#!/usr/bin/env python

# Copyright 2019-2021 Yinjian Zhao
#
# This file is part of WarpX.
#
# License: BSD-3-Clause-LBNL

# This script tests the embedded boundary in RZ.
# A cylindrical surface (r=0.1) has a fixed potential 1 V.
# The outer surface has 0 V fixed.
# Thus the analytical solution has the form:
# phi(r) = A+B*log(r), Er(r) = -B/r.

# Possible errors:
# tolerance: 0.004
# Possible running time: < 1 s

import os
import sys

import numpy as np
import yt

sys.path.insert(1, '../../../../warpx/Regression/Checksum/')
import checksumAPI

tolerance = 0.004

fn = sys.argv[1]
ds = yt.load( fn )

all_data_level_0 = ds.covering_grid(level=0,left_edge=ds.domain_left_edge, dims=ds.domain_dimensions)
phi = all_data_level_0['boxlib', 'phi'].v.squeeze()
Er = all_data_level_0['boxlib', 'Ex'].v.squeeze()

Dx = ds.domain_width/ds.domain_dimensions
dr = Dx[0]
rmin = ds.domain_left_edge[0]
rmax = ds.domain_right_edge[0]
nr = phi.shape[0]
r = np.linspace(rmin+dr/2.,rmax-dr/2.,nr)
B = 1.0/np.log(0.1/0.5)
A = -B*np.log(0.5)

err = 0.0
errmax_phi = 0.0
errmax_Er = 0.0
for i in range(len(r)):
    if r[i]>=0.1:
        phi_theory = A+B*np.log(r[i])
        Er_theory = -B/float(r[i])
        err = abs( phi_theory - phi[i,:] ).max() / phi_theory
        if err>errmax_phi:
            errmax_phi = err
        err = abs( Er_theory - Er[i,:] ).max() / Er_theory
        # Exclude the last inaccurate interpolation.
        if err>errmax_Er and i<len(r)-1:
            errmax_Er = err

print('max error of phi = ', errmax_phi)
print('max error of Er = ', errmax_Er)
print('tolerance = ', tolerance)
assert(errmax_phi<tolerance and errmax_Er<tolerance)

test_name = os.path.split(os.getcwd())[1]
checksumAPI.evaluate_checksum(test_name, fn, do_particles=False)