from __future__ import division
##############################################################################
#
# Copyright (c) 2003-2018 by The University of Queensland
# http://www.uq.edu.au
#
# Primary Business: Queensland, Australia
# Licensed under the Apache License, version 2.0
# http://www.apache.org/licenses/LICENSE-2.0
#
# Development until 2012 by Earth Systems Science Computational Center (ESSCC)
# Development 2012-2013 by School of Earth Sciences
# Development from 2014 by Centre for Geoscience Computing (GeoComp)
#
##############################################################################

__copyright__="""Copyright (c) 2003-2018 by The University of Queensland
http://www.uq.edu.au
Primary Business: Queensland, Australia"""
__license__="""Licensed under the Apache License, version 2.0
http://www.apache.org/licenses/LICENSE-2.0"""
__url__="https://launchpad.net/escript-finley"

from esys.escript import *
from esys.escript.models import DarcyFlow
try:
    from esys.finley import Rectangle
    HAVE_FINLEY = True
except ImportError:
    HAVE_FINLEY = False
from esys.weipa import saveVTK

if not HAVE_FINLEY:
    print("Finley module not available")
else:
    # generate domain:
    mydomain = Rectangle(l0=2.,l1=1.,n0=40, n1=20)
    # normal flux is given 
    x = mydomain.getX()

    # set location of fixed pressure and flux:
    p_BC=whereZero(x[1]-1.)*wherePositive(x[0]-1.)
    u_BC=(whereZero(x[0])+whereZero(x[0]-2.)) * [1.,0.] + \
         (whereZero(x[1]) + whereZero(x[1]-1.)*whereNonPositive(x[0]-1.0)) * [0., 1.]

    # define darcy flow solver:
    mypde = DarcyFlow(domain=mydomain)

    mypde.setValue(g=[0., 2],
                   location_of_fixed_pressure=p_BC,
                   location_of_fixed_flux=u_BC,
                   permeability=100.)

    u,p=mypde.solve(u0=x[1]*[0., -1.], p0=0)

    # write u to an external file
    saveVTK("u.vtu",flux=u, pressure=p)