// Copyright (c) 2017-2018, 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 <string.h>
#include "ceed-ref.h"

static int CeedOperatorDestroy_Ref(CeedOperator op) {
  int ierr;
  CeedOperator_Ref *impl;
  ierr = CeedOperatorGetData(op, (void*)&impl); CeedChk(ierr);

  for (CeedInt i=0; i<impl->numein+impl->numeout; i++) {
    ierr = CeedVectorDestroy(&impl->evecs[i]); CeedChk(ierr);
  }
  ierr = CeedFree(&impl->evecs); CeedChk(ierr);
  ierr = CeedFree(&impl->edata); CeedChk(ierr);

  for (CeedInt i=0; i<impl->numein; i++) {
    ierr = CeedVectorDestroy(&impl->evecsin[i]); CeedChk(ierr);
    ierr = CeedVectorDestroy(&impl->qvecsin[i]); CeedChk(ierr);
  }
  ierr = CeedFree(&impl->evecsin); CeedChk(ierr);
  ierr = CeedFree(&impl->qvecsin); CeedChk(ierr);

  for (CeedInt i=0; i<impl->numeout; i++) {
    ierr = CeedVectorDestroy(&impl->evecsout[i]); CeedChk(ierr);
    ierr = CeedVectorDestroy(&impl->qvecsout[i]); CeedChk(ierr);
  }
  ierr = CeedFree(&impl->evecsout); CeedChk(ierr);
  ierr = CeedFree(&impl->qvecsout); CeedChk(ierr);

  ierr = CeedFree(&impl); CeedChk(ierr);
  return 0;
}

/*
  Setup infields or outfields
 */
static int CeedOperatorSetupFields_Ref(CeedQFunction qf, CeedOperator op,
                                       bool inOrOut,
                                       CeedVector *fullevecs, CeedVector *evecs,
                                       CeedVector *qvecs, CeedInt starte,
                                       CeedInt numfields, CeedInt Q) {
  CeedInt dim, ierr, ncomp;
  Ceed ceed;
  ierr = CeedOperatorGetCeed(op, &ceed); CeedChk(ierr);
  CeedBasis basis;
  CeedElemRestriction Erestrict;
  CeedOperatorField *opfields;
  CeedQFunctionField *qffields;
  if (inOrOut) {
    ierr = CeedOperatorGetFields(op, NULL, &opfields);
    CeedChk(ierr);
    ierr = CeedQFunctionGetFields(qf, NULL, &qffields);
    CeedChk(ierr);
  } else {
    ierr = CeedOperatorGetFields(op, &opfields, NULL);
    CeedChk(ierr);
    ierr = CeedQFunctionGetFields(qf, &qffields, NULL);
    CeedChk(ierr);
  }

  // Loop over fields
  for (CeedInt i=0; i<numfields; i++) {
    CeedEvalMode emode;
    ierr = CeedQFunctionFieldGetEvalMode(qffields[i], &emode); CeedChk(ierr);

    if (emode != CEED_EVAL_WEIGHT) {
      ierr = CeedOperatorFieldGetElemRestriction(opfields[i], &Erestrict);
      CeedChk(ierr);
      ierr = CeedElemRestrictionCreateVector(Erestrict, NULL,
                                             &fullevecs[i+starte]);
      CeedChk(ierr);
    }

    switch(emode) {
    case CEED_EVAL_NONE:
      ierr = CeedQFunctionFieldGetNumComponents(qffields[i], &ncomp);
      CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q*ncomp, &qvecs[i]); CeedChk(ierr);
      break;
    case CEED_EVAL_INTERP:
      ierr = CeedQFunctionFieldGetNumComponents(qffields[i], &ncomp);
      CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q*ncomp, &evecs[i]); CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q*ncomp, &qvecs[i]); CeedChk(ierr);
      break;
    case CEED_EVAL_GRAD:
      ierr = CeedOperatorFieldGetBasis(opfields[i], &basis); CeedChk(ierr);
      ierr = CeedQFunctionFieldGetNumComponents(qffields[i], &ncomp);
      ierr = CeedBasisGetDimension(basis, &dim); CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q*ncomp, &evecs[i]); CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q*ncomp*dim, &qvecs[i]); CeedChk(ierr);
      break;
    case CEED_EVAL_WEIGHT: // Only on input fields
      ierr = CeedOperatorFieldGetBasis(opfields[i], &basis); CeedChk(ierr);
      ierr = CeedVectorCreate(ceed, Q, &qvecs[i]); CeedChk(ierr);
      ierr = CeedBasisApply(basis, 1, CEED_NOTRANSPOSE, CEED_EVAL_WEIGHT,
                            NULL, qvecs[i]); CeedChk(ierr);
      break;
    case CEED_EVAL_DIV:
      break; // Not implimented
    case CEED_EVAL_CURL:
      break; // Not implimented
    }
  }
  return 0;
}

