# -*- coding: utf-8 -*-
# Copyright 2018 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 itertools

from six.moves import zip

import attr

from synapse.api.constants import EventTypes, JoinRules, Membership
from synapse.api.room_versions import RoomVersions
from synapse.event_auth import auth_types_for_event
from synapse.events import FrozenEvent
from synapse.state.v2 import lexicographical_topological_sort, resolve_events_with_store
from synapse.types import EventID

from tests import unittest

ALICE = "@alice:example.com"
BOB = "@bob:example.com"
CHARLIE = "@charlie:example.com"
EVELYN = "@evelyn:example.com"
ZARA = "@zara:example.com"

ROOM_ID = "!test:example.com"

MEMBERSHIP_CONTENT_JOIN = {"membership": Membership.JOIN}
MEMBERSHIP_CONTENT_BAN = {"membership": Membership.BAN}


ORIGIN_SERVER_TS = 0


class FakeEvent(object):
    """A fake event we use as a convenience.

    NOTE: Again as a convenience we use "node_ids" rather than event_ids to
    refer to events. The event_id has node_id as localpart and example.com
    as domain.
    """

    def __init__(self, id, sender, type, state_key, content):
        self.node_id = id
        self.event_id = EventID(id, "example.com").to_string()
        self.sender = sender
        self.type = type
        self.state_key = state_key
        self.content = content

    def to_event(self, auth_events, prev_events):
        """Given the auth_events and prev_events, convert to a Frozen Event

        Args:
            auth_events (list[str]): list of event_ids
            prev_events (list[str]): list of event_ids

        Returns:
            FrozenEvent
        """
        global ORIGIN_SERVER_TS

        ts = ORIGIN_SERVER_TS
        ORIGIN_SERVER_TS = ORIGIN_SERVER_TS + 1

        event_dict = {
            "auth_events": [(a, {}) for a in auth_events],
            "prev_events": [(p, {}) for p in prev_events],
            "event_id": self.node_id,
            "sender": self.sender,
            "type": self.type,
            "content": self.content,
            "origin_server_ts": ts,
            "room_id": ROOM_ID,
        }

        if self.state_key is not None:
            event_dict["state_key"] = self.state_key

        return FrozenEvent(event_dict)


# All graphs start with this set of events
INITIAL_EVENTS = [
    FakeEvent(
        id="CREATE",
        sender=ALICE,
        type=EventTypes.Create,
        state_key="",
        content={"creator": ALICE},
    ),
    FakeEvent(
        id="IMA",
        sender=ALICE,
        type=EventTypes.Member,
        state_key=ALICE,
        content=MEMBERSHIP_CONTENT_JOIN,
    ),
    FakeEvent(
        id="IPOWER",
        sender=ALICE,
        type=EventTypes.PowerLevels,
        state_key="",
        content={"users": {ALICE: 100}},
    ),
    FakeEvent(
        id="IJR",
        sender=ALICE,
        type=EventTypes.JoinRules,
        state_key="",
        content={"join_rule": JoinRules.PUBLIC},
    ),
    FakeEvent(
        id="IMB",
        sender=BOB,
        type=EventTypes.Member,
        state_key=BOB,
        content=MEMBERSHIP_CONTENT_JOIN,
    ),
    FakeEvent(
        id="IMC",
        sender=CHARLIE,
        type=EventTypes.Member,
        state_key=CHARLIE,
        content=MEMBERSHIP_CONTENT_JOIN,
    ),
    FakeEvent(
        id="IMZ",
        sender=ZARA,
        type=EventTypes.Member,
        state_key=ZARA,
        content=MEMBERSHIP_CONTENT_JOIN,
    ),
    FakeEvent(
        id="START", sender=ZARA, type=EventTypes.Message, state_key=None, content={}
    ),
    FakeEvent(
        id="END", sender=ZARA, type=EventTypes.Message, state_key=None, content={}
    ),
]

