#!/usr/bin/env python
# Copyright (c) 2019, Anthony Latorre <tlatorre at uchicago>
#
# 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, see <https://www.gnu.org/licenses/>.

from __future__ import print_function, division
import yaml
try:
    from yaml import CLoader as Loader
except ImportError:
    from yaml.loader import SafeLoader as Loader
import numpy as np
from scipy.stats import iqr
from matplotlib.lines import Line2D

# from https://stackoverflow.com/questions/287871/how-to-print-colored-text-in-terminal-in-python
class bcolors:
    HEADER = '\033[95m'
    OKBLUE = '\033[94m'
    OKGREEN = '\033[92m'
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'
    BOLD = '\033[1m'
    UNDERLINE = '\033[4m'

# on retina screens, the default plots are way too small
# by using Qt5 and setting QT_AUTO_SCREEN_SCALE_FACTOR=1
# Qt5 will scale everything using the dpi in ~/.Xresources
import matplotlib
matplotlib.use("Qt5Agg")

SNOMAN_MASS = {
    20: 0.511,
    21: 0.511,
    22: 105.658,
    23: 105.658
}

AV_RADIUS = 600.0

# Data cleaning bitmasks.
DC_MUON           = 0x1
DC_JUNK           = 0x2
DC_CRATE_ISOTROPY = 0x4
DC_QVNHIT         = 0x8
DC_NECK           = 0x10
DC_FLASHER        = 0x20
DC_ESUM           = 0x40
DC_OWL            = 0x80
DC_OWL_TRIGGER    = 0x100
DC_FTS            = 0x200

def plot_hist(df, title=None):
    for id, df_id in sorted(df.groupby('id')):
        if id == 20:
            plt.subplot(3,4,1)
        elif id == 22:
            plt.subplot(3,4,2)
        elif id == 2020:
            plt.subplot(3,4,5)
        elif id == 2022:
            plt.subplot(3,4,6)
        elif id == 2222:
            plt.subplot(3,4,7)
        elif id == 202020:
            plt.subplot(3,4,9)
        elif id == 202022:
            plt.subplot(3,4,10)
        elif id == 202222:
            plt.subplot(3,4,11)
        elif id == 222222:
            plt.subplot(3,4,12)

        plt.hist(df_id.ke.values, bins=np.linspace(20,10e3,100), histtype='step')
        plt.xlabel("Energy (MeV)")
        plt.title(str(id))

    if title:
        plt.suptitle(title)

    if len(df):
        plt.tight_layout()

def chunks(l, n):
    """Yield successive n-sized chunks from l."""
    for i in range(0, len(l), n):
        yield l[i:i + n]

def print_warning(msg):
    print(bcolors.FAIL + msg + bcolors.ENDC,file=sys.stderr)

if __name__ == '__main__':
    import argparse
    import matplotlib.pyplot as plt
    import numpy as np
    import pandas as pd
    import sys

    parser = argparse.ArgumentParser("plot fit results")
    parser.add_argument("filenames", nargs='+', help="input files")
    args = parser.parse_args()

    events = []
    fit_results = []

    for filename in args.filenames:
        print(filename)
        with open(filename) as f:
            data = yaml.load(f,Loader=Loader)

        for i, event in enumerate(data['data']):
            for ev in event['ev']:
                events.append((
                    ev['run'],
                    ev['gtr'],
                    ev['nhit'],
                    ev['gtid'],
                    ev['dc'],
                    ev['ftp']['x'] if 'ftp' in ev else np.nan,
                    ev['ftp']['y'] if 'ftp' in ev else np.nan,
                    ev['ftp']['z'] if 'ftp' in ev else np.nan,
                    ev['rsp']['energy'] if 'rsp' in ev and ev['rsp']['energy'] > 0 else np.nan,
                    ))

                if 'fit' not in ev:
                    continue

                for id, fit_result in [x for x in ev['fit'].iteritems() if isinstance(x[0],int)]:
                    # FIXME: Should I just store the particle ids in the YAML
                    # output as a list of particle ids instead of a single
                    # integer?
                    ids = map(int,chunks(str(id),2))
                    energy = 0.0
                    skip = False
                    for i, ke in zip(ids,np.atleast_1d(fit_result['energy'])):
                        energy += ke + SNOMAN_MASS[i]

