'''
Common snippets for argument processing in command line scripts.
'''

import argparse
import sys
import warnings

def flatten(S):
    if S == []:
        return S
    if isinstance(S[0], list):
        return flatten(S[0]) + flatten(S[1:])
    return S[:1] + flatten(S[1:])

def make_action_sharedlist(opname, listname):
    class opAction(argparse.Action):
        def __call__(self, parser, args, values, option_string=None):
            if (not hasattr(args, listname)) or getattr(args, listname) is None:
                setattr(args, listname, list())
            getattr(args, listname).append((opname, values))
    return opAction

def make_dict_action(argtype=None, postaction='store', first_is_key=True):
    class DictAction(argparse.Action):
        #def __init__(self, option_strings, dest, nargs=None, **kwargs):
        #    if nargs is not None:
        #    raise ValueError("nargs not allowed")
        #    super(DictAction, self).__init__(option_strings, dest, **kwargs)
        def __call__(self, parser, namespace, values, option_string=None):
            if first_is_key: # For the labeled versions
                key = values[0]
                vals = values[1:]
            else: # For the default values
                key = None
                vals = values
            if argtype is not None:
                if (first_is_key and self.nargs == 2) or (not first_is_key and self.nargs == 1):
                    vals = argtype(vals[0]) # avoid having lists in this case
                else:
                    vals = [argtype(val) for val in vals]
            ledict = getattr(namespace, self.dest, {})
            if ledict is None:
                ledict = {}
            if postaction=='store':
                ledict[key] = vals
            elif postaction=='append':
                lelist = ledict.get(key, [])
                lelist.append(vals)
                ledict[key] = lelist
            setattr(namespace, self.dest, ledict)
    return DictAction


class ArgumentProcessingError(Exception):
    pass

class AppendTupleAction(argparse.Action):
    ''' A variation on the 'append' builtin action from argparse, but uses tuples for the internal groupings instead of lists ''' 
    def __call__(self, parser, args, values, option_string=None):
        if (not hasattr(args, self.dest)) or getattr(args, self.dest) is None:
            setattr(args, self.dest, list())
        getattr(args, self.dest).append(tuple(values))

def float_range(string):
    """Tries to parse a string either as one individual float value
    or one of the following patterns:
    
    first:last:increment
    first:last|steps
    first:last
    
    (The last one is equivalent to first:last|50.)
    Returns either float or numpy array.
    """
    try:
        res = float(string)
        return res
    except ValueError:
        import re
        steps = None
        match = re.match(r's?([^:]+):([^|]+)\|(.+)', string)
        if match:
            steps = int(match.group(3))
        else:
            match = re.match(r's?([^:]+):([^:]+):(.+)', string)
            if match:
                increment = float(match.group(3))
            else:
                match = re.match(r's?([^:]+):(.+)', string)
                if match:
                    steps = 50
                else: 
                    argparse.ArgumentTypeError('Invalid float/sequence format: "%s"' % string)
        first = float(match.group(1))
        last = float(match.group(2))
        import numpy as np
        if steps is not None:
            return np.linspace(first, last, num=steps)
        else:
            return np.arange(first, last, increment)

def int_or_None(string):
    """Tries to parse a string either as an int or None (if it contains only whitespaces)"""
    try:
        return int(string)
    except ValueError as ve:
        if string.strip() == '':
            return None
        else:
            raise ve

def sslice(string):
    """Tries to parse a string either as one individual int value
    or one of the following patterns:
    
    first:last:increment
    first:last

    first, last and increment must be parseable as ints
    or be empty (then 

    In each case, 's' letter can be prepended to the whole string to avoid
    argparse interpreting this as a new option (if the argument contains
    '-' or '+').
    
    Returns either int or slice containing ints or Nones.
    """
    if string[0] == 's':
        string = string[1:]
    try:
        res = int(string)
        return res
    except ValueError:
        import re
        match = re.match(r'([^:]*):([^:]*):(.*)', string)
        if match:
            step = int_or_None(match.group(3))
        else:
            match = re.match(r'([^:]*):(.*)', string)
            if match:
                step = None
            else: 
                argparse.ArgumentTypeError('Invalid int/slice format: "%s"' % string)
        start = int_or_None(match.group(1))
        stop = int_or_None(match.group(2))
        return slice(start, stop, step)

def sfloat(string):
    '''Tries to match a float, or a float with prepended 's'

    Used as a workaraound for argparse's negative number matcher, which does not recognize
    scientific notation.
    '''
    try:
        res = float(string)
    except ValueError as exc:
        if string[0] == 's':
            res = float(string[1:])
        else: raise exc
    return res

def sint(string):
    '''Tries to match an int, or an int with prepended 's'

    Used as a workaraound for argparse's negative number matcher if '+' is used as a
    prefix 
    '''
    try:
        res = int(string)
    except ValueError as exc:
        if string[0] == 's':
            res = int(string[1:])
        else: raise exc
    return res

def material_spec(string):
    """Tries to parse a string as a material specification, i.e. a 
    real or complex number or one of the string in built-in Lorentz-Drude models.

