"""
Django Extensions additional model fields
"""
import re
import six
try:
    import uuid
    HAS_UUID = True
except ImportError:
    HAS_UUID = False

from django.core.exceptions import ImproperlyConfigured
from django.template.defaultfilters import slugify
from django.db.models import DateTimeField, CharField, SlugField

try:
    from django.utils.timezone import now as datetime_now
    assert datetime_now
except ImportError:
    import datetime
    datetime_now = datetime.datetime.now

try:
    from django.utils.encoding import force_unicode  # NOQA
except ImportError:
    from django.utils.encoding import force_text as force_unicode  # NOQA


class AutoSlugField(SlugField):
    """ AutoSlugField

    By default, sets editable=False, blank=True.

    Required arguments:

    populate_from
        Specifies which field or list of fields the slug is populated from.

    Optional arguments:

    separator
        Defines the used separator (default: '-')

    overwrite
        If set to True, overwrites the slug on every save (default: False)

    Inspired by SmileyChris' Unique Slugify snippet:
    http://www.djangosnippets.org/snippets/690/
    """
    def __init__(self, *args, **kwargs):
        kwargs.setdefault('blank', True)
        kwargs.setdefault('editable', False)

        populate_from = kwargs.pop('populate_from', None)
        if populate_from is None:
            raise ValueError("missing 'populate_from' argument")
        else:
            self._populate_from = populate_from
        self.separator = kwargs.pop('separator', six.u('-'))
        self.overwrite = kwargs.pop('overwrite', False)
        self.allow_duplicates = kwargs.pop('allow_duplicates', False)
        super(AutoSlugField, self).__init__(*args, **kwargs)

    def _slug_strip(self, value):
        """
        Cleans up a slug by removing slug separator characters that occur at
        the beginning or end of a slug.

        If an alternate separator is used, it will also replace any instances
        of the default '-' separator with the new separator.
        """
        re_sep = '(?:-|%s)' % re.escape(self.separator)
        value = re.sub('%s+' % re_sep, self.separator, value)
        return re.sub(r'^%s+|%s+$' % (re_sep, re_sep), '', value)

    def get_queryset(self, model_cls, slug_field):
        for field, model in model_cls._meta.get_fields_with_model():
            if model and field == slug_field:
                return model._default_manager.all()
        return model_cls._default_manager.all()

    def slugify_func(self, content):
        if content:
            return slugify(content)
        return ''

    def create_slug(self, model_instance, add):
        # get fields to populate from and slug field to set
        if not isinstance(self._populate_from, (list, tuple)):
            self._populate_from = (self._populate_from, )
        slug_field = model_instance._meta.get_field(self.attname)

        if add or self.overwrite:
            # slugify the original field content and set next step to 2
            slug_for_field = lambda field: self.slugify_func(getattr(model_instance, field))
            slug = self.separator.join(map(slug_for_field, self._populate_from))
            next = 2
        else:
            # get slug from the current model instance
            slug = getattr(model_instance, self.attname)
            # model_instance is being modified, and overwrite is False,
            # so instead of doing anything, just return the current slug
            return slug

        # strip slug depending on max_length attribute of the slug field
        # and clean-up
        slug_len = slug_field.max_length
        if slug_len:
            slug = slug[:slug_len]
        slug = self._slug_strip(slug)
        original_slug = slug

        if self.allow_duplicates:
            return slug

        # exclude the current model instance from the queryset used in finding
        # the next valid slug
        queryset = self.get_queryset(model_instance.__class__, slug_field)
        if model_instance.pk:
            queryset = queryset.exclude(pk=model_instance.pk)

        # form a kwarg dict used to impliment any unique_together contraints
        kwargs = {}
        for params in model_instance._meta.unique_together:
            if self.attname in params:
                for param in params:
                    kwargs[param] = getattr(model_instance, param, None)
        kwargs[self.attname] = slug

