# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

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

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""

Base form classes

-----------------

.. Note:

   Form is the glue that bind a context to a set of fields, and is rendered

   using a form renderer. No display is actually done here, though you'll find

   some attributes of form that are used to control the rendering process.

Besides the automagic form we'll see later, there are roughly two main

form classes in |cubicweb|:

.. autoclass:: cubicweb.web.views.forms.FieldsForm

.. autoclass:: cubicweb.web.views.forms.EntityFieldsForm

As you have probably guessed, choosing between them is easy. Simply ask you the

question 'I am editing an entity or not?'. If the answer is yes, use

:class:`EntityFieldsForm`, else use :class:`FieldsForm`.

Actually there exists a third form class:

.. autoclass:: cubicweb.web.views.forms.CompositeForm

but you'll use this one rarely.

"""

from __future__ import with_statement

__docformat__ = "restructuredtext en"

from warnings import warn

from logilab.common import dictattr, tempattr

from logilab.common.decorators import iclassmethod, cached

from logilab.common.compat import any

from logilab.common.textutils import splitstrip

from logilab.common.deprecation import deprecated

from cubicweb import ValidationError, typed_eid

from cubicweb.utils import support_args

from cubicweb.predicates import non_final_entity, match_kwargs, one_line_rset

from cubicweb.web import RequestError, ProcessFormError

from cubicweb.web.formfields import guess_field

class FieldsForm(form.Form):

    """This is the base class for fields based forms.

    **Attributes**

    The following attributes may be either set on subclasses or given on

    form selection to customize the generated form:

    :attr:`needs_js`

      sequence of javascript files that should be added to handle this form

      (through :meth:`~cubicweb.web.request.Request.add_js`)

    :attr:`needs_css`

      sequence of css files that should be added to handle this form (through

      :meth:`~cubicweb.web.request.Request.add_css`)

    :attr:`domid`

      value for the "id" attribute of the <form> tag

    :attr:`action`

      value for the "action" attribute of the <form> tag

    :attr:`onsubmit`

      value for the "onsubmit" attribute of the <form> tag

    :attr:`cssclass`

      value for the "class" attribute of the <form> tag

    :attr:`cssstyle`

      value for the "style" attribute of the <form> tag

    :attr:`cwtarget`

      value for the "cubicweb:target" attribute of the <form> tag

    :attr:`redirect_path`

      relative to redirect to after submitting the form

    :attr:`copy_nav_params`

      flag telling if navigation parameters should be copied back in hidden

      inputs

    :attr:`form_buttons`

      sequence of form control (:class:`~cubicweb.web.formwidgets.Button`

      widgets instances)

    :attr:`form_renderer_id`

      identifier of the form renderer to use to render the form

    :attr:`fieldsets_in_order`

      sequence of fieldset names , to control order

    **Generic methods**

    .. automethod:: cubicweb.web.form.Form.field_by_name(name, role=None)

    .. automethod:: cubicweb.web.form.Form.fields_by_name(name, role=None)

    **Form construction methods**

    .. automethod:: cubicweb.web.form.Form.remove_field(field)

    .. automethod:: cubicweb.web.form.Form.append_field(field)

    .. automethod:: cubicweb.web.form.Form.insert_field_before(field, name, role=None)

    .. automethod:: cubicweb.web.form.Form.insert_field_after(field, name, role=None)

    .. automethod:: cubicweb.web.form.Form.add_hidden(name, value=None, **kwargs)

    **Form rendering methods**

    .. automethod:: cubicweb.web.views.forms.FieldsForm.render

    **Form posting methods**

    Once a form is posted, you can retrieve the form on the controller side and

    use the following methods to ease processing. For "simple" forms, this

    should looks like :

    .. sourcecode :: python

        form = self._cw.vreg['forms'].select('myformid', self._cw)

        posted = form.process_posted()

        # do something with the returned dictionary

    Notice that form related to entity edition should usually use the

    `edit` controller which will handle all the logic for you.

