# copyright 2003-2012 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/>.
"""Specific views for schema related entities"""

__docformat__ = "restructuredtext en"
from cubicweb import _

from itertools import cycle

import tempfile
import os, os.path as osp
import codecs

from six import text_type

from logilab.common.graph import GraphGenerator, DotBackend
from logilab.common.ureports import Section, Table
from logilab.common.registry import yes
from logilab.mtconverter import xml_escape
from yams import BASE_TYPES, schema2dot as s2d
from yams.buildobjs import DEFAULT_ATTRPERMS

from cubicweb.predicates import (is_instance, match_user_groups, match_kwargs,
                                has_related_entities, authenticated_user)
from cubicweb.schema import (META_RTYPES, SCHEMA_TYPES, SYSTEM_RTYPES,
                             WORKFLOW_TYPES, INTERNAL_TYPES)
from cubicweb.utils import make_uid
from cubicweb.view import EntityView, StartupView
from cubicweb import tags, uilib
from cubicweb.web import action, facet, schemaviewer
from cubicweb.web.views import uicfg, primary, baseviews, tabs, tableview, ibreadcrumbs

ALWAYS_SKIP_TYPES = BASE_TYPES | SCHEMA_TYPES
SKIP_TYPES  = (ALWAYS_SKIP_TYPES | META_RTYPES | SYSTEM_RTYPES | WORKFLOW_TYPES
               | INTERNAL_TYPES)
SKIP_TYPES.update(set(('CWUser', 'CWGroup', 'EmailAddress', 'Bookmark')))

def skip_types(req):
    if int(req.form.get('skipmeta', True)):
        return SKIP_TYPES
    return ALWAYS_SKIP_TYPES

_pvs = uicfg.primaryview_section
_pvdc = uicfg.primaryview_display_ctrl

for _action in ('read', 'add', 'update', 'delete'):
    _pvs.tag_subject_of(('*', '%s_permission' % _action, '*'), 'hidden')
    _pvs.tag_object_of(('*', '%s_permission' % _action, '*'), 'hidden')

for _etype in ('CWEType', 'CWRType', 'CWAttribute', 'CWRelation'):
    _pvdc.tag_attribute((_etype, 'description'), {'showlabel': False})

_pvs.tag_attribute(('CWEType', 'name'), 'hidden')
_pvs.tag_attribute(('CWEType', 'final'), 'hidden')
_pvs.tag_object_of(('*', 'workflow_of', 'CWEType'), 'hidden')
_pvs.tag_subject_of(('CWEType', 'default_workflow', '*'), 'hidden')
_pvs.tag_object_of(('*', 'specializes', 'CWEType'), 'hidden')
_pvs.tag_subject_of(('CWEType', 'specializes', '*'), 'hidden')
_pvs.tag_object_of(('*', 'from_entity', 'CWEType'), 'hidden')
_pvs.tag_object_of(('*', 'to_entity', 'CWEType'), 'hidden')

_pvs.tag_attribute(('CWRType', 'name'), 'hidden')
_pvs.tag_attribute(('CWRType', 'final'), 'hidden')
_pvs.tag_object_of(('*', 'relation_type', 'CWRType'), 'hidden')

_pvs.tag_subject_of(('CWAttribute', 'constrained_by', '*'), 'hidden')
_pvs.tag_subject_of(('CWRelation', 'constrained_by', '*'), 'hidden')


class SecurityViewMixIn(object):
    """mixin providing methods to display security information for a entity,
    relation or relation definition schema
    """
    cssclass = "listing schemaInfo"

    def permissions_table(self, erschema, permissions=None):
        self._cw.add_css('cubicweb.acl.css')
        w = self.w
        _ = self._cw._
        w(u'<table class="%s">' % self.cssclass)
        w(u'<tr><th>%s</th><th>%s</th><th>%s</th></tr>' % (
            _("permission"), _('granted to groups'), _('rql expressions')))
        for action in erschema.ACTIONS:
            w(u'<tr><td>%s</td><td>' % _(action))
            if permissions is None:
                groups = erschema.get_groups(action)
                rqlexprs = sorted(e.expression for e in erschema.get_rqlexprs(action))
            else:
                groups = permissions[action][0]
                rqlexprs = permissions[action][1]
            # XXX get group entity and call it's incontext view
            groups = [u'<a class="%s" href="%s">%s</a>' % (
                group, self._cw.build_url('cwgroup/%s' % group), label)
                      for label, group in sorted((_(g), g) for g in groups)]
            w(u'<br/>'.join(groups))
            w(u'</td><td>')
            w(u'<br/>'.join(rqlexprs))
            w(u'</td></tr>\n')
        w(u'</table>')

