#include <forstio/error.hpp>
#include <forstio/codec/data.hpp>
#include <forstio/codec/schema.hpp>
#include <forstio/codec/schema_hash.hpp>
#include <forstio/codec/schema_stringify.hpp>
#include <forstio/templates.hpp>

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

#include <iostream>

namespace saw {
namespace binding {
/**
 * The synchronous simple interface
 */
struct SyncC {};
}

/**
 * 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 string_literal name = "int8";
	static constexpr string_literal value = "int8_t";
};

template<>
struct c_primitive_string<schema::Int16> {
	static constexpr string_literal name = "int16";
	static constexpr string_literal value = "int16_t";
};

template<>
struct c_primitive_string<schema::Int32> {
	static constexpr string_literal name = "int32";
	static constexpr string_literal value = "int32_t";
};

template<>
struct c_primitive_string<schema::Int64> {
	static constexpr string_literal name = "int64";
	static constexpr string_literal value = "int64_t";
};

template<>
struct c_primitive_string<schema::UInt8> {
	static constexpr string_literal name = "uint8";
	static constexpr string_literal value = "uint8_t";
};

template<>
struct c_primitive_string<schema::UInt16> {
	static constexpr string_literal name = "uint16";
	static constexpr string_literal value = "uint16_t";
};

template<>
struct c_primitive_string<schema::UInt32> {
	static constexpr string_literal name = "uint32";
	static constexpr string_literal value = "uint32_t";
};

template<>
struct c_primitive_string<schema::UInt64> {
	static constexpr string_literal name = "uint64";
	static constexpr string_literal value = "uint64_t";
};

template<>
struct c_primitive_string<schema::Float32> {
	static constexpr string_literal name = "float32";
	static constexpr string_literal value = "float";
};

template<>
struct c_primitive_string<schema::Float64> {
	static constexpr string_literal name = "float64";
	static constexpr string_literal value = "double";
};

struct language_binding_config {
	std::string prefix;
};

namespace impl {
template<typename Schema, typename Lang>
struct lang_bind {
	static_assert(always_false<Schema>, "Not supported");
};

struct language_binding_state {
	struct info {
		std::string type;
	};
	std::map<uint32_t, language_binding_state::info> hashes;
};

struct lang_bind_helper {
	static error_or<void> append_string(buffer& buff, const std::string_view& str){
		for(uint64_t i = 0; i < str.size(); ++i){
			auto err = buff.push(static_cast<uint8_t>(str[i]));
			if(!err.template is_type<err::no_error>()){
				return err;
			}
		}
		return void_t{};
	}

	static error_or<void> append_hashed_type(buffer& buff, const std::string_view& prefix, uint32_t hash){
		{
			auto eov = append_string(buff, prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = append_string(buff, std::to_string(hash));
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = append_string(buff, "_t");
			if(eov.is_error()){
				return eov;
			}
		}
		return void_t{};
	}
};


template<typename T, uint64_t L>
struct lang_bind<schema::Primitive<T,L>, binding::SyncC> {
	using Schema = schema::Primitive<T,L>;
	
	static error_or<void> generate_c_to_cpp(buffer& src, const language_binding_config& cfg, language_binding_state& state, const std::string_view& cpp_name, const std::string_view& c_name ){
		{
			auto eov = lang_bind_helper::append_string(src, "\t");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, cpp_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, ".set(*");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, c_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, ");\n");
			if(eov.is_error()){
				return eov;
			}
		}
		return void_t{};
	}
	
	static error_or<void> generate_cpp_to_c(buffer& src, const language_binding_config& cfg, language_binding_state& state, const std::string_view& cpp_name, const std::string_view& c_name ){

		{
			auto eov = lang_bind_helper::append_string(src, "\t*");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, c_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, " = ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, cpp_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, ".get();\n");
			if(eov.is_error()){
				return eov;
			}
		}

		return void_t{};
	}

	static error_or<void> generate(buffer& buff, buffer& src, const language_binding_config& cfg, language_binding_state& state){
		constexpr uint64_t hash = schema_hash<Schema>::apply();

		{
			std::string hash_type_str = cfg.prefix + "_" + std::to_string(hash) + "_t";
			auto emp = state.hashes.emplace(std::make_pair(hash, hash_type_str));
			if(emp.second){
				{
					auto eov = lang_bind_helper::append_string(buff, "typedef ");
					if(eov.is_error()){
						return eov;
					}
				}
				{
					auto eov = lang_bind_helper::append_string(buff, c_primitive_string<Schema>::value.view());
					if(eov.is_error()){
						return eov;
					}
				}
				{
					auto eov = lang_bind_helper::append_string(buff, " ");
					if(eov.is_error()){
						return eov;
					}
				}
				{
					auto eov = lang_bind_helper::append_string(buff, hash_type_str);
					if(eov.is_error()){
						return eov;
					}
				}
				{
					auto eov = lang_bind_helper::append_string(buff, ";\n");
					if(eov.is_error()){
						return eov;
					}
				}
			}
		}

