text: # -*- coding: utf-8 -*-
  # Copyright 2019 New Vector Ltd
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import logging
  
  import attr
  
  from twisted.internet import defer
  
  from synapse.api.constants import RelationTypes
  from synapse.api.errors import SynapseError
  from synapse.storage._base import SQLBaseStore
  from synapse.storage.stream import generate_pagination_where_clause
  from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
  
  logger = logging.getLogger(__name__)
  
  
  @attr.s
  class PaginationChunk(object):
      """Returned by relation pagination APIs.
  
      Attributes:
          chunk (list): The rows returned by pagination
          next_batch (Any|None): Token to fetch next set of results with, if
              None then there are no more results.
          prev_batch (Any|None): Token to fetch previous set of results with, if
              None then there are no previous results.
      """
  
      chunk = attr.ib()
      next_batch = attr.ib(default=None)
      prev_batch = attr.ib(default=None)
  
      def to_dict(self):
          d = {"chunk": self.chunk}
  
          if self.next_batch:
              d["next_batch"] = self.next_batch.to_string()
  
          if self.prev_batch:
              d["prev_batch"] = self.prev_batch.to_string()
  
          return d
  
  
  @attr.s(frozen=True, slots=True)
  class RelationPaginationToken(object):
      """Pagination token for relation pagination API.
  
      As the results are in topological order, we can use the
      `topological_ordering` and `stream_ordering` fields of the events at the
      boundaries of the chunk as pagination tokens.
  
      Attributes:
          topological (int): The topological ordering of the boundary event
          stream (int): The stream ordering of the boundary event.
      """
  
      topological = attr.ib()
      stream = attr.ib()
  
      @staticmethod
      def from_string(string):
          try:
              t, s = string.split("-")
              return RelationPaginationToken(int(t), int(s))
          except ValueError:
              raise SynapseError(400, "Invalid token")
  
      def to_string(self):
          return "%d-%d" % (self.topological, self.stream)
  
      def as_tuple(self):
          return attr.astuple(self)
  
  
  @attr.s(frozen=True, slots=True)
  class AggregationPaginationToken(object):
      """Pagination token for relation aggregation pagination API.
  
      As the results are order by count and then MAX(stream_ordering) of the
      aggregation groups, we can just use them as our pagination token.
  
      Attributes:
          count (int): The count of relations in the boundar group.
          stream (int): The MAX stream ordering in the boundary group.
      """
  
      count = attr.ib()
      stream = attr.ib()
  
      @staticmethod
      def from_string(string):
          try:
              c, s = string.split("-")
              return AggregationPaginationToken(int(c), int(s))
          except ValueError:
              raise SynapseError(400, "Invalid token")
  
      def to_string(self):
          return "%d-%d" % (self.count, self.stream)
  
      def as_tuple(self):
          return attr.astuple(self)
  
  
  class RelationsWorkerStore(SQLBaseStore):
      @cached(tree=True)
      def get_relations_for_event(
          self,
          event_id,
          relation_type=None,
          event_type=None,
          aggregation_key=None,
          limit=5,
          direction="b",
          from_token=None,
          to_token=None,
      ):
          """Get a list of relations for an event, ordered by topological ordering.
  
          Args:
              event_id (str): Fetch events that relate to this event ID.
              relation_type (str|None): Only fetch events with this relation
                  type, if given.
              event_type (str|None): Only fetch events with this event type, if
                  given.
              aggregation_key (str|None): Only fetch events with this aggregation
                  key, if given.
              limit (int): Only fetch the most recent `limit` events.
              direction (str): Whether to fetch the most recent first (`"b"`) or
                  the oldest first (`"f"`).
              from_token (RelationPaginationToken|None): Fetch rows from the given
                  token, or from the start if None.
              to_token (RelationPaginationToken|None): Fetch rows up to the given
                  token, or up to the end if None.
  
