"""field classes for form construction

:organization: Logilab

:copyright: 2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

from warnings import warn

from datetime import datetime

from logilab.mtconverter import xml_escape

from yams.constraints import (SizeConstraint, StaticVocabularyConstraint,

                              FormatConstraint)

from cubicweb.utils import ustrftime, compute_cardinality

from cubicweb.common import tags, uilib

from cubicweb.web import INTERNAL_FIELD_VALUE

from cubicweb.web.formwidgets import (

    HiddenInput, TextInput, FileInput, PasswordInput, TextArea, FCKEditor,

    Radio, Select, DateTimePicker)

class Field(object):

    """field class is introduced to control what's displayed in forms. It makes

    the link between something to edit and its display in the form. Actual

    display is handled by a widget associated to the field.

    Attributes

    ----------

    all the attributes described below have sensible default value which may be

    overriden by value given to field's constructor.

    :name:

       name of the field (basestring), should be unique in a form.

    :id:

       dom identifier (default to the same value as `name`), should be unique in

       a form.

    :label:

       label of the field (default to the same value as `name`).

    :help:

       help message about this field.

    :widget:

       widget associated to the field. Each field class has a default widget

       class which may be overriden per instance.

    :required:

       bool flag telling if the field is required or not.

    :initial:

       initial value, used when no value specified by other means.

    :choices:

       static vocabulary for this field. May be a list of values or a list of

       (label, value) tuples if specified.

    :sort:

       bool flag telling if the vocabulary (either static vocabulary specified

       in `choices` or dynamic vocabulary fetched from the form) should be

       sorted on label.

    :internationalizable:

       bool flag telling if the vocabulary labels should be translated using the

       current request language.

    :eidparam:

       bool flag telling if this field is linked to a specific entity

    :role:

       when the field is linked to an entity attribute or relation, tells the

       role of the entity in the relation (eg 'subject' or 'object')

    :fieldset:

       optional fieldset to which this field belongs to

    """

    # default widget associated to this class of fields. May be overriden per

    # instance

    widget = TextInput

    # does this field requires a multipart form

    needs_multipart = False

    # class attribute used for ordering of fields in a form

    __creation_rank = 0

    def __init__(self, name=None, id=None, label=None, help=None,

                 widget=None, required=False, initial=None,

                 choices=None, sort=True, internationalizable=False,

                 eidparam=False, role='subject', fieldset=None):

        self.name = name

        self.id = id or name

        self.label = label or name

        self.help = help

        self.required = required

        self.initial = initial

        self.choices = choices

        self.sort = sort

        self.internationalizable = internationalizable

        self.eidparam = eidparam

        self.role = role

        self.fieldset = fieldset

        self.init_widget(widget)

        # ordering number for this field instance

        self.creation_rank = Field.__creation_rank

        Field.__creation_rank += 1

    def __unicode__(self):

        return u'<%s name=%r label=%r id=%r initial=%r visible=%r @%x>' % (

            self.__class__.__name__, self.name, self.label,

            self.id, self.initial, self.is_visible(), id(self))

    def __repr__(self):

        return self.__unicode__().encode('utf-8')

    def init_widget(self, widget):

        if widget is not None:

            self.widget = widget

        elif self.choices and not self.widget.vocabulary_widget:

            self.widget = Select()

        if isinstance(self.widget, type):

            self.widget = self.widget()

    def set_name(self, name):

        """automatically set .id and .label when name is set"""

        assert name

        self.name = name

        if not self.id:

            self.id = name

        if not self.label:

            self.label = name

    def is_visible(self):

        """return true if the field is not an hidden field"""

        return not isinstance(self.widget, HiddenInput)

    def actual_fields(self, form):

        """return actual fields composing this field in case of a compound

        field, usually simply return self

        """

        yield self

    def format_value(self, req, value):

        """return value suitable for display where value may be a list or tuple

        of values

        """

        if isinstance(value, (list, tuple)):

            return [self.format_single_value(req, val) for val in value]

        return self.format_single_value(req, value)

    def format_single_value(self, req, value):

        """return value suitable for display"""

        if value is None or value is False:

            return u''

        if value is True:

            return u'1'

        return unicode(value)

    def get_widget(self, form):

        """return the widget instance associated to this field"""

        return self.widget

    def example_format(self, req):

        """return a sample string describing what can be given as input for this

        field

        """

        return u''

    def render(self, form, renderer):

        """render this field, which is part of form, using the given form

        renderer

        """

        widget = self.get_widget(form)

        try:

            return widget.render(form, self, renderer)

        except TypeError:

            warn('widget.render now take the renderer as third argument, please update %s implementation'

                 % widget.__class__.__name__, DeprecationWarning)

            return widget.render(form, self)

    def vocabulary(self, form):

        """return vocabulary for this field. This method will be called by

        widgets which desire it."""

        if self.choices is not None:

            if callable(self.choices):

                try:

                    vocab = self.choices(form=form)

                except TypeError:

                    warn('vocabulary method (eg field.choices) should now take '

                         'the form instance as argument', DeprecationWarning)

                    vocab = self.choices(req=form.req)

            else:

                vocab = self.choices

            if vocab and not isinstance(vocab[0], (list, tuple)):

                vocab = [(x, x) for x in vocab]

        else:

            vocab = form.form_field_vocabulary(self)

        if self.internationalizable:

            vocab = [(form.req._(label), value) for label, value in vocab]

        if self.sort:

            vocab = sorted(vocab)

        return vocab

    def form_init(self, form):