		return void_t{};
	}
};

template<typename T, uint64_t D>
struct lang_bind<schema::Array<T,D>, binding::SyncC> {
	using Schema = schema::Array<T,D>;

	static_assert(is_primitive<T>::value, "Currently only primitive type arrays are supported");

	static error_or<void> generate_c_to_cpp(buffer& src, const language_binding_config& cfg, language_binding_state& state, const std::string_view& cpp_name, const std::string_view& c_name ){
		return make_error<err::not_implemented>();
	}
	
	static error_or<void> generate_cpp_to_c(buffer& src, const language_binding_config& cfg, language_binding_state& state, const std::string_view& c_name, const std::string_view& cpp_name ){
		return make_error<err::not_implemented>();
	}

	static error_or<void> generate(buffer& buff, buffer& src, const language_binding_config& cfg, language_binding_state& state){
		constexpr uint64_t hash = schema_hash<Schema>::apply();
		
		std::string hash_type_str = cfg.prefix + "_" + std::to_string(hash) + "_t";
		auto emp = state.hashes.emplace(std::make_pair(hash, hash_type_str));
		if(emp.second){
			{
					auto eov = lang_bind<schema::UInt64, binding::SyncC>::generate(buff, src, cfg, state);
					if(eov.is_error()){
						return eov;
					}
			}
			{
					auto eov = lang_bind<T, binding::SyncC>::generate(buff, src, cfg, state);
					if(eov.is_error()){
						return eov;
					}
			}
	
			{
				auto eov = lang_bind_helper::append_string(buff, "struct ");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_hashed_type(buff, cfg.prefix, hash);
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, " {\n\t");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_hashed_type(buff, cfg.prefix, schema_hash<T>::apply());
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, "* data;\n\t");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_hashed_type(buff, cfg.prefix, schema_hash<schema::UInt64>::apply());
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, " length;\n};\n");
				if(eov.is_error()){
					return eov;
				}
			}
		}

		return void_t{};
	}
};

template<typename Input, typename Output>
struct lang_bind<schema::Function<Input, Output>, binding::SyncC> {
	static error_or<void> append_function_def(buffer& buff, const language_binding_config& cfg, language_binding_state& state, const std::string_view& f_name){
		/**
		 * Generate the base function declaration
		 */
		{
			auto eov = lang_bind_helper::append_string(buff, "int ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, " ( ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_context* ctx, const ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_input_t* input, ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_output_t* output )");
			if(eov.is_error()){
				return eov;
			}
		}

		return void_t{};
	}

	static error_or<void> generate(buffer& buff, buffer& src, const language_binding_config& cfg, language_binding_state& state, const std::string_view& f_name){
		constexpr uint64_t input_hash = schema_hash<Input>::apply();
		constexpr uint64_t output_hash = schema_hash<Output>::apply();

		/**
		 * Source
		 */
		{
			auto eov = append_function_def(src, cfg, state, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "{\n\tif(!ctx || !(ctx->ctx)) return -1;\n\tif(!input) return -1;\n\tif(!output) return -1;\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "\n\tauto& iface = ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "_get_cpp_interface_priv(*ctx);\n\t");
			if(eov.is_error()){
				return eov;
			}
		}
		/**
		 * Check declarations and definitions.
		 * Translate input.
		 */
		{
			auto eov = lang_bind_helper::append_string(src, "saw::data<");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			std::stringstream ss;
			try{
				{
					schema_stringify<Input>::apply(ss);
					auto eov = lang_bind_helper::append_string(src, ss.str());
					if(eov.is_error()){
						return eov;
					}
				}
			}catch(const std::exception&){
				return make_error<err::out_of_memory>();
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "> cpp_input_root;\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind<Input, binding::SyncC>::generate(buff, src, cfg, state);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind<Input, binding::SyncC>::generate_c_to_cpp(src, cfg, state, "c_input_root", "cpp_input_root");
			if(eov.is_error()){
				return eov;
			}
		}
		/**
		 * Call the c++ implementation
		 */
		{
			auto eov = lang_bind_helper::append_string(src, "\n\tauto eov = iface.template call<\"");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "\">(std::move(cpp_input_root));\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "\tif(eov.is_error()){\n\t\tauto& err = eov.get_error();\n\t\treturn err.get_code();\n\t}\n\tauto& cpp_output_root = eov.get_value();\n\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind<Input, binding::SyncC>::generate_cpp_to_c(src, cfg, state, "cpp_output_root", "c_output_root");
			if(eov.is_error()){
				return eov;
			}
		}