/*
  CeedOperator needs to connect all the named fields (be they active or passive)
  to the named inputs and outputs of its CeedQFunction.
 */
static int CeedOperatorSetup_Ref(CeedOperator op) {
  int ierr;
  bool setupdone;
  ierr = CeedOperatorGetSetupStatus(op, &setupdone); CeedChk(ierr);
  if (setupdone) return 0;
  Ceed ceed;
  ierr = CeedOperatorGetCeed(op, &ceed); CeedChk(ierr);
  CeedOperator_Ref *impl;
  ierr = CeedOperatorGetData(op, (void*)&impl); CeedChk(ierr);
  CeedQFunction qf;
  ierr = CeedOperatorGetQFunction(op, &qf); CeedChk(ierr);
  CeedInt Q, numinputfields, numoutputfields;
  ierr = CeedOperatorGetNumQuadraturePoints(op, &Q); CeedChk(ierr);
  ierr = CeedQFunctionGetNumArgs(qf, &numinputfields, &numoutputfields);
  CeedChk(ierr);
  CeedOperatorField *opinputfields, *opoutputfields;
  ierr = CeedOperatorGetFields(op, &opinputfields, &opoutputfields);
  CeedChk(ierr);
  CeedQFunctionField *qfinputfields, *qfoutputfields;
  ierr = CeedQFunctionGetFields(qf, &qfinputfields, &qfoutputfields);
  CeedChk(ierr);

  // Allocate
  ierr = CeedCalloc(numinputfields + numoutputfields, &impl->evecs);
  CeedChk(ierr);
  ierr = CeedCalloc(numinputfields + numoutputfields, &impl->edata);
  CeedChk(ierr);

  ierr = CeedCalloc(16, &impl->evecsin); CeedChk(ierr);
  ierr = CeedCalloc(16, &impl->evecsout); CeedChk(ierr);
  ierr = CeedCalloc(16, &impl->qvecsin); CeedChk(ierr);
  ierr = CeedCalloc(16, &impl->qvecsout); CeedChk(ierr);

  impl->numein = numinputfields; impl->numeout = numoutputfields;

  // Set up infield and outfield evecs and qvecs
  // Infields
  ierr = CeedOperatorSetupFields_Ref(qf, op, 0, impl->evecs,
                                     impl->evecsin, impl->qvecsin, 0,
                                     numinputfields, Q);
  CeedChk(ierr);

  // Outfields
  ierr = CeedOperatorSetupFields_Ref(qf, op, 1, impl->evecs,
                                     impl->evecsout, impl->qvecsout,
                                     numinputfields, numoutputfields, Q);
  CeedChk(ierr);

  ierr = CeedOperatorSetSetupDone(op); CeedChk(ierr);

  return 0;
}

static int CeedOperatorApply_Ref(CeedOperator op, CeedVector invec,
                                 CeedVector outvec, CeedRequest *request) {
  int ierr;
  CeedOperator_Ref *impl;
  ierr = CeedOperatorGetData(op, (void*)&impl); CeedChk(ierr);
  CeedQFunction qf;
  ierr = CeedOperatorGetQFunction(op, &qf); CeedChk(ierr);
  CeedInt Q, numelements, elemsize, numinputfields, numoutputfields, ncomp;
  ierr = CeedOperatorGetNumQuadraturePoints(op, &Q); CeedChk(ierr);
  ierr = CeedOperatorGetNumElements(op, &numelements); CeedChk(ierr);
  ierr= CeedQFunctionGetNumArgs(qf, &numinputfields, &numoutputfields);
  CeedChk(ierr);
  CeedTransposeMode lmode;
  CeedOperatorField *opinputfields, *opoutputfields;
  ierr = CeedOperatorGetFields(op, &opinputfields, &opoutputfields);
  CeedChk(ierr);
  CeedQFunctionField *qfinputfields, *qfoutputfields;
  ierr = CeedQFunctionGetFields(qf, &qfinputfields, &qfoutputfields);
  CeedChk(ierr);
  CeedEvalMode emode;
  CeedVector vec;
  CeedBasis basis;
  CeedElemRestriction Erestrict;

  // Setup
  ierr = CeedOperatorSetup_Ref(op); CeedChk(ierr);

