/**
 * \file    utils.hpp
 * \brief   Utilities header
 *
 * \author
 *    Christos Choutouridis AEM:8997
 *    <cchoutou@ece.auth.gr>
 */
#ifndef UTILS_HPP_
#define UTILS_HPP_

#include <iostream>
#include <chrono>
#include <unistd.h>
#include <mpi.h>

//#include "matrix.hpp"
#include "config.h"


template<typename TID = int>
struct MPI_t {
    using ID_t = TID; // Export TID type (currently int defined by the standard)

    void init(int *argc, char ***argv) {
        // Initialize the MPI environment
        MPI_Init(argc, argv);

        // Get the number of processes
        int size_value, rank_value;
        size_ = static_cast<ID_t>(MPI_Comm_size(MPI_COMM_WORLD, &size_value));
        rank_ = static_cast<ID_t>(MPI_Comm_rank(MPI_COMM_WORLD, &rank_value));

        // Get the name of the processor
        char processor_name[MPI_MAX_PROCESSOR_NAME];
        int name_len;
        MPI_Get_processor_name(processor_name, &name_len);
        name_ = std::string (processor_name, name_len);
    }

    void finalize() {
        // Finalize the MPI environment.
        MPI_Finalize();
    }

    bool exchange(ID_t partner, const void *send_data, void *recv_data, int data_count, MPI_Datatype datatype) {
        bool ret = true;
        MPI_Status status;
        MPI_Sendrecv(
                send_data, data_count, datatype, partner, 0,
                recv_data, data_count, datatype, partner, 0,
                MPI_COMM_WORLD, &status
        );
        if (status.MPI_ERROR != MPI_SUCCESS)
            ret = false;

        return ret;
    }

    // Accessors
    [[nodiscard]] ID_t rank() const noexcept { return rank_; }
    [[nodiscard]] ID_t size() const noexcept { return size_; }
    [[nodiscard]] const std::string& name() const noexcept { return name_; }

private:
    ID_t rank_{};
    ID_t size_{};
    std::string name_{};
};

extern MPI_t<>  mpi;
using mpi_id_t = MPI_t<>::ID_t;

/*!
 * A Logger for entire program.
 */
struct Log {
    struct Endl {
    } endl;    //!< a tag object to to use it as a new line request.

    //! We provide logging via << operator
    template<typename T>
    Log &operator<<(T &&t) {
        if (session.verbose) {
            if (line_) {
                std::cout << "[Log]: " << t;
                line_ = false;
            } else
                std::cout << t;
        }
        return *this;
    }

    // overload for special end line handling
    Log &operator<<(Endl e) {
        (void) e;
        if (session.verbose) {
            std::cout << '\n';
            line_ = true;
        }
        return *this;
    }

private:
    bool line_{true};
};

extern Log logger;

/*!
 * A small timing utility based on chrono.
 */
struct Timing {
    using Tpoint = std::chrono::steady_clock::time_point;
    using microseconds = std::chrono::microseconds;
    using milliseconds = std::chrono::milliseconds;
    using seconds = std::chrono::seconds;

    //! tool to mark the starting point
    Tpoint start() noexcept { return start_ = std::chrono::steady_clock::now(); }

    //! tool to mark the ending point
    Tpoint stop() noexcept { return stop_ = std::chrono::steady_clock::now(); }

    auto dt() noexcept {
        return std::chrono::duration_cast<std::chrono::microseconds>(stop_ - start_).count();
    }

    //! tool to print the time interval
    void print_dt(const char *what) noexcept {
        if (session.timing) {
            auto t = stop_ - start_;
            if (std::chrono::duration_cast<microseconds>(t).count() < 10000)
                std::cout << "[Timing]: " << what << ": "
                          << std::to_string(std::chrono::duration_cast<microseconds>(t).count()) << " [usec]\n";
            else if (std::chrono::duration_cast<milliseconds>(t).count() < 10000)
                std::cout << "[Timing]: " << what << ": "
                          << std::to_string(std::chrono::duration_cast<milliseconds>(t).count()) << " [msec]\n";
            else
                std::cout << "[Timing]: " << what << ": "
                          << std::to_string(std::chrono::duration_cast<seconds>(t).count()) << " [sec]\n";
        }
    }

private:
    Tpoint start_;
    Tpoint stop_;
};

#endif /* UTILS_HPP_ */