        # increases the number while searching for the next valid slug
        # depending on the given slug, clean-up
        while not slug or queryset.filter(**kwargs):
            slug = original_slug
            end = '%s%s' % (self.separator, next)
            end_len = len(end)
            if slug_len and len(slug) + end_len > slug_len:
                slug = slug[:slug_len - end_len]
                slug = self._slug_strip(slug)
            slug = '%s%s' % (slug, end)
            kwargs[self.attname] = slug
            next += 1
        return slug

    def pre_save(self, model_instance, add):
        value = force_unicode(self.create_slug(model_instance, add))
        setattr(model_instance, self.attname, value)
        return value

    def get_internal_type(self):
        return "SlugField"

    def south_field_triple(self):
        "Returns a suitable description of this field for South."
        # We'll just introspect the _actual_ field.
        from south.modelsinspector import introspector
        field_class = '%s.AutoSlugField' % self.__module__
        args, kwargs = introspector(self)
        kwargs.update({
            'populate_from': repr(self._populate_from),
            'separator': repr(self.separator),
            'overwrite': repr(self.overwrite),
            'allow_duplicates': repr(self.allow_duplicates),
        })
        # That's our definition!
        return (field_class, args, kwargs)


class CreationDateTimeField(DateTimeField):
    """ CreationDateTimeField

    By default, sets editable=False, blank=True, default=datetime.now
    """

    def __init__(self, *args, **kwargs):
        kwargs.setdefault('editable', False)
        kwargs.setdefault('blank', True)
        kwargs.setdefault('default', datetime_now)
        DateTimeField.__init__(self, *args, **kwargs)

    def get_internal_type(self):
        return "DateTimeField"

    def south_field_triple(self):
        "Returns a suitable description of this field for South."
        # We'll just introspect ourselves, since we inherit.
        from south.modelsinspector import introspector
        field_class = "django.db.models.fields.DateTimeField"
        args, kwargs = introspector(self)
        return (field_class, args, kwargs)


class ModificationDateTimeField(CreationDateTimeField):
    """ ModificationDateTimeField

    By default, sets editable=False, blank=True, default=datetime.now

    Sets value to datetime.now() on each save of the model.
    """

    def pre_save(self, model, add):
        value = datetime_now()
        setattr(model, self.attname, value)
        return value

    def get_internal_type(self):
        return "DateTimeField"

    def south_field_triple(self):
        "Returns a suitable description of this field for South."
        # We'll just introspect ourselves, since we inherit.
        from south.modelsinspector import introspector
        field_class = "django.db.models.fields.DateTimeField"
        args, kwargs = introspector(self)
        return (field_class, args, kwargs)


class UUIDVersionError(Exception):
    pass


class UUIDField(CharField):
    """ UUIDField

    By default uses UUID version 4 (randomly generated UUID).

    The field support all uuid versions which are natively supported by the uuid python module, except version 2.
    For more information see: http://docs.python.org/lib/module-uuid.html
    """

    def __init__(self, verbose_name=None, name=None, auto=True, version=4, node=None, clock_seq=None, namespace=None, **kwargs):
        if not HAS_UUID:
            raise ImproperlyConfigured("'uuid' module is required for UUIDField. (Do you have Python 2.5 or higher installed ?)")
        kwargs.setdefault('max_length', 36)
        if auto:
            self.empty_strings_allowed = False
            kwargs['blank'] = True
            kwargs.setdefault('editable', False)
        self.auto = auto
        self.version = version
        if version == 1:
            self.node, self.clock_seq = node, clock_seq
        elif version == 3 or version == 5:
            self.namespace, self.name = namespace, name
        CharField.__init__(self, verbose_name, name, **kwargs)

    def get_internal_type(self):
        return CharField.__name__

    def create_uuid(self):
        if not self.version or self.version == 4:
            return uuid.uuid4()
        elif self.version == 1:
            return uuid.uuid1(self.node, self.clock_seq)
        elif self.version == 2:
            raise UUIDVersionError("UUID version 2 is not supported.")
        elif self.version == 3:
            return uuid.uuid3(self.namespace, self.name)
        elif self.version == 5:
            return uuid.uuid5(self.namespace, self.name)
        else:
            raise UUIDVersionError("UUID version %s is not valid." % self.version)

    def pre_save(self, model_instance, add):
        value = super(UUIDField, self).pre_save(model_instance, add)
        if self.auto and add and value is None:
            value = force_unicode(self.create_uuid())
            setattr(model_instance, self.attname, value)
            return value
        else:
            if self.auto and not value:
                value = force_unicode(self.create_uuid())
                setattr(model_instance, self.attname, value)
        return value

    def formfield(self, **kwargs):
        if self.auto:
            return None
        return super(UUIDField, self).formfield(**kwargs)

    def south_field_triple(self):
        "Returns a suitable description of this field for South."
        # We'll just introspect the _actual_ field.
        from south.modelsinspector import introspector
        field_class = "django.db.models.fields.CharField"
        args, kwargs = introspector(self)
        # That's our definition!
        return (field_class, args, kwargs)


class PostgreSQLUUIDField(UUIDField):
    def db_type(self, connection=None):
        return "UUID"
