# Source code for PyMca5.PyMcaPhysics.xrf.IncoherentScattering

    #/*##########################################################################
    #
    # The PyMca X-Ray Fluorescence Toolkit
    #
    # Copyright (c) 2004-2014 European Synchrotron Radiation Facility
    #
    # This file is part of the PyMca X-ray Fluorescence Toolkit developed at
    # the ESRF by the Software group.
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    # Permission is hereby granted, free of charge, to any person obtaining a copy
    # of this software and associated documentation files (the "Software"), to deal
    # in the Software without restriction, including without limitation the rights
    # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    # copies of the Software, and to permit persons to whom the Software is
    # furnished to do so, subject to the following conditions:
    #
    # The above copyright notice and this permission notice shall be included in
    # all copies or substantial portions of the Software.
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    # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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    __author__ = "V.A. Sole - ESRF Data Analysis"
    __contact__ = "sole@esrf.fr"
    __license__ = "MIT"
    __copyright__ = "European Synchrotron Radiation Facility, Grenoble, France"
    import os
    import numpy
    from PyMca5.PyMcaIO import ConfigDict
    from PyMca5 import PyMcaDataDir

    ElementList= ['H','He','Li','Be','B','C','N','O','F','Ne',
                  'Na','Mg','Al','Si','P','S','Cl','Ar','K','Ca','Sc','Ti','V','Cr','Mn','Fe','Co','Ni','Cu','Zn',
         'Ga','Ge','As','Se','Br','Kr',
         'Rb','Sr','Y','Zr','Nb','Mo','Tc','Ru','Rh','Pd','Ag','Cd',
         'In','Sn','Sb','Te','I','Xe','Cs','Ba','La','Ce','Pr','Nd',
         'Pm','Sm','Eu','Gd','Tb','Dy','Ho','Er','Tm','Yb','Lu','Hf',
         'Ta','W','Re','Os','Ir','Pt','Au','Hg','Tl','Pb','Bi','Po','At',
         'Rn','Fr','Ra','Ac','Th','Pa','U','Np','Pu','Am','Cm','Bk','Cf',
         'Es','Fm','Md','No','Lr','Rf','Db','Sg','Bh','Hs','Mt']

    dirmod = PyMcaDataDir.PYMCA_DATA_DIR
    ffile   = os.path.join(dirmod,"attdata")
    ffile   = os.path.join(ffile,"incoh.dict")
    if not os.path.exists(ffile):
        #freeze does bad things with the path ...
        dirmod = os.path.dirname(dirmod)
        ffile = os.path.join(dirmod, "attdata")
        ffile = os.path.join(ffile, "incoh.dict")
        if not os.path.exists(ffile):
            if dirmod.lower().endswith(".zip"):
                dirmod = os.path.dirname(dirmod)
                ffile = os.path.join(dirmod,"attdata")
                ffile = os.path.join(ffile, "incoh.dict")
        if not os.path.exists(ffile):
            print("Cannot find file ", ffile)
            raise IOError("Cannot find file %s" % ffile)

    COEFFICIENTS = ConfigDict.ConfigDict()
    COEFFICIENTS.read(ffile)
    xvalues = COEFFICIENTS['ISCADT']['XSVAL']
    svalues = numpy.reshape(COEFFICIENTS['ISCADT']['SCATF'], (100, len(xvalues)))
    #svalues = COEFFICIENTS['ISCADT']['SCATF']
    #print svalues[100:110]
    KEVTOANG = 12.39852000
    R0 = 2.82E-13 #electron radius in cm

    def getZ(ele):
        if ele in ElementList:
            return float(ElementList.index(ele)+1)
        else:
            return None

    def getElementComptonFormFactor(ele, theta, energy):
        return getElementIncoherentScatteringFunction(ele, theta, energy)

    def getComptonScatteringEnergy(energy, theta):
        return energy/(1.0 + \
                (energy/511.) * (1 - numpy.cos(theta*(numpy.pi / 180.0))))

    def getElementIncoherentScatteringFunction(ele, theta, energy):
        """
        Usage:
            getIncoherentScatteringFunction(ele,theta, energy):

        ele   - Element
        theta - Scattering angle in degrees
        energy- Photon Energy in keV

        This routine calculates the incoherent scattering function
        in electron units an interpolation to EGS4 tabulation of S(x,Z)/Z
        """
        if ele in ElementList:
            z = getZ(ele)
        else:
            z = float(ele)
        wavelength = KEVTOANG / energy
        sinhalftheta = numpy.sin(theta * (numpy.pi / 360.0))
        #Hubbel just give this term
        x =  sinhalftheta / wavelength

        #print "x old = ",x
        e = energy/511.0
        #Fajardo uses:
        x = x * numpy.sqrt(1.0 + e* (e+2.0)* pow(sinhalftheta, 2))/ \
                (1.0 + 2.0 * e * pow(sinhalftheta, 2))
        #print "x new = ",x

        ilow  = 0
        ihigh = 44
        i     = 22
        while (ihigh - ilow) > 1:
            if x < xvalues[i]:ihigh = i
            else:ilow =i
            i = int((ihigh+ilow)/2)

        if z > 100:
            if ihigh == ilow:
                value = svalues[int(99),ilow]
            else:
                A = (x - xvalues[ilow])/(xvalues[ihigh]-xvalues[ilow])
                value = ((1.0 - A ) * svalues[int(99),ilow] + \
                        A * svalues[int(99),ihigh])
            value = value * (z/100.)
        else:
            if ihigh == ilow:
                value = svalues[int(z-1),ilow]
            else:
                A = (x - xvalues[ilow])/(xvalues[ihigh]-xvalues[ilow])
                value = ((1.0 - A ) * svalues[int(z-1),ilow] + \
                        A * svalues[int(z-1),ihigh])

        return value

    def getElementComptonDifferentialCrossSection(ele, theta, energy, p1=None):
        if p1 is None:p1=0.0
        if (p1 > 1.0) or (p1 < -1):
            raise ValueError(\
            "Invalid degree of linear polarization respect to the scattering plane")
        thetasin2 = pow(numpy.sin(theta * numpy.pi / 180.0), 2)
        thetacos  =  numpy.cos(theta * numpy.pi/180.0)
        e = energy/(1.0 + (energy/511.) * (1.0 - thetacos))
        return 0.5 * ((e/energy) + (energy/e) + (p1-1.0) * thetasin2) * \
               pow(R0*(e/energy)*getElementIncoherentScatteringFunction(ele, theta, energy),2)

    getElementIncoherentDifferentialCrossSection=\
                getElementComptonDifferentialCrossSection

    if __name__ == "__main__":
        import sys
        if len(sys.argv) >  3:
            ele   = sys.argv[1]
            theta = float(sys.argv[2])
            energy= float(sys.argv[3])
            print(getElementComptonFormFactor(ele, theta, energy))
        else:
            print("Usage:")
            print("python IncoherentScatteringFunction.py Element Theta(deg) Energy(kev)")