        """method called before by form_build_context to trigger potential field

        initialization requiring the form instance

        """

        pass

class StringField(Field):

    widget = TextArea

    def __init__(self, max_length=None, **kwargs):

        self.max_length = max_length # must be set before super call

        super(StringField, self).__init__(**kwargs)

    def init_widget(self, widget):

        if widget is None:

            if self.choices:

                widget = Select()

            elif self.max_length and self.max_length < 257:

                widget = TextInput()

        super(StringField, self).init_widget(widget)

        if isinstance(self.widget, TextArea):

            self.init_text_area(self.widget)

        elif isinstance(self.widget, TextInput):

            self.init_text_input(self.widget)

    def init_text_input(self, widget):

        if self.max_length:

            widget.attrs.setdefault('size', min(45, self.max_length))

            widget.attrs.setdefault('maxlength', self.max_length)

    def init_text_area(self, widget):

        if self.max_length < 513:

            widget.attrs.setdefault('cols', 60)

            widget.attrs.setdefault('rows', 5)

class RichTextField(StringField):

    widget = None

    def __init__(self, format_field=None, **kwargs):

        super(RichTextField, self).__init__(**kwargs)

        self.format_field = format_field

    def init_text_area(self, widget):

        pass

    def get_widget(self, form):

        if self.widget is None:

            if self.use_fckeditor(form):

                return FCKEditor()

            widget = TextArea()

            self.init_text_area(widget)

            return widget

        return self.widget

    def get_format_field(self, form):

        if self.format_field:

            return self.format_field

        # we have to cache generated field since it's use as key in the

        # context dictionnary

        req = form.req

        try:

            return req.data[self]

        except KeyError:

            fkwargs = {}

            if self.use_fckeditor(form):

                # if fckeditor is used and format field isn't explicitly

                # deactivated, we want an hidden field for the format

                fkwargs['widget'] = HiddenInput()

                fkwargs['initial'] = 'text/html'

            else:

                # else we want a format selector

                fkwargs['widget'] = Select()

                fcstr = FormatConstraint()

                fkwargs['choices'] = fcstr.vocabulary(req=req)

                fkwargs['internationalizable'] = True

                fkwargs['initial'] = lambda f: f.form_field_format(self)

            field = StringField(name=self.name + '_format', **fkwargs)

            req.data[self] = field

            return field

    def actual_fields(self, form):

        yield self

        format_field = self.get_format_field(form)

        if format_field:

            yield format_field

    def use_fckeditor(self, form):

        """return True if fckeditor should be used to edit entity's attribute named

        `attr`, according to user preferences

        """

        if form.req.use_fckeditor():

            return form.form_field_format(self) == 'text/html'

        return False

    def render(self, form, renderer):

        format_field = self.get_format_field(form)

        if format_field:

            # XXX we want both fields to remain vertically aligned

            format_field.widget.attrs['style'] = 'display: block'

            result = format_field.render(form, renderer)

        else:

            result = u''

        return result + self.get_widget(form).render(form, self, renderer)

class FileField(StringField):

    widget = FileInput

    needs_multipart = True

    def __init__(self, format_field=None, encoding_field=None, **kwargs):

        super(FileField, self).__init__(**kwargs)

        self.format_field = format_field

        self.encoding_field = encoding_field

    def actual_fields(self, form):

        yield self

        if self.format_field:

            yield self.format_field

        if self.encoding_field:

            yield self.encoding_field

    def render(self, form, renderer):

        wdgs = [self.get_widget(form).render(form, self, renderer)]

        if self.format_field or self.encoding_field:

            divid = '%s-advanced' % form.context[self]['name']

            wdgs.append(u'<a href="%s" title="%s"><img src="%s" alt="%s"/></a>' %

                        (xml_escape(uilib.toggle_action(divid)),

                         form.req._('show advanced fields'),

                         xml_escape(form.req.build_url('data/puce_down.png')),

                         form.req._('show advanced fields')))

            wdgs.append(u'<div id="%s" class="hidden">' % divid)

            if self.format_field:

                wdgs.append(self.render_subfield(form, self.format_field, renderer))

            if self.encoding_field:

                wdgs.append(self.render_subfield(form, self.encoding_field, renderer))

            wdgs.append(u'</div>')

        if not self.required and form.context[self]['value']:

            # trick to be able to delete an uploaded file

            wdgs.append(u'<br/>')

            wdgs.append(tags.input(name=u'%s__detach' % form.context[self]['name'],

                                   type=u'checkbox'))

            wdgs.append(form.req._('detach attached file'))

        return u'\n'.join(wdgs)

    def render_subfield(self, form, field, renderer):

        return (renderer.render_label(form, field)

                + field.render(form, renderer)

                + renderer.render_help(form, field)

                + u'<br/>')

class EditableFileField(FileField):

    editable_formats = ('text/plain', 'text/html', 'text/rest')

    def render(self, form, renderer):

        wdgs = [super(EditableFileField, self).render(form, renderer)]

        if form.form_field_format(self) in self.editable_formats:

            data = form.form_field_value(self, load_bytes=True)

            if data:

                encoding = form.form_field_encoding(self)

                try:

                    form.context[self]['value'] = unicode(data.getvalue(), encoding)

                except UnicodeError:

                    pass

                else:

                    if not self.required:

                        msg = form.req._(

                            'You can either submit a new file using the browse button above'

                            ', or choose to remove already uploaded file by checking the '

                            '"detach attached file" check-box, or edit file content online '

                            'with the widget below.')

                    else:

                        msg = form.req._(

                            'You can either submit a new file using the browse button above'

                            ', or edit file content online with the widget below.')

                    wdgs.append(u'<p><b>%s</b></p>' % msg)

                    wdgs.append(TextArea(setdomid=False).render(form, self, renderer))

                    # XXX restore form context?

        return '\n'.join(wdgs)

class IntField(Field):

    def __init__(self, min=None, max=None, **kwargs):

        super(IntField, self).__init__(**kwargs)