// 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 <ceed-impl.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

/// @file
/// Implementation of public CeedQFunctionContext interfaces

/// ----------------------------------------------------------------------------
/// CeedQFunctionContext Library Internal Functions
/// ----------------------------------------------------------------------------
/// @addtogroup CeedQFunctionDeveloper
/// @{

/**
  @brief Get index for QFunctionContext field

  @param ctx         CeedQFunctionContext
  @param field_name  Name of field
  @param field_index Index of field, or -1 if field is not registered

  @return An error code: 0 - success, otherwise - failure

  @ref Developer
**/
int CeedQFunctionContextGetFieldIndex(CeedQFunctionContext ctx,
                                      const char *field_name, CeedInt *field_index) {
  *field_index = -1;
  for (CeedInt i=0; i<ctx->num_fields; i++)
    if (!strcmp(ctx->field_labels[i]->name, field_name))
      *field_index = i;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Common function for registering QFunctionContext fields

  @param ctx               CeedQFunctionContext
  @param field_name        Name of field to register
  @param field_offset      Offset of field to register
  @param field_description Description of field, or NULL for none
  @param field_type        Field data type, such as double or int32
  @param field_size        Size of field, in bytes
  @param num_values        Number of values to register, must be contiguous in memory

  @return An error code: 0 - success, otherwise - failure

  @ref Developer
**/
int CeedQFunctionContextRegisterGeneric(CeedQFunctionContext ctx,
                                        const char *field_name, size_t field_offset,
                                        const char *field_description,
                                        CeedContextFieldType field_type,
                                        size_t field_size, size_t num_values) {
  int ierr;

  // Check for duplicate
  CeedInt field_index = -1;
  ierr = CeedQFunctionContextGetFieldIndex(ctx, field_name, &field_index);
  CeedChk(ierr);
  if (field_index != -1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "QFunctionContext field with name \"%s\" already registered",
                     field_name);
  // LCOV_EXCL_STOP

  // Allocate space for field data
  if (ctx->num_fields == 0) {
    ierr = CeedCalloc(1, &ctx->field_labels); CeedChk(ierr);
    ctx->max_fields = 1;
  } else if (ctx->num_fields == ctx->max_fields) {
    ierr = CeedRealloc(2*ctx->max_fields, &ctx->field_labels);
    CeedChk(ierr);
    ctx->max_fields *= 2;
  }
  ierr = CeedCalloc(1, &ctx->field_labels[ctx->num_fields]); CeedChk(ierr);

  // Copy field data
  ierr = CeedStringAllocCopy(field_name,
                             (char **)&ctx->field_labels[ctx->num_fields]->name);
  CeedChk(ierr);
  ierr = CeedStringAllocCopy(field_description,
                             (char **)&ctx->field_labels[ctx->num_fields]->description);
  CeedChk(ierr);
  ctx->field_labels[ctx->num_fields]->type = field_type;
  ctx->field_labels[ctx->num_fields]->offset = field_offset;
  ctx->field_labels[ctx->num_fields]->size = field_size * num_values;
  ctx->field_labels[ctx->num_fields]->num_values = num_values;
  ctx->num_fields++;
  return CEED_ERROR_SUCCESS;
}

/// @}

/// ----------------------------------------------------------------------------
/// CeedQFunctionContext Backend API
/// ----------------------------------------------------------------------------
/// @addtogroup CeedQFunctionBackend
/// @{

/**
  @brief Get the Ceed associated with a CeedQFunctionContext

  @param ctx        CeedQFunctionContext
  @param[out] ceed  Variable to store Ceed

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextGetCeed(CeedQFunctionContext ctx, Ceed *ceed) {
  *ceed = ctx->ceed;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Check for valid data in a CeedQFunctionContext

  @param ctx                  CeedQFunctionContext to check validity
  @param[out] has_valid_data  Variable to store validity

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextHasValidData(CeedQFunctionContext ctx,
                                     bool *has_valid_data) {
  int ierr;

  if (!ctx->HasValidData)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support HasValidData");
  // LCOV_EXCL_STOP

  ierr = ctx->HasValidData(ctx, has_valid_data); CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Check for borrowed data of a specific CeedMemType in a
           CeedQFunctionContext

