#! /usr/bin/env python
# ==========================================================================
# This script shows how to make a spectrum using obsutils.
#
# Copyright (C) 2014-2015 Juergen Knoedlseder
#
# 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 <http://www.gnu.org/licenses/>.
#
# ==========================================================================
#import gammalib
import ctools
import cscripts
try:
    import matplotlib.pyplot as plt
    has_matplotlib = True
except:
    has_matplotlib = False


# =============== #
# Make a spectrum #
# =============== #
def make_spectrum():
    """
    Make a spectrum.
    """
    # Set script parameters
    model_name  = "${CTOOLS}/share/models/crab.xml"
    caldb       = "prod2"
    irf         = "South_50h"
    ra          =   83.63
    dec         =   22.01
    rad_sim     =    3.0
    tstart      =    0.0
    tstop       = 1800.0
    emin        =    0.1
    emax        =  100.0
    enumbins    =     10

    # Simulate events
    sim = ctools.ctobssim()
    sim["inmodel"] = model_name
    sim["caldb"]   = caldb
    sim["irf"]     = irf
    sim["ra"]      = ra
    sim["dec"]     = dec
    sim["rad"]     = rad_sim
    sim["tmin"]    = tstart
    sim["tmax"]    = tstop
    sim["emin"]    = emin
    sim["emax"]    = emax
    sim.run()

    # Generate an energy binning
    #e_min   = gammalib.GEnergy(emin, "TeV")
    #e_max   = gammalib.GEnergy(emax, "TeV")
    #ebounds = gammalib.GEbounds(10, e_min, e_max)

    # Setup csspec run
    spec = cscripts.csspec(sim.obs())
    spec["srcname"]  = "Crab"
    spec["outfile"]  = "spectrum.fits"
    spec["expcube"]  = "NONE"
    spec["psfcube"]  = "NONE"
    spec["bkgcube"]  = "NONE"
    spec["edisp"]    = False
    spec["emin"]     = emin
    spec["emax"]     = emax
    spec["enumbins"] = enumbins
    spec["binned"]   = False
    spec.run()

    # Get copy of spectrum
    spectrum = spec.spectrum().copy()

    # Return
    return spectrum


# ============= #
# Plot spectrum #
# ============= #
def plot_spectrum(spectrum):
    """
    Plot spectrum.
    """
    # Read spectrum file    
    table    = spectrum.table(1)
    c_energy = table["Energy"]
    c_ed     = table["ed_Energy"]
    c_eu     = table["eu_Energy"]
    c_flux   = table["Flux"]
    c_eflux  = table["e_Flux"]
    c_ts     = table["TS"]
    c_upper  = table["UpperLimit"]

    # Initialise arrays to be filled
    energies    = []
    flux        = []
    ed_engs     = []
    eu_engs     = []
    e_flux      = []
    ul_energies = []
    ul_ed_engs  = []
    ul_eu_engs  = []
    ul_flux     = []

    # Loop over rows of the file
    nrows = table.nrows()
    for row in range(nrows):

        # Get TS
        ts    = c_ts.real(row)
        flx   = c_flux.real(row)
        e_flx = c_eflux.real(row)

        # Switch
        if ts > 9.0 and e_flx < flx:

            # Add information
            energies.append(c_energy.real(row))
            flux.append(c_flux.real(row))
            ed_engs.append(c_ed.real(row))
            eu_engs.append(c_eu.real(row))
            e_flux.append(c_eflux.real(row))

        #
        else:

            # Add information
            ul_energies.append(c_energy.real(row))
            ul_flux.append(c_upper.real(row))
            ul_ed_engs.append(c_ed.real(row))
            ul_eu_engs.append(c_eu.real(row))

    # Create figure
    plt.figure()
    plt.title("Crab spectrum")

    # Plot the spectrum 
    plt.loglog()
    plt.grid()
    plt.errorbar(energies, flux, yerr=e_flux, xerr=[ed_engs, eu_engs], fmt='ro')
    plt.errorbar(ul_energies, ul_flux, xerr=[ul_ed_engs, ul_eu_engs], yerr=1.0e-11, uplims=True, fmt='ro')
    plt.xlabel("Energy (TeV)")
    plt.ylabel(r"dN/dE (erg cm$^{-2}$ s$^{-1}$)")    

    # Show spectrum
    plt.show()

    # Return
    return


#==========================#
# Main routine entry point #
#==========================#
if __name__ == '__main__':
    """
    Generate a Crab spectrum.
    """
    # Generate spectrum
    spectrum = make_spectrum()

    # Plot spectrum
    if has_matplotlib:
        plot_spectrum(spectrum)