    def grouped_permissions_table(self, rschema):
        # group relation definitions with identical permissions
        perms = {}
        for rdef in rschema.rdefs.values():
            rdef_perms = []
            for action in rdef.ACTIONS:
                groups = sorted(rdef.get_groups(action))
                exprs = sorted(e.expression for e in rdef.get_rqlexprs(action))
                rdef_perms.append( (action, (tuple(groups), tuple(exprs))) )
            rdef_perms = tuple(rdef_perms)
            if rdef_perms in perms:
                perms[rdef_perms].append( (rdef.subject, rdef.object) )
            else:
                perms[rdef_perms] = [(rdef.subject, rdef.object)]
        # set layout permissions in a table for each group of relation
        # definition
        w = self.w
        _ = self._cw._
        w(u'<div style="margin: 0px 1.5em">')
        tmpl = u'<strong>%s</strong> %s <strong>%s</strong>'
        for perm, rdefs in perms.items():
            w(u'<div>%s</div>' % u', '.join(
                tmpl % (_(s.type), _(rschema.type), _(o.type)) for s, o in rdefs))
            # accessing rdef from previous loop by design: only used to get
            # ACTIONS
            self.permissions_table(rdef, dict(perm))
        w(u'</div>')


# global schema view ###########################################################

class SchemaView(tabs.TabsMixin, StartupView):
    """display schema information (graphically, listing tables...) in tabs"""
    __regid__ = 'schema'
    title = _('data model schema')
    tabs = [_('schema-diagram'), _('schema-entity-types'),
            _('schema-relation-types')]
    default_tab = 'schema-diagram'

    def call(self):
        self.w(u'<h1>%s</h1>' % self._cw._(self.title))
        self.render_tabs(self.tabs, self.default_tab)


class SchemaImageTab(StartupView):
    __regid__ = 'schema-diagram'

    def call(self):
        _ = self._cw._
        self.w(self._cw._(
            u'<div>This schema of the data model <em>excludes</em> the '
            'meta-data, but you can also display a <a href="%s">complete '
            'schema with meta-data</a>.</div>')
               % xml_escape(self._cw.build_url('view', vid='schemagraph', skipmeta=0)))
        self.w(u'<div><a href="%s">%s</a></div>' %
               (self._cw.build_url('view', vid='owl'),
                self._cw._(u'Download schema as OWL')))
        self.wview('schemagraph')

class SchemaETypeTab(StartupView):
    __regid__ = 'schema-entity-types'

    def call(self):
        self.wview('table', self._cw.execute(
            'Any X ORDERBY N WHERE X is CWEType, X name N, X final FALSE'))


class SchemaRTypeTab(StartupView):
    __regid__ = 'schema-relation-types'

    def call(self):
        self.wview('table', self._cw.execute(
            'Any X ORDERBY N WHERE X is CWRType, X name N, X final FALSE'))

# CWEType ######################################################################

# register msgid generated in entity relations tables
_('i18ncard_1'), _('i18ncard_?'), _('i18ncard_+'), _('i18ncard_*')

class CWETypePrimaryView(tabs.TabbedPrimaryView):
    __select__ = is_instance('CWEType')
    tabs = [_('cwetype-description'), _('cwetype-box'), _('cwetype-workflow'),
            _('cwetype-views'), _('cwetype-permissions')]
    default_tab = 'cwetype-description'


class CWETypeDescriptionTab(tabs.PrimaryTab):
    __regid__ = 'cwetype-description'
    __select__ = tabs.PrimaryTab.__select__ & is_instance('CWEType')