  @param ctx                             CeedQFunctionContext to check
  @param mem_type                        Memory type to check
  @param[out] has_borrowed_data_of_type  Variable to store result

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextHasBorrowedDataOfType(CeedQFunctionContext ctx,
    CeedMemType mem_type, bool *has_borrowed_data_of_type) {
  int ierr;

  if (!ctx->HasBorrowedDataOfType)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support HasBorrowedDataOfType");
  // LCOV_EXCL_STOP

  ierr = ctx->HasBorrowedDataOfType(ctx, mem_type, has_borrowed_data_of_type);
  CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get the state of a CeedQFunctionContext

  @param ctx         CeedQFunctionContext to retrieve state
  @param[out] state  Variable to store state

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextGetState(CeedQFunctionContext ctx, uint64_t *state) {
  *state = ctx->state;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get backend data of a CeedQFunctionContext

  @param ctx        CeedQFunctionContext
  @param[out] data  Variable to store data

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextGetBackendData(CeedQFunctionContext ctx, void *data) {
  *(void **)data = ctx->data;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set backend data of a CeedQFunctionContext

  @param[out] ctx  CeedQFunctionContext
  @param data      Data to set

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextSetBackendData(CeedQFunctionContext ctx, void *data) {
  ctx->data = data;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get label for a registered QFunctionContext field, or `NULL` if no
           field has been registered with this `field_name`

  @param[in] ctx           CeedQFunctionContext
  @param[in] field_name    Name of field to retrieve label
  @param[out] field_label  Variable to field label

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextGetFieldLabel(CeedQFunctionContext ctx,
                                      const char *field_name,
                                      CeedContextFieldLabel *field_label) {
  int ierr;

  CeedInt field_index;
  ierr = CeedQFunctionContextGetFieldIndex(ctx, field_name, &field_index);
  CeedChk(ierr);

  if (field_index != -1) {
    *field_label = ctx->field_labels[field_index];
  } else {
    *field_label = NULL;
  }

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set QFunctionContext field

  @param ctx         CeedQFunctionContext
  @param field_label Label of field to set
  @param field_type  Type of field to set
  @param value       Value to set

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextSetGeneric(CeedQFunctionContext ctx,
                                   CeedContextFieldLabel field_label,
                                   CeedContextFieldType field_type,
                                   void *value) {
  int ierr;

  // Check field type
  if (field_label->type != field_type)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "QFunctionContext field with name \"%s\" registered as %s, "
                     "not registered as %s", field_label->name,
                     CeedContextFieldTypes[field_label->type],
                     CeedContextFieldTypes[field_type]);
  // LCOV_EXCL_STOP

  char *data;
  ierr = CeedQFunctionContextGetData(ctx, CEED_MEM_HOST, &data); CeedChk(ierr);
  memcpy(&data[field_label->offset], value, field_label->size);
  ierr = CeedQFunctionContextRestoreData(ctx, &data); CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set QFunctionContext field holding a double precision value

  @param ctx         CeedQFunctionContext
  @param field_label Label for field to register
  @param values      Values to set

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextSetDouble(CeedQFunctionContext ctx,
                                  CeedContextFieldLabel field_label, double *values) {
  int ierr;

  if (!field_label)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Invalid field label");
  // LCOV_EXCL_STOP

  ierr = CeedQFunctionContextSetGeneric(ctx, field_label,
                                        CEED_CONTEXT_FIELD_DOUBLE,
                                        values); CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set QFunctionContext field holding an int32 value

  @param ctx         CeedQFunctionContext
  @param field_label Label for field to register
  @param values      Values to set

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextSetInt32(CeedQFunctionContext ctx,
                                 CeedContextFieldLabel field_label, int *values) {
  int ierr;

  if (!field_label)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Invalid field label");
  // LCOV_EXCL_STOP

  ierr = CeedQFunctionContextSetGeneric(ctx, field_label,
                                        CEED_CONTEXT_FIELD_INT32,
                                        values); CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get additional destroy routine for CeedQFunctionContext user data

  @param[in] ctx          CeedQFunctionContext to get user destroy function
  @param[out] f_mem_type  Memory type to use when passing data into `f`
  @param[out] f           Additional routine to use to destroy user data