    .. automethod:: cubicweb.web.views.forms.FieldsForm.process_posted

    .. automethod:: cubicweb.web.views.forms.FieldsForm.iter_modified_fields

    """

    __regid__ = 'base'

    # attributes overrideable by subclasses or through __init__

    needs_js = ('cubicweb.ajax.js', 'cubicweb.edition.js',)

    needs_css = ('cubicweb.form.css',)

    action = None

    cssclass = None

    cssstyle = None

    cwtarget = None

    redirect_path = None

    form_buttons = None

    form_renderer_id = 'default'

    fieldsets_in_order = None

    @property

    def needs_multipart(self):

        """true if the form needs enctype=multipart/form-data"""

        return any(field.needs_multipart for field in self.fields)

    def _get_onsubmit(self):

        try:

            return self._onsubmit

        except AttributeError:

            return "return freezeFormButtons('%(domid)s');" % dictattr(self)

    def _set_onsubmit(self, value):

        self._onsubmit = value

    onsubmit = property(_get_onsubmit, _set_onsubmit)

    def add_media(self):

        """adds media (CSS & JS) required by this widget"""

        if self.needs_js:

            self._cw.add_js(self.needs_js)

        if self.needs_css:

            self._cw.add_css(self.needs_css)

    def render(self, formvalues=None, renderer=None, **kwargs):

        """Render this form, using the `renderer` given as argument or the

        default according to :attr:`form_renderer_id`. The rendered form is

        returned as an unicode string.

        `formvalues` is an optional dictionary containing values that will be

        considered as field's value.

        Extra keyword arguments will be given to renderer's :meth:`render` method.

        """

        w = kwargs.pop('w', None)

        if w is None:

            warn('[3.10] you should specify "w" to form.render() named arguments',

                 DeprecationWarning, stacklevel=2)

            data = []

            w = data.append

        else:

            data = None

        self.build_context(formvalues)

        if renderer is None:

            renderer = self.default_renderer()

        if support_args(renderer.render, 'w'):

            renderer.render(w, self, kwargs)

        else:

            warn('[3.10] you should add "w" as first argument o %s.render()'

                 % renderer.__class__, DeprecationWarning)

            w(renderer.render(self, kwargs))

        if data is not None:

            return '\n'.join(data)

    def default_renderer(self):

        return self._cw.vreg['formrenderers'].select(

            self.form_renderer_id, self._cw,

            rset=self.cw_rset, row=self.cw_row, col=self.cw_col or 0)

    formvalues = None

    def build_context(self, formvalues=None):

        """build form context values (the .context attribute which is a

        dictionary with field instance as key associated to a dictionary

        containing field 'name' (qualified), 'id', 'value' (for display, always

        a string).

        """

        if self.formvalues is not None:

            return # already built

        self.formvalues = formvalues or {}

        # use a copy in case fields are modified while context is built (eg

        # __linkto handling for instance)

        for field in self.fields[:]:

            for field in field.actual_fields(self):

                field.form_init(self)

        # store used field in an hidden input for later usage by a controller

        fields = set()

        eidfields = set()

        for field in self.fields:

            if field.eidparam:

                eidfields.add(field.role_name())

            elif field.name not in self.control_fields:

                fields.add(field.role_name())

        if fields:

            self.add_hidden('_cw_fields', u','.join(fields))

        if eidfields:

            self.add_hidden('_cw_entity_fields', u','.join(eidfields),

                            eidparam=True)

    _default_form_action_path = 'edit'

    def form_action(self):

        try:

            action = self.get_action() # avoid spurious warning w/ autoform bw compat property

        except AttributeError:

            action = self.action

        if action is None:

            return self._cw.build_url(self._default_form_action_path)

        return action

    # controller form processing methods #######################################

    def iter_modified_fields(self, editedfields=None, entity=None):

        """return a generator on field that has been modified by the posted

        form.

        """

        if editedfields is None:

            try:

                editedfields = self._cw.form['_cw_fields']

            except KeyError:

                raise RequestError(self._cw._('no edited fields specified'))

        entityform = entity and self.field_by_name.im_func.func_code.co_argcount == 4 # XXX

        for editedfield in splitstrip(editedfields):

            try:

                name, role = editedfield.split('-')

            except Exception:

                name = editedfield

                role = None

            if entityform:

                field = self.field_by_name(name, role, eschema=entity.e_schema)

            else:

                field = self.field_by_name(name, role)

            if field.has_been_modified(self):

                yield field

    def process_posted(self):

        """use this method to process the content posted by a simple form.  it

        will return a dictionary with field names as key and typed value as

        associated value.