    Tries to interpret the string as 1) float, 2) complex, 3) Lorentz-Drude key.
    Raises argparse.ArgumentTypeError on failure.
    """
    from .cymaterials import lorentz_drude
    if string in lorentz_drude.keys():
        return string
    else:
        try: lemat = float(string)
        except ValueError:
            try: lemat = complex(string)
            except ValueError as ve:
                raise argpares.ArgumentTypeError("Material specification must be a supported material name %s, or a number" % (str(lorentz_drude.keys()),)) from ve
        return lemat

class ArgParser:
    ''' Common argument parsing engine for QPMS python CLI scripts. '''
    
    def __add_planewave_argparse_group(ap):
        pwgrp = ap.add_argument_group('Incident wave specification', """
        Incident wave direction is given in terms of ISO polar and azimuthal angles θ, φ, 
        which translate into cartesian coordinates as r̂ = (x, y, z) = (sin(θ) cos(φ), sin(θ) sin(φ), cos(θ)).

        Wave polarisation is given in terms of parameters ψ, χ, where ψ is the angle between a polarisation 
        ellipse axis and meridian tangent θ̂, and tg χ determines axes ratio; 
        the electric field in the origin is then

        E⃗ = cos(χ) (cos(ψ) θ̂ + sin(ψ) φ̂) + i sin(χ) (sin(ψ) θ̂ + cos(ψ) φ̂).

        All the angles are given as multiples of π/2.
        """ # TODO EXAMPLES
        )
        pwgrp.add_argument("-φ", "--phi", type=float, default=0,
            help='Incident wave asimuth in multiples of π/2.')
        pwgrp.add_argument("-θ", "--theta", type=float_range, default=0,
            help='Incident wave polar angle in multiples of π/2. This might be a sequence in format FIRST:LAST:INCREMENT.')
        pwgrp.add_argument("-ψ", "--psi", type=float, default=0,
            help='Angle between polarisation ellipse axis and meridian tangent θ̂ in multiples of π/2.')
        pwgrp.add_argument("-χ", "--chi", type=float, default=0,
            help='Polarisation parameter χ in multiples of π/2. 0 for linear, 0.5 for circular pol.')

    def __add_manyparticle_argparse_group(ap):
        mpgrp = ap.add_argument_group('Many particle specification', "TODO DOC")
        mpgrp.add_argument("-p", "--position", nargs='+', action=make_dict_action(argtype=sfloat, postaction='append',
            first_is_key=False), help="Particle positions, cartesion coordinates (default particle properties)")
        mpgrp.add_argument("+p", "++position", nargs='+', action=make_dict_action(argtype=sfloat, postaction='append', 
            first_is_key=True), help="Particle positions, cartesian coordinates (labeled)")
        mpgrp.add_argument("-L", "--lMax", nargs=1, default={},
                action=make_dict_action(argtype=int, postaction='store', first_is_key=False,),
                help="Cutoff multipole degree (default)")
        mpgrp.add_argument("+L", "++lMax", nargs=2, 
                action=make_dict_action(argtype=int, postaction='store', first_is_key=True,),
            help="Cutoff multipole degree (labeled)")
        mpgrp.add_argument("-m", "--material", nargs=1, default={},
                action=make_dict_action(argtype=material_spec, postaction='store', first_is_key=False,),
                help='particle material (Au, Ag, ... for Lorentz-Drude or number for constant refractive index) (default)')
        mpgrp.add_argument("+m", "++material", nargs=2,
                action=make_dict_action(argtype=material_spec, postaction='store', first_is_key=True,),
                help='particle material (Au, Ag, ... for Lorentz-Drude or number for constant refractive index) (labeled)')
        mpgrp.add_argument("-r", "--radius", nargs=1, default={},
                action=make_dict_action(argtype=float, postaction='store', first_is_key=False,),
                help='particle radius (sphere or cylinder; default)')
        mpgrp.add_argument("+r", "++radius", nargs=2,
                action=make_dict_action(argtype=float, postaction='store', first_is_key=True,),
                help='particle radius (sphere or cylinder; labeled)')
        mpgrp.add_argument("-H", "--height", nargs=1, default={},
                action=make_dict_action(argtype=float, postaction='store', first_is_key=False,),
                help='particle radius (cylinder; default)')
        mpgrp.add_argument("+H", "++height", nargs=2,
                action=make_dict_action(argtype=float, postaction='store', first_is_key=True,),
                help='particle radius (cylinder; labeled)')