          Returns:
              Deferred[PaginationChunk]: List of event IDs that match relations
              requested. The rows are of the form `{"event_id": "..."}`.
          """
  
          where_clause = ["relates_to_id = ?"]
          where_args = [event_id]
  
          if relation_type is not None:
              where_clause.append("relation_type = ?")
              where_args.append(relation_type)
  
          if event_type is not None:
              where_clause.append("type = ?")
              where_args.append(event_type)
  
          if aggregation_key:
              where_clause.append("aggregation_key = ?")
              where_args.append(aggregation_key)
  
          pagination_clause = generate_pagination_where_clause(
              direction=direction,
              column_names=("topological_ordering", "stream_ordering"),
              from_token=attr.astuple(from_token) if from_token else None,
              to_token=attr.astuple(to_token) if to_token else None,
              engine=self.database_engine,
          )
  
          if pagination_clause:
              where_clause.append(pagination_clause)
  
          if direction == "b":
              order = "DESC"
          else:
              order = "ASC"
  
          sql = """
              SELECT event_id, topological_ordering, stream_ordering
              FROM event_relations
              INNER JOIN events USING (event_id)
              WHERE %s
              ORDER BY topological_ordering %s, stream_ordering %s
              LIMIT ?
          """ % (
              " AND ".join(where_clause),
              order,
              order,
          )
  
          def _get_recent_references_for_event_txn(txn):
              txn.execute(sql, where_args + [limit + 1])
  
              last_topo_id = None
              last_stream_id = None
              events = []
              for row in txn:
                  events.append({"event_id": row[0]})
                  last_topo_id = row[1]
                  last_stream_id = row[2]
  
              next_batch = None
              if len(events) > limit and last_topo_id and last_stream_id:
                  next_batch = RelationPaginationToken(last_topo_id, last_stream_id)
  
              return PaginationChunk(
                  chunk=list(events[:limit]), next_batch=next_batch, prev_batch=from_token
              )
  
          return self.runInteraction(
              "get_recent_references_for_event", _get_recent_references_for_event_txn
          )
  
      @cached(tree=True)
      def get_aggregation_groups_for_event(
          self,
          event_id,
          event_type=None,
          limit=5,
          direction="b",
          from_token=None,
          to_token=None,
      ):
          """Get a list of annotations on the event, grouped by event type and
          aggregation key, sorted by count.
  
          This is used e.g. to get the what and how many reactions have happend
          on an event.
  
          Args:
              event_id (str): Fetch events that relate to this event ID.
              event_type (str|None): Only fetch events with this event type, if
                  given.
              limit (int): Only fetch the `limit` groups.
              direction (str): Whether to fetch the highest count first (`"b"`) or
                  the lowest count first (`"f"`).
              from_token (AggregationPaginationToken|None): Fetch rows from the
                  given token, or from the start if None.
              to_token (AggregationPaginationToken|None): Fetch rows up to the
                  given token, or up to the end if None.
  
  
          Returns:
              Deferred[PaginationChunk]: List of groups of annotations that
              match. Each row is a dict with `type`, `key` and `count` fields.
          """
  
          where_clause = ["relates_to_id = ?", "relation_type = ?"]
          where_args = [event_id, RelationTypes.ANNOTATION]
  
          if event_type:
              where_clause.append("type = ?")
              where_args.append(event_type)
  
          having_clause = generate_pagination_where_clause(
              direction=direction,
              column_names=("COUNT(*)", "MAX(stream_ordering)"),
              from_token=attr.astuple(from_token) if from_token else None,
              to_token=attr.astuple(to_token) if to_token else None,
              engine=self.database_engine,
          )
  
          if direction == "b":
              order = "DESC"
          else:
              order = "ASC"
  
          if having_clause:
              having_clause = "HAVING " + having_clause
          else:
              having_clause = ""
  
          sql = """
              SELECT type, aggregation_key, COUNT(DISTINCT sender), MAX(stream_ordering)
              FROM event_relations
              INNER JOIN events USING (event_id)
              WHERE {where_clause}
              GROUP BY relation_type, type, aggregation_key
              {having_clause}
              ORDER BY COUNT(*) {order}, MAX(stream_ordering) {order}
              LIMIT ?
          """.format(
              where_clause=" AND ".join(where_clause),
              order=order,
              having_clause=having_clause,
          )
  
          def _get_aggregation_groups_for_event_txn(txn):
              txn.execute(sql, where_args + [limit + 1])
  
              next_batch = None
              events = []
              for row in txn:
                  events.append({"type": row[0], "key": row[1], "count": row[2]})
                  next_batch = AggregationPaginationToken(row[2], row[3])
  
              if len(events) <= limit:
                  next_batch = None
  
              return PaginationChunk(
                  chunk=list(events[:limit]), next_batch=next_batch, prev_batch=from_token
              )
  
          return self.runInteraction(
              "get_aggregation_groups_for_event", _get_aggregation_groups_for_event_txn
          )
  
      @cachedInlineCallbacks()
      def get_applicable_edit(self, event_id):
          """Get the most recent edit (if any) that has happened for the given
          event.
  
