// Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other
// CEED contributors. All Rights Reserved. See the top-level LICENSE and NOTICE
// files for details.
//
// SPDX-License-Identifier: BSD-2-Clause
//
// This file is part of CEED:  http://github.com/ceed

#include "ceed-sycl-common.hpp"

#include <string>
#include <sycl/sycl.hpp>

//------------------------------------------------------------------------------
// Device information backend init
//------------------------------------------------------------------------------
int CeedInit_Sycl(Ceed ceed, const char *resource) {
  Ceed_Sycl  *data;
  const char *device_spec = std::strstr(resource, ":device_id=");
  const int   device_id   = (device_spec) ? atoi(device_spec + 11) : 0;

  sycl::info::device_type device_type;
  if (std::strstr(resource, "/gpu/sycl")) {
    device_type = sycl::info::device_type::gpu;
  } else if (std::strstr(resource, "/cpu/sycl")) {
    device_type = sycl::info::device_type::cpu;
  } else {
    return CeedError(ceed, CEED_ERROR_BACKEND, "Unsupported SYCL device type requested");
  }

  auto sycl_devices = sycl::device::get_devices(device_type);
  int  device_count = sycl_devices.size();

  if (0 == device_count) {
    return CeedError(ceed, CEED_ERROR_BACKEND, "No SYCL devices of the requested type are available");
  }

  // Validate the requested device_id
  if (device_count < device_id + 1) {
    return CeedError(ceed, CEED_ERROR_BACKEND, "Invalid SYCL device id requested");
  }

  sycl::device sycl_device{sycl_devices[device_id]};
  // Check that the device supports explicit device allocations
  if (!sycl_device.has(sycl::aspect::usm_device_allocations)) {
    return CeedError(ceed, CEED_ERROR_BACKEND,
                     "The requested SYCL device does not support explicit "
                     "device allocations.");
  }

  // Creating an asynchronous error handler
  sycl::async_handler sycl_async_handler = [&](sycl::exception_list exceptionList) {
    for (std::exception_ptr const &e : exceptionList) {
      try {
        std::rethrow_exception(e);
      } catch (sycl::exception const &e) {
        std::ostringstream error_msg;
        error_msg << "SYCL asynchronous exception caught:\n";
        error_msg << e.what() << std::endl;
        return CeedError(ceed, CEED_ERROR_BACKEND, error_msg.str().c_str());
      }
    }
    return CEED_ERROR_SUCCESS;
  };

  sycl::context sycl_context{sycl_device.get_platform().get_devices()};
  sycl::queue   sycl_queue{sycl_context, sycl_device, sycl_async_handler};

  CeedCallBackend(CeedGetData(ceed, &data));

  data->sycl_device  = sycl_device;
  data->sycl_context = sycl_context;
  data->sycl_queue   = sycl_queue;
  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Backend destroy
//------------------------------------------------------------------------------
int CeedDestroy_Sycl(Ceed ceed) {
  Ceed_Sycl *data;

  CeedCallBackend(CeedGetData(ceed, &data));
  CeedCallBackend(CeedFree(&data));
  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Use an external queue
//------------------------------------------------------------------------------
int CeedSetStream_Sycl(Ceed ceed, void *handle) {
  Ceed       ceed_delegate = NULL, ceed_fallback = NULL;
  Ceed_Sycl *data;

  CeedCallBackend(CeedGetData(ceed, &data));

  CeedCheck(handle, ceed, CEED_ERROR_BACKEND, "Stream handle is null");
  sycl::queue *q = static_cast<sycl::queue *>(handle);

  // Ensure we are using the expected device
  CeedCheck(data->sycl_device == q->get_device(), ceed, CEED_ERROR_BACKEND, "Device mismatch between provided queue and ceed object");
  data->sycl_device  = q->get_device();
  data->sycl_context = q->get_context();
  data->sycl_queue   = *q;

  // Revisit this when we have a hierarchy of delegates
  CeedCallBackend(CeedGetDelegate(ceed, &ceed_delegate));
  if (ceed_delegate) {
    Ceed_Sycl *delegate_data;

    CeedCallBackend(CeedGetData(ceed_delegate, &delegate_data));
    delegate_data->sycl_device  = q->get_device();
    delegate_data->sycl_context = q->get_context();
    delegate_data->sycl_queue   = *q;
  }

  // Set queue and context for Ceed Fallback object
  CeedGetOperatorFallbackCeed(ceed, &ceed_fallback);
  if (ceed_fallback) {
    Ceed_Sycl *fallback_data;

    CeedCallBackend(CeedGetData(ceed_fallback, &fallback_data));
    fallback_data->sycl_device  = q->get_device();
    fallback_data->sycl_context = q->get_context();
    fallback_data->sycl_queue   = *q;
  }
  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------