    atomic_arguments = {
            'rectlattice2d_periods': lambda ap: ap.add_argument("-p", "--period", type=float, nargs='+', required=True, help='square/rectangular lattice periods', metavar=('px','[py]')),
            'rectlattice2d_counts': lambda ap: ap.add_argument("--size", type=int, nargs=2, required=True, help='rectangular array size (particle column, row count)', metavar=('NCOLS', 'NROWS')),
            'single_frequency_eV': lambda ap: ap.add_argument("-f", "--eV", type=float, required=True, help='radiation angular frequency in eV'),
            'multiple_frequency_eV_optional': lambda ap: ap.add_argument("-f", "--eV", type=float, nargs='*', help='radiation angular frequency in eV (additional)'),
            'seq_frequency_eV': lambda ap: ap.add_argument("-F", "--eV-seq", type=float, nargs=3, required=True, help='uniform radiation angular frequency sequence in eV', metavar=('FIRST', 'INCREMENT', 'LAST')),
            'real_frequencies_eV_ng': lambda ap: ap.add_argument("-f", "--eV", type=float_range, nargs=1, action='append', required=True, help='Angular frequency (or angular frequency range) in eV'), # nargs='+', action='extend' would be better, but action='extend' requires python>=3.8
            'single_material': lambda ap: ap.add_argument("-m", "--material", help='particle material (Au, Ag, ... for Lorentz-Drude or number for constant refractive index)', type=material_spec, required=True),
            'single_radius': lambda ap: ap.add_argument("-r", "--radius", type=float, required=True, help='particle radius (sphere or cylinder)'),
            'single_height': lambda ap: ap.add_argument("-H", "--height", type=float, help='cylindrical particle height; if not provided, particle is assumed to be spherical'),
            'single_kvec2': lambda ap: ap.add_argument("-k", '--kx-lim', nargs=2, type=sfloat, required=True, help='k vector', metavar=('KX_MIN', 'KX_MAX')),
            'kpi': lambda ap: ap.add_argument("--kpi", action='store_true', help="Indicates that the k vector is given in natural units instead of SI, i.e. the arguments given by -k shall be automatically multiplied by pi / period (given by -p argument)"),
            'bg_real_refractive_index': lambda ap: ap.add_argument("-n", "--refractive-index", type=float, default=1., help='background medium strictly real refractive index'),
            'bg_analytical': lambda ap: ap.add_argument("-B", "--background", type=material_spec, default=1., help="Background medium specification (constant real or complex refractive index, or supported material label)"),
            'single_lMax': lambda ap: ap.add_argument("-L", "--lMax", type=int, required=True, default=3, help='multipole degree cutoff'),
            'single_lMax_extend': lambda ap: ap.add_argument("--lMax-extend", type=int, required=False, default=6, help='multipole degree cutoff for T-matrix calculation (cylindrical particles only'),
            'outfile': lambda ap: ap.add_argument("-o", "--output", type=str, required=False, help='output path (if not provided, will be generated automatically)'), # TODO consider type=argparse.FileType('w')
            'plot_out': lambda ap: ap.add_argument("-O", "--plot-out", type=str, required=False, help="path to plot output (optional)"),
            'plot_do': lambda ap: ap.add_argument("-P", "--plot", action='store_true', help="if -p not given, plot to a default path"),
            'lattice2d_basis': lambda ap: ap.add_argument("-b", "--basis-vector", nargs='+', action=AppendTupleAction, help="basis vector in xy-cartesian coordinates (two required)", required=True, type=sfloat, dest='basis_vectors', metavar=('X', 'Y')),
            'planewave_pol_angles': __add_planewave_argparse_group,
            'multi_particle': __add_manyparticle_argparse_group,
    }

