#! /usr/bin/env python

# Copyright (C) 2016 Christopher M. Biwer
#
# 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.

import argparse
import h5py
import logging
import matplotlib as mpl; mpl.use("Agg")
import matplotlib.pyplot as plt
import numpy
import sys
import corner
from pycbc import pnutils, results
from pycbc.inference import option_utils

# command line usage
parser = argparse.ArgumentParser(
    description="Plots corner plot of posteriors from inference sampler.")
# verbose option
parser.add_argument("--verbose", action="store_true", default=False,
    help="Print logging info.")
# output plot options
parser.add_argument("--output-file", type=str, required=True,
    help="Path to output plot.")
parser.add_argument("--quantiles", type=float, nargs="+",
    default=[0.16, 0.5, 0.84],
    help="Quantiles to plot on 1-D histograms.")
parser.add_argument("--show-titles", action="store_true", default=True,
    help="Display median and lower and maximal quantiles as error bounds.")
# add results group
option_utils.add_inference_results_option_group(parser)

# parse the command line
opts = parser.parse_args()

# setup log
if opts.verbose:
    log_level = logging.DEBUG
else:
    log_level = logging.WARN
logging.basicConfig(format="%(asctime)s : %(message)s", level=log_level)

# load the results
fp, parameters, labels, samples = option_utils.results_from_cli(opts,
    load_samples=True, walkers=None)

# convert the samples to a 2D array
x = numpy.zeros((samples.size, len(parameters)))
for ii,p in enumerate(parameters):
    x[:,ii] = samples[p]

# plot posterior
logging.info("Plot posteriors")
fig = corner.corner(x, labels=labels, quantiles=opts.quantiles, color='navy',
                   show_titles=opts.show_titles)

# if there is only one histogram then change some formatting
if len(parameters) == 1:

    # make plot larger
    fig.set_size_inches(8, 6)

    # get max and min values in order to expand plot to show all values
    xmin = x.min()
    xmax = x.max()

    # determine width of each bin the histogram
    axs = fig.axes[0]
    poly_xy = axs.patches[0].get_xy()
    step = poly_xy[2][0] - poly_xy[0][0]

    # remove whitespace that corner.corner creates
    fig.subplots_adjust(left=0.125, bottom=0.2, right=0.9, top=0.9,
                        wspace=0.2, hspace=0.2)
    fig.axes[0].xaxis.set_label_coords(0.5, -0.2)

    # set new x-axis limits
    fig.axes[0].set_xlim(xmin - step, xmax + step)

    # make 10 tick marks on the boundaries of bins from the histogram
    fig.axes[0].set_xticks(numpy.arange(xmin - step, xmax+2*step, (xmax-xmin)/step/10*step))

# save figure with meta-data
caption_kwargs = {
    "quantiles" : ", ".join(map(str, opts.quantiles)),
    "thin_start" : opts.thin_start,
    "thin_interval" : opts.thin_interval,
    "niterations" : len(x[0]),
}
caption = """Posterior distributions for waveform parameters. The dashed
vertical lines correspond to the {quantiles} quantiles. The thinning used to
make this plot took samples beginning at the {thin_start} and then every
{thin_interval}-th sample after that. Each chain of samples had {niterations}
iterations.""".format(**caption_kwargs)
if len(parameters) == 1:
    title = "Posterior Distribution for %s" % labels[0]
else:
    title = "Posterior Distributions"
results.save_fig_with_metadata(fig, opts.output_file,
                               cmd=" ".join(sys.argv),
                               title=title,
                               caption=caption)
plt.close()

# exit
fp.close()
logging.info("Done")