# Copyright (C) 2022 Richard Stiskalek
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU 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 General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
"""
MPI script to calculate density field-derived fields in the CSiBORG
simulations' final snapshot.
"""
from argparse import ArgumentParser
from datetime import datetime
from distutils.util import strtobool

import numpy
from mpi4py import MPI

try:
    import csiborgtools
except ModuleNotFoundError:
    import sys
    sys.path.append("../")
    import csiborgtools

comm = MPI.COMM_WORLD
rank = comm.Get_rank()
nproc = comm.Get_size()
verbose = nproc == 1

parser = ArgumentParser()
parser.add_argument("--ics", type=int, nargs="+", default=None,
                    help="IC realisations. If `-1` processes all simulations.")
parser.add_argument("--kind", type=str, choices=["potential", "velocity"],
                    help="What derived field to calculate?")
parser.add_argument("--MAS", type=str, choices=["NGP", "CIC", "TSC", "PCS"])
parser.add_argument("--grid", type=int, help="Grid resolution.")
parser.add_argument("--in_rsp", type=lambda x: bool(strtobool(x)),
                    help="Calculate from the RSP density field?")
args = parser.parse_args()
paths = csiborgtools.read.Paths(**csiborgtools.paths_glamdring)

if args.ics is None or args.ics[0] == -1:
    ics = paths.get_ics()
else:
    ics = args.ics


for i in csiborgtools.fits.split_jobs(len(ics), nproc)[rank]:
    nsim = ics[i]
    if verbose:
        print(f"{datetime.now()}: rank {rank} working on simulation {nsim}.",
              flush=True)
    nsnap = max(paths.get_snapshots(nsim))
    box = csiborgtools.read.CSiBORGBox(nsnap, nsim, paths)
    density_gen = csiborgtools.field.DensityField(box, args.MAS)

    rho = numpy.load(paths.field_path("density", args.MAS, args.grid, nsim,
                                      args.in_rsp))
    rho = density_gen.overdensity_field(rho)

    if args.kind == "potential":
        gen = csiborgtools.field.PotentialField(box, args.MAS)
    else:
        raise RuntimeError(f"Field {args.kind} is not implemented yet.")

    field = gen(rho)
    fout = paths.field_path("potential", args.MAS, args.grid, nsim,
                            args.in_rsp)
    print(f"{datetime.now()}: rank {rank} saving output to `{fout}`.")
    numpy.save(fout, field)