// 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/ceed.h>
#include <ceed/backend.h>
#include <cuda_runtime.h>
#include <string.h>
#include "ceed-cuda-ref.h"

//------------------------------------------------------------------------------
// Sync host to device
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextSyncH2D_Cuda(
  const CeedQFunctionContext ctx) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  if (!impl->h_data)
    // LCOV_EXCL_START
    return CeedError(ceed, CEED_ERROR_BACKEND,
                     "No valid host data to sync to device");
  // LCOV_EXCL_STOP

  size_t ctxsize;
  ierr = CeedQFunctionContextGetContextSize(ctx, &ctxsize); CeedChkBackend(ierr);

  if (impl->d_data_borrowed) {
    impl->d_data = impl->d_data_borrowed;
  } else if (impl->d_data_owned) {
    impl->d_data = impl->d_data_owned;
  } else {
    ierr = cudaMalloc((void **)&impl->d_data_owned, ctxsize);
    CeedChk_Cu(ceed, ierr);
    impl->d_data = impl->d_data_owned;
  }

  ierr = cudaMemcpy(impl->d_data, impl->h_data, ctxsize,
                    cudaMemcpyHostToDevice); CeedChk_Cu(ceed, ierr);

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Sync device to host
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextSyncD2H_Cuda(
  const CeedQFunctionContext ctx) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  if (!impl->d_data)
    // LCOV_EXCL_START
    return CeedError(ceed, CEED_ERROR_BACKEND,
                     "No valid device data to sync to host");
  // LCOV_EXCL_STOP

  size_t ctxsize;
  ierr = CeedQFunctionContextGetContextSize(ctx, &ctxsize); CeedChkBackend(ierr);

  if (impl->h_data_borrowed) {
    impl->h_data = impl->h_data_borrowed;
  } else if (impl->h_data_owned) {
    impl->h_data = impl->h_data_owned;
  } else {
    ierr = CeedMallocArray(1, ctxsize, &impl->h_data_owned);
    CeedChkBackend(ierr);
    impl->h_data = impl->h_data_owned;
  }

  ierr = cudaMemcpy(impl->h_data, impl->d_data, ctxsize,
                    cudaMemcpyDeviceToHost); CeedChk_Cu(ceed, ierr);

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Sync data of type
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextSync_Cuda(
  const CeedQFunctionContext ctx, CeedMemType mem_type) {
  switch (mem_type) {
  case CEED_MEM_HOST: return CeedQFunctionContextSyncD2H_Cuda(ctx);
  case CEED_MEM_DEVICE: return CeedQFunctionContextSyncH2D_Cuda(ctx);
  }
  return CEED_ERROR_UNSUPPORTED;
}

//------------------------------------------------------------------------------
// Set all pointers as invalid
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextSetAllInvalid_Cuda(
  const CeedQFunctionContext ctx) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  impl->h_data = NULL;
  impl->d_data = NULL;

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Check if ctx has valid data
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextHasValidData_Cuda(
  const CeedQFunctionContext ctx, bool *has_valid_data) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  *has_valid_data = !!impl->h_data || !!impl->d_data;

