import math

from shapely import geometry as shgeo
from shapely.validation import explain_validity

from ..i18n import _
from ..stitches import legacy_fill
from ..svg import PIXELS_PER_MM
from ..utils import cache
from .element import param, EmbroideryElement, Patch


class Fill(EmbroideryElement):
    element_name = _("Fill")

    def __init__(self, *args, **kwargs):
        super(Fill, self).__init__(*args, **kwargs)

    @property
    @param('auto_fill',
           _('Manually routed fill stitching'),
           tooltip=_('AutoFill is the default method for generating fill stitching.'),
           type='toggle',
           inverse=True,
           default=True)
    def auto_fill(self):
        return self.get_boolean_param('auto_fill', True)

    @property
    @param('angle',
           _('Angle of lines of stitches'),
           tooltip=_('The angle increases in a counter-clockwise direction.  0 is horizontal.  Negative angles are allowed.'),
           unit='deg',
           type='float',
           default=0)
    @cache
    def angle(self):
        return math.radians(self.get_float_param('angle', 0))

    @property
    def color(self):
        # SVG spec says the default fill is black
        return self.get_style("fill", "#000000")

    @property
    @param(
        'skip_last',
        _('Skip last stitch in each row'),
        tooltip=_('The last stitch in each row is quite close to the first stitch in the next row.  '
                  'Skipping it decreases stitch count and density.'),
        type='boolean',
        default=False)
    def skip_last(self):
        return self.get_boolean_param("skip_last", False)

    @property
    @param(
        'flip',
        _('Flip fill (start right-to-left)'),
        tooltip=_('The flip option can help you with routing your stitch path.  '
                  'When you enable flip, stitching goes from right-to-left instead of left-to-right.'),
        type='boolean',
        default=False)
    def flip(self):
        return self.get_boolean_param("flip", False)

    @property
    @param('row_spacing_mm',
           _('Spacing between rows'),
           tooltip=_('Distance between rows of stitches.'),
           unit='mm',
           type='float',
           default=0.25)
    def row_spacing(self):
        return max(self.get_float_param("row_spacing_mm", 0.25), 0.1 * PIXELS_PER_MM)

    @property
    def end_row_spacing(self):
        return self.get_float_param("end_row_spacing_mm")

    @property
    @param('max_stitch_length_mm',
           _('Maximum fill stitch length'),
           tooltip=_('The length of each stitch in a row.  Shorter stitch may be used at the start or end of a row.'),
           unit='mm',
           type='float',
           default=3.0)
    def max_stitch_length(self):
        return max(self.get_float_param("max_stitch_length_mm", 3.0), 0.1 * PIXELS_PER_MM)

    @property
    @param('staggers',
           _('Stagger rows this many times before repeating'),
           tooltip=_('Setting this dictates how many rows apart the stitches will be before they fall in the same column position.'),
           type='int',
           default=4)
    def staggers(self):
        return self.get_int_param("staggers", 4)

    @property
    @cache
    def paths(self):
        return self.flatten(self.parse_path())

    @property
    @cache
    def shape(self):
        # shapely's idea of "holes" are to subtract everything in the second set
        # from the first. So let's at least make sure the "first" thing is the
        # biggest path.
        paths = self.paths
        paths.sort(key=lambda point_list: shgeo.Polygon(point_list).area, reverse=True)
        polygon = shgeo.MultiPolygon([(paths[0], paths[1:])])

        if not polygon.is_valid:
            why = explain_validity(polygon)

            # I Wish this weren't so brittle...
            if "Hole lies outside shell" in why:
                self.fatal(_("this object is made up of unconnected shapes.  This is not allowed because "
                             "Ink/Stitch doesn't know what order to stitch them in.  Please break this "
                             "object up into separate shapes."))
            else:
                self.fatal(_("shape is not valid.  This can happen if the border crosses over itself."))

        return polygon

    def to_patches(self, last_patch):
        stitch_lists = legacy_fill(self.shape,
                                   self.angle,
                                   self.row_spacing,
                                   self.end_row_spacing,
                                   self.max_stitch_length,
                                   self.flip,
                                   self.staggers,
                                   self.skip_last)
        return [Patch(stitches=stitch_list, color=self.color) for stitch_list in stitch_lists]