# 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.

from _ceed_cffi import ffi, lib
import tempfile
import numpy as np
from abc import ABC
from .ceed_constants import REQUEST_IMMEDIATE, REQUEST_ORDERED, MEM_HOST, COPY_VALUES, TRANSPOSE, NOTRANSPOSE, INTERLACED, NONINTERLACED
from .ceed_vector import _VectorWrap

# ------------------------------------------------------------------------------
class _ElemRestrictionBase(ABC):
  """Ceed ElemRestriction: restriction from local vectors to elements."""

  # Attributes
  _ceed = ffi.NULL
  _pointer = ffi.NULL

  # Destructor
  def __del__(self):
    # libCEED call
    lib.CeedElemRestrictionDestroy(self._pointer)

  # Representation
  def __repr__(self):
    return "<CeedElemRestriction instance at " + hex(id(self)) + ">"

  # String conversion for print() to stdout
  def __str__(self):
    """View an ElemRestriction via print()."""

    # libCEED call
    with tempfile.NamedTemporaryFile() as key_file:
      with open(key_file.name, 'r+') as stream_file:
        stream = ffi.cast("FILE *", stream_file)

        lib.CeedElemRestrictionView(self._pointer[0], stream)

        stream_file.seek(0)
        out_string = stream_file.read()

    return out_string

  # Apply CeedElemRestriction
  def apply(self, u, v, tmode=NOTRANSPOSE, request=REQUEST_IMMEDIATE):
    """Restrict a local vector to an element vector or apply its transpose.

       Args:
         u: input vector
         v: output vector
         **tmode: apply restriction or transpose, default CEED_NOTRANSPOSE
         **request: Ceed request, default CEED_REQUEST_IMMEDIATE"""

    # libCEED call
    lib.CeedElemRestrictionApply(self._pointer[0], tmode, u._pointer[0],
                                 v._pointer[0], request)

  # Transpose an ElemRestriction
  @property
  def T(self):
    """Transpose an ElemRestriction."""

    return TransposeElemRestriction(self)

  # Transpose an ElemRestriction
  @property
  def transpose(self):
    """Transpose an ElemRestriction."""

    return TransposeElemRestriction(self)

  # Create restriction vectors
  def create_vector(self, createLvec = True, createEvec = True):
    """Create Vectors associated with an ElemRestriction.

       Args:
         **createLvec: flag to create local vector, default True
         **createEvec: flag to create element vector, default True

       Returns:
         [lvec, evec]: local vector and element vector, or None if flag set to false"""

    # Vector pointers
    lvecPointer = ffi.new("CeedVector *") if createLvec else ffi.NULL
    evecPointer = ffi.new("CeedVector *") if createEvec else ffi.NULL

    # libCEED call
    lib.CeedElemRestrictionCreateVector(self._pointer[0], lvecPointer,
                                        evecPointer)

    # Return vectors
    lvec = _VectorWrap(self._ceed._pointer, lvecPointer) if createLvec else None
    evec = _VectorWrap(self._ceed._pointer, evecPointer) if createEvec else None

    # Return
    return [lvec, evec]

  # Get ElemRestriction multiplicity
  def get_multiplicity(self):
    """Get the multiplicity of nodes in an ElemRestriction.

       Returns:
         mult: local vector containing multiplicity of nodes in ElemRestriction"""

    # Create mult vector
    [mult, evec] = self.create_vector(createEvec = False)
    mult.set_value(0)

    # libCEED call
    lib.CeedElemRestrictionGetMultiplicity(self._pointer[0], mult._pointer[0])

    # Return
    return mult

# ------------------------------------------------------------------------------
class ElemRestriction(_ElemRestrictionBase):
  """Ceed ElemRestriction: restriction from local vectors to elements."""

  # Constructor
  def __init__(self, ceed, nelem, elemsize, nnodes, ncomp, indices,
               memtype=MEM_HOST, cmode=COPY_VALUES, imode=NONINTERLACED):
    # CeedVector object
    self._pointer = ffi.new("CeedElemRestriction *")

    # Reference to Ceed
    self._ceed = ceed

    # Setup the numpy array for the libCEED call
    indices_pointer = ffi.new("const CeedInt *")
    indices_pointer = ffi.cast("const CeedInt *",
                               indices.__array_interface__['data'][0])

    # libCEED call
    lib.CeedElemRestrictionCreate(self._ceed._pointer[0], imode, nelem,
                                  elemsize, nnodes, ncomp, memtype, cmode,
                                  indices_pointer, self._pointer)

# ------------------------------------------------------------------------------
class IdentityElemRestriction(_ElemRestrictionBase):
  """Ceed Identity ElemRestriction: identity restriction from local vectors to elements."""