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Check if ctx has borrowed data
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextHasBorrowedDataOfType_Cuda(
  const CeedQFunctionContext ctx, CeedMemType mem_type,
  bool *has_borrowed_data_of_type) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  switch (mem_type) {
  case CEED_MEM_HOST:
    *has_borrowed_data_of_type = !!impl->h_data_borrowed;
    break;
  case CEED_MEM_DEVICE:
    *has_borrowed_data_of_type = !!impl->d_data_borrowed;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Check if data of given type needs sync
//------------------------------------------------------------------------------
static inline int CeedQFunctionContextNeedSync_Cuda(
  const CeedQFunctionContext ctx, CeedMemType mem_type, bool *need_sync) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  bool has_valid_data = true;
  ierr = CeedQFunctionContextHasValidData(ctx, &has_valid_data);
  CeedChkBackend(ierr);
  switch (mem_type) {
  case CEED_MEM_HOST:
    *need_sync = has_valid_data && !impl->h_data;
    break;
  case CEED_MEM_DEVICE:
    *need_sync = has_valid_data && !impl->d_data;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Set data from host
//------------------------------------------------------------------------------
static int CeedQFunctionContextSetDataHost_Cuda(const CeedQFunctionContext ctx,
    const CeedCopyMode copy_mode, void *data) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  ierr = CeedFree(&impl->h_data_owned); CeedChkBackend(ierr);
  switch (copy_mode) {
  case CEED_COPY_VALUES: {
    size_t ctxsize;
    ierr = CeedQFunctionContextGetContextSize(ctx, &ctxsize); CeedChkBackend(ierr);
    ierr = CeedMallocArray(1, ctxsize, &impl->h_data_owned);
    CeedChkBackend(ierr);
    impl->h_data_borrowed = NULL;
    impl->h_data = impl->h_data_owned;
    memcpy(impl->h_data, data, ctxsize);
  } break;
  case CEED_OWN_POINTER:
    impl->h_data_owned = data;
    impl->h_data_borrowed = NULL;
    impl->h_data = data;
    break;
  case CEED_USE_POINTER:
    impl->h_data_borrowed = data;
    impl->h_data = data;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Set data from device
//------------------------------------------------------------------------------
static int CeedQFunctionContextSetDataDevice_Cuda(
  const CeedQFunctionContext ctx, const CeedCopyMode copy_mode, void *data) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  ierr = cudaFree(impl->d_data_owned); CeedChk_Cu(ceed, ierr);
  impl->d_data_owned = NULL;
  switch (copy_mode) {
  case CEED_COPY_VALUES: {
    size_t ctxsize;
    ierr = CeedQFunctionContextGetContextSize(ctx, &ctxsize); CeedChkBackend(ierr);
    ierr = cudaMalloc((void **)&impl->d_data_owned, ctxsize);
    CeedChk_Cu(ceed, ierr);
    impl->d_data_borrowed = NULL;
    impl->d_data = impl->d_data_owned;
    ierr = cudaMemcpy(impl->d_data, data, ctxsize,
                      cudaMemcpyDeviceToDevice); CeedChk_Cu(ceed, ierr);
  } break;
  case CEED_OWN_POINTER:
    impl->d_data_owned = data;
    impl->d_data_borrowed = NULL;
    impl->d_data = data;
    break;
  case CEED_USE_POINTER:
    impl->d_data_owned = NULL;
    impl->d_data_borrowed = data;
    impl->d_data = data;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Set the data used by a user context,
//   freeing any previously allocated data if applicable
//------------------------------------------------------------------------------
static int CeedQFunctionContextSetData_Cuda(const CeedQFunctionContext ctx,
    const CeedMemType mem_type, const CeedCopyMode copy_mode, void *data) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);

  ierr = CeedQFunctionContextSetAllInvalid_Cuda(ctx); CeedChkBackend(ierr);
  switch (mem_type) {
  case CEED_MEM_HOST:
    return CeedQFunctionContextSetDataHost_Cuda(ctx, copy_mode, data);
  case CEED_MEM_DEVICE:
    return CeedQFunctionContextSetDataDevice_Cuda(ctx, copy_mode, data);
  }

  return CEED_ERROR_UNSUPPORTED;
}

//------------------------------------------------------------------------------
// Take data
//------------------------------------------------------------------------------
static int CeedQFunctionContextTakeData_Cuda(const CeedQFunctionContext ctx,
    const CeedMemType mem_type, void *data) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  // Sync data to requested mem_type
  bool need_sync = false;
  ierr = CeedQFunctionContextNeedSync_Cuda(ctx, mem_type, &need_sync);
  CeedChkBackend(ierr);
  if (need_sync) {
    ierr = CeedQFunctionContextSync_Cuda(ctx, mem_type); CeedChkBackend(ierr);
  }

