from itertools import cycle

from logilab.mtconverter import html_escape

from logilab.common.graph import escape, GraphGenerator, DotBackend

from yams import schema2dot as s2d

from cubicweb.selectors import implements, rql_condition, yes

from cubicweb.view import EntityView, StartupView

from cubicweb.web.action import Action

from cubicweb.web.views import TmpFileViewMixin

class ViewSchemaAction(Action):

    id = 'schema'

    __select__ = yes()

    title = _("site schema")

    category = 'siteactions'

    order = 30

    def url(self):

        return self.build_url(self.id)

# schema entity types views ###################################################

class EETypeOneLineView(baseviews.OneLineView):

    __select__ = implements('EEType')

    def cell_call(self, row, col, **kwargs):

        entity = self.entity(row, col)

        final = entity.final

        if final:

            self.w(u'<em class="finalentity">')

        super(EETypeOneLineView, self).cell_call(row, col, **kwargs)

        if final:

            self.w(u'</em>')

# in memory schema views (yams class instances) ###############################

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

class ImageView(EntityView):

    id = 'image'

    title = _('image')

    def cell_call(self, row, col):

        url = entity.absolute_url(vid='eschemagraph')

            html_escape(url),

            html_escape(self.req._('graphical schema for %s') % entity.name)))

class RestrictedSchemaDotPropsHandler(s2d.SchemaDotPropsHandler):

    def __init__(self, req):

        # FIXME: colors are arbitrary

        self.nextcolor = cycle( ('#aa0000', '#00aa00', '#0000aa',

                                 '#000000', '#888888') ).next

        self.req = req

    def display_attr(self, rschema):

        return not rschema.meta and (rschema.has_local_role('read')

                                     or rschema.has_perm(self.req, 'read'))

    # XXX remove this method once yams > 0.20 is out

    def node_properties(self, eschema):

        """return default DOT drawing options for an entity schema"""

        label = ['{',eschema.type,'|']

        label.append(r'\l'.join(rel.type for rel in eschema.subject_relations()

                                if rel.final and self.display_attr(rel)))

        label.append(r'\l}') # trailing \l ensure alignement of the last one

        return {'label' : ''.join(label), 'shape' : "record",

                'fontname' : "Courier", 'style' : "filled"}

    def edge_properties(self, rschema, subjnode, objnode):

        kwargs = super(RestrictedSchemaDotPropsHandler, self).edge_properties(rschema, subjnode, objnode)

        # symetric rels are handled differently, let yams decide what's best

        if not rschema.symetric:

            kwargs['color'] = self.nextcolor()

        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'

        return kwargs

class RestrictedSchemaVisitorMiIn:

    def __init__(self, req, *args, **kwargs):

        # hack hack hack

        assert len(self.__class__.__bases__) == 2

        self.__parent = self.__class__.__bases__[1]

        self.__parent.__init__(self, *args, **kwargs)

        self.req = req

    def nodes(self):

        for etype, eschema in self.__parent.nodes(self):

            if eschema.has_local_role('read') or eschema.has_perm(self.req, 'read'):

                yield eschema.type, eschema

    def edges(self):

        for setype, oetype, rschema in self.__parent.edges(self):

            if rschema.has_local_role('read') or rschema.has_perm(self.req, 'read'):

                yield setype, oetype, rschema

class FullSchemaVisitor(RestrictedSchemaVisitorMiIn, s2d.FullSchemaVisitor):

    pass

class OneHopESchemaVisitor(RestrictedSchemaVisitorMiIn, s2d.OneHopESchemaVisitor):

    pass

class OneHopRSchemaVisitor(RestrictedSchemaVisitorMiIn, s2d.OneHopRSchemaVisitor):

    pass

class SchemaImageView(TmpFileViewMixin, StartupView):

    id = 'schemagraph'

    content_type = 'image/png'

    skip_rels = ('owned_by', 'created_by', 'identity', 'is', 'is_instance_of')

    def _generate(self, tmpfile):

        """display global schema information"""

        skipmeta = not int(self.req.form.get('withmeta', 0))

        visitor = FullSchemaVisitor(self.req, self.schema, skiprels=self.skip_rels, skipmeta=skipmeta)

        s2d.schema2dot(outputfile=tmpfile, visitor=visitor,

                       prophdlr=RestrictedSchemaDotPropsHandler(self.req))

class EETypeSchemaImageView(TmpFileViewMixin, EntityView):

    id = 'eschemagraph'

    content_type = 'image/png'

    __select__ = implements('EEType')

    skip_rels = ('owned_by', 'created_by', 'identity', 'is', 'is_instance_of')

    def _generate(self, tmpfile):

        """display schema information for an entity"""

        entity = self.entity(self.row, self.col)

        eschema = self.vreg.schema.eschema(entity.name)

        visitor = OneHopESchemaVisitor(self.req, eschema, skiprels=self.skip_rels)

        s2d.schema2dot(outputfile=tmpfile, visitor=visitor,

                       prophdlr=RestrictedSchemaDotPropsHandler(self.req))

class ERTypeSchemaImageView(EETypeSchemaImageView):

    __select__ = implements('ERType')

    def _generate(self, tmpfile):

        """display schema information for an entity"""

        entity = self.entity(self.row, self.col)

        rschema = self.vreg.schema.rschema(entity.name)

        visitor = OneHopRSchemaVisitor(self.req, rschema)

        s2d.schema2dot(outputfile=tmpfile, visitor=visitor,

                       prophdlr=RestrictedSchemaDotPropsHandler(self.req))