"""
Cartesian fields




"""

#-----------------------------------------------------------------------------
# Copyright (c) 2013, yt Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------

import numpy as np
from .coordinate_handler import \
    CoordinateHandler, \
    _unknown_coord, \
    _get_coord_fields
import yt.visualization._MPL as _MPL

class CartesianCoordinateHandler(CoordinateHandler):

    def __init__(self, ds, ordering = ('x','y','z')):
        super(CartesianCoordinateHandler, self).__init__(ds, ordering)

    def setup_fields(self, registry):
        for axi, ax in enumerate(self.axis_order):
            f1, f2 = _get_coord_fields(axi)
            registry.add_field(("index", "d%s" % ax), function = f1,
                               display_field = False,
                               units = "code_length")
            registry.add_field(("index", "path_element_%s" % ax), function = f1,
                               display_field = False,
                               units = "code_length")
            registry.add_field(("index", "%s" % ax), function = f2,
                               display_field = False,
                               units = "code_length")
        def _cell_volume(field, data):
            rv  = data["index", "dx"].copy(order='K')
            rv *= data["index", "dy"]
            rv *= data["index", "dz"]
            return rv
        registry.add_field(("index", "cell_volume"), function=_cell_volume,
                           display_field=False, units = "code_length**3")
        registry.check_derived_fields(
            [("index", "dx"), ("index", "dy"), ("index", "dz"),
             ("index", "x"), ("index", "y"), ("index", "z"),
             ("index", "cell_volume")])

    def pixelize(self, dimension, data_source, field, bounds, size,
                 antialias = True, periodic = True):
        if dimension < 3:
            return self._ortho_pixelize(data_source, field, bounds, size,
                                        antialias, dimension, periodic)
        else:
            return self._oblique_pixelize(data_source, field, bounds, size,
                                          antialias)

    def _ortho_pixelize(self, data_source, field, bounds, size, antialias,
                        dim, periodic):
        # We should be using fcoords
        period = self.period[:2].copy() # dummy here
        period[0] = self.period[self.x_axis[dim]]
        period[1] = self.period[self.y_axis[dim]]
        if hasattr(period, 'in_units'):
            period = period.in_units("code_length").d
        buff = _MPL.Pixelize(data_source['px'], data_source['py'],
                             data_source['pdx'], data_source['pdy'],
                             data_source[field], size[0], size[1],
                             bounds, int(antialias),
                             period, int(periodic)).transpose()
        return buff

    def _oblique_pixelize(self, data_source, field, bounds, size, antialias):
        indices = np.argsort(data_source['dx'])[::-1]
        buff = _MPL.CPixelize(data_source['x'], data_source['y'],
                              data_source['z'], data_source['px'],
                              data_source['py'], data_source['pdx'],
                              data_source['pdy'], data_source['pdz'],
                              data_source.center, data_source._inv_mat, indices,
                              data_source[field], size[0], size[1], bounds).transpose()
        return buff

    def convert_from_cartesian(self, coord):
        return coord

    def convert_to_cartesian(self, coord):
        return coord

    def convert_to_cylindrical(self, coord):
        center = self.ds.domain_center
        return cartesian_to_cylindrical(coord, center)

    def convert_from_cylindrical(self, coord):
        center = self.ds.domain_center
        return cylindrical_to_cartesian(coord, center)

    def convert_to_spherical(self, coord):
        raise NotImplementedError

    def convert_from_spherical(self, coord):
        raise NotImplementedError

    _x_pairs = (('x', 'y'), ('y', 'z'), ('z', 'x'))
    _y_pairs = (('x', 'z'), ('y', 'x'), ('z', 'y'))

    @property
    def period(self):
        return self.ds.domain_width

