// Copyright (c) 2020 Tom Deakin
// University of Bristol HPC
//
// For full license terms please see the LICENSE file distributed with this
// source code

#include "STDRangesStream.hpp"
#include <ranges>

#ifndef ALIGNMENT
#define ALIGNMENT (2*1024*1024) // 2MB
#endif

template <class T>
STDRangesStream<T>::STDRangesStream(const int ARRAY_SIZE, int device)
noexcept : array_size{ARRAY_SIZE},
  a(alloc_raw<T>(ARRAY_SIZE)), b(alloc_raw<T>(ARRAY_SIZE)), c(alloc_raw<T>(ARRAY_SIZE))
{
    std::cout << "Backing storage typeid: " << typeid(a).name() << std::endl;
#ifdef USE_ONEDPL
    std::cout << "Using oneDPL backend: ";
#if ONEDPL_USE_DPCPP_BACKEND
    std::cout << "SYCL USM (device=" << exe_policy.queue().get_device().get_info<sycl::info::device::name>() << ")";
#elif ONEDPL_USE_TBB_BACKEND
    std::cout << "TBB " TBB_VERSION_STRING;
#elif ONEDPL_USE_OPENMP_BACKEND
    std::cout << "OpenMP";
#else
    std::cout << "Default";
#endif
    std::cout << std::endl;
#endif
}

template<class T>
STDRangesStream<T>::~STDRangesStream() {
  dealloc_raw(a);
  dealloc_raw(b);
  dealloc_raw(c);
}

template <class T>
void STDRangesStream<T>::init_arrays(T initA, T initB, T initC)
{
  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size, // loop range
    [&] (int i) {
      a[i] = initA;
      b[i] = initB;
      c[i] = initC;
    }
  );
}

template <class T>
void STDRangesStream<T>::read_arrays(std::vector<T>& h_a, std::vector<T>& h_b, std::vector<T>& h_c)
{
  // Element-wise copy.
    std::copy(a, a + array_size, h_a.begin());
    std::copy(b, b + array_size, h_b.begin());
    std::copy(c, c + array_size, h_c.begin());
}

template <class T>
void STDRangesStream<T>::copy()
{
  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size,
    [&] (int i) {
      c[i] = a[i];
    }
  );
}

template <class T>
void STDRangesStream<T>::mul()
{
  const T scalar = startScalar;

  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size,
    [&] (int i) {
      b[i] = scalar * c[i];
    }
  );
}

template <class T>
void STDRangesStream<T>::add()
{
  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size,
    [&] (int i) {
      c[i] = a[i] + b[i];
    }
  );
}

template <class T>
void STDRangesStream<T>::triad()
{
  const T scalar = startScalar;

  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size,
    [&] (int i) {
      a[i] = b[i] + scalar * c[i];
    }
  );
}

template <class T>
void STDRangesStream<T>::nstream()
{
  const T scalar = startScalar;

  std::for_each_n(
    exe_policy,
    std::views::iota(0).begin(), array_size,
    [&] (int i) {
      a[i] += b[i] + scalar * c[i];
    }
  );
}

template <class T>
T STDRangesStream<T>::dot()
{
  // sum += a[i] * b[i];
  return
    std::transform_reduce(
      exe_policy,
      a, a + array_size, b, 0.0);
}

void listDevices(void)
{
  std::cout << "C++20 does not expose devices" << std::endl;
}

std::string getDeviceName(const int)
{
  return std::string("Device name unavailable");
}

std::string getDeviceDriver(const int)
{
  return std::string("Device driver unavailable");
}

template class STDRangesStream<float>;
template class STDRangesStream<double>;