          Correctly handles checking whether edits were allowed to happen.
  
          Args:
              event_id (str): The original event ID
  
          Returns:
              Deferred[EventBase|None]: Returns the most recent edit, if any.
          """
  
          # We only allow edits for `m.room.message` events that have the same sender
          # and event type. We can't assert these things during regular event auth so
          # we have to do the checks post hoc.
  
          # Fetches latest edit that has the same type and sender as the
          # original, and is an `m.room.message`.
          sql = """
              SELECT edit.event_id FROM events AS edit
              INNER JOIN event_relations USING (event_id)
              INNER JOIN events AS original ON
                  original.event_id = relates_to_id
                  AND edit.type = original.type
                  AND edit.sender = original.sender
              WHERE
                  relates_to_id = ?
                  AND relation_type = ?
                  AND edit.type = 'm.room.message'
              ORDER by edit.origin_server_ts DESC, edit.event_id DESC
              LIMIT 1
          """
  
          def _get_applicable_edit_txn(txn):
              txn.execute(sql, (event_id, RelationTypes.REPLACE))
              row = txn.fetchone()
              if row:
                  return row[0]
  
          edit_id = yield self.runInteraction(
              "get_applicable_edit", _get_applicable_edit_txn
          )
  
          if not edit_id:
              return
  
          edit_event = yield self.get_event(edit_id, allow_none=True)
          defer.returnValue(edit_event)
  
      def has_user_annotated_event(self, parent_id, event_type, aggregation_key, sender):
          """Check if a user has already annotated an event with the same key
          (e.g. already liked an event).
  
          Args:
              parent_id (str): The event being annotated
              event_type (str): The event type of the annotation
              aggregation_key (str): The aggregation key of the annotation
              sender (str): The sender of the annotation
  
          Returns:
              Deferred[bool]
          """
  
          sql = """
              SELECT 1 FROM event_relations
              INNER JOIN events USING (event_id)
              WHERE
                  relates_to_id = ?
                  AND relation_type = ?
                  AND type = ?
                  AND sender = ?
                  AND aggregation_key = ?
              LIMIT 1;
          """
  
          def _get_if_user_has_annotated_event(txn):
              txn.execute(
                  sql,
                  (
                      parent_id,
                      RelationTypes.ANNOTATION,
                      event_type,
                      sender,
                      aggregation_key,
                  ),
              )
  
              return bool(txn.fetchone())
  
          return self.runInteraction(
              "get_if_user_has_annotated_event", _get_if_user_has_annotated_event
          )
  
  
  class RelationsStore(RelationsWorkerStore):
      def _handle_event_relations(self, txn, event):
          """Handles inserting relation data during peristence of events
  
          Args:
              txn
              event (EventBase)
          """
          relation = event.content.get("m.relates_to")
          if not relation:
              # No relations
              return
  
          rel_type = relation.get("rel_type")
          if rel_type not in (
              RelationTypes.ANNOTATION,
              RelationTypes.REFERENCE,
              RelationTypes.REPLACE,
          ):
              # Unknown relation type
              return
  
          parent_id = relation.get("event_id")
          if not parent_id:
              # Invalid relation
              return
  
          aggregation_key = relation.get("key")
  
          self._simple_insert_txn(
              txn,
              table="event_relations",
              values={
                  "event_id": event.event_id,
                  "relates_to_id": parent_id,
                  "relation_type": rel_type,
                  "aggregation_key": aggregation_key,
              },
          )
  
          txn.call_after(self.get_relations_for_event.invalidate_many, (parent_id,))
          txn.call_after(
              self.get_aggregation_groups_for_event.invalidate_many, (parent_id,)
          )
  
          if rel_type == RelationTypes.REPLACE:
              txn.call_after(self.get_applicable_edit.invalidate, (parent_id,))
  
      def _handle_redaction(self, txn, redacted_event_id):
          """Handles receiving a redaction and checking whether we need to remove
          any redacted relations from the database.
  
          Args:
              txn
              redacted_event_id (str): The event that was redacted.
          """
  
          self._simple_delete_txn(
              txn, table="event_relations", keyvalues={"event_id": redacted_event_id}
          )
  