    feature_sets_available = { # name : (description, dependencies, atoms not in other dependencies, methods called after parsing, "virtual" features provided) 
            'const_real_background': ("Background medium with constant real refractive index", (), ('bg_real_refractive_index',), ('_eval_const_background_epsmu',), ('background', 'background_analytical')),
            'background' : ("Most general background medium specification currently supported", ('background_analytical',), (), (), ()),
            'background_analytical' : ("Background medium model holomorphic for 'reasonably large' complex frequency areas", (), ('bg_analytical',), ('_eval_analytical_background_epsmugen',), ('background',)),
            'single_particle': ("Single particle definition (shape [currently spherical or cylindrical]) and materials, incl. background)", ('background',), ('single_material', 'single_radius', 'single_height', 'single_lMax_extend'), ('_eval_single_tmgen',), ()),
            'multi_particle': ("One or more particle definition (shape [curently spherical or cylindrical]), materials, and positions)", ('background',), ('multi_particle',), ('_process_multi_particle',), ()),
            'single_lMax': ("Single particle lMax definition", (), ('single_lMax',), (), ()),
            'single_omega': ("Single angular frequency", (), ('single_frequency_eV',), ('_eval_single_omega',), ()),
            'omega_seq': ("Equidistant real frequency range with possibility of adding individual frequencies", (), ('seq_frequency_eV', 'multiple_frequency_eV_optional',), ('_eval_omega_seq',), ()),
            'omega_seq_real_ng': ("Equidistant real frequency ranges or individual frequencies (new syntax)", (), ('real_frequencies_eV_ng',), ('_eval_omega_seq_real_ng',), ()),
            'lattice2d': ("Specification of a generic 2d lattice (spanned by the x,y axes)", (), ('lattice2d_basis',), ('_eval_lattice2d',), ()),
            'rectlattice2d': ("Specification of a rectangular 2d lattice; conflicts with lattice2d", (), ('rectlattice2d_periods',), ('_eval_rectlattice2d',), ()),
            'rectlattice2d_finite': ("Specification of a rectangular 2d lattice; conflicts with lattice2d", ('rectlattice2d',), ('rectlattice2d_counts',), (), ()),
            'planewave': ("Specification of a normalised plane wave (typically used for scattering) with a full polarisation state", (), ('planewave_pol_angles',), ("_process_planewave_angles",), ()),
    }


    def __init__(self, features=[]):
        prefix_chars = '+-' if 'multi_particle' in features else '-'
        self.ap = argparse.ArgumentParser(prefix_chars=prefix_chars)
        self.features_enabled = set()
        self.call_at_parse_list = []
        self.parsed = False
        for feat in features:
            self.add_feature(feat)
        self._emg_register = {} # EpsMuGenerator dictionary to avoid recreating equivalent instances; filled by _add_emg()
        self._tmg_register = {} # TMatrixGenerator dictionary to avoid recreating equivalent instances; filled by _add_tmg()
        self._bspec_register = {} # Dictionary of used BaseSpecs to keep the equivalent instances unique; filled by _add_bspec()

    def _add_emg(self, emgspec):
        """Looks up whether if an EpsMuGenerator from given material_spec has been already registered, and if not, creates a new one"""
        from .cymaterials import EpsMu, EpsMuGenerator, lorentz_drude
        if emgspec in self._emg_register.keys():
            return self._emg_register[emgspec]
        else:
            if isinstance(emgspec, (float, complex)):
                emg = EpsMuGenerator(EpsMu(emgspec**2))
            else:
                emg = EpsMuGenerator(lorentz_drude[emgspec])
            self._emg_register[emgspec] = emg
            return emg

    def _add_tmg(self, tmgspec):
        """Looks up whether if a T-matrix from given T-matrix specification tuple has been already registered, and if not, creates a new one
        
        T-matrix specification shall be of the form 
        (bg_material_spec, fg_material_spec, shape_spec) where shape_spec is
        (radius, height, lMax_extend)
        """
        if tmgspec in self._tmg_register.keys():
            return self._tmg_register[tmgspec]
        else:
            from .cytmatrices import TMatrixGenerator
            bgspec, fgspec, (radius, height, lMax_extend) = tmgspec
            bg = self._add_emg(bgspec)
            fg = self._add_emg(fgspec)
            if height is None:
                tmgen = TMatrixGenerator.sphere(bg, fg, radius)
            else:
                tmgen = TMatrixGenerator.cylinder(bg, fg, radius, height, lMax_extend=lMax_extend)
            self._tmg_register[tmgspec] = tmgen
            return tmgen