    def render_entity_attributes(self, entity):
        super(CWETypeDescriptionTab, self).render_entity_attributes(entity)
        _ = self._cw._
        # inheritance
        if entity.specializes:
            self.w(u'<div><strong>%s</strong>' % _('Parent class:'))
            self.wview('csv', entity.related('specializes', 'subject'))
            self.w(u'</div>')
        if entity.reverse_specializes:
            self.w(u'<div><strong>%s</strong>' % _('Sub-classes:'))
            self.wview('csv', entity.related('specializes', 'object'))
            self.w(u'</div>')
        # entity schema image
        self.wview('schemagraph', etype=entity.name)
        # entity schema attributes
        self.w(u'<h2>%s</h2>' % _('CWAttribute_plural'))
        rset = self._cw.execute(
            'Any A,ON,D,C,A,DE,A, IDX,FTI,I18N,R,O,RN,S ORDERBY AA '
            'WHERE A is CWAttribute, A from_entity S, S eid %(x)s, '
            'A ordernum AA, A defaultval D, A description DE, A cardinality C, '
            'A fulltextindexed FTI, A internationalizable I18N, A indexed IDX, '
            'A relation_type R, R name RN, A to_entity O, O name ON',
            {'x': entity.eid})
        self.wview('table', rset, 'null',
                   cellvids={0: 'rdef-name-cell',
                             2: 'etype-attr-defaultval-cell',
                             3: 'etype-attr-cardinality-cell',
                             4: 'rdef-constraints-cell',
                             6: 'rdef-options-cell'},
                   headers=(_(u'name'), _(u'type'),
                            _(u'default value'), _(u'required'),
                            _(u'constraints'), _(u'description'), _('options')))
        # entity schema relations
        self.w(u'<h2>%s</h2>' % _('CWRelation_plural'))
        cellvids = {0: 'rdef-name-cell',
                    2: 'etype-rel-cardinality-cell',
                    3: 'rdef-constraints-cell',
                    4: 'rdef-options-cell'}
        headers= [_(u'name'), _(u'object type'), _(u'cardinality'),
                  _(u'constraints'), _(u'options')]
        rset = self._cw.execute(
            'Any A,TT,"i18ncard_"+SUBSTRING(C,1,1),A,A, K,TTN,R,RN ORDERBY RN '
            'WHERE A is CWRelation, A from_entity S, S eid %(x)s, '
            'A composite K, A cardinality C, '
            'A relation_type R, R name RN, A to_entity TT, TT name TTN',
            {'x': entity.eid})
        if rset:
            self.w(u'<h5>%s %s</h5>' % (entity.name, _('is subject of:')))
            self.wview('table', rset, cellvids=cellvids, headers=headers)
        rset = self._cw.execute(
            'Any A,TT,"i18ncard_"+SUBSTRING(C,1,1),A,A, K,TTN,R,RN ORDERBY RN '
            'WHERE A is CWRelation, A to_entity O, O eid %(x)s, '
            'A composite K, A cardinality C, '
            'A relation_type R, R name RN, A from_entity TT, TT name TTN',
            {'x': entity.eid})
        if rset:
            cellvids[0] = 'rdef-object-name-cell'
            headers[1] = _(u'subject type')
            self.w(u'<h5>%s %s</h5>' % (entity.name, _('is object of:')))
            self.wview('table', rset, cellvids=cellvids, headers=headers)


class CWETypeAttributeCardinalityCell(baseviews.FinalView):
    __regid__ = 'etype-attr-cardinality-cell'

    def cell_call(self, row, col):
        if self.cw_rset.rows[row][col][0] == '1':
            self.w(self._cw._(u'yes'))
        else:
            self.w(self._cw._(u'no'))


class CWETypeAttributeDefaultValCell(baseviews.FinalView):
    __regid__ = 'etype-attr-defaultval-cell'

    def cell_call(self, row, col):
        defaultval = self.cw_rset.rows[row][col]
        if defaultval is not None:
            self.w(text_type(self.cw_rset.rows[row][col].unzpickle()))

class CWETypeRelationCardinalityCell(baseviews.FinalView):
    __regid__ = 'etype-rel-cardinality-cell'

