"""

Helper functions for creating Form classes from Django models

and database field objects.

"""

from django.utils.encoding import smart_unicode, force_unicode

from django.utils.datastructures import SortedDict

from django.utils.text import get_text_list, capfirst

from django.utils.translation import ugettext_lazy as _, ugettext

from util import ValidationError, ErrorList

from forms import BaseForm, get_declared_fields, NON_FIELD_ERRORS

from fields import Field, ChoiceField, IntegerField, EMPTY_VALUES

from widgets import Select, SelectMultiple, HiddenInput, MultipleHiddenInput

from widgets import media_property

from formsets import BaseFormSet, formset_factory, DELETION_FIELD_NAME

try:

    set

except NameError:

    from sets import Set as set     # Python 2.3 fallback

__all__ = (

    'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',

    'save_instance', 'form_for_fields', 'ModelChoiceField',

    'ModelMultipleChoiceField',

)

def save_instance(form, instance, fields=None, fail_message='saved',

                  commit=True, exclude=None):

    """

    Saves bound Form ``form``'s cleaned_data into model instance ``instance``.

    If commit=True, then the changes to ``instance`` will be saved to the

    database. Returns ``instance``.

    """

    from django.db import models

    opts = instance._meta

    if form.errors:

        raise ValueError("The %s could not be %s because the data didn't"

                         " validate." % (opts.object_name, fail_message))

    cleaned_data = form.cleaned_data

    file_field_list = []

    for f in opts.fields:

        if not f.editable or isinstance(f, models.AutoField) \

                or not f.name in cleaned_data:

            continue

        if fields and f.name not in fields:

            continue

        if exclude and f.name in exclude:

            continue

        # OneToOneField doesn't allow assignment of None. Guard against that

        # instead of allowing it and throwing an error.

        if isinstance(f, models.OneToOneField) and cleaned_data[f.name] is None:

            continue

        # Defer saving file-type fields until after the other fields, so a

        # callable upload_to can use the values from other fields.

        if isinstance(f, models.FileField):

            file_field_list.append(f)

        else:

            f.save_form_data(instance, cleaned_data[f.name])

    for f in file_field_list:

        f.save_form_data(instance, cleaned_data[f.name])

    # Wrap up the saving of m2m data as a function.

    def save_m2m():

        opts = instance._meta

        cleaned_data = form.cleaned_data

        for f in opts.many_to_many:

            if fields and f.name not in fields:

                continue

            if f.name in cleaned_data:

                f.save_form_data(instance, cleaned_data[f.name])

    if commit:

        # If we are committing, save the instance and the m2m data immediately.

        instance.save()

        save_m2m()

    else:

        # We're not committing. Add a method to the form to allow deferred

        # saving of m2m data.

        form.save_m2m = save_m2m

    return instance

def make_model_save(model, fields, fail_message):

    """Returns the save() method for a Form."""

    def save(self, commit=True):

        return save_instance(self, model(), fields, fail_message, commit)

    return save

def make_instance_save(instance, fields, fail_message):

    """Returns the save() method for a Form."""

    def save(self, commit=True):

        return save_instance(self, instance, fields, fail_message, commit)

    return save

def form_for_fields(field_list):

    """

    Returns a Form class for the given list of Django database field instances.

    """

    fields = SortedDict([(f.name, f.formfield())

                         for f in field_list if f.editable])

    return type('FormForFields', (BaseForm,), {'base_fields': fields})

# ModelForms #################################################################

def model_to_dict(instance, fields=None, exclude=None):

    """

    Returns a dict containing the data in ``instance`` suitable for passing as

    a Form's ``initial`` keyword argument.

    ``fields`` is an optional list of field names. If provided, only the named

    fields will be included in the returned dict.

    ``exclude`` is an optional list of field names. If provided, the named

    fields will be excluded from the returned dict, even if they are listed in

    the ``fields`` argument.

    """

    # avoid a circular import

    from django.db.models.fields.related import ManyToManyField, OneToOneField

    opts = instance._meta

    data = {}

    for f in opts.fields + opts.many_to_many:

        if not f.editable:

            continue

        if fields and not f.name in fields:

            continue

        if exclude and f.name in exclude:

            continue

        if isinstance(f, ManyToManyField):

            # If the object doesn't have a primry key yet, just use an empty

            # list for its m2m fields. Calling f.value_from_object will raise

            # an exception.

            if instance.pk is None:

                data[f.name] = []

            else:

                # MultipleChoiceWidget needs a list of pks, not object instances.

                data[f.name] = [obj.pk for obj in f.value_from_object(instance)]

        else:

            data[f.name] = f.value_from_object(instance)

    return data

def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda f: f.formfield()):

    """

    Returns a ``SortedDict`` containing form fields for the given model.

