###############################################################################
# This file is part of SWIFT.
# Copyright (c) 2016 Matthieu Schaller (schaller@strw.leidenuniv.nl)
#
# 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 h5py
from numpy import *

# Generates a swift IC file for the 1D Noh problem test in a periodic box

# Parameters
numPart = 1001
gamma = 5.0 / 3.0  # Gas adiabatic index
rho0 = 1.0  # Background density
P0 = 1.0e-6  # Background pressure
fileName = "noh.hdf5"

# ---------------------------------------------------
coords = zeros((numPart, 3))
h = zeros(numPart)
vol = 2.0

for i in range(numPart):
    coords[i, 0] = i * vol / numPart + vol / (2.0 * numPart)
    h[i] = 1.2348 * vol / numPart

# Generate extra arrays
v = zeros((numPart, 3))
ids = linspace(1, numPart, numPart)
m = zeros(numPart)
u = zeros(numPart)

m[:] = rho0 * vol / numPart
u[:] = P0 / (rho0 * (gamma - 1))
v[coords[:, 0] < vol / 2.0, 0] = 1
v[coords[:, 0] > vol / 2.0, 0] = -1

# --------------------------------------------------

# File
file = h5py.File(fileName, "w")

# Header
grp = file.create_group("/Header")
grp.attrs["BoxSize"] = [vol, vol, vol]
grp.attrs["NumPart_Total"] = [numPart, 0, 0, 0, 0, 0]
grp.attrs["NumPart_Total_HighWord"] = [0, 0, 0, 0, 0, 0]
grp.attrs["NumPart_ThisFile"] = [numPart, 0, 0, 0, 0, 0]
grp.attrs["Time"] = 0.0
grp.attrs["NumFilesPerSnapshot"] = 1
grp.attrs["MassTable"] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
grp.attrs["Flag_Entropy_ICs"] = 0
grp.attrs["Dimension"] = 1

# Units
grp = file.create_group("/Units")
grp.attrs["Unit length in cgs (U_L)"] = 1.0
grp.attrs["Unit mass in cgs (U_M)"] = 1.0
grp.attrs["Unit time in cgs (U_t)"] = 1.0
grp.attrs["Unit current in cgs (U_I)"] = 1.0
grp.attrs["Unit temperature in cgs (U_T)"] = 1.0

# Particle group
grp = file.create_group("/PartType0")
grp.create_dataset("Coordinates", data=coords, dtype="d")
grp.create_dataset("Velocities", data=v, dtype="f")
grp.create_dataset("Masses", data=m, dtype="f")
grp.create_dataset("SmoothingLength", data=h, dtype="f")
grp.create_dataset("InternalEnergy", data=u, dtype="f")
grp.create_dataset("ParticleIDs", data=ids, dtype="L")

file.close()