  // Update pointer
  switch (mem_type) {
  case CEED_MEM_HOST:
    *(void **)data = impl->h_data_borrowed;
    impl->h_data_borrowed = NULL;
    impl->h_data = NULL;
    break;
  case CEED_MEM_DEVICE:
    *(void **)data = impl->d_data_borrowed;
    impl->d_data_borrowed = NULL;
    impl->d_data = NULL;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Core logic for GetData.
//   If a different memory type is most up to date, this will perform a copy
//------------------------------------------------------------------------------
static int CeedQFunctionContextGetDataCore_Cuda(const CeedQFunctionContext ctx,
    const CeedMemType mem_type, void *data) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  // Sync data to requested mem_type
  bool need_sync = false;
  ierr = CeedQFunctionContextNeedSync_Cuda(ctx, mem_type, &need_sync);
  CeedChkBackend(ierr);
  if (need_sync) {
    ierr = CeedQFunctionContextSync_Cuda(ctx, mem_type); CeedChkBackend(ierr);
  }

  // Update pointer
  switch (mem_type) {
  case CEED_MEM_HOST:
    *(void **)data = impl->h_data;
    break;
  case CEED_MEM_DEVICE:
    *(void **)data = impl->d_data;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Get read-only access to the data
//------------------------------------------------------------------------------
static int CeedQFunctionContextGetDataRead_Cuda(const CeedQFunctionContext ctx,
    const CeedMemType mem_type, void *data) {
  return CeedQFunctionContextGetDataCore_Cuda(ctx, mem_type, data);
}

//------------------------------------------------------------------------------
// Get read/write access to the data
//------------------------------------------------------------------------------
static int CeedQFunctionContextGetData_Cuda(const CeedQFunctionContext ctx,
    const CeedMemType mem_type, void *data) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  ierr = CeedQFunctionContextGetDataCore_Cuda(ctx, mem_type, data);
  CeedChkBackend(ierr);

  // Mark only pointer for requested memory as valid
  ierr = CeedQFunctionContextSetAllInvalid_Cuda(ctx); CeedChkBackend(ierr);
  switch (mem_type) {
  case CEED_MEM_HOST:
    impl->h_data = *(void **)data;
    break;
  case CEED_MEM_DEVICE:
    impl->d_data = *(void **)data;
    break;
  }

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// Destroy the user context
//------------------------------------------------------------------------------
static int CeedQFunctionContextDestroy_Cuda(const CeedQFunctionContext ctx) {
  int ierr;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);
  CeedQFunctionContext_Cuda *impl;
  ierr = CeedQFunctionContextGetBackendData(ctx, &impl); CeedChkBackend(ierr);

  ierr = cudaFree(impl->d_data_owned); CeedChk_Cu(ceed, ierr);
  ierr = CeedFree(&impl->h_data_owned); CeedChkBackend(ierr);
  ierr = CeedFree(&impl); CeedChkBackend(ierr);

  return CEED_ERROR_SUCCESS;
}

//------------------------------------------------------------------------------
// QFunctionContext Create
//------------------------------------------------------------------------------
int CeedQFunctionContextCreate_Cuda(CeedQFunctionContext ctx) {
  int ierr;
  CeedQFunctionContext_Cuda *impl;
  Ceed ceed;
  ierr = CeedQFunctionContextGetCeed(ctx, &ceed); CeedChkBackend(ierr);

  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "HasValidData",
                                CeedQFunctionContextHasValidData_Cuda);
  CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx,
                                "HasBorrowedDataOfType",
                                CeedQFunctionContextHasBorrowedDataOfType_Cuda);
  CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "SetData",
                                CeedQFunctionContextSetData_Cuda); CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "TakeData",
                                CeedQFunctionContextTakeData_Cuda); CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "GetData",
                                CeedQFunctionContextGetData_Cuda); CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "GetDataRead",
                                CeedQFunctionContextGetDataRead_Cuda); CeedChkBackend(ierr);
  ierr = CeedSetBackendFunction(ceed, "QFunctionContext", ctx, "Destroy",
                                CeedQFunctionContextDestroy_Cuda); CeedChkBackend(ierr);

  ierr = CeedCalloc(1, &impl); CeedChkBackend(ierr);
  ierr = CeedQFunctionContextSetBackendData(ctx, impl); CeedChkBackend(ierr);

  return CEED_ERROR_SUCCESS;
}
//------------------------------------------------------------------------------