    ``fields`` is an optional list of field names. If provided, only the named

    fields will be included in the returned fields.

    ``exclude`` is an optional list of field names. If provided, the named

    fields will be excluded from the returned fields, even if they are listed

    in the ``fields`` argument.

    """

    field_list = []

    opts = model._meta

    for f in opts.fields + opts.many_to_many:

        if not f.editable:

            continue

        if fields and not f.name in fields:

            continue

        if exclude and f.name in exclude:

            continue

        formfield = formfield_callback(f)

        if formfield:

            field_list.append((f.name, formfield))

    field_dict = SortedDict(field_list)

    if fields:

        field_dict = SortedDict([(f, field_dict.get(f)) for f in fields if (not exclude) or (exclude and f not in exclude)])

    return field_dict

class ModelFormOptions(object):

    def __init__(self, options=None):

        self.model = getattr(options, 'model', None)

        self.fields = getattr(options, 'fields', None)

        self.exclude = getattr(options, 'exclude', None)

class ModelFormMetaclass(type):

    def __new__(cls, name, bases, attrs):

        formfield_callback = attrs.pop('formfield_callback',

                lambda f: f.formfield())

        try:

            parents = [b for b in bases if issubclass(b, ModelForm)]

        except NameError:

            # We are defining ModelForm itself.

            parents = None

        declared_fields = get_declared_fields(bases, attrs, False)

        new_class = super(ModelFormMetaclass, cls).__new__(cls, name, bases,

                attrs)

        if not parents:

            return new_class

        if 'media' not in attrs:

            new_class.media = media_property(new_class)

        opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))

        if opts.model:

            # If a model is defined, extract form fields from it.

            fields = fields_for_model(opts.model, opts.fields,

                                      opts.exclude, formfield_callback)

            # Override default model fields with any custom declared ones

            # (plus, include all the other declared fields).

            fields.update(declared_fields)

        else:

            fields = declared_fields

        new_class.declared_fields = declared_fields

        new_class.base_fields = fields

        return new_class

class BaseModelForm(BaseForm):

    def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,

                 initial=None, error_class=ErrorList, label_suffix=':',

                 empty_permitted=False, instance=None):

        opts = self._meta

        if instance is None:

            # if we didn't get an instance, instantiate a new one

            self.instance = opts.model()

            object_data = {}

        else:

            self.instance = instance

            object_data = model_to_dict(instance, opts.fields, opts.exclude)

        # if initial was provided, it should override the values from instance

        if initial is not None:

            object_data.update(initial)

        super(BaseModelForm, self).__init__(data, files, auto_id, prefix, object_data,

                                            error_class, label_suffix, empty_permitted)

    def clean(self):

        self.validate_unique()

        return self.cleaned_data

    def validate_unique(self):

        unique_checks, date_checks = self._get_unique_checks()

        form_errors = []

        bad_fields = set()

        field_errors, global_errors = self._perform_unique_checks(unique_checks)

        bad_fields.union(field_errors)

        form_errors.extend(global_errors)

        field_errors, global_errors = self._perform_date_checks(date_checks)

        bad_fields.union(field_errors)

        form_errors.extend(global_errors)

        for field_name in bad_fields:

            del self.cleaned_data[field_name]

        if form_errors:

            # Raise the unique together errors since they are considered

            # form-wide.

            raise ValidationError(form_errors)

    def _get_unique_checks(self):

        from django.db.models.fields import FieldDoesNotExist, Field as ModelField

        # Gather a list of checks to perform. We only perform unique checks

        # for fields present and not None in cleaned_data.  Since this is a

        # ModelForm, some fields may have been excluded; we can't perform a unique

        # check on a form that is missing fields involved in that check.  It also does

        # not make sense to check data that didn't validate, and since NULL does not

        # equal NULL in SQL we should not do any unique checking for NULL values.

        unique_checks = []

        # these are checks for the unique_for_<date/year/month>

        date_checks = []

        for check in self.instance._meta.unique_together[:]:

            fields_on_form = [field for field in check if self.cleaned_data.get(field) is not None]

            if len(fields_on_form) == len(check):

                unique_checks.append(check)

        # Gather a list of checks for fields declared as unique and add them to

        # the list of checks. Again, skip empty fields and any that did not validate.

        for name in self.fields:

            try:

                f = self.instance._meta.get_field_by_name(name)[0]

            except FieldDoesNotExist:

                # This is an extra field that's not on the ModelForm, ignore it

                continue

            if not isinstance(f, ModelField):

                # This is an extra field that happens to have a name that matches,

                # for example, a related object accessor for this model.  So

                # get_field_by_name found it, but it is not a Field so do not proceed

                # to use it as if it were.

                continue

            if self.cleaned_data.get(name) is None:

                continue

            if f.unique:

                unique_checks.append((name,))

            if f.unique_for_date and self.cleaned_data.get(f.unique_for_date) is not None:

                date_checks.append(('date', name, f.unique_for_date))

            if f.unique_for_year and self.cleaned_data.get(f.unique_for_year) is not None:

                date_checks.append(('year', name, f.unique_for_year))

            if f.unique_for_month and self.cleaned_data.get(f.unique_for_month) is not None:

                date_checks.append(('month', name, f.unique_for_month))

        return unique_checks, date_checks

    def _perform_unique_checks(self, unique_checks):

        bad_fields = set()

        form_errors = []

        for unique_check in unique_checks:

            # Try to look up an existing object with the same values as this

            # object's values for all the unique field.

            lookup_kwargs = {}

            for field_name in unique_check:

                lookup_value = self.cleaned_data[field_name]

                # ModelChoiceField will return an object instance rather than

                # a raw primary key value, so convert it to a pk value before

                # using it in a lookup.

                if isinstance(self.fields[field_name], ModelChoiceField):

                    lookup_value =  lookup_value.pk

                lookup_kwargs[str(field_name)] = lookup_value

            qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)

            # Exclude the current object from the query if we are editing an

            # instance (as opposed to creating a new one)

            if self.instance.pk is not None:

                qs = qs.exclude(pk=self.instance.pk)

            # This cute trick with extra/values is the most efficient way to

            # tell if a particular query returns any results.

            if qs.extra(select={'a': 1}).values('a').order_by():

                if len(unique_check) == 1:

                    self._errors[unique_check[0]] = ErrorList([self.unique_error_message(unique_check)])

                else:

                    form_errors.append(self.unique_error_message(unique_check))

                # Mark these fields as needing to be removed from cleaned data

                # later.

                for field_name in unique_check:

                    bad_fields.add(field_name)

        return bad_fields, form_errors

    def _perform_date_checks(self, date_checks):

        bad_fields = set()

        for lookup_type, field, unique_for in date_checks:

            lookup_kwargs = {}

            # there's a ticket to add a date lookup, we can remove this special

            # case if that makes it's way in

            if lookup_type == 'date':

                date = self.cleaned_data[unique_for]

                lookup_kwargs['%s__day' % unique_for] = date.day

                lookup_kwargs['%s__month' % unique_for] = date.month

                lookup_kwargs['%s__year' % unique_for] = date.year

            else:

                lookup_kwargs['%s__%s' % (unique_for, lookup_type)] = getattr(self.cleaned_data[unique_for], lookup_type)

            lookup_kwargs[field] = self.cleaned_data[field]

            qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)

            # Exclude the current object from the query if we are editing an

            # instance (as opposed to creating a new one)

            if self.instance.pk is not None:

                qs = qs.exclude(pk=self.instance.pk)

            # This cute trick with extra/values is the most efficient way to

            # tell if a particular query returns any results.

            if qs.extra(select={'a': 1}).values('a').order_by():

                self._errors[field] = ErrorList([

                    self.date_error_message(lookup_type, field, unique_for)

                ])

                bad_fields.add(field)

        return bad_fields, []

    def date_error_message(self, lookup_type, field, unique_for):

        return _(u"%(field_name)s must be unique for %(date_field)s %(lookup)s.") % {

            'field_name': unicode(self.fields[field].label),

            'date_field': unicode(self.fields[unique_for].label),

            'lookup': lookup_type,

        }

    def unique_error_message(self, unique_check):

        model_name = capfirst(self.instance._meta.verbose_name)

        # A unique field

        if len(unique_check) == 1:

            field_name = unique_check[0]

            field_label = self.fields[field_name].label

            # Insert the error into the error dict, very sneaky

            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {

                'model_name': unicode(model_name),

                'field_label': unicode(field_label)

            }

        # unique_together

        else:

            field_labels = [self.fields[field_name].label for field_name in unique_check]

            field_labels = get_text_list(field_labels, _('and'))

            return _(u"%(model_name)s with this %(field_label)s already exists.") %  {

                'model_name': unicode(model_name),

                'field_label': unicode(field_labels)

            }

    def save(self, commit=True):