    def cell_call(self, row, col):
        self.w(self._cw._(self.cw_rset.rows[row][col]))


class CWETypeBoxTab(EntityView):
    __regid__ = 'cwetype-box'
    __select__ = is_instance('CWEType')

    def cell_call(self, row, col):
        viewer = schemaviewer.SchemaViewer(self._cw)
        entity = self.cw_rset.get_entity(row, col)
        eschema = self._cw.vreg.schema.eschema(entity.name)
        layout = viewer.visit_entityschema(eschema)
        self.w(uilib.ureport_as_html(layout))
        self.w(u'<br class="clear"/>')


class CWETypePermTab(SecurityViewMixIn, EntityView):
    __regid__ = 'cwetype-permissions'
    __select__ = is_instance('CWEType') & authenticated_user()

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        eschema = self._cw.vreg.schema.eschema(entity.name)
        self.w(u'<h4>%s</h4>' % self._cw._('This entity type permissions:'))
        self.permissions_table(eschema)
        self.w(u'<div style="margin: 0px 1.5em">')
        self.w(u'<h4>%s</h4>' % self._cw._('Attributes permissions:'))
        for attr, etype in  eschema.attribute_definitions():
            if attr not in META_RTYPES:
                rdef = eschema.rdef(attr)
                attrtype = str(rdef.rtype)
                self.w(u'<h4 class="schema">%s (%s)</h4> '
                       % (attrtype, self._cw._(attrtype)))
                self.permissions_table(rdef)
        self.w(u'</div>')


class CWETypeWorkflowTab(EntityView):
    __regid__ = 'cwetype-workflow'
    __select__ = (is_instance('CWEType')
                  & has_related_entities('workflow_of', 'object'))

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        if entity.default_workflow:
            wf = entity.default_workflow[0]
            if len(entity.reverse_workflow_of) > 1:
                self.w(u'<h1>%s (%s)</h1>'
                       % (wf.name, self._cw._('default_workflow')))
            self.display_workflow(wf)
            defaultwfeid = wf.eid
        else:
            self.w(u'<div class="error">%s</div>'
                   % self._cw._('There is no default workflow'))
            defaultwfeid = None
        for altwf in entity.reverse_workflow_of:
            if altwf.eid == defaultwfeid:
                continue
            self.w(u'<h1>%s</h1>' % altwf.name)
            self.display_workflow(altwf)

    def display_workflow(self, wf):
        self.w(wf.view('wfgraph'))
        self.w('<a href="%s">%s</a>' % (
            wf.absolute_url(), self._cw._('more info about this workflow')))


class CWETypeViewsTab(EntityView):
    """possible views for this entity type"""
    __regid__ = 'cwetype-views'
    __select__ = EntityView.__select__ & is_instance('CWEType')

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        _ = self._cw._
        self.w('<div>%s</div>' % _('Non exhaustive list of views that may '
                                   'apply to entities of this type'))
        views = [(view.content_type, view.__regid__, _(view.title))
                 for view in self.possible_views(entity.name)]
        self.wview('pyvaltable', pyvalue=sorted(views),
                   headers=(_(u'content type'), _(u'view identifier'),
                            _(u'view title')))

    def possible_views(self, etype):
        rset = self._cw.etype_rset(etype)
        return [v for v in self._cw.vreg['views'].possible_views(self._cw, rset)
                if v.category != 'startupview']


class CWETypeOneLineView(baseviews.OneLineView):
    __select__ = is_instance('CWEType')

    def cell_call(self, row, col, **kwargs):
        entity = self.cw_rset.get_entity(row, col)
        if entity.final:
            self.w(u'<em class="finalentity">')
        super(CWETypeOneLineView, self).cell_call(row, col, **kwargs)
        if entity.final:
            self.w(u'</em>')