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextGetDataDestroy(CeedQFunctionContext ctx,
                                       CeedMemType *f_mem_type, CeedQFunctionContextDataDestroyUser *f) {
  if (f_mem_type) *f_mem_type = ctx->data_destroy_mem_type;
  if (f) *f = ctx->data_destroy_function;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Destroy user data held by CeedQFunctionContext, using function set by
     CeedQFunctionContextSetDataDestroy, if applicable

  @param[in,out] ctx  CeedQFunctionContext to destroy user data

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextDestroyData(CeedQFunctionContext ctx) {
  int ierr;

  if (ctx->DataDestroy) {
    ierr = ctx->DataDestroy(ctx); CeedChk(ierr);
  } else {
    CeedQFunctionContextDataDestroyUser data_destroy_function;
    CeedMemType data_destroy_mem_type;

    ierr = CeedQFunctionContextGetDataDestroy(ctx, &data_destroy_mem_type,
           &data_destroy_function); CeedChk(ierr);
    if (data_destroy_function) {
      void *data;

      ierr = CeedQFunctionContextGetData(ctx, data_destroy_mem_type, &data);
      CeedChk(ierr);
      ierr = data_destroy_function(data); CeedChk(ierr);
      ierr = CeedQFunctionContextRestoreData(ctx, &data); CeedChk(ierr);
    }
  }

  return CEED_ERROR_SUCCESS;
}

/**
  @brief Increment the reference counter for a CeedQFunctionContext

  @param ctx  CeedQFunctionContext to increment the reference counter

  @return An error code: 0 - success, otherwise - failure

  @ref Backend
**/
int CeedQFunctionContextReference(CeedQFunctionContext ctx) {
  ctx->ref_count++;
  return CEED_ERROR_SUCCESS;
}

/// @}

/// ----------------------------------------------------------------------------
/// CeedQFunctionContext Public API
/// ----------------------------------------------------------------------------
/// @addtogroup CeedQFunctionUser
/// @{

/**
  @brief Create a CeedQFunctionContext for storing CeedQFunction user context data

  @param ceed      A Ceed object where the CeedQFunctionContext will be created
  @param[out] ctx  Address of the variable where the newly created
                     CeedQFunctionContext will be stored

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextCreate(Ceed ceed, CeedQFunctionContext *ctx) {
  int ierr;

  if (!ceed->QFunctionContextCreate) {
    Ceed delegate;
    ierr = CeedGetObjectDelegate(ceed, &delegate, "Context"); CeedChk(ierr);

    if (!delegate)
      // LCOV_EXCL_START
      return CeedError(ceed, CEED_ERROR_UNSUPPORTED,
                       "Backend does not support ContextCreate");
    // LCOV_EXCL_STOP

    ierr = CeedQFunctionContextCreate(delegate, ctx); CeedChk(ierr);
    return CEED_ERROR_SUCCESS;
  }

  ierr = CeedCalloc(1, ctx); CeedChk(ierr);
  (*ctx)->ceed = ceed;
  ierr = CeedReference(ceed); CeedChk(ierr);
  (*ctx)->ref_count = 1;
  ierr = ceed->QFunctionContextCreate(*ctx); CeedChk(ierr);
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Copy the pointer to a CeedQFunctionContext. Both pointers should
           be destroyed with `CeedQFunctionContextDestroy()`;
           Note: If `*ctx_copy` is non-NULL, then it is assumed that
           `*ctx_copy` is a pointer to a CeedQFunctionContext. This
           CeedQFunctionContext will be destroyed if `*ctx_copy` is the
           only reference to this CeedQFunctionContext.

  @param ctx            CeedQFunctionContext to copy reference to
  @param[out] ctx_copy  Variable to store copied reference

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextReferenceCopy(CeedQFunctionContext ctx,
                                      CeedQFunctionContext *ctx_copy) {
  int ierr;

  ierr = CeedQFunctionContextReference(ctx); CeedChk(ierr);
  ierr = CeedQFunctionContextDestroy(ctx_copy); CeedChk(ierr);
  *ctx_copy = ctx;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set the data used by a CeedQFunctionContext, freeing any previously allocated
           data if applicable. The backend may copy values to a different
           memtype, such as during @ref CeedQFunctionApply().
           See also @ref CeedQFunctionContextTakeData().

