# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# 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.

from synapse.rest import admin
from synapse.rest.client import login, room, sync

from tests.unittest import HomeserverTestCase


class RedactionsTestCase(HomeserverTestCase):
    """Tests that various redaction events are handled correctly"""

    servlets = [
        admin.register_servlets,
        room.register_servlets,
        login.register_servlets,
        sync.register_servlets,
    ]

    def make_homeserver(self, reactor, clock):
        config = self.default_config()

        config["rc_message"] = {"per_second": 0.2, "burst_count": 10}
        config["rc_admin_redaction"] = {"per_second": 1, "burst_count": 100}

        return self.setup_test_homeserver(config=config)

    def prepare(self, reactor, clock, hs):
        # register a couple of users
        self.mod_user_id = self.register_user("user1", "pass")
        self.mod_access_token = self.login("user1", "pass")
        self.other_user_id = self.register_user("otheruser", "pass")
        self.other_access_token = self.login("otheruser", "pass")

        # Create a room
        self.room_id = self.helper.create_room_as(
            self.mod_user_id, tok=self.mod_access_token
        )

        # Invite the other user
        self.helper.invite(
            room=self.room_id,
            src=self.mod_user_id,
            tok=self.mod_access_token,
            targ=self.other_user_id,
        )
        # The other user joins
        self.helper.join(
            room=self.room_id, user=self.other_user_id, tok=self.other_access_token
        )

    def _redact_event(self, access_token, room_id, event_id, expect_code=200):
        """Helper function to send a redaction event.

        Returns the json body.
        """
        path = "/_matrix/client/r0/rooms/%s/redact/%s" % (room_id, event_id)

        channel = self.make_request("POST", path, content={}, access_token=access_token)
        self.assertEqual(int(channel.result["code"]), expect_code)
        return channel.json_body

    def _sync_room_timeline(self, access_token, room_id):
        channel = self.make_request("GET", "sync", access_token=self.mod_access_token)
        self.assertEqual(channel.result["code"], b"200")
        room_sync = channel.json_body["rooms"]["join"][room_id]
        return room_sync["timeline"]["events"]

    def test_redact_event_as_moderator(self):
        # as a regular user, send a message to redact
        b = self.helper.send(room_id=self.room_id, tok=self.other_access_token)
        msg_id = b["event_id"]

        # as the moderator, send a redaction
        b = self._redact_event(self.mod_access_token, self.room_id, msg_id)
        redaction_id = b["event_id"]

        # now sync
        timeline = self._sync_room_timeline(self.mod_access_token, self.room_id)

        # the last event should be the redaction
        self.assertEqual(timeline[-1]["event_id"], redaction_id)
        self.assertEqual(timeline[-1]["redacts"], msg_id)

        # and the penultimate should be the redacted original
        self.assertEqual(timeline[-2]["event_id"], msg_id)
        self.assertEqual(timeline[-2]["unsigned"]["redacted_by"], redaction_id)
        self.assertEqual(timeline[-2]["content"], {})

    def test_redact_event_as_normal(self):
        # as a regular user, send a message to redact
        b = self.helper.send(room_id=self.room_id, tok=self.other_access_token)
        normal_msg_id = b["event_id"]

        # also send one as the admin
        b = self.helper.send(room_id=self.room_id, tok=self.mod_access_token)
        admin_msg_id = b["event_id"]

        # as a normal, try to redact the admin's event
        self._redact_event(
            self.other_access_token, self.room_id, admin_msg_id, expect_code=403
        )

        # now try to redact our own event
        b = self._redact_event(self.other_access_token, self.room_id, normal_msg_id)
        redaction_id = b["event_id"]

        # now sync
        timeline = self._sync_room_timeline(self.other_access_token, self.room_id)

        # the last event should be the redaction of the normal event
        self.assertEqual(timeline[-1]["event_id"], redaction_id)
        self.assertEqual(timeline[-1]["redacts"], normal_msg_id)

        # the penultimate should be the unredacted one from the admin
        self.assertEqual(timeline[-2]["event_id"], admin_msg_id)
        self.assertNotIn("redacted_by", timeline[-2]["unsigned"])
        self.assertTrue(timeline[-2]["content"]["body"], {})

        # and the antepenultimate should be the redacted normal
        self.assertEqual(timeline[-3]["event_id"], normal_msg_id)
        self.assertEqual(timeline[-3]["unsigned"]["redacted_by"], redaction_id)
        self.assertEqual(timeline[-3]["content"], {})

    def test_redact_nonexistent_event(self):
        # control case: an existing event
        b = self.helper.send(room_id=self.room_id, tok=self.other_access_token)
        msg_id = b["event_id"]
        b = self._redact_event(self.other_access_token, self.room_id, msg_id)
        redaction_id = b["event_id"]

        # room moderators can send redactions for non-existent events
        self._redact_event(self.mod_access_token, self.room_id, "$zzz")

        # ... but normals cannot
        self._redact_event(
            self.other_access_token, self.room_id, "$zzz", expect_code=404
        )

        # when we sync, we should see only the valid redaction
        timeline = self._sync_room_timeline(self.other_access_token, self.room_id)
        self.assertEqual(timeline[-1]["event_id"], redaction_id)
        self.assertEqual(timeline[-1]["redacts"], msg_id)

        # and the penultimate should be the redacted original
        self.assertEqual(timeline[-2]["event_id"], msg_id)
        self.assertEqual(timeline[-2]["unsigned"]["redacted_by"], redaction_id)
        self.assertEqual(timeline[-2]["content"], {})

    def test_redact_create_event(self):
        # control case: an existing event
        b = self.helper.send(room_id=self.room_id, tok=self.mod_access_token)
        msg_id = b["event_id"]
        self._redact_event(self.mod_access_token, self.room_id, msg_id)

        # sync the room, to get the id of the create event
        timeline = self._sync_room_timeline(self.other_access_token, self.room_id)
        create_event_id = timeline[0]["event_id"]

        # room moderators cannot send redactions for create events
        self._redact_event(
            self.mod_access_token, self.room_id, create_event_id, expect_code=403
        )

        # and nor can normals
        self._redact_event(
            self.other_access_token, self.room_id, create_event_id, expect_code=403
        )

    def test_redact_event_as_moderator_ratelimit(self):
        """Tests that the correct ratelimiting is applied to redactions"""

        message_ids = []
        # as a regular user, send messages to redact
        for _ in range(20):
            b = self.helper.send(room_id=self.room_id, tok=self.other_access_token)
            message_ids.append(b["event_id"])
            self.reactor.advance(10)  # To get around ratelimits

        # as the moderator, send a bunch of redactions
        for msg_id in message_ids:
            # These should all succeed, even though this would be denied by
            # the standard message ratelimiter
            self._redact_event(self.mod_access_token, self.room_id, msg_id)