  // Input Evecs and Restriction
  for (CeedInt i=0; i<numinputfields; i++) {
    ierr = CeedQFunctionFieldGetEvalMode(qfinputfields[i], &emode);
    CeedChk(ierr);
    if (emode == CEED_EVAL_WEIGHT) { // Skip
    } else {
      // Get input vector
      ierr = CeedOperatorFieldGetVector(opinputfields[i], &vec); CeedChk(ierr);
      if (vec == CEED_VECTOR_ACTIVE)
        vec = invec;
      // Restrict
      ierr = CeedOperatorFieldGetElemRestriction(opinputfields[i], &Erestrict);
      CeedChk(ierr);
      ierr = CeedOperatorFieldGetLMode(opinputfields[i], &lmode); CeedChk(ierr);
      ierr = CeedElemRestrictionApply(Erestrict, CEED_NOTRANSPOSE,
                                      lmode, vec, impl->evecs[i],
                                      request); CeedChk(ierr);
      // Get evec
      ierr = CeedVectorGetArrayRead(impl->evecs[i], CEED_MEM_HOST,
                                    (const CeedScalar **) &impl->edata[i]);
      CeedChk(ierr);
    }
  }

  // Output Evecs
  for (CeedInt i=0; i<numoutputfields; i++) {
    ierr = CeedVectorGetArray(impl->evecs[i+impl->numein], CEED_MEM_HOST,
                              &impl->edata[i + numinputfields]); CeedChk(ierr);
  }

  // Loop through elements
  for (CeedInt e=0; e<numelements; e++) {
    // Input basis apply if needed
    for (CeedInt i=0; i<numinputfields; i++) {
      // Get elemsize, emode, ncomp
      ierr = CeedOperatorFieldGetElemRestriction(opinputfields[i], &Erestrict);
      CeedChk(ierr);
      ierr = CeedElemRestrictionGetElementSize(Erestrict, &elemsize);
      CeedChk(ierr);
      ierr = CeedQFunctionFieldGetEvalMode(qfinputfields[i], &emode);
      CeedChk(ierr);
      ierr = CeedQFunctionFieldGetNumComponents(qfinputfields[i], &ncomp);
      CeedChk(ierr);
      // Basis action
      switch(emode) {
      case CEED_EVAL_NONE:
        ierr = CeedVectorSetArray(impl->qvecsin[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i][e*Q*ncomp]); CeedChk(ierr);
        break;
      case CEED_EVAL_INTERP:
        ierr = CeedOperatorFieldGetBasis(opinputfields[i], &basis); CeedChk(ierr);
        ierr = CeedVectorSetArray(impl->evecsin[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i][e*elemsize*ncomp]);
        CeedChk(ierr);
        ierr = CeedBasisApply(basis, 1, CEED_NOTRANSPOSE,
                              CEED_EVAL_INTERP, impl->evecsin[i],
                              impl->qvecsin[i]); CeedChk(ierr);
        break;
      case CEED_EVAL_GRAD:
        ierr = CeedOperatorFieldGetBasis(opinputfields[i], &basis); CeedChk(ierr);
        ierr = CeedVectorSetArray(impl->evecsin[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i][e*elemsize*ncomp]);
        CeedChk(ierr);
        ierr = CeedBasisApply(basis, 1, CEED_NOTRANSPOSE,
                              CEED_EVAL_GRAD, impl->evecsin[i],
                              impl->qvecsin[i]); CeedChk(ierr);
        break;
      case CEED_EVAL_WEIGHT:
        break;  // No action
      case CEED_EVAL_DIV:
        break; // Not implimented
      case CEED_EVAL_CURL:
        break; // Not implimented
      }
    }
    // Output pointers
    for (CeedInt i=0; i<numoutputfields; i++) {
      ierr = CeedQFunctionFieldGetEvalMode(qfoutputfields[i], &emode);
      CeedChk(ierr);
      if (emode == CEED_EVAL_NONE) {
        ierr = CeedQFunctionFieldGetNumComponents(qfoutputfields[i], &ncomp);
        CeedChk(ierr);
        ierr = CeedVectorSetArray(impl->qvecsout[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i + numinputfields][e*Q*ncomp]);
        CeedChk(ierr);
      }
    }
    // Q function
    ierr = CeedQFunctionApply(qf, Q, impl->qvecsin, impl->qvecsout); CeedChk(ierr);

