interface>
struct c_iface_translater {
	static_assert(always_false<Interface>,"Not supported");
};

template<class... Request, class Response, string_literal... Lits>
struct c_iface_translater<schema::Function<schema::Struct<schema::Member<Request, Lits>...>, Response>> {
    using StructMap = typename c_types::c_struct_map;
	using FuncMap = typename c_types::c_func_map;

	template<size_t i>
    static error_or<void> generate_request_member(c_types::state& c_state, std::array<std::string, sizeof...(Request)>& type_arr){
			using Type = typename parameter_pack_type<i, Request...>::type;
			// constexpr string_literal lit = parameter_key_pack_type<i, Lits...>::literal;

			auto eov = c_data_translater<Type>::generate(c_state, type_arr.at(i));
			if(eov.is_error()){
				return eov;
			}

			if constexpr ((i+1) < sizeof...(Request)){
				auto eov = generate_request_member<i+1>(c_state, type_arr);
				return eov;
			}

			return void_t{};
	}

	template<size_t i>
	static error_or<void> generate_parameter(std::string& param_use, const std::array<std::string, sizeof...(Request)>& req_type_arr){
		using Type = typename parameter_pack_type<i, Request...>::type;
		constexpr string_literal lit = parameter_key_pack_type<i, Lits...>::literal;
		
		std::string used_param;
		if constexpr (c_is_primitive<Type>::value){
				used_param += req_type_arr.at(i);
		} else {
				used_param += "const " + req_type_arr.at(i) + "*";
		}
		param_use += used_param + " " + std::string{lit.view()};

		if constexpr ( (i+1) < sizeof...(Request) ){
				param_use += ", ";
				return generate_parameter<i+1>(param_use, req_type_arr);
		}

		return void_t{};
	}

	static error_or<void> generate(c_types::state& c_state, const std::string& func_name){
		std::array<std::string, sizeof...(Request)> request_type_arr;

		if constexpr (sizeof...(Request) > 0){
				auto eov = generate_request_member<0>(c_state, request_type_arr);
				if(eov.is_error()){
						return eov;
				}
		}
		std::string response_type_str;
		{
				auto eov = c_data_translater<Response>::generate(c_state, response_type_str);
				if(eov.is_error()){
						return eov;
				}
		}
		std::string c_func_name = c_state.prefix + "_" + func_name;

		c_types::c_func fn;
		fn.cpp_name = func_name;
		fn.def = "int";
		std::string iface_ctx = c_state.prefix + "_iface_context* ctx";
		fn.def += " " + c_func_name + "(" + iface_ctx;
		fn.def += ", " + response_type_str + "* out";
		if constexpr ( sizeof...(Request) > 0 ){
				fn.def += ", ";
				auto eov = generate_parameter<0>(fn.def, request_type_arr);
				if(eov.is_error()){
						return eov;
				}
		}
		fn.def += ")";

		fn.source = "{\n";
		// Check necessary pointers
		fn.source += "\tassert(ctx);\n";
		fn.source += "\tif(!ctx){return -1;}\n\n";
		fn.source += "\tauto rmt = reinterpret_cast<interface<IfaceSchema, ";
		fn.source += c_state.encoding;
		fn.source += ">*>(ctx);\n";

		// translate the input data
		if constexpr (sizeof...(Request) > 0){
				// I need a recursive search for the types
		}

		// Call the remote interface
		fn.source += "\tauto eov = rmt->template call<\"" + fn.cpp_name + "\">(std::move(input));";
		fn.source += ");\n";

		// translate the output data
		fn.source += "";

		// Close the brace

		fn.source += "}\n";
		
		c_state.func_map.emplace(std::make_pair(c_func_name, std::move(fn)));
		
		return void_t{};
	}
};

template<class... Requests, class... Responses, string_literal... Names>
struct c_iface_translater<schema::Interface<schema::Member<schema::Function<Requests, Responses>, Names>...>> {
	using Schema = schema::Interface<schema::Member<schema::Function<Requests, Responses>, Names>...>;

	template<size_t i>
	static error_or<void> generate_member(c_types::state& c_state){
		using Req = typename parameter_pack_type<i,Requests...>::type;
		using Resp = typename parameter_pack_type<i,Responses...>::type;
		constexpr string_literal lit = parameter_key_pack_type<i, Names...>::literal;

		try{
				std::stringstream iss;
				schema_stringify<Schema>::apply(iss);
				c_state.interface_schema = iss.str();
		}catch(const std::exception& e){
				(void) e;
				return make_error<err::critical>();
		}

		std::string c_func_name = c_state.prefix + "_" + std::string{lit.view()};
		if(c_state.func_map.find(c_func_name) != c_state.func_map.end()){
			return make_error<err::already_exists>();
		}