        """

        with tempattr(self, 'formvalues', {}): # init fields value cache

            errors = []

            processed = {}

            for field in self.iter_modified_fields():

                try:

                    for field, value in field.process_posted(self):

                        processed[field.role_name()] = value

                except ProcessFormError, exc:

                    errors.append((field, exc))

            if errors:

                errors = dict((f.role_name(), unicode(ex)) for f, ex in errors)

                raise ValidationError(None, errors)

            return processed

_AFF = uicfg.autoform_field

_AFF_KWARGS = uicfg.autoform_field_kwargs

class EntityFieldsForm(FieldsForm):

    """This class is designed for forms used to edit some entities. It should

    handle for you all the underlying stuff necessary to properly work with the

    generic :class:`~cubicweb.web.views.editcontroller.EditController`.

    """

    __regid__ = 'base'

    __select__ = (match_kwargs('entity')

                  | (one_line_rset() & non_final_entity()))

    domid = 'entityForm'

    @iclassmethod

    def field_by_name(cls_or_self, name, role=None, eschema=None):

        """return field with the given name and role. If field is not explicitly

        defined for the form but `eclass` is specified, guess_field will be

        called.

        """

        try:

            return super(EntityFieldsForm, cls_or_self).field_by_name(name, role)

        except form.FieldNotFound:

            if eschema is None or role is None or not name in eschema.schema:

                raise

            rschema = eschema.schema.rschema(name)

            # XXX use a sample target type. Document this.

            tschemas = rschema.targets(eschema, role)

            fieldcls = _AFF.etype_get(eschema, rschema, role, tschemas[0])

            kwargs = _AFF_KWARGS.etype_get(eschema, rschema, role, tschemas[0])

            if kwargs is None:

                kwargs = {}

            if fieldcls:

                if not isinstance(fieldcls, type):

                    return fieldcls # already and instance

                return fieldcls(name=name, role=role, eidparam=True, **kwargs)

            field = guess_field(eschema, rschema, role, eidparam=True, **kwargs)

            if field is None:

                raise

            return field

    def __init__(self, _cw, rset=None, row=None, col=None, **kwargs):

        try:

            self.edited_entity = kwargs.pop('entity')

        except KeyError:

            self.edited_entity = rset.complete_entity(row or 0, col or 0)

        msg = kwargs.pop('submitmsg', None)

        super(EntityFieldsForm, self).__init__(_cw, rset, row, col, **kwargs)

        self.add_hidden('__type', self.edited_entity.__regid__, eidparam=True)

        self.add_hidden('eid', self.edited_entity.eid)

        # mainform default to true in parent, hence default to True

        if kwargs.get('mainform', True) or kwargs.get('mainentity', False):

            self.add_hidden(u'__maineid', self.edited_entity.eid)

            # If we need to directly attach the new object to another one

            if '__linkto' in self._cw.form:

                if msg:

                    msg = '%s %s' % (msg, self._cw._('and linked'))

                else:

                    msg = self._cw._('entity linked')

        if msg:

            msgid = self._cw.set_redirect_message(msg)

            self.add_hidden('_cwmsgid', msgid)

    def add_linkto_hidden(self):

        """add the __linkto hidden field used to directly attach the new object

        to an existing other one when the relation between those two is not

        already present in the form.

        Warning: this method must be called only when all form fields are setup

        """

        for (rtype, role), eids in self.linked_to.iteritems():

            # if the relation is already setup by a form field, do not add it

            # in a __linkto hidden to avoid setting it twice in the controller

            try:

                self.field_by_name(rtype, role)

            except form.FieldNotFound:

                for eid in eids:

                    self.add_hidden('__linkto', '%s:%s:%s' % (rtype, eid, role))

    def render(self, *args, **kwargs):

        self.add_linkto_hidden()

        return super(EntityFieldsForm, self).render(*args, **kwargs)

    @property

    @cached

    def linked_to(self):

        # if current form is not the main form, exit immediately

        try:

            self.field_by_name('__maineid')

        except form.FieldNotFound:

            return {}

        linked_to = {}

        for linkto in self._cw.list_form_param('__linkto'):

            ltrtype, eid, ltrole = linkto.split(':')