# CWRType ######################################################################

class CWRTypePrimaryView(tabs.TabbedPrimaryView):
    __select__ = is_instance('CWRType')
    tabs = [_('cwrtype-description'), _('cwrtype-permissions')]
    default_tab = 'cwrtype-description'


class CWRTypeDescriptionTab(tabs.PrimaryTab):
    __regid__ = 'cwrtype-description'
    __select__ = is_instance('CWRType')

    def render_entity_attributes(self, entity):
        super(CWRTypeDescriptionTab, self).render_entity_attributes(entity)
        _ = self._cw._
        if not entity.final:
            self.wview('schemagraph', rtype=entity.name)
        rset = self._cw.execute('Any R,C,R,R, RT WHERE '
                                'R relation_type RT, RT eid %(x)s, '
                                'R cardinality C', {'x': entity.eid})
        self.wview('table', rset, 'null',
                   headers=(_(u'relation'),  _(u'cardinality'), _(u'constraints'),
                            _(u'options')),
                   cellvids={2: 'rdef-constraints-cell',
                             3: 'rdef-options-cell'})


class CWRTypePermTab(SecurityViewMixIn, EntityView):
    __regid__ = 'cwrtype-permissions'
    __select__ = is_instance('CWRType') & authenticated_user()

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        rschema = self._cw.vreg.schema.rschema(entity.name)
        self.grouped_permissions_table(rschema)


# CWAttribute / CWRelation #####################################################

class RDEFPrimaryView(tabs.TabbedPrimaryView):
    __select__ = is_instance('CWRelation', 'CWAttribute')
    tabs = [_('rdef-description'), _('rdef-permissions')]
    default_tab = 'rdef-description'


class RDEFDescriptionTab(tabs.PrimaryTab):
    __regid__ = 'rdef-description'
    __select__ = is_instance('CWRelation', 'CWAttribute')

    def render_entity_attributes(self, entity):
        super(RDEFDescriptionTab, self).render_entity_attributes(entity)
        rdef = entity.yams_schema()
        if rdef.constraints:
            self.w(u'<h4>%s</h4>' % self._cw._('constrained_by'))
            self.w(entity.view('rdef-constraints-cell'))


class RDEFPermTab(SecurityViewMixIn, EntityView):
    __regid__ = 'rdef-permissions'
    __select__ = is_instance('CWRelation', 'CWAttribute') & authenticated_user()

    def cell_call(self, row, col):
        self.permissions_table(self.cw_rset.get_entity(row, col).yams_schema())


class RDEFNameView(tableview.CellView):
    """display relation name and its translation only in a cell view, link to
    relation definition's primary view (for use in entity type relations table
    for instance)
    """
    __regid__ = 'rdef-name-cell'
    __select__ = is_instance('CWRelation', 'CWAttribute')

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        rtype = entity.relation_type[0].name
        # XXX use context entity + pgettext
        self.w(u'<a href="%s">%s</a> (%s)' % (
            entity.absolute_url(), rtype, self._cw._(rtype)))

class RDEFObjectNameView(tableview.CellView):
    """same as RDEFNameView but when the context is the object entity
    """
    __regid__ = 'rdef-object-name-cell'
    __select__ = is_instance('CWRelation', 'CWAttribute')

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        rtype = entity.relation_type[0].name
        # XXX use context entity + pgettext
        self.w(u'<a href="%s">%s</a> (%s)' % (
            entity.absolute_url(), rtype, self._cw.__(rtype + '_object')))

class RDEFConstraintsCell(EntityView):
    __regid__ = 'rdef-constraints-cell'
    __select__ = is_instance('CWAttribute', 'CWRelation')

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        rschema = self._cw.vreg.schema.rschema(entity.rtype.name)
        rdef = rschema.rdefs[(entity.stype.name, entity.otype.name)]
        constraints = [xml_escape(text_type(c)) for c in getattr(rdef, 'constraints')]
        self.w(u'<br/>'.join(constraints))

class CWAttributeOptionsCell(EntityView):
    __regid__ = 'rdef-options-cell'
    __select__ = is_instance('CWAttribute')

