from __future__ import print_function, division
import sys, petsc4py
petsc4py.init(sys.argv)
import mpi4py.MPI as mpi
from petsc4py import PETSc
import numpy as np

from elasticity import *

def rhs(coords, rhs):
    x = coords[..., 0]
    mask = x > 9.8
    rhs[mask, 0] = 0
    rhs[mask, 1] = -10

def lame_coeff(x, y, v1, v2):
    output = np.empty(x.shape)
    mask = np.logical_and(.4<=y, y<=.6)
    output[mask] = v1
    output[np.logical_not(mask)] = v2
    return output

OptDB = PETSc.Options()
Lx = OptDB.getInt('Lx', 10)
Ly = OptDB.getInt('Ly', 1)
n  = OptDB.getInt('n', 16)
nx = OptDB.getInt('nx', Lx*n)
ny = OptDB.getInt('ny', Ly*n)
hx = Lx/(nx - 1)
hy = Ly/(ny - 1)

da = PETSc.DMDA().create([nx, ny], dof=2, stencil_width=1)
da.setUniformCoordinates(xmax=Lx, ymax=Ly)

# non constant young modulus
E = buildCellArrayWithFunction(da, lame_coeff, (100000, 30000))
# non constant Poisson coefficient
nu = buildCellArrayWithFunction(da, lame_coeff, (0.4, 0.4))

lamb = (nu*E)/((1+nu)*(1-2*nu)) 
mu = .5*E/(1+nu)

x = da.createGlobalVec()
b = buildRHS(da, [hx, hy], rhs)
A = buildElasticityMatrix(da, [hx, hy], lamb, mu)
A.assemble()

bcApplyWest(da, A, b)

ksp = PETSc.KSP().create()
ksp.setOperators(A)
ksp.setFromOptions()

ksp.solve(b, x)

viewer = PETSc.Viewer().createVTK('solution2d_nonconst.vts', 'w', comm = PETSc.COMM_WORLD)
x.view(viewer)