  # Constructor
  def __init__(self, ceed, nelem, elemsize, nnodes, ncomp, imode=NONINTERLACED):
    # CeedVector object
    self._pointer = ffi.new("CeedElemRestriction *")

    # Reference to Ceed
    self._ceed = ceed

    # libCEED call
    lib.CeedElemRestrictionCreateIdentity(self._ceed._pointer[0], imode, nelem,
                                          elemsize, nnodes, ncomp,
                                          self._pointer)

# ------------------------------------------------------------------------------
class BlockedElemRestriction(_ElemRestrictionBase):
  """Ceed Blocked ElemRestriction: blocked restriction from local vectors to elements."""

  # Constructor
  def __init__(self, ceed, nelem, elemsize, blksize, nnodes, ncomp, indices,
               memtype=MEM_HOST, cmode=COPY_VALUES, imode=NONINTERLACED):
    # CeedVector object
    self._pointer = ffi.new("CeedElemRestriction *")

    # Reference to Ceed
    self._ceed = ceed

    # Setup the numpy array for the libCEED call
    indices_pointer = ffi.new("const CeedInt *")
    indices_pointer = ffi.cast("const CeedInt *",
                               indices.__array_interface__['data'][0])

    # libCEED call
    lib.CeedElemRestrictionCreateBlocked(self._ceed._pointer[0], imode, nelem,
                                         elemsize, blksize, nnodes, ncomp,
                                         memtype, cmode, indices_pointer,
                                         self._pointer)

  # Transpose a Blocked ElemRestriction
  @property
  def T(self):
    """Transpose a BlockedElemRestriction."""

    return TransposeBlockedElemRestriction(self)

  # Transpose a Blocked ElemRestriction
  @property
  def transpose(self):
    """Transpose a BlockedElemRestriction."""

    return TransposeBlockedElemRestriction(self)

  # Apply CeedElemRestriction to single block
  def apply_block(self, block, u, v, tmode=NOTRANSPOSE,
                  request=REQUEST_IMMEDIATE):
    """Restrict a local vector to a block of an element vector or apply its transpose.

       Args:
         block: block number to restrict to/from, i.e. block=0 will handle
                  elements [0 : blksize] and block=3 will handle elements
                  [3*blksize : 4*blksize]
         u: input vector
         v: output vector
         **tmode: apply restriction or transpose, default CEED_NOTRANSPOSE
         **request: Ceed request, default CEED_REQUEST_IMMEDIATE"""

    # libCEED call
    lib.CeedElemRestrictionApplyBlock(self._pointer[0], block, tmode,
                                      u._pointer[0], v._pointer[0], request)

# ------------------------------------------------------------------------------
class TransposeElemRestriction():
  """Ceed ElemRestriction: transpose restriction from elements to local vectors."""

  # Attributes
  _elemrestriction = None

  # Constructor
  def __init__(self, elemrestriction):

    # Reference elemrestriction
    self._elemrestriction = elemrestriction

  # Representation
  def __repr__(self):
    return "<Transpose CeedElemRestriction instance at " + hex(id(self)) + ">"


  # Apply Transpose CeedElemRestriction
  def apply(self, u, v, request=REQUEST_IMMEDIATE):
    """Restrict an element vector to a local vector.

       Args:
         u: input vector
         v: output vector
         **request: Ceed request, default CEED_REQUEST_IMMEDIATE"""

    # libCEED call
    self._elemrestriction.apply(u, v, request=request, tmode=TRANSPOSE)

# ------------------------------------------------------------------------------
class TransposeBlockedElemRestriction(TransposeElemRestriction):
  """Transpose Ceed Blocked ElemRestriction: blocked transpose restriction from elements
       to local vectors."""

  # Apply Transpose CeedElemRestriction
  def apply_block(self, block, u, v, request=REQUEST_IMMEDIATE):
    """Restrict a block of an element vector to a local vector.

       Args:
         block: block number to restrict to/from, i.e. block=0 will handle
                  elements [0 : blksize] and block=3 will handle elements
                  [3*blksize : 4*blksize]
         u: input vector
         v: output vector
         **request: Ceed request, default CEED_REQUEST_IMMEDIATE"""

    # libCEED call
    self._elemrestriction.apply_block(block, u, v, request=request,
                                      tmode=TRANSPOSE)

# ------------------------------------------------------------------------------