# coding=utf-8
"""
"""
from __future__ import absolute_import

import sqlalchemy as sa

from abilian.i18n import _
from abilian.core.models.tag import Tag, entity_tag_tbl
from .extension import ENTITY_DEFAULT_NS_ATTR
from ..search.criterion import BaseCriterion


class TagCriterion(BaseCriterion):
  """
  Filter entities with selected tag(s).
  """
  form_default_value = u''

  def __init__(self, *args, **kwargs):
    if len(args) == 0:
      kwargs.setdefault('name', 'tags')

    if len(args) < 2:
      kwargs.setdefault('label', _(u'Tags'))

    super(TagCriterion, self).__init__(*args, **kwargs)
  
  @BaseCriterion.model.setter
  def model(self, model):
    BaseCriterion.model.fset(self, model)
    self.ns = getattr(model, ENTITY_DEFAULT_NS_ATTR)

  @property
  def valid_tags(self):
    join_clause = entity_tag_tbl.join(
      self.model,
      self.model.id == entity_tag_tbl.c.entity_id,
    )
    model_tags = sa.sql.select([entity_tag_tbl.c.tag_id], from_obj=join_clause)
    return Tag.query.filter(Tag.ns == self.ns,
                            Tag.id.in_(model_tags))\
                    .all()

  def get_request_values(self, request):
    tag_ids = []

    for val in request.values.getlist(self.name):
      try:
        tag_ids.append(int(val))        
      except ValueError:
        pass

    valid_tags = set(self.valid_tags)
    tags = []
    for tid in tag_ids:
      t = Tag.query.get(tid)
      if t in valid_tags:
        tags.append(t)

    return tags

  
  def filter(self, query, module, request, searched_text, *args, **kwargs):
    """
    """
    tags = self.get_request_values(request)
    if not tags:
      return query

    cond = sa.sql.exists(
      sa.sql.select([1], entity_tag_tbl.c.entity_id == self.model.id)
    )
    return query.filter(cond)
    
  @property
  def form_filter_type(self):
    return "select"

  @property
  def form_unset_value(self):
    return []
  
  @property
  def form_filter_args(self):
    # expected value: [list of selectable items, is multiple?]
    return [
      [(unicode(t.id), t.label) for t in self.valid_tags],
      True,
    ]
  