    def _add_bspec(self, key):
        if key in self._bspec_register.keys():
            return self._bspec_register[key]
        else:
            from .cybspec import BaseSpec
            if isinstance(key, BaseSpec):
                bspec = key
            elif isinstance(key, int):
                bspec = self._add_bspec(BaseSpec(lMax=key))
            else: raise TypeError("Can't register this as a BaseSpec")
            self._bspec_register[key] = bspec
            return bspec

    def add_feature(self, feat):
        if feat not in self.features_enabled:
            if feat not in ArgParser.feature_sets_available:
                raise ValueError("Unknown ArgParser feature: %s" % feat)
            #resolve dependencies
            _, deps, atoms, atparse, provides_virtual = ArgParser.feature_sets_available[feat]
            for dep in deps:
                self.add_feature(dep)
            for atom in atoms: # maybe check whether that atom has already been added sometimes in the future?
                ArgParser.atomic_arguments[atom](self.ap)
            for methodname in atparse:
                self.call_at_parse_list.append(methodname)
            self.features_enabled.add(feat)
            for feat_virt in provides_virtual:
                self.features_enabled.add(feat_virt)

    def add_argument(self, *args, **kwargs):
        '''Add a custom argument directly to the standard library ArgParser object'''
        return self.ap.add_argument(*args, **kwargs)
    
    def add_argument_group(self, *args, **kwargs):
        '''Add a custom argument group directly to the standard library ArgParser object'''
        return self.ap.add_argument_group(*args, **kwargs)

    def parse_args(self, process_data = True,  *args, **kwargs):
        self.args = self.ap.parse_args(*args, **kwargs)
        if process_data:
            for method in self.call_at_parse_list:
                try:
                    getattr(self, method)()
                except ArgumentProcessingError:
                    err = sys.exc_info()[1]
                    self.ap.error(str(err))
        return self.args
    
    def __getattr__(self, name):
        return getattr(self.args, name)
        

    # Methods to initialise the related data structures:

    def _eval_const_background_epsmu(self): # feature: const_real_background
        self.args.background = self.args.refractive_index
        self._eval_analytical_background_epsmugen()
    
    def _eval_analytical_background_epsmugen(self): # feature: background_analytical
        a = self.args
        from .cymaterials import EpsMu
        if isinstance(a.background, (float, complex)):
            self.background_epsmu = EpsMu(a.background**2)
        self.background_emg = self._add_emg(a.background)

    def _eval_single_tmgen(self): # feature: single_particle
        a = self.args
        from .cymaterials import EpsMuGenerator, lorentz_drude
        from .cytmatrices import TMatrixGenerator
        self.foreground_emg = self._add_emg(a.material)
        self.tmgen = self._add_tmg((a.background, a.material, (a.radius, a.height, a.lMax_extend)))
        self.bspec = self._add_bspec(a.lMax)

    def _eval_single_omega(self): # feature: single_omega
        from .constants import eV, hbar
        self.omega = self.args.eV * eV / hbar

    def _eval_omega_seq(self): # feature: omega_seq
        import numpy as np
        from .constants import eV, hbar
        start, step, stop = self.args.eV_seq
        self.omegas = np.arange(start, stop, step)
        if self.args.eV:
            self.omegas = np.concatenate((self.omegas, np.array(self.args.eV)))
            self.omegas.sort()
        self.omegas *= eV/hbar

    def _eval_omega_seq_real_ng(self): # feature: omega_seq_real_ng
        import numpy as np
        from .constants import eV, hbar
        eh = eV / hbar
        self.omegas = [omega_eV * eh for  omega_eV in flatten(self.args.eV)]
        self.omega_max = max(om if isinstance(om, float) else max(om) for om in self.omegas)
        self.omega_min = min(om if isinstance(om, float) else min(om) for om in self.omegas)
        self.omega_singles = [om for om in self.omegas if isinstance(om, float)]
        self.omega_ranges = [om for om in self.omegas if not isinstance(om, float)]
        self.omega_descr = ("%geV" % (self.omega_max / eh)) if (self.omega_max == self.omega_min) else (
                "%g–%geV" % (self.omega_min / eh, self.omega_max / eh))
        self.allomegas = []
        for om in self.omegas:
            if isinstance(om, float):
                self.allomegas.append(om)
            else:
                self.allomegas.extend(om)
        self.allomegas = np.unique(self.allomegas)


