#!/usr/bin/env python

##
 # -*-Pyth-*-
 # ###################################################################
 #  FiPy - Python-based finite volume PDE solver
 #
 #  FILE: "pysparseSolver.py"
 #
 #  Author: Jonathan Guyer <guyer@nist.gov>
 #  Author: Daniel Wheeler <daniel.wheeler@nist.gov>
 #  Author: James Warren   <jwarren@nist.gov>
 #    mail: NIST
 #     www: http://www.ctcms.nist.gov/fipy/
 #
 # ========================================================================
 # This software was developed at the National Institute of Standards
 # of Standards and Technology, an agency of the Federal Government.
 # Pursuant to title 17 section 105 of the United States Code,
 # United States Code this software is not subject to copyright
 # protection, and this software is considered to be in the public domain.
 # FiPy is an experimental system.
 # NIST assumes no responsibility whatsoever for its use by whatsoever for its use by
 # other parties, and makes no guarantees, expressed or implied, about
 # its quality, reliability, or any other characteristic.  We would
 # appreciate acknowledgement if the software is used.
 #
 # To the extent that NIST may hold copyright in countries other than the
 # United States, you are hereby granted the non-exclusive irrevocable and
 # unconditional right to print, publish, prepare derivative works and
 # distribute this software, in any medium, or authorize others to do so on
 # your behalf, on a royalty-free basis throughout the world.
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 # You may improve, modify, and create derivative works of the software or
 # any portion of the software, and you may copy and distribute such
 # modifications or works.  Modified works should carry a notice stating
 # that you changed the software and should note the date and nature of any
 # such change.  Please explicitly acknowledge the National Institute of
 # Standards and Technology as the original source.
 #
 # This software can be redistributed and/or modified freely provided that
 # any derivative works bear some notice that they are derived from it, and
 # any modified versions bear some notice that they have been modified.
 # ========================================================================
 #
 # ###################################################################
 ##

__docformat__ = 'restructuredtext'

import os
from fipy.solvers.pysparseMatrixSolver import _PysparseMatrixSolver

__all__ = ["PysparseSolver"]

class PysparseSolver(_PysparseMatrixSolver):
    """
    The base `pysparseSolver` class.

    .. attention:: This class is abstract. Always create one of its subclasses.
    """
    def __init__(self, *args, **kwargs):
        if self.__class__ is PysparseSolver:
            raise NotImplementedError, \
                  "can't instantiate abstract base class"

        super(PysparseSolver, self).__init__(*args, **kwargs)

    def _solve_(self, L, x, b):
        """
        `_solve_` is only for use by solvers which may use
        preconditioning. If you are writing a solver which
        doesn't use preconditioning, this must be overridden.

        :Parameters:
            - `L`: a `fipy.matrices.pysparseMatrix._PysparseMeshMatrix`.
            - `x`: a `numpy.ndarray`.
            - `b`: a `numpy.ndarray`.
        """

        A = L.matrix

        if self.preconditioner is None:
            P = None
        else:
            P, A = self.preconditioner._applyToMatrix(A)

        info, iter, relres = self.solveFnc(A, b, x, self.tolerance,
                                           self.iterations, P)

        self._raiseWarning(info, iter, relres)

        if 'FIPY_VERBOSE_SOLVER' in os.environ:
            from fipy.tools.debug import PRINT
            PRINT('iterations: %d / %d' % (iter, self.iterations))

            if info < 0:
                PRINT('failure', self._warningList[info].__class__.__name__)
            PRINT('relres:', relres)

    def _solve(self):

        if self.var.mesh.communicator.Nproc > 1:
            raise Exception("PySparse solvers cannot be used with multiple processors")

        array = self.var.numericValue.ravel()

        from fipy.terms import SolutionVariableNumberError

        if ((self.matrix == 0)
            or (self.matrix.matrix.shape[0] != self.matrix.matrix.shape[1])
            or (self.matrix.matrix.shape[0] != len(array))):

            raise SolutionVariableNumberError

        self._solve_(self.matrix, array, self.RHSvector)
        factor = self.var.unit.factor
        if factor != 1:
            array /= self.var.unit.factor

        self.var[:] = array.reshape(self.var.shape)
