###############################################################################
# This file is part of SWIFT.
# Copyright (c) 2016 Stefan Arridge (stefan.arridge@durham.ac.uk)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
##############################################################################

import numpy as np
import h5py as h5
import matplotlib

matplotlib.use("Agg")
from pylab import *
import sys


def do_binning(x, y, x_bin_edges):

    # x and y are arrays, where y = f(x)
    # returns number of elements of x in each bin, and the total of the y elements corresponding to those x values

    n_bins = x_bin_edges.size - 1
    count = np.zeros(n_bins)
    y_totals = np.zeros(n_bins)

    for i in range(n_bins):
        ind = np.intersect1d(
            np.where(x > bin_edges[i])[0], np.where(x <= bin_edges[i + 1])[0]
        )
        count[i] = ind.size
        binned_y = y[ind]
        y_totals[i] = np.sum(binned_y)

    return (count, y_totals)


# for the plotting
max_r = float(sys.argv[1])
n_radial_bins = int(sys.argv[2])
n_snaps = int(sys.argv[3])

# some constants
OMEGA = 0.3  # Cosmological matter fraction at z = 0
PARSEC_IN_CGS = 3.0856776e18
KM_PER_SEC_IN_CGS = 1.0e5
CONST_G_CGS = 6.672e-8
CONST_m_H_CGS = 1.67e-24
h = 0.67777  # hubble parameter
gamma = 5.0 / 3.0
eta = 1.2349
H_0_cgs = 100.0 * h * KM_PER_SEC_IN_CGS / (1.0e6 * PARSEC_IN_CGS)

# read some header/parameter information from the first snapshot

filename = "Hydrostatic_0000.hdf5"
f = h5.File(filename, "r")
params = f["Parameters"]
unit_mass_cgs = float(params.attrs["InternalUnitSystem:UnitMass_in_cgs"])
unit_length_cgs = float(params.attrs["InternalUnitSystem:UnitLength_in_cgs"])
unit_velocity_cgs = float(params.attrs["InternalUnitSystem:UnitVelocity_in_cgs"])
unit_time_cgs = unit_length_cgs / unit_velocity_cgs
v_c = float(params.attrs["IsothermalPotential:vrot"])
v_c_cgs = v_c * unit_velocity_cgs
header = f["Header"]
N = header.attrs["NumPart_Total"][0]
box_centre = np.array(header.attrs["BoxSize"])

# calculate r_vir and M_vir from v_c
r_vir_cgs = v_c_cgs / (10.0 * H_0_cgs * np.sqrt(OMEGA))
M_vir_cgs = r_vir_cgs * v_c_cgs ** 2 / CONST_G_CGS

for i in range(n_snaps):

    filename = "Hydrostatic_%04d.hdf5" % i
    f = h5.File(filename, "r")
    coords_dset = f["PartType0/Coordinates"]
    coords = np.array(coords_dset)

    # translate coords by centre of box
    header = f["Header"]
    snap_time = header.attrs["Time"]
    snap_time_cgs = snap_time * unit_time_cgs
    coords[:, 0] -= box_centre[0] / 2.0
    coords[:, 1] -= box_centre[1] / 2.0
    coords[:, 2] -= box_centre[2] / 2.0
    radius = np.sqrt(coords[:, 0] ** 2 + coords[:, 1] ** 2 + coords[:, 2] ** 2)
    radius_cgs = radius * unit_length_cgs
    radius_over_virial_radius = radius_cgs / r_vir_cgs

    # get the internal energies
    u_dset = f["PartType0/InternalEnergy"]
    u = np.array(u_dset)

    # make dimensionless
    u /= v_c ** 2 / (2.0 * (gamma - 1.0))
    r = radius_over_virial_radius

    bin_edges = np.linspace(0, max_r, n_radial_bins + 1)
    (hist, u_totals) = do_binning(r, u, bin_edges)

    bin_widths = bin_edges[1] - bin_edges[0]
    radial_bin_mids = np.linspace(
        bin_widths / 2.0, max_r - bin_widths / 2.0, n_radial_bins
    )
    binned_u = u_totals / hist

    figure()
    plot(radial_bin_mids, binned_u, "ko", label="Numerical solution")
    legend(loc="lower right")
    xlabel(r"$r / r_{vir}$")
    ylabel(r"$u / (v_c^2 / (2(\gamma - 1)) $")
    title(
        r"$\mathrm{Time}= %.3g \, s \, , \, %d \, \, \mathrm{particles} \,,\, v_c = %.1f \, \mathrm{km / s}$"
        % (snap_time_cgs, N, v_c)
    )
    ylim((0, 2))
    plot_filename = "./plots/internal_energy/internal_energy_profile_%03d.png" % i
    savefig(plot_filename, format="png")
    close()