    def _eval_lattice2d(self): # feature: lattice2d
        l = len(self.args.basis_vectors)
        if l != 2: raise ValueError('Two basis vectors must be specified (have %d)' % l)
        from .qpms_c import lll_reduce
        self.direct_basis = lll_reduce(self.args.basis_vectors, delta=1.)
        import numpy as np
        self.reciprocal_basis1 = np.linalg.inv(self.direct_basis.T)
        self.reciprocal_basis2pi = 2 * np.pi * self.reciprocal_basis1
    
    def _eval_rectlattice2d(self): # feature: rectlattice2d
        a = self.args
        l = len(a.period)
        if (l == 1): # square lattice
            a.period = (a.period[0], a.period[0])
        else:
            a.period = (a.period[0], a.period[1])
            if (l > 2):
                raise ValueError("At most two lattice periods allowed for a rectangular lattice (got %d)" % l)

        import numpy as np
        a.basis_vectors = [(a.period[0], 0.), (0., a.period[1])]
        self.direct_basis = np.array(a.basis_vectors)
        self.reciprocal_basis1 = np.linalg.inv(self.direct_basis.T)
        self.reciprocal_basis2pi = 2 * np.pi * self.reciprocal_basis1

    def _process_planewave_angles(self): #feature: planewave
        import math
        pi2 = math.pi/2
        a = self.args
        a.chi = a.chi * pi2
        a.psi = a.psi * pi2
        a.theta = a.theta * pi2
        a.phi = a.phi * pi2

    def _process_multi_particle(self): # feature: multi_particle
        a = self.args
        self.tmspecs = {}
        self.tmgens = {}
        self.bspecs = {}
        self.positions = {}
        pos13, pos23, pos33 = False, False, False # used to 
        if len(a.position.keys()) == 0:
            warnings.warn("No particle position (-p or +p) specified, assuming single particle in the origin / single particle per unit cell!")
            a.position[None] = [(0.,0.,0.)]
        for poslabel in a.position.keys():
            try:
                lMax = a.lMax.get(poslabel, False) or a.lMax[None]
                radius = a.radius.get(poslabel, False) or a.radius[None]
                # Height is "inherited" only together with radius
                height = a.height.get(poslabel, None) if poslabel in a.radius.keys() else a.height.get(None, None)
                if hasattr(a, 'lMax_extend'):
                    lMax_extend = a.lMax_extend.get(poslabel, False) or a.lMax_extend.get(None, False) or None
                else:
                    lMax_extend = None
                material = a.material.get(poslabel, False) or a.material[None]
            except (TypeError, KeyError) as exc:
                if poslabel is None:
                    raise ArgumentProcessingError("Unlabeled particles' positions (-p) specified, but some default particle properties are missing (--lMax, --radius, and --material have to be specified)") from exc
                else:
                    raise ArgumentProcessingError(("Incomplete specification of '%s'-labeled particles: you must"
                        "provide at least ++lMax, ++radius, ++material arguments with the label, or the fallback arguments"
                        "--lMax, --radius, --material.")%(str(poslabel),)) from exc
            tmspec = (a.background, material, (radius, height, lMax_extend)) 
            self.tmspecs[poslabel] = tmspec
            self.tmgens[poslabel] = self._add_tmg(tmspec)
            self.bspecs[poslabel] = self._add_bspec(lMax)
            poslist_cured = []
            for pos in a.position[poslabel]:
                if len(pos) == 1:
                    pos_cured = (0., 0., pos[0])
                    pos13 = True
                elif len(pos) == 2:
                    pos_cured = (pos[0], pos[1], 0.)
                    pos23 = True
                elif len(pos) == 3:
                    pos_cured = pos
                    pos33 = True
                else:
                    raise argparse.ArgumentTypeError("Each -p / +p argument requires 1 to 3 cartesian coordinates")
                poslist_cured.append(pos_cured)
            self.positions[poslabel] = poslist_cured
        if pos13 and pos23:
            warnings.warn("Both 1D and 2D position specifications used. The former are interpreted as z coordinates while the latter as x, y coordinates")

    def get_particles(self):
        """Creates a list of Particle instances that can be directly used in ScatteringSystem.create().

        Assumes that self._process_multi_particle() has been already called.
        """
        from .qpms_c import Particle
        plist = []
        for poslabel, poss in self.positions.items():
            t = self.tmgens[poslabel]
            bspec = self.bspecs[poslabel]
            plist.extend([Particle(pos, t, bspec=bspec) for pos in poss])
        return plist