		{
			std::string type_str;
			auto eov = c_iface_translater<schema::Function<Req, Resp>>::generate(c_state, std::string{lit.view()});
			if(eov.is_error()){
				return eov;
			}
		}

		if constexpr ((i+1) < sizeof...(Requests) ){
			return generate_member<i+1>(c_state);
		}
		return void_t{};
	}

	static error_or<void> generate(c_types::state& c_state){
		if constexpr ( sizeof...(Requests) > 0 ){
			return generate_member<0>(c_state);
		}

		return void_t{};
	}
};
}

template<typename Interface>
error_or<void> generate_c_interface(typename impl::c_types::state& state){
	auto eov = impl::c_iface_translater<Interface>::generate(state);
	return eov;
}

error_or<void> generate_iface_example(){
    using Request1 = schema::Struct<
		schema::Member<schema::Int32, "foo">,
		schema::Member<schema::Float64, "bar">,
		schema::Member<schema::Array<schema::Float32,1>, "baz">
    >;
	using Response1 = schema::Int32;

	using Func1 = schema::Function<Request1, Response1>;

	using Iface = schema::Interface<
		schema::Member<Func1, "func_one">
    >;

	impl::c_types::state c_state;
	c_state.prefix = "c_saw";
	c_state.encoding = "saw::encode::Native";

	typename impl::c_types::c_struct_map& type_map = c_state.struct_map;
	typename impl::c_types::c_func_map& func_map = c_state.func_map;
	auto eov = generate_c_interface<Iface>(c_state);
    if(eov.is_error()){
		return eov;
	}
	std::cout<<"Interface: "<<c_state.interface_schema<<std::endl;
	std::cout<<"Prefix: "<<c_state.prefix<<std::endl;
	std::cout<<"\nTypes: "<<std::endl;

	for(auto& iter : type_map){
		std::cout<<"\nType: \""<<iter.first<<"\""<<std::endl;
		std::cout<<"Definition:\n\"\"\"\n";
		std::cout<<iter.second.def;
		std::cout<<"\"\"\""<<std::endl;
		std::cout<<"Schema: "<<iter.second.cpp_schema<<std::endl;
	}
	std::cout<<"\nFunctions: "<<std::endl;

	for(auto& iter : func_map){
		std::cout<<"\nSymbol: \""<<iter.first<<"\""<<std::endl;
		std::cout<<"Definition:\n\"\"\"\n";
		std::cout<<iter.second.def<<";\n";
		std::cout<<"\"\"\""<<std::endl;
		std::cout<<"\nSource:\n"<<iter.second.source<<std::endl;
	}

	return eov;
}

error_or<void> generate_array_example(){
	using Schema1 = schema::Array<schema::Int32,2>;
	
	using Schema2 = schema::Array<schema::Float64,5>;
	
	using Schema3 = schema::Array<schema::UInt16,1>;

	std::string prefix = "c_saw";
	impl::c_types::state c_state;
	c_state.prefix = prefix;
	{
		std::string type_str;
		auto eov = impl::c_data_translater<Schema1>::generate(c_state, type_str);
		if(eov.is_error()){
			return eov;
		}
	}
	{
		std::string type_str;
		auto eov = impl::c_data_translater<Schema2>::generate(c_state, type_str);
		if(eov.is_error()){
			return eov;
		}
	}
	{
		std::string type_str;
		auto eov = impl::c_data_translater<Schema3>::generate(c_state, type_str);
		if(eov.is_error()){
			return eov;
		}
	}

	std::cout<<"Prefix: "<<c_state.prefix<<std::endl;

	for(auto& iter : c_state.struct_map){
		std::cout<<"\nType: \""<<iter.first<<"\""<<std::endl;
		std::cout<<"Definition:\n\"\"\"\n";
		std::cout<<iter.second.def;
		std::cout<<"\"\"\""<<std::endl;
	}

	return void_t{};
}
}