from django import forms
from django.core import validators


class LatLonWidget(forms.MultiWidget):
    """
    A Widget that splits Point input into two latitude/longitude boxes.
    """

    def __init__(self, attrs=None, date_format=None, time_format=None):
        widgets = (forms.HiddenInput(attrs=attrs), forms.HiddenInput(attrs=attrs))
        super(LatLonWidget, self).__init__(widgets, attrs)

    def decompress(self, value):
        if value:
            return tuple(reversed(value.coords))
        return (None, None)


class LatLonField(forms.MultiValueField):

    widget = LatLonWidget
    srid = 4326

    default_error_messages = {
        "invalid_latitude": (u"Entrez une latitude valide."),
        "invalid_longitude": (u"Entrez une longitude valide."),
    }

    def __init__(self, *args, **kwargs):
        fields = (
            forms.FloatField(min_value=-90, max_value=90),
            forms.FloatField(min_value=-180, max_value=180),
        )
        super(LatLonField, self).__init__(fields, *args, **kwargs)

    def compress(self, data_list):
        if data_list:
            # Raise a validation error if latitude or longitude is empty
            # (possible if LatLongField has required=False).
            if data_list[0] in validators.EMPTY_VALUES:
                raise forms.ValidationError(self.error_messages["invalid_latitude"])
            if data_list[1] in validators.EMPTY_VALUES:
                raise forms.ValidationError(self.error_messages["invalid_longitude"])
            # SRID=4326;POINT(1.12345789 1.123456789)
            srid_str = "SRID=%d" % self.srid
            point_str = "POINT(%f %f)" % tuple(reversed(data_list))
            return ";".join([srid_str, point_str])
        return None