INITIAL_EDGES = ["START", "IMZ", "IMC", "IMB", "IJR", "IPOWER", "IMA", "CREATE"]


class StateTestCase(unittest.TestCase):
    def test_ban_vs_pl(self):
        events = [
            FakeEvent(
                id="PA",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="MA",
                sender=ALICE,
                type=EventTypes.Member,
                state_key=ALICE,
                content={"membership": Membership.JOIN},
            ),
            FakeEvent(
                id="MB",
                sender=ALICE,
                type=EventTypes.Member,
                state_key=BOB,
                content={"membership": Membership.BAN},
            ),
            FakeEvent(
                id="PB",
                sender=BOB,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
        ]

        edges = [["END", "MB", "MA", "PA", "START"], ["END", "PB", "PA"]]

        expected_state_ids = ["PA", "MA", "MB"]

        self.do_check(events, edges, expected_state_ids)

    def test_join_rule_evasion(self):
        events = [
            FakeEvent(
                id="JR",
                sender=ALICE,
                type=EventTypes.JoinRules,
                state_key="",
                content={"join_rules": JoinRules.PRIVATE},
            ),
            FakeEvent(
                id="ME",
                sender=EVELYN,
                type=EventTypes.Member,
                state_key=EVELYN,
                content={"membership": Membership.JOIN},
            ),
        ]

        edges = [["END", "JR", "START"], ["END", "ME", "START"]]

        expected_state_ids = ["JR"]

        self.do_check(events, edges, expected_state_ids)

    def test_offtopic_pl(self):
        events = [
            FakeEvent(
                id="PA",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="PB",
                sender=BOB,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50, CHARLIE: 50}},
            ),
            FakeEvent(
                id="PC",
                sender=CHARLIE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50, CHARLIE: 0}},
            ),
        ]

        edges = [["END", "PC", "PB", "PA", "START"], ["END", "PA"]]

        expected_state_ids = ["PC"]

        self.do_check(events, edges, expected_state_ids)

    def test_topic_basic(self):
        events = [
            FakeEvent(
                id="T1", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="PA1",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="T2", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="PA2",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 0}},
            ),
            FakeEvent(
                id="PB",
                sender=BOB,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="T3", sender=BOB, type=EventTypes.Topic, state_key="", content={}
            ),
        ]

        edges = [["END", "PA2", "T2", "PA1", "T1", "START"], ["END", "T3", "PB", "PA1"]]

        expected_state_ids = ["PA2", "T2"]

        self.do_check(events, edges, expected_state_ids)

    def test_topic_reset(self):
        events = [
            FakeEvent(
                id="T1", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="PA",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="T2", sender=BOB, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="MB",
                sender=ALICE,
                type=EventTypes.Member,
                state_key=BOB,
                content={"membership": Membership.BAN},
            ),
        ]

        edges = [["END", "MB", "T2", "PA", "T1", "START"], ["END", "T1"]]

        expected_state_ids = ["T1", "MB", "PA"]

        self.do_check(events, edges, expected_state_ids)

    def test_topic(self):
        events = [
            FakeEvent(
                id="T1", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="PA1",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="T2", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="PA2",
                sender=ALICE,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 0}},
            ),
            FakeEvent(
                id="PB",
                sender=BOB,
                type=EventTypes.PowerLevels,
                state_key="",
                content={"users": {ALICE: 100, BOB: 50}},
            ),
            FakeEvent(
                id="T3", sender=BOB, type=EventTypes.Topic, state_key="", content={}
            ),
            FakeEvent(
                id="MZ1",
                sender=ZARA,
                type=EventTypes.Message,
                state_key=None,
                content={},
            ),
            FakeEvent(
                id="T4", sender=ALICE, type=EventTypes.Topic, state_key="", content={}
            ),
        ]

        edges = [
            ["END", "T4", "MZ1", "PA2", "T2", "PA1", "T1", "START"],
            ["END", "MZ1", "T3", "PB", "PA1"],
        ]

        expected_state_ids = ["T4", "PA2"]

        self.do_check(events, edges, expected_state_ids)

    def do_check(self, events, edges, expected_state_ids):
        """Take a list of events and edges and calculate the state of the
        graph at END, and asserts it