// Copyright (c) 2017, Lawrence Livermore National Security, LLC. Produced at
// the Lawrence Livermore National Laboratory. LLNL-CODE-734707. All Rights
// reserved. See files LICENSE and NOTICE for details.
//
// This file is part of CEED, a collection of benchmarks, miniapps, software
// libraries and APIs for efficient high-order finite element and spectral
// element discretizations for exascale applications. For more information and
// source code availability see http://github.com/ceed.
//
// The CEED research is supported by the Exascale Computing Project 17-SC-20-SC,
// a collaborative effort of two U.S. Department of Energy organizations (Office
// of Science and the National Nuclear Security Administration) responsible for
// the planning and preparation of a capable exascale ecosystem, including
// software, applications, hardware, advanced system engineering and early
// testbed platforms, in support of the nation's exascale computing imperative.

#include <ceed-impl.h>
#include <string.h>

/// @file
/// Implementation of public CeedQFunction interfaces
///
/// @addtogroup CeedQFunction
/// @{

/**
  @brief Create a CeedQFunction for evaluating interior (volumetric) terms.

  @param ceed       A Ceed object where the CeedQFunction will be created
  @param vlength    Vector length.  Caller must ensure that number of quadrature
                    points is a multiple of vlength.
  @param f          Function pointer to evaluate action at quadrature points.
                    See below.
  @param focca      OCCA identifier "file.c:function_name" for definition of `f`
  @param[out] qf    Address of the variable where the newly created
                     CeedQFunction will be stored

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

  The arguments of the call-back 'function' are:

   1. [void *ctx][in/out] - user data, this is the 'ctx' pointer stored in
              the CeedQFunction, set by calling CeedQFunctionSetContext

   2. [CeedInt nq][in] - number of quadrature points to process

   3. [const CeedScalar *const *u][in] - input fields data at quadrature pts, listed in the order given by the user

   4. [CeedScalar *const *v][out] - output fields data at quadrature points, again listed in order given by the user

  @ref Basic
**/
int CeedQFunctionCreateInterior(Ceed ceed, CeedInt vlength,
                                int (*f)(void*, CeedInt, const CeedScalar *const*, CeedScalar *const*),
                                const char *focca, CeedQFunction *qf) {
  int ierr;
  char *focca_copy;

  if (!ceed->QFunctionCreate)
    return CeedError(ceed, 1, "Backend does not support QFunctionCreate");
  ierr = CeedCalloc(1,qf); CeedChk(ierr);
  (*qf)->ceed = ceed;
  ceed->refcount++;
  (*qf)->refcount = 1;
  (*qf)->vlength = vlength;
  (*qf)->function = f;
  ierr = CeedCalloc(strlen(focca)+1, &focca_copy); CeedChk(ierr);
  strcpy(focca_copy, focca);
  (*qf)->focca = focca_copy;
  ierr = ceed->QFunctionCreate(*qf); CeedChk(ierr);
  return 0;
}

/**
  @brief Set a CeedQFunction field, used by CeedQFunctionAddInput/Output

  @param f          CeedQFunctionField
  @param fieldname  Name of QFunction field
  @param ncomp      Number of components per quadrature node
  @param emode      \ref CEED_EVAL_NONE to use values directly,
                      \ref CEED_EVAL_INTERP to use interpolated values,
                      \ref CEED_EVAL_GRAD to use gradients.

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

  @ref Developer
**/
static int CeedQFunctionFieldSet(struct CeedQFunctionField *f,
                                 const char *fieldname, CeedInt ncomp,
                                 CeedEvalMode emode) {
  size_t len = strlen(fieldname);
  char *tmp;
  int ierr =  CeedCalloc(len+1, &tmp); CeedChk(ierr);
  memcpy(tmp, fieldname, len+1);
  f->fieldname = tmp;
  f->ncomp = ncomp;
  f->emode = emode;
  return 0;
}

/**
  @brief Add a CeedQFunction input

  @param qf         CeedQFunction
  @param fieldname  Name of QFunction field
  @param ncomp      Number of components per quadrature node
  @param emode      \ref CEED_EVAL_NONE to use values directly,
                      \ref CEED_EVAL_INTERP to use interpolated values,
                      \ref CEED_EVAL_GRAD to use gradients.

