//
// Created by Patrick Maschek on 08/04/2024.
//

#ifndef CONST_CONTAINER_TEST_DEFINE_TEST_HPP_
#define CONST_CONTAINER_TEST_DEFINE_TEST_HPP_

#include <array>
#include <concepts>
#include <iostream>
#include <ranges>
#include <tuple>

#include "test_ret_val.h"

template<typename Suite>
struct quick_test_def;

enum class EvalFlag { RUNTIME, CONSTEVAL, RUNTIME_CONSTEVAL };

struct test_def_base {};

template<std::invocable Func>
struct test_def_func_base : public test_def_base {
	using FuncType = Func;
	
	const char *name;
	Func func;
	EvalFlag evalFlag = EvalFlag::RUNTIME;
	
	constexpr test_def_func_base(const char * name, Func func) : name(name), func(func) {}
	constexpr test_def_func_base(const char * name, Func func, EvalFlag evalFlag) 
		: name(name), func(func), evalFlag(evalFlag) {}
	
	virtual constexpr std::invoke_result_t<Func> operator()() { return std::apply(func, std::make_tuple()); }
	
	consteval auto run_consteval() { return operator()(); }
};

template<std::invocable Func, typename ...Args>
struct test_definition : public test_def_func_base<Func> {
	using base = test_def_func_base<Func>;
	static constexpr std::size_t ARG_SIZE = sizeof...(Args);
	
	std::tuple<Args...> args;
	
	constexpr test_definition(const char *name, Func func, Args ...args) 
		: test_def_func_base<Func>(name, func), args(std::make_tuple(args...)) {}
		
	constexpr test_definition(const char *name, Func func, EvalFlag evalFlag, Args ...args) 
		: test_def_func_base<Func>(name, func, evalFlag), args(std::make_tuple(args...)) {}
	
	constexpr std::invoke_result_t<Func, Args...> operator()() override { return std::apply(base::func, args); }
};


struct test_suite_base {
	const char *name;
};

template<typename ...TestDefs>
	requires (sizeof...(TestDefs) == 0 || (std::derived_from<TestDefs, test_def_func_base<typename TestDefs::FuncType>> && ...))
class test_suite : public test_suite_base {
			
	public:
		static constexpr std::size_t TEST_NR = sizeof...(TestDefs);
		
		constexpr test_suite(const char *name, std::tuple<TestDefs...> tests) : test_suite_base(name), tests(tests) {}
		
		
		ret_val<TEST_NR> run() const {
			
			constexpr auto is = std::make_index_sequence<TEST_NR>();
			
			std::cout << "--------------\n";
			
			constexpr auto test_arr = expand_tuple(tests, is);
			constexpr auto const_test_arr = test_arr 
					| std::views::enumerate
					| std::views::filter([](auto e) consteval { return noexcept(e.run_consteval()); });
			
			for (auto [i, test_ref] : std::ranges::views::enumerate(test_arr)) {
				auto test = test_ref.get();

				std::cout << "Running Test: \"" << test.name << "\"\n";
				if (test.evalFlag == EvalFlag::RUNTIME || test.evalFlag == EvalFlag::RUNTIME_CONSTEVAL) {
					ret_val_s ret = test();

					std::cout << "Result of Runtime Evaluation of Test \"" << ret.test_name << "\" (number: " << i
							  << "): "
							  << (ret.val == ReturnCode::PASSED ? "PASSED" : "FAILED") << "\n"
							  << "\t" << ret.msg << "\n";
				}

				std::optional<ret_val_s> cret;

				if (test.evalFlag == EvalFlag::CONSTEVAL || test.evalFlag == EvalFlag::RUNTIME_CONSTEVAL) {
					//cret = run_consteval_test<>();
				}

				if (cret.has_value()) {
					auto ret = cret.value();
					std::cout << "Result of Consteval Evaluation of Test \"" << ret.test_name << "\" (number: " << i
							  << "): "
							  << (ret.val == ReturnCode::PASSED ? "PASSED" : "FAILED") << "\n"
							  << "\t" << ret.msg << "\n";
				}
			}
			
			ret_val<TEST_NR> ret = { name };
			//std::ranges::move(v, ret.vals.begin());
			
			return ret;
		}
	
	private:
		static constexpr std::tuple<std::reference_wrapper<TestDefs>...> tests;
		
		template<std::size_t ...Is>
		static constexpr auto expand_tuple(const auto &tests, std::index_sequence<Is...>) {
			return std::array { (std::reference_wrapper(std::get<Is>(tests)), ...) };
		}
		
		template<auto Test, typename Func>
			requires (std::derived_from<decltype(Test), test_def_func_base<Func>>)
		static consteval ret_val_s run_consteval_test() {
			return Test();
		}
		
		friend class quick_test_def<test_suite<TestDefs...>>;
};

template<typename Suite>
struct quick_test_def {
	Suite current;
	
	template<std::invocable Func, typename ...Args>
	constexpr auto operator()(const char *name, Func func, Args... args) {
		return operator()(name, func, EvalFlag::RUNTIME, std::forward(args)...);
	}
	
	template<std::invocable Func, typename ...Args>
	constexpr auto operator()(const char *name, Func func, EvalFlag evalFlag, Args... args) {
		auto test = test_definition(name, func, evalFlag, args...);
		auto new_suite = test_suite(current.name, std::tuple_cat(current.tests, std::make_tuple(test)));
		return quick_test_def<decltype(new_suite)> { new_suite };
	}
	
	constexpr operator Suite() {
		return current;
	}
};

template<typename ...TestDefs>
test_suite(quick_test_def<test_suite<TestDefs...>>) -> test_suite<TestDefs...>;

constexpr auto define_tests(const char *name) {
	return quick_test_def { test_suite<>{ name, std::make_tuple() } };
}

#endif //CONST_CONTAINER_TEST_DEFINE_TEST_HPP_