/*        /\         +------------------------------------------------------+
 *   ____/  \____   /| - Open source game framework licensed to freely use, |
 *   \          /  / |   copy, modify and sell without restriction          |
 * +--\ ^__^   /--+  |                                                      |
 * | ~/        \~ |  | - created for <https://foam.shampoo.ooo>             |
 * | ~~~~~~~~~~~~ |  +------------------------------------------------------+
 * | SPACE ~~~~~  | /
 * |  ~~~~~~~ BOX |/
 * +--------------+
 *
 * time_it
 * =======
 * 
 * This class is used for printing the running time of a function or lambda. It can be
 * inserted inline into existing code by wrapping the block to time in a lambda. It can also be
 * given a function and optionally the function's arguments and will return a value of the type specified.
 * 
 * The following code
 * 
 * ~~~{.cpp}
 *     std::string fake(std::string x, std::string y)
 *     {
 *         return x + y;
 *     }
 *
 *     // Needs SPACEBOX initialization for log call
 *     int ii = 0;
 *     time_it()([&] { while (ii++ < 1000); });
 *     ii = 0;
 *     int revolving = time_it<int, int>("for revolving")([&](int x) -> int { while (ii++ < 10000); return x; }, 1);
 *     ii = 0;
 *     std::cout << "Revolving is " << revolving << std::endl;
 *     std::string addition = time_it<std::string, std::string, std::string>("for combination")(fake, "Hello, ", "World!");
 *     std::cout << "Combination is " << addition << std::endl;
 *     time_it("for many combinations")([&] { while (ii++ < 100000) { fake("a", "b"); } });
 * ~~~
 *
 * gives the expected output
 * 
 *     Elapsed time: 2.588e-06s
 *     Elapsed time for revolving: 2.1547e-05s
 *     Revolving is 1
 *     Elapsed time for combination: 7.27e-07s
 *     Combination is Hello, World!
 *     Elapsed time for many combinations: 0.0107351s
 */

#pragma once

#include <string>
#include <iostream>
#include <chrono>
#include <functional>
#include <type_traits>

template<typename return_type = void, typename... arguments>
class time_it
{

private:

    std::string info = "";

public:

    time_it(std::string info = "") : info(info) {};

    return_type operator()(const std::function<return_type(arguments...)>&& block, arguments... args)
    {
        std::cout << "{Elapsed time";
        if (!info.empty())
        {
            std::cout << " " << info;
        }
        std::cout << ": ";
        auto start = std::chrono::steady_clock::now();
        std::chrono::duration<float> elapsed;
        if constexpr (std::is_same_v<return_type, void>)
        {
            block(args...);
            elapsed = std::chrono::steady_clock::now() - start;
            std::cout << elapsed.count() << "s}" << std::endl;
        }
        else
        {
            return_type result = block(args...);
            elapsed = std::chrono::steady_clock::now() - start;
            std::cout << elapsed.count() << "s}" << std::endl;
            return result;
        }
    }

};