		/**
		 * Check declarations and definitions.
		 * Translate output.
		 */
		{
				auto eov = lang_bind<Output, binding::SyncC>::generate(buff, src, cfg, state);
				if(eov.is_error()){
					return eov;
				}
		}
		/**
		 * End source declaration
		 */
		{
			auto eov = lang_bind_helper::append_string(src, "\treturn 0;\n}\n\n");
			if(eov.is_error()){
				return eov;
			}
		}
		/**
		 * Header
		 */
		{
			auto eov = lang_bind_helper::append_string(buff, "typedef ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_hashed_type(buff, cfg.prefix, schema_hash<Input>::apply());
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, " ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_input_t;\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "typedef ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_hashed_type(buff, cfg.prefix, schema_hash<Output>::apply());
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, " ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_output_t;\n");
			if(eov.is_error()){
				return eov;
			}
		}
		/**
		 * Function generations
		 */
		{
			auto eov = append_function_def(buff, cfg, state, f_name);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, ";\n\n");
			if(eov.is_error()){
				return eov;
			}
		}

		return void_t{};
	}
};

template<typename... M>
struct lang_bind<schema::Interface<M...>, binding::SyncC> {
	template<uint64_t i>
	static error_or<void> generate_element(buffer& buff, buffer& src, const language_binding_config& cfg, language_binding_state& state){
		using Member = typename parameter_pack_type<i, M...>::type;
		using MValue = typename Member::ValueType;
		static constexpr string_literal MKey = Member::KeyLiteral;

		{
			auto eov = lang_bind<MValue, binding::SyncC>::generate(buff, src, cfg, state, MKey.view());
			if(eov.is_error()){
				return eov;
			}
		}

		if constexpr ((i+1) < sizeof...(M) ){
			return generate_element<i+1>(buff, src, cfg, state);
		}
		return void_t{};
	}

	static error_or<void> generate(buffer& buff, buffer& src, const language_binding_config& cfg){
		if(cfg.prefix.size() == 0){
			return make_error<err::invalid_state>("C interfaces need a prefix.");
		}

		language_binding_state state;
		/**
		 * Setup context creation to bind interface to a context
		 */
		/**
		 * Interface type helper
		 */
		{
			auto eov = lang_bind_helper::append_string(src, "namespace {\nnamespace schema {\n");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "using InterfaceType = ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			std::stringstream ss;
			schema_stringify<schema::Interface<M...>>::apply(ss);
			try {
				auto eov = lang_bind_helper::append_string(src, ss.str());
				if(eov.is_error()){
					return eov;
				}
			}catch(const std::exception&){
				return make_error<err::out_of_memory>("No memory after stringification");
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, ";\n}\n}\n\n");
			if(eov.is_error()){
				return eov;
			}
		}

		/**
		 * Context definition
		 */
			/// @todo Add Macro which reduces typing time ? Not really that much shorter :/
			// SAW_CALL_AND_RETURN_ON_ERROR(lang_bind_helper::append_string(buff, "struct "));
		{
			auto eov = lang_bind_helper::append_string(buff, "struct ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(buff, "_context {\n\tvoid* ctx;\n};\n\n");
			if(eov.is_error()){
				return eov;
			}
		}
		/**
		 * Create and destroy declaration
		 */
		auto ctx_func = [&](std::string_view str) -> error_or<void>{
			{
				auto eov = lang_bind_helper::append_string(buff, "int ");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, "_context_");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, str);
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, " ( ");
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, cfg.prefix);
				if(eov.is_error()){
					return eov;
				}
			}
			{
				auto eov = lang_bind_helper::append_string(buff, "_context* ctx );\n\n");
				if(eov.is_error()){
					return eov;
				}
			}
			
			return void_t{};
		};

		{
			auto eov = ctx_func("create");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = ctx_func("destroy");
			if(eov.is_error()){
				return eov;
			}
		}

		/**
		 * Create a casting helper in sources for the interface type
		 */
		{
			auto eov = lang_bind_helper::append_string(src, "saw::interface<schema::InterfaceType>& ");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "_get_cpp_interface_priv(");
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, cfg.prefix);
			if(eov.is_error()){
				return eov;
			}
		}
		{
			auto eov = lang_bind_helper::append_string(src, "& ctx){\n\treturn *reinterpret_cast<saw::interface<schema::InterfaceType>*>(ctx.ctx);\n}\n\n");
			if(eov.is_error()){
				return eov;
			}
		}

		if constexpr (sizeof...(M) > 0){
			return generate_element<0>(buff, src, cfg, state);
		}

		return void_t{};
	}
};
}

template<typename IfaceSchema, typename Binding>
struct language_binding {
	static_assert(always_false<IfaceSchema, Binding>, "Case not supported.");
};

template<typename IfaceSchema>
struct language_binding<IfaceSchema, binding::SyncC> {
	static error_or<void> generate(buffer& buff, buffer& src, const language_binding_config& cfg){
		return impl::lang_bind<IfaceSchema, binding::SyncC>::generate(buff, src, cfg);
	}
};
}