                        # This is a bit of a hack. It appears that many times
                        # the fit will actually do much better by including a
                        # very low energy electron or muon. I believe the
                        # reason for this is that of course my likelihood
                        # function is not perfect (for example, I don't include
                        # the correct angular distribution for Rayleigh
                        # scattered light), and so the fitter often wants to
                        # add a very low energy electron or muon to fix things.
                        #
                        # Ideally I would fix the likelihood function, but for
                        # now we just discard any fit results which have a very
                        # low energy electron or muon.
                        if len(ids) > 1 and i == 20 and ke < 20.0:
                            skip = True

                        if len(ids) > 1 and i == 22 and ke < 200.0:
                            skip = True

                    if skip:
                        continue

                    # Calculate the approximate Ockham factor.
                    # See Chapter 20 in "Probability Theory: The Logic of Science" by Jaynes
                    #
                    # Note: This is a really approximate form by assuming that
                    # the shape of the likelihood space is equal to the average
                    # uncertainty in the different parameters.
                    w = len(ids)*np.log(0.1*0.001) + np.sum(np.log(fit_result['energy'])) + len(ids)*np.log(1e-4/(4*np.pi))

                    fit_results.append((
                        ev['run'],
                        ev['gtid'],
                        id,
                        fit_result['posx'],
                        fit_result['posy'],
                        fit_result['posz'],
                        fit_result['t0'],
                        energy,
                        np.atleast_1d(fit_result['theta'])[0],
                        np.atleast_1d(fit_result['phi'])[0],
                        fit_result['fmin'] - w,
                        fit_result['psi']/ev['nhit']))

    # create a dataframe
    # note: we have to first create a numpy structured array since there is no
    # way to pass a list of data types to the DataFrame constructor. See
    # https://github.com/pandas-dev/pandas/issues/4464
    array = np.array(fit_results,
                     dtype=[('run',np.int),      # run number
                            ('gtid',np.int),     # gtid
                            ('id',np.int),       # particle id
                            ('x', np.double),    # x
                            ('y',np.double),     # y
                            ('z',np.double),     # z
                            ('t0',np.double),    # t0
                            ('ke',np.double),    # kinetic energy
                            ('theta',np.double), # direction of 1st particle
                            ('phi',np.double),   # direction of 2nd particle
                            ('fmin',np.double),  # negative log likelihood
                            ('psi',np.double)]   # goodness of fit parameter
                   )
    df = pd.DataFrame.from_records(array)

    array = np.array(events,
                     dtype=[('run',np.int),           # run number
                            ('gtr',np.double),        # 50 MHz clock in ns
                            ('nhit',np.int),          # number of PMTs hit
                            ('gtid',np.int),          # gtid
                            ('dc',np.int),            # data cleaning word
                            ('ftpx',np.double),       # FTP fitter X position
                            ('ftpy',np.double),       # FTP fitter Y position
                            ('ftpz',np.double),       # FTP fitter Z position
                            ('rsp_energy',np.double)] # RSP energy
                   )
    df_ev = pd.DataFrame.from_records(array)

    # Make sure events are in order. We use run number and GTID here which
    # should be in time order as well except for bit flips in the GTID
    # This is important for later when we look at time differences in the 50
    # MHz clock. We should perhaps do a check here based on the 10 MHz clock to
    # make sure things are in order
    df_ev = df_ev.sort_values(by=['run','gtid'])

    print("number of events = %i" % len(df_ev))

    # First, do basic data cleaning which is done for all events.
    df_ev = df_ev[df_ev.dc & (DC_JUNK | DC_CRATE_ISOTROPY | DC_QVNHIT | DC_FLASHER | DC_NECK) == 0]

    print("number of events after data cleaning = %i" % len(df_ev))

    # Now, we select events tagged by the muon tag which should tag only
    # external muons. We keep the sample of muons since it's needed later to
    # identify Michel electrons and to apply the muon follower cut
    muons = df_ev[(df_ev.dc & DC_MUON) != 0]

    print("number of muons = %i" % len(muons))

    # Now, select prompt events.
    #
    # We define a prompt event here as any event with an NHIT > 100 and whose
    # previous > 100 nhit event was more than 250 ms ago
    #
    # Should I use 10 MHz clock here since the time isn't critical and then I
    # don't have to worry about 50 MHz clock rollover?
    prompt = df_ev[df_ev.nhit >= 100]
    prompt_mask = np.concatenate(([True],np.diff(prompt.gtr.values) > 250e6))

    # Michel electrons and neutrons can be any event which is not a prompt
    # event
    follower = pd.concat([df_ev[df_ev.nhit < 100],prompt[~prompt_mask]])