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        options = []
        if entity.indexed:
            options.append(self._cw._('indexed'))
        if entity.fulltextindexed:
            options.append(self._cw._('fulltextindexed'))
        if entity.internationalizable:
            options.append(self._cw._('internationalizable'))
        self.w(u','.join(options))

class CWRelationOptionsCell(EntityView):
    __regid__ = 'rdef-options-cell'
    __select__ = is_instance('CWRelation',)

    def cell_call(self, row, col):
        entity = self.cw_rset.get_entity(row, col)
        rtype = entity.rtype
        options = []
        if rtype.symmetric:
            options.append(self._cw._('symmetric'))
        if rtype.inlined:
            options.append(self._cw._('inlined'))
        if rtype.fulltext_container:
            options.append('%s=%s' % (self._cw._('fulltext_container'),
                                      self._cw._(rtype.fulltext_container)))
        if entity.composite:
            options.append('%s=%s' % (self._cw._('composite'),
                                      self._cw._(entity.composite)))
        self.w(u','.join(options))


# schema images ###############################################################

class RestrictedSchemaVisitorMixIn(object):
    def __init__(self, req, *args, **kwargs):
        self._cw = req
        super(RestrictedSchemaVisitorMixIn, self).__init__(*args, **kwargs)

    def should_display_schema(self, rschema):
        return (super(RestrictedSchemaVisitorMixIn, self).should_display_schema(rschema)
                and rschema.may_have_permission('read', self._cw))

    def should_display_attr(self, eschema, rschema):
        return (super(RestrictedSchemaVisitorMixIn, self).should_display_attr(eschema, rschema)
                and eschema.rdef(rschema).may_have_permission('read', self._cw))


class FullSchemaVisitor(RestrictedSchemaVisitorMixIn, s2d.FullSchemaVisitor):
    pass

class OneHopESchemaVisitor(RestrictedSchemaVisitorMixIn,
                           s2d.OneHopESchemaVisitor):
    pass

class OneHopRSchemaVisitor(RestrictedSchemaVisitorMixIn,
                           s2d.OneHopRSchemaVisitor):
    pass

class CWSchemaDotPropsHandler(s2d.SchemaDotPropsHandler):
    def __init__(self, visitor, cw):
        self.visitor = visitor
        self.cw = cw
        self._cycle = iter(cycle(('#ff7700', '#000000', '#ebbc69', '#888888')))
        self.nextcolor = lambda: next(self._cycle)

        self.colors = {}

    def node_properties(self, eschema):
        """return DOT drawing options for an entity schema include href"""
        label = ['{',eschema.type,'|']
        label.append(r'\l'.join('%s (%s)' % (rel.type, eschema.rdef(rel.type).object)
                                for rel in eschema.ordered_relations()
                                    if rel.final and self.visitor.should_display_attr(eschema, rel)))
        label.append(r'\l}') # trailing \l ensure alignement of the last one
        return {'label' : ''.join(label), 'shape' : "record",
                'fontname' : "Courier", 'style' : "filled",
                'href': self.cw.build_url('cwetype/%s' % eschema.type),
                'fontsize': '10px'
                }

    def edge_properties(self, rschema, subjnode, objnode):
        """return default DOT drawing options for a relation schema"""
        # Inheritance relation (i.e 'specializes').
        if rschema is None:
            kwargs = {'label': 'Parent class',
                      'color' : 'grey',  'style' : 'filled',
                      'arrowhead': 'empty',
                      'fontsize': '10px'}
        # symmetric rels are handled differently, let yams decide what's best
        elif rschema.symmetric:
            kwargs = {'label': rschema.type,
                      'color': '#887788', 'style': 'dashed',
                      'dir': 'both', 'arrowhead': 'normal', 'arrowtail': 'normal',
                      'fontsize': '10px',
                      'href': self.cw.build_url('cwrtype/%s' % rschema.type)}
        else:
            kwargs = {'label': rschema.type,
                      'color' : 'black',  'style' : 'filled', 'fontsize': '10px',
                      'href': self.cw.build_url('cwrtype/%s' % rschema.type)}
            rdef = rschema.rdef(subjnode, objnode)
            composite = rdef.composite
            if rdef.composite == 'subject':
                kwargs['arrowhead'] = 'none'
                kwargs['arrowtail'] = 'diamond'
            elif rdef.composite == 'object':
                kwargs['arrowhead'] = 'diamond'
                kwargs['arrowtail'] = 'none'
            else:
                kwargs['arrowhead'] = 'open'
                kwargs['arrowtail'] = 'none'
            # UML like cardinalities notation, omitting 1..1
            if rdef.cardinality[1] != '1':
                kwargs['taillabel'] = s2d.CARD_MAP[rdef.cardinality[1]]
            if rdef.cardinality[0] != '1':
                kwargs['headlabel'] = s2d.CARD_MAP[rdef.cardinality[0]]
            try:
                kwargs['color'] = self.colors[rschema]
            except KeyError:
                kwargs['color'] = self.nextcolor()
                self.colors[rschema] = kwargs['color']
        kwargs['fontcolor'] = kwargs['color']
        # dot label decoration is just awful (1 line underlining the label
        # + 1 line going to the closest edge spline point)
        kwargs['decorate'] = 'false'
        #kwargs['labelfloat'] = 'true'
        return kwargs