    // Output basis apply if needed
    for (CeedInt i=0; i<numoutputfields; i++) {
      // Get elemsize, emode, ncomp
      ierr = CeedOperatorFieldGetElemRestriction(opoutputfields[i], &Erestrict);
      CeedChk(ierr);
      ierr = CeedElemRestrictionGetElementSize(Erestrict, &elemsize);
      CeedChk(ierr);
      ierr = CeedQFunctionFieldGetEvalMode(qfoutputfields[i], &emode);
      CeedChk(ierr);
      ierr = CeedQFunctionFieldGetNumComponents(qfoutputfields[i], &ncomp);
      CeedChk(ierr);
      // Basis action
      switch(emode) {
      case CEED_EVAL_NONE:
        break; // No action
      case CEED_EVAL_INTERP:
        ierr = CeedOperatorFieldGetBasis(opoutputfields[i], &basis);
        CeedChk(ierr);
        ierr = CeedVectorSetArray(impl->evecsout[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i + numinputfields][e*elemsize*ncomp]);
        ierr = CeedBasisApply(basis, 1, CEED_TRANSPOSE,
                              CEED_EVAL_INTERP, impl->qvecsout[i],
                              impl->evecsout[i]); CeedChk(ierr);
        break;
      case CEED_EVAL_GRAD:
        ierr = CeedOperatorFieldGetBasis(opoutputfields[i], &basis);
        CeedChk(ierr);
        ierr = CeedVectorSetArray(impl->evecsout[i], CEED_MEM_HOST,
                                  CEED_USE_POINTER,
                                  &impl->edata[i + numinputfields][e*elemsize*ncomp]);
        ierr = CeedBasisApply(basis, 1, CEED_TRANSPOSE,
                              CEED_EVAL_GRAD, impl->qvecsout[i],
                              impl->evecsout[i]); CeedChk(ierr);
        break;
      case CEED_EVAL_WEIGHT: {
        Ceed ceed;
        ierr = CeedOperatorGetCeed(op, &ceed); CeedChk(ierr);
        return CeedError(ceed, 1,
                         "CEED_EVAL_WEIGHT cannot be an output evaluation mode");
        break; // Should not occur
      }
      case CEED_EVAL_DIV:
        break; // Not implimented
      case CEED_EVAL_CURL:
        break; // Not implimented
      }
    }
  }

  // Zero lvecs
  for (CeedInt i=0; i<numoutputfields; i++) {
    ierr = CeedOperatorFieldGetVector(opoutputfields[i], &vec); CeedChk(ierr);
    if (vec == CEED_VECTOR_ACTIVE)
      vec = outvec;
    ierr = CeedVectorSetValue(vec, 0.0); CeedChk(ierr);
  }

  // Output restriction
  for (CeedInt i=0; i<numoutputfields; i++) {
    // Restore evec
    ierr = CeedVectorRestoreArray(impl->evecs[i+impl->numein],
                                  &impl->edata[i + numinputfields]);
    CeedChk(ierr);
    // Get output vector
    ierr = CeedOperatorFieldGetVector(opoutputfields[i], &vec); CeedChk(ierr);
    // Active
    if (vec == CEED_VECTOR_ACTIVE)
      vec = outvec;
    // Restrict
    ierr = CeedOperatorFieldGetElemRestriction(opoutputfields[i], &Erestrict);
    CeedChk(ierr);
    ierr = CeedOperatorFieldGetLMode(opoutputfields[i], &lmode); CeedChk(ierr);
    ierr = CeedElemRestrictionApply(Erestrict, CEED_TRANSPOSE,
                                    lmode, impl->evecs[i+impl->numein], vec,
                                    request); CeedChk(ierr);
  }

  // Restore input arrays
  for (CeedInt i=0; i<numinputfields; i++) {
    ierr = CeedQFunctionFieldGetEvalMode(qfinputfields[i], &emode);
    CeedChk(ierr);
    if (emode == CEED_EVAL_WEIGHT) { // Skip
    } else {
      ierr = CeedVectorRestoreArrayRead(impl->evecs[i],
                                        (const CeedScalar **) &impl->edata[i]);
      CeedChk(ierr);
    }
  }

  return 0;
}

int CeedOperatorCreate_Ref(CeedOperator op) {
  int ierr;
  Ceed ceed;
  ierr = CeedOperatorGetCeed(op, &ceed); CeedChk(ierr);
  CeedOperator_Ref *impl;

  ierr = CeedCalloc(1, &impl); CeedChk(ierr);
  ierr = CeedOperatorSetData(op, (void*)&impl);

  ierr = CeedSetBackendFunction(ceed, "Operator", op, "Apply",
                                CeedOperatorApply_Ref); CeedChk(ierr);
  ierr = CeedSetBackendFunction(ceed, "Operator", op, "Destroy",
                                CeedOperatorDestroy_Ref); CeedChk(ierr);
  return 0;
}