    # Apply the prompt mask
    prompt = prompt[prompt_mask]

    # Try to identify Michel electrons. Currenly, the event selection is based
    # on Richie's thesis. Here, we do the following:
    #
    # 1. Apply more data cleaning cuts to potential Michel electrons
    # 2. Nhit >= 100
    # 3. It must be > 800 ns and less than 20 microseconds from a prompt event
    #    or a muon
    prompt_plus_muons = pd.concat([prompt,muons])

    print("number of events after prompt nhit cut = %i" % len(prompt))

    if prompt_plus_muons.size and follower.size:
        # require Michel events to pass more of the SNO data cleaning cuts
        michel = follower[follower.dc & (DC_JUNK | DC_CRATE_ISOTROPY | DC_QVNHIT | DC_FLASHER | DC_NECK | DC_ESUM | DC_OWL | DC_OWL_TRIGGER | DC_FTS) == DC_FTS]
        michel = michel[michel.nhit >= 100]
        # accept events which had a muon more than 800 nanoseconds but less than 20 microseconds before them
        # The 800 nanoseconds cut comes from Richie's thesis. He also mentions
        # that the In Time Channel Spread Cut is very effective at cutting
        # electrons events caused by muons, so I should implement that
        michel = michel[np.any((michel.run.values == prompt_plus_muons.run.values[:,np.newaxis]) & \
                               (michel.gtr.values > prompt_plus_muons.gtr.values[:,np.newaxis] + 800) & \
                               (michel.gtr.values < prompt_plus_muons.gtr.values[:,np.newaxis] + 20e3),axis=0)]
    else:
        michel = pd.DataFrame(columns=follower.columns)

    if prompt.size and follower.size:
        # neutron followers have to obey stricter set of data cleaning cuts
        neutron = follower[follower.dc & (DC_JUNK | DC_CRATE_ISOTROPY | DC_QVNHIT | DC_FLASHER | DC_NECK | DC_ESUM | DC_OWL | DC_OWL_TRIGGER | DC_FTS) == DC_FTS]
        neutron = neutron[~np.isnan(neutron.ftpx) & ~np.isnan(neutron.rsp_energy)]
        r = np.sqrt(neutron.ftpx**2 + neutron.ftpy**2 + neutron.ftpz**2)
        neutron = neutron[r < AV_RADIUS]
        neutron = neutron[neutron.rsp_energy > 4.0]
        # neutron events accepted after 20 microseconds and before 250 ms (50 ms during salt)
        # FIXME: need to deal with 50 MHz clock rollover
        neutron_mask = np.any((neutron.run.values == prompt.run.values[:,np.newaxis]) & \
                              (neutron.gtr.values > prompt.gtr.values[:,np.newaxis] + 20e3) & \
                              (neutron.gtr.values < prompt.gtr.values[:,np.newaxis] + 250e6),axis=1)
        df_atm = prompt[neutron_mask]
        prompt = prompt[~neutron_mask]
    else:
        df_atm = pd.DataFrame(columns=prompt.columns)

    print("number of events after neutron follower cut = %i" % len(prompt))

    # Get rid of muon events in our main event sample
    prompt = prompt[(prompt.dc & DC_MUON) == 0]
    df_atm = df_atm[(df_atm.dc & DC_MUON) == 0]

    print("number of events after muon cut = %i" % len(prompt))

    if muons.size:
        # FIXME: need to deal with 50 MHz clock rollover
        # remove events 200 microseconds after a muon
        prompt = prompt[~np.any((prompt.run.values == muons.run.values[:,np.newaxis]) & \
                                (prompt.gtr.values > muons.gtr.values[:,np.newaxis]) & \
                                (prompt.gtr.values <= (muons.gtr.values[:,np.newaxis] + 200e3)),axis=0)]
        df_atm = df_atm[~np.any((df_atm.run.values == muons.run.values[:,np.newaxis]) & \
                                (df_atm.gtr.values > muons.gtr.values[:,np.newaxis]) & \
                                (df_atm.gtr.values <= (muons.gtr.values[:,np.newaxis] + 200e3)),axis=0)]