class SchemaGraphView(StartupView):
    __regid__ = 'schemagraph'

    def call(self, etype=None, rtype=None, alt=''):
        if 'MSIE 8' in self._cw.useragent():
            return
        schema = self._cw.vreg.schema
        if etype:
            assert rtype is None
            visitor = OneHopESchemaVisitor(self._cw, schema.eschema(etype),
                                           skiptypes=skip_types(self._cw))
            alt = self._cw._('graphical representation of the %(etype)s '
                             'entity type from %(appid)s data model')
        elif rtype:
            visitor = OneHopRSchemaVisitor(self._cw, schema.rschema(rtype),
                                           skiptypes=skip_types(self._cw))
            alt = self._cw._('graphical representation of the %(rtype)s '
                             'relation type from %(appid)s data model')
        else:
            visitor = FullSchemaVisitor(self._cw, schema,
                                        skiptypes=skip_types(self._cw))
            alt = self._cw._('graphical representation of %(appid)s data model')
        alt %= {'rtype': rtype, 'etype': etype,
                'appid': self._cw.vreg.config.appid}
        prophdlr = CWSchemaDotPropsHandler(visitor, self._cw)
        generator = GraphGenerator(DotBackend('schema', 'BT',
                                              ratio='compress',size=None,
                                              renderer='dot',
                                              additionnal_param={
                                                  'overlap':'false',
                                                  'splines':'true',
                                                  'sep':'0.2',
                                              }))
        # svg image file
        fd, tmpfile = tempfile.mkstemp('.svg')
        os.close(fd)
        generator.generate(visitor, prophdlr, tmpfile)
        with codecs.open(tmpfile, 'rb', encoding='utf-8') as svgfile:
            self.w(svgfile.read())

# breadcrumbs ##################################################################

class CWRelationIBreadCrumbsAdapter(ibreadcrumbs.IBreadCrumbsAdapter):
    __select__ = is_instance('CWRelation')
    def parent_entity(self):
        return self.entity.rtype

class CWAttributeIBreadCrumbsAdapter(ibreadcrumbs.IBreadCrumbsAdapter):
    __select__ = is_instance('CWAttribute')
    def parent_entity(self):
        return self.entity.stype

class CWConstraintIBreadCrumbsAdapter(ibreadcrumbs.IBreadCrumbsAdapter):
    __select__ = is_instance('CWConstraint')
    def parent_entity(self):
        if self.entity.reverse_constrained_by:
            return self.entity.reverse_constrained_by[0]

class RQLExpressionIBreadCrumbsAdapter(ibreadcrumbs.IBreadCrumbsAdapter):
    __select__ = is_instance('RQLExpression')
    def parent_entity(self):
        return self.entity.expression_of


# misc: facets, actions ########################################################

class CWFinalFacet(facet.AttributeFacet):
    __regid__ = 'cwfinal-facet'
    __select__ = facet.AttributeFacet.__select__ & is_instance('CWEType', 'CWRType')
    rtype = 'final'


class ViewSchemaAction(action.Action):
    __regid__ = 'schema'
    __select__ = yes()

    title = _('data model schema')
    order = 30
    category = 'manage'

    def url(self):
        return self._cw.build_url(self.__regid__)