from django.conf import settings

from django.utils.html import escape

# Converts a dictionary to a single string with key="value", XML-style with

# a leading space. Assumes keys do not need to be XML-escaped.

flatatt = lambda attrs: u''.join([u' %s="%s"' % (k, escape(v)) for k, v in attrs.items()])

def smart_unicode(s):

    if not isinstance(s, basestring):

        if hasattr(s, '__unicode__'):

            s = unicode(s)

        else:

            s = unicode(str(s), settings.DEFAULT_CHARSET)

    elif not isinstance(s, unicode):

        s = unicode(s, settings.DEFAULT_CHARSET)

    return s

class StrAndUnicode(object):

    """

    A class whose __str__ returns its __unicode__ as a bytestring

    according to settings.DEFAULT_CHARSET.

    Useful as a mix-in.

    """

    def __str__(self):

        return self.__unicode__().encode(settings.DEFAULT_CHARSET)

class ErrorDict(dict):

    """

    A collection of errors that knows how to display itself in various formats.

    The dictionary keys are the field names, and the values are the errors.

    """

    def __str__(self):

        return self.as_ul()

    def as_ul(self):

        if not self: return u''

        return u'<ul class="errorlist">%s</ul>' % ''.join([u'<li>%s%s</li>' % (k, v) for k, v in self.items()])

    def as_text(self):

        return u'\n'.join([u'* %s\n%s' % (k, u'\n'.join([u'  * %s' % i for i in v])) for k, v in self.items()])

class ErrorList(list):

    """

    A collection of errors that knows how to display itself in various formats.

    """

    def __str__(self):

        return self.as_ul()

    def as_ul(self):

        if not self: return u''

        return u'<ul class="errorlist">%s</ul>' % ''.join([u'<li>%s</li>' % e for e in self])

    def as_text(self):

        if not self: return u''

        return u'\n'.join([u'* %s' % e for e in self])

class ValidationError(Exception):

    def __init__(self, message):

        "ValidationError can be passed a string or a list."

        if isinstance(message, list):

            self.messages = ErrorList([smart_unicode(msg) for msg in message])

        else:

            assert isinstance(message, basestring), ("%s should be a basestring" % repr(message))

            message = smart_unicode(message)

            self.messages = ErrorList([message])

    def __str__(self):

        # This is needed because, without a __str__(), printing an exception

        # instance would result in this:

        # AttributeError: ValidationError instance has no attribute 'args'

        # See http://www.python.org/doc/current/tut/node10.html#handling

        return repr(self.messages)