/**++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 *
 *                                              PANIC
 *                              Portable Algorithms and Numerics In C++
 *
 *                       Scientific computing from scratch, with feeling.
 *
 * Copyright (c) 2026 Michelle Bausager
 *
 * This file is part of PANIC.
 *
 * PANIC is free software licensed under the GNU General Public License v3.0 or later.
 * You may redistribute and/or modify it under the terms of the GPL.
 *
 * PANIC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the LICENSE file for the full license text.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 *++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 *
 * Project Name:      PANIC
 * Module Name:       config
 * File Name:         omp.hpp
 * Revision:          0.1.0
 * Date:              20-06-2026
 * Author:            Michelle Bausager
 *
 * Description:
 * Defines which types will be used in the rest of the libraries.
 *
 *++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
#pragma once

//---------------------------------------------------------------------------------------------------------------------------
// INCLUDE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

// None.

//---------------------------------------------------------------------------------------------------------------------------
// DEFINE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

//---------------------------------------------------------------------------------------------------------------------------
// OPENMP CONFIGURATION DEFAULTS
//---------------------------------------------------------------------------------------------------------------------------

// If CMake did not define PANIC_USE_OPENMP, define it as 0.
// This makes OpenMP disabled by default.
//
// CMake can override this with:
//   PANIC_USE_OPENMP=1
#ifndef PANIC_USE_OPENMP
#define PANIC_USE_OPENMP 0
#endif

// If CMake did not define PANIC_OMP_NUM_THREADS, define it as 0.
//
// Meaning:
//   0 = let OpenMP choose the default number of threads
//   1 = use 1 thread
//   2 = use 2 threads
//   4 = use 4 threads
//   etc.
#ifndef PANIC_OMP_NUM_THREADS
#define PANIC_OMP_NUM_THREADS 0
#endif

//---------------------------------------------------------------------------------------------------------------------------
// OPENMP AVAILABILITY CHECK
//---------------------------------------------------------------------------------------------------------------------------

// PANIC_HAS_OPENMP becomes 1 only if:
//
//   1. PANIC_USE_OPENMP is enabled by CMake
//   2. The compiler actually has OpenMP enabled
//
// _OPENMP is automatically defined by the compiler when OpenMP support is active.
// For example, GCC defines _OPENMP when compiling with -fopenmp.
#if PANIC_USE_OPENMP && defined(_OPENMP)
#define PANIC_HAS_OPENMP 1
#else
#define PANIC_HAS_OPENMP 0
#endif

//---------------------------------------------------------------------------------------------------------------------------
// STRINGIFY HELPERS
//---------------------------------------------------------------------------------------------------------------------------

// These macros turn macro values into text.
//
// Example:
//   PANIC_OMP_NUM_THREADS = 4
//
// We need to turn that into:
//
//   "omp parallel for num_threads(4)"
//
// The two-step version is needed so that macros expand before becoming text.
#define PANIC_STRINGIFY_DETAIL(x) #x
#define PANIC_STRINGIFY(x) PANIC_STRINGIFY_DETAIL(x)

//---------------------------------------------------------------------------------------------------------------------------
// OPENMP PARALLEL FOR MACROS
//---------------------------------------------------------------------------------------------------------------------------

#if PANIC_HAS_OPENMP

    #if PANIC_OMP_NUM_THREADS > 0

        // Expands to:
        //   #pragma omp parallel for num_threads(PANIC_OMP_NUM_THREADS)
        #define PANIC_OMP_PARALLEL_FOR \
            _Pragma(PANIC_STRINGIFY(omp parallel for num_threads(PANIC_OMP_NUM_THREADS)))

        // Expands to:
        //   #pragma omp parallel for if(condition) num_threads(PANIC_OMP_NUM_THREADS)
        //
        // The loop only runs in parallel if condition is true.
        #define PANIC_OMP_PARALLEL_FOR_IF(condition) \
            _Pragma(PANIC_STRINGIFY(omp parallel for if(condition) num_threads(PANIC_OMP_NUM_THREADS)))

    #else

        // Expands to:
        //   #pragma omp parallel for
        //
        // OpenMP chooses the default number of threads.
        #define PANIC_OMP_PARALLEL_FOR \
            _Pragma("omp parallel for")

        // Expands to:
        //   #pragma omp parallel for if(condition)
        //
        // OpenMP chooses the default number of threads.
        // The loop only runs in parallel if condition is true.
        #define PANIC_OMP_PARALLEL_FOR_IF(condition) \
            _Pragma(PANIC_STRINGIFY(omp parallel for if(condition)))

    #endif

#else

    // If OpenMP is disabled or unavailable, these macros expand to nothing.
    //
    // So this:
    //
    //   PANIC_OMP_PARALLEL_FOR
    //   for (...) {
    //       ...
    //   }
    //
    // becomes just:
    //
    //   for (...) {
    //       ...
    //   }
    //
    // That means the same code still works on microcontrollers and non-OpenMP builds.
    #define PANIC_OMP_PARALLEL_FOR
    #define PANIC_OMP_PARALLEL_FOR_IF(condition)

#endif

//---------------------------------------------------------------------------------------------------------------------------
// TYPE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

// None.

//---------------------------------------------------------------------------------------------------------------------------
// VARIABLE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

// None.

//---------------------------------------------------------------------------------------------------------------------------
// FUNCTION PROTOTYPE
//---------------------------------------------------------------------------------------------------------------------------

// None.

//PANIC_OMP_PARALLEL_FOR
//for (panic::uint_t i = 0; i < length; ++i) {
//    data[i] = value;
//}