    # Check to see if there are any events with missing fit information
    df_atm_ra = df_atm[['run','gtid']].to_records(index=False)
    muons_ra = muons[['run','gtid']].to_records(index=False)
    prompt_ra = prompt[['run','gtid']].to_records(index=False)
    michel_ra = michel[['run','gtid']].to_records(index=False)
    df_ra = df[['run','gtid']].to_records(index=False)

    if np.count_nonzero(~np.isin(df_atm_ra,df_ra)):
        print_warning("skipping %i atmospheric events because they are missing fit information!" % np.count_nonzero(~np.isin(df_atm_ra,df_ra)))

    if np.count_nonzero(~np.isin(muons_ra,df_ra)):
        print_warning("skipping %i muon events because they are missing fit information!" % np.count_nonzero(~np.isin(muons_ra,df_ra)))

    if np.count_nonzero(~np.isin(prompt_ra,df_ra)):
        print_warning("skipping %i signal events because they are missing fit information!" % np.count_nonzero(~np.isin(prompt_ra,df_ra)))

    if np.count_nonzero(~np.isin(michel_ra,df_ra)):
        print_warning("skipping %i Michel events because they are missing fit information!" % np.count_nonzero(~np.isin(michel_ra,df_ra)))

    # Now, we merge the event info with the fitter info.
    #
    # Note: This means that the dataframe now contains multiple rows for each
    # event, one for each fit hypothesis.
    df_atm = pd.merge(df,df_atm,how='inner',on=['run','gtid'])
    muons = pd.merge(df,muons,how='inner',on=['run','gtid'])
    michel = pd.merge(df,michel,how='inner',on=['run','gtid'])
    df = pd.merge(df,prompt,how='inner',on=['run','gtid'])

    # get rid of events which don't have a fit
    nan = np.isnan(df.fmin.values)

    if np.count_nonzero(nan):
        print_warning("skipping %i signal events because the negative log likelihood is nan!" % len(df[nan].groupby(['run','gtid'])))

    df = df[~nan]

    nan_atm = np.isnan(df_atm.fmin.values)

    if np.count_nonzero(nan_atm):
        print_warning("skipping %i atmospheric events because the negative log likelihood is nan!" % len(df_atm[nan_atm].groupby(['run','gtid'])))

    df_atm = df_atm[~nan_atm]

    nan_muon = np.isnan(muons.fmin.values)

    if np.count_nonzero(nan_muon):
        print_warning("skipping %i muons because the negative log likelihood is nan!" % len(muons[nan_muon].groupby(['run','gtid'])))

    muons = muons[~nan_muon]

    nan_michel = np.isnan(michel.fmin.values)

    if np.count_nonzero(nan_michel):
        print_warning("skipping %i michel electron events because the negative log likelihood is nan!" % len(michel[nan_michel].groupby(['run','gtid'])))

    michel = michel[~nan_michel]

    # get the best fit
    df = df.sort_values('fmin').groupby(['run','gtid']).first()
    df_atm = df_atm.sort_values('fmin').groupby(['run','gtid']).first()
    michel_best_fit = michel.sort_values('fmin').groupby(['run','gtid']).first()
    muon_best_fit = muons.sort_values('fmin').groupby(['run','gtid']).first()
    muons = muons[muons.id == 22]

    # require r < 6 meters
    df = df[np.sqrt(df.x.values**2 + df.y.values**2 + df.z.values**2) < AV_RADIUS]
    df_atm = df_atm[np.sqrt(df_atm.x.values**2 + df_atm.y.values**2 + df_atm.z.values**2) < AV_RADIUS]

    print("number of events after radius cut = %i" % len(df))

    # Note: Need to design and apply a psi based cut here

    plt.figure()
    plot_hist(df,"Without Neutron Follower")
    plt.figure()
    plot_hist(df_atm,"With Neutron Follower")
    plt.figure()
    plot_hist(michel_best_fit,"Michel Electrons")
    plt.figure()
    plot_hist(muon_best_fit,"External Muons")

    # Plot the energy and angular distribution for external muons
    plt.figure()
    plt.subplot(2,1,1)
    plt.hist(muons.ke.values, bins=np.logspace(3,7,100), histtype='step')
    plt.xlabel("Energy (MeV)")
    plt.gca().set_xscale("log")
    plt.subplot(2,1,2)
    plt.hist(np.cos(muons.theta.values), bins=np.linspace(-1,1,100), histtype='step')
    plt.xlabel(r"$\cos(\theta)$")
    plt.suptitle("Muons")

    # For the Michel energy plot, we only look at the single particle electron
    # fit
    michel = michel[michel.id == 20]

    plt.figure()
    plt.hist(michel.ke.values, bins=np.linspace(20,100,100), histtype='step', label="My fitter")
    if michel.size:
        plt.hist(michel[~np.isnan(michel.rsp_energy.values)].rsp_energy.values, bins=np.linspace(20,100,100), histtype='step',label="RSP")
    plt.xlabel("Energy (MeV)")
    plt.title("Michel Electrons")
    plt.legend()
    plt.show()