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

  @ref Basic
**/
int CeedQFunctionAddInput(CeedQFunction qf, const char *fieldname,
                          CeedInt ncomp, CeedEvalMode emode) {
  int ierr = CeedQFunctionFieldSet(&qf->inputfields[qf->numinputfields++],
                                   fieldname, ncomp, emode); CeedChk(ierr);
  return 0;
}

/**
  @brief Add a CeedQFunction output

  @param qf         CeedQFunction
  @param fieldname  Name of QFunction field
  @param ncomp      Number of components per quadrature node
  @param emode      \ref CEED_EVAL_NONE to use values directly,
                      \ref CEED_EVAL_INTERP to use interpolated values,
                      \ref CEED_EVAL_GRAD to use gradients.

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

  @ref Basic
**/
int CeedQFunctionAddOutput(CeedQFunction qf, const char *fieldname,
                           CeedInt ncomp, CeedEvalMode emode) {
  if (emode == CEED_EVAL_WEIGHT)
    return CeedError(qf->ceed, 1,
                     "Cannot create qfunction output with CEED_EVAL_WEIGHT");
  int ierr = CeedQFunctionFieldSet(&qf->outputfields[qf->numoutputfields++],
                                   fieldname, ncomp, emode); CeedChk(ierr);
  return 0;
}

/**
  @brief Get the number of inputs and outputs to a CeedQFunction

  @param qf              CeedQFunction
  @param[out] numinput   Number of input fields
  @param[out] numoutput  Number of output fields

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

  @ref Utility
**/

int CeedQFunctionGetNumArgs(CeedQFunction qf, CeedInt *numinput,
                            CeedInt *numoutput) {
  if (numinput) *numinput = qf->numinputfields;
  if (numoutput) *numoutput = qf->numoutputfields;
  return 0;
}

/**
  @brief Set global context for a quadrature function

  @param qf       CeedQFunction
  @param ctx      Context data to set
  @param ctxsize  Size of context data values

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

  @ref Basic
**/
int CeedQFunctionSetContext(CeedQFunction qf, void *ctx, size_t ctxsize) {
  qf->ctx = ctx;
  qf->ctxsize = ctxsize;
  return 0;
}

/**
  @brief Apply the action of a CeedQFunction

  @param qf      CeedQFunction
  @param Q       Number of quadrature points
  @param[in] u   Array of input data arrays
  @param[out] v  Array of output data arrays

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

  @ref Advanced
**/
int CeedQFunctionApply(CeedQFunction qf, CeedInt Q,
                       const CeedScalar *const *u,
                       CeedScalar *const *v) {
  int ierr;
  if (!qf->Apply)
    return CeedError(qf->ceed, 1, "Backend does not support QFunctionApply");
  if (Q % qf->vlength)
    return CeedError(qf->ceed, 2,
                     "Number of quadrature points %d must be a multiple of %d",
                     Q, qf->vlength);
  ierr = qf->Apply(qf, Q, u, v); CeedChk(ierr);
  return 0;
}

/**
  @brief Destroy a CeedQFunction

  @param qf CeedQFunction to destroy

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

  @ref Basic
**/
int CeedQFunctionDestroy(CeedQFunction *qf) {
  int ierr;

  if (!*qf || --(*qf)->refcount > 0) return 0;
  // Free field names
  for (int i=0; i<(*qf)->numinputfields; i++) {
    ierr = CeedFree(&(*qf)->inputfields[i].fieldname); CeedChk(ierr);
  }
  for (int i=0; i<(*qf)->numoutputfields; i++) {
    ierr = CeedFree(&(*qf)->outputfields[i].fieldname); CeedChk(ierr);
  }
  if ((*qf)->Destroy) {
    ierr = (*qf)->Destroy(*qf); CeedChk(ierr);
  }
  ierr = CeedFree(&(*qf)->focca); CeedChk(ierr);
  ierr = CeedDestroy(&(*qf)->ceed); CeedChk(ierr);
  ierr = CeedFree(qf); CeedChk(ierr);
  return 0;
}

/// @}