from django import forms
from django.core.validators import validate_email

class MultiEmailField(forms.Field):
    def to_python(self, value):
        "Normalize data to a list of strings."

        # Return an empty list if no input was given.
        if not value:
            return []

        if isinstance(value, basestring):
            values = value.split(',')
            return [ x.strip() for x in values if x.strip() ]
        else:
            return value

    def validate(self, value):
        "Check if value consists only of valid emails."

        # Use the parent's handling of required fields, etc.
        super(MultiEmailField, self).validate(value)

        for email in value:
            validate_email(email)

def yyyymmdd_to_strftime_format(fmt):
    translation_table = sorted([
        ("yyyy", "%Y"),
        ("yy", "%y"),
        ("mm", "%m"),
        ("m", "%-m"),
        ("MM", "%B"),
        ("M", "%b"),
        ("dd", "%d"),
        ("d", "%-d"),
    ], key=lambda t: len(t[0]), reverse=True)

    res = ""
    remaining = fmt
    while remaining:
        for pattern, replacement in translation_table:
            if remaining.startswith(pattern):
                res += replacement
                remaining = remaining[len(pattern):]
                break
        else:
            res += remaining[0]
            remaining = remaining[1:]
    return res

class DatepickerDateField(forms.DateField):
    """DateField with some glue for triggering JS Bootstrap datepicker."""

    def __init__(self, date_format, picker_settings={}, *args, **kwargs):
        strftime_format = yyyymmdd_to_strftime_format(date_format)
        kwargs["input_formats"] = [strftime_format]
        kwargs["widget"] = forms.DateInput(format=strftime_format)
        super(DatepickerDateField, self).__init__(*args, **kwargs)

        self.widget.attrs["data-provide"] = "datepicker"
        self.widget.attrs["data-date-format"] = date_format
        if "placeholder" not in self.widget.attrs:
            self.widget.attrs["placeholder"] = date_format
        for k, v in picker_settings.iteritems():
            self.widget.attrs["data-date-%s" % k] = v