  @param ctx        CeedQFunctionContext
  @param mem_type   Memory type of the data being passed
  @param copy_mode  Copy mode for the data
  @param size       Size of data, in bytes
  @param data       Data to be used

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextSetData(CeedQFunctionContext ctx, CeedMemType mem_type,
                                CeedCopyMode copy_mode,
                                size_t size, void *data) {
  int ierr;

  if (!ctx->SetData)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support ContextSetData");
  // LCOV_EXCL_STOP

  if (ctx->state % 2 == 1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot grant CeedQFunctionContext data access, the "
                     "access lock is already in use");
  // LCOV_EXCL_STOP

  ierr = CeedQFunctionContextDestroyData(ctx); CeedChk(ierr);
  ctx->ctx_size = size;
  ierr = ctx->SetData(ctx, mem_type, copy_mode, data); CeedChk(ierr);
  ctx->state += 2;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Take ownership of the data in a CeedQFunctionContext via the specified memory type.
           The caller is responsible for managing and freeing the memory.

  @param ctx        CeedQFunctionContext to access
  @param mem_type   Memory type on which to access the data. If the backend
                      uses a different memory type, this will perform a copy.
  @param[out] data  Data on memory type mem_type

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextTakeData(CeedQFunctionContext ctx, CeedMemType mem_type,
                                 void *data) {
  int ierr;

  bool has_valid_data = true;
  ierr = CeedQFunctionContextHasValidData(ctx, &has_valid_data); CeedChk(ierr);
  if (!has_valid_data)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_BACKEND,
                     "CeedQFunctionContext has no valid data to take, must set data");
  // LCOV_EXCL_STOP

  if (!ctx->TakeData)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support TakeData");
  // LCOV_EXCL_STOP

  if (ctx->state % 2 == 1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot grant CeedQFunctionContext data access, the "
                     "access lock is already in use");
  // LCOV_EXCL_STOP

  bool has_borrowed_data_of_type = true;
  ierr = CeedQFunctionContextHasBorrowedDataOfType(ctx, mem_type,
         &has_borrowed_data_of_type); CeedChk(ierr);
  if (!has_borrowed_data_of_type)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_BACKEND,
                     "CeedQFunctionContext has no borowed %s data, "
                     "must set data with CeedQFunctionContextSetData",
                     CeedMemTypes[mem_type]);
  // LCOV_EXCL_STOP

  void *temp_data = NULL;
  ierr = ctx->TakeData(ctx, mem_type, &temp_data); CeedChk(ierr);
  if (data) (*(void **)data) = temp_data;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get read/write access to a CeedQFunctionContext via the specified memory type.
           Restore access with @ref CeedQFunctionContextRestoreData().

  @param ctx        CeedQFunctionContext to access
  @param mem_type   Memory type on which to access the data. If the backend
                      uses a different memory type, this will perform a copy.
  @param[out] data  Data on memory type mem_type

  @note The CeedQFunctionContextGetData() and @ref CeedQFunctionContextRestoreData() functions
    provide access to array pointers in the desired memory space. Pairing
    get/restore allows the Context to track access.

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextGetData(CeedQFunctionContext ctx, CeedMemType mem_type,
                                void *data) {
  int ierr;

  if (!ctx->GetData)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support GetData");
  // LCOV_EXCL_STOP

  if (ctx->state % 2 == 1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot grant CeedQFunctionContext data access, the "
                     "access lock is already in use");
  // LCOV_EXCL_STOP

  if (ctx->num_readers > 0)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot grant CeedQFunctionContext data access, a "
                     "process has read access");
  // LCOV_EXCL_STOP

  bool has_valid_data = true;
  ierr = CeedQFunctionContextHasValidData(ctx, &has_valid_data); CeedChk(ierr);
  if (!has_valid_data)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_BACKEND,
                     "CeedQFunctionContext has no valid data to get, must set data");
  // LCOV_EXCL_STOP

  ierr = ctx->GetData(ctx, mem_type, data); CeedChk(ierr);
  ctx->state++;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get read only access to a CeedQFunctionContext via the specified memory type.
           Restore access with @ref CeedQFunctionContextRestoreData().

  @param ctx        CeedQFunctionContext to access
  @param mem_type   Memory type on which to access the data. If the backend
                      uses a different memory type, this will perform a copy.
  @param[out] data  Data on memory type mem_type

  @note The CeedQFunctionContextGetDataRead() and @ref CeedQFunctionContextRestoreDataRead()
    functions provide access to array pointers in the desired memory space. Pairing
    get/restore allows the Context to track access.

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextGetDataRead(CeedQFunctionContext ctx,
                                    CeedMemType mem_type,
                                    void *data) {
  int ierr;

  if (!ctx->GetDataRead)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_UNSUPPORTED,
                     "Backend does not support GetDataRead");
  // LCOV_EXCL_STOP

  if (ctx->state % 2 == 1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot grant CeedQFunctionContext data access, the "
                     "access lock is already in use");
  // LCOV_EXCL_STOP

  bool has_valid_data = true;
  ierr = CeedQFunctionContextHasValidData(ctx, &has_valid_data); CeedChk(ierr);
  if (!has_valid_data)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, CEED_ERROR_BACKEND,
                     "CeedQFunctionContext has no valid data to get, must set data");
  // LCOV_EXCL_STOP

  ierr = ctx->GetDataRead(ctx, mem_type, data); CeedChk(ierr);
  ctx->num_readers++;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Restore data obtained using @ref CeedQFunctionContextGetData()

  @param ctx   CeedQFunctionContext to restore
  @param data  Data to restore

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextRestoreData(CeedQFunctionContext ctx, void *data) {
  int ierr;

  if (ctx->state % 2 != 1)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot restore CeedQFunctionContext array access, "
                     "access was not granted");
  // LCOV_EXCL_STOP

  if (ctx->RestoreData) {
    ierr = ctx->RestoreData(ctx); CeedChk(ierr);
  }
  *(void **)data = NULL;
  ctx->state++;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Restore data obtained using @ref CeedQFunctionContextGetDataRead()

  @param ctx   CeedQFunctionContext to restore
  @param data  Data to restore

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextRestoreDataRead(CeedQFunctionContext ctx, void *data) {
  int ierr;

  if (ctx->num_readers == 0)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Cannot restore CeedQFunctionContext array access, "
                     "access was not granted");
  // LCOV_EXCL_STOP

  if (ctx->RestoreDataRead) {
    ierr = ctx->RestoreData(ctx); CeedChk(ierr);
  }
  *(void **)data = NULL;
  ctx->num_readers--;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Register QFunctionContext a field holding a double precision value

  @param ctx               CeedQFunctionContext
  @param field_name        Name of field to register
  @param field_offset      Offset of field to register
  @param num_values        Number of values to register, must be contiguous in memory
  @param field_description Description of field, or NULL for none

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextRegisterDouble(CeedQFunctionContext ctx,
                                       const char *field_name, size_t field_offset,
                                       size_t num_values,
                                       const char *field_description) {
  return CeedQFunctionContextRegisterGeneric(ctx, field_name, field_offset,
         field_description, CEED_CONTEXT_FIELD_DOUBLE, sizeof(double), num_values);
}

/**
  @brief Register QFunctionContext a field holding a int32 value

  @param ctx               CeedQFunctionContext
  @param field_name        Name of field to register
  @param field_offset      Offset of field to register
  @param num_values        Number of values to register, must be contiguous in memory
  @param field_description Description of field, or NULL for none

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextRegisterInt32(CeedQFunctionContext ctx,
                                      const char *field_name, size_t field_offset,
                                      size_t num_values,
                                      const char *field_description) {
  return CeedQFunctionContextRegisterGeneric(ctx, field_name, field_offset,
         field_description, CEED_CONTEXT_FIELD_INT32, sizeof(int), num_values);
}

/**
  @brief Get labels for all registered QFunctionContext fields

  @param ctx                CeedQFunctionContext
  @param[out] field_labels  Variable to hold array of field labels
  @param[out] num_fields    Length of field descriptions array

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextGetAllFieldLabels(CeedQFunctionContext ctx,
    const CeedContextFieldLabel **field_labels, CeedInt *num_fields) {
  *field_labels = ctx->field_labels;
  *num_fields = ctx->num_fields;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get the descriptive information about a CeedContextFieldLabel

  @param[in] label              CeedContextFieldLabel
  @param[out] field_name        Name of labeled field
  @param[out] field_description Description of field, or NULL for none
  @param[out] num_values        Number of values registered
  @param[out] field_type        CeedContextFieldType

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedContextFieldLabelGetDescription(CeedContextFieldLabel label,
                                        const char **field_name,
                                        const char **field_description,
                                        size_t *num_values,
                                        CeedContextFieldType *field_type) {
  if (field_name) *field_name = label->name;
  if (field_description) *field_description = label->description;
  if (num_values) *num_values = label->num_values;
  if (field_type) *field_type = label->type;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Get data size for a Context

  @param ctx            CeedQFunctionContext
  @param[out] ctx_size  Variable to store size of context data values

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextGetContextSize(CeedQFunctionContext ctx,
                                       size_t *ctx_size) {
  *ctx_size = ctx->ctx_size;
  return CEED_ERROR_SUCCESS;
}


/**
  @brief View a CeedQFunctionContext

  @param[in] ctx     CeedQFunctionContext to view
  @param[in] stream  Filestream to write to

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextView(CeedQFunctionContext ctx, FILE *stream) {
  fprintf(stream, "CeedQFunctionContext\n");
  fprintf(stream, "  Context Data Size: %ld\n", ctx->ctx_size);
  for (CeedInt i = 0; i < ctx->num_fields; i++) {
    // LCOV_EXCL_START
    fprintf(stream, "  Labeled %s field: %s\n",
            CeedContextFieldTypes[ctx->field_labels[i]->type],
            ctx->field_labels[i]->name);
    // LCOV_EXCL_STOP
  }
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Set additional destroy routine for CeedQFunctionContext user data

  @param[in] ctx         CeedQFunctionContext to set user destroy function
  @param[in] f_mem_type  Memory type to use when passing data into `f`
  @param[in] f           Additional routine to use to destroy user data

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextSetDataDestroy(CeedQFunctionContext ctx,
                                       CeedMemType f_mem_type, CeedQFunctionContextDataDestroyUser f) {
  if (!f)
    // LCOV_EXCL_START
    return CeedError(ctx->ceed, 1,
                     "Must provide valid callback function for destroying user data");
  // LCOV_EXCL_STOP
  ctx->data_destroy_mem_type = f_mem_type;
  ctx->data_destroy_function = f;
  return CEED_ERROR_SUCCESS;
}

/**
  @brief Destroy a CeedQFunctionContext

  @param ctx  CeedQFunctionContext to destroy

  @return An error code: 0 - success, otherwise - failure

  @ref User
**/
int CeedQFunctionContextDestroy(CeedQFunctionContext *ctx) {
  int ierr;

  if (!*ctx || --(*ctx)->ref_count > 0)
    return CEED_ERROR_SUCCESS;

  if ((*ctx) && ((*ctx)->state % 2) == 1)
    // LCOV_EXCL_START
    return CeedError((*ctx)->ceed, 1,
                     "Cannot destroy CeedQFunctionContext, the access "
                     "lock is in use");
  // LCOV_EXCL_STOP

  ierr = CeedQFunctionContextDestroyData(*ctx); CeedChk(ierr);
  if ((*ctx)->Destroy) {
    ierr = (*ctx)->Destroy(*ctx); CeedChk(ierr);
  }
  for (CeedInt i=0; i<(*ctx)->num_fields; i++) {
    ierr = CeedFree(&(*ctx)->field_labels[i]->name); CeedChk(ierr);
    ierr = CeedFree(&(*ctx)->field_labels[i]->description); CeedChk(ierr);
    ierr = CeedFree(&(*ctx)->field_labels[i]); CeedChk(ierr);
  }
  ierr = CeedFree(&(*ctx)->field_labels); CeedChk(ierr);
  ierr = CeedDestroy(&(*ctx)->ceed); CeedChk(ierr);
  ierr = CeedFree(ctx); CeedChk(ierr);

  return CEED_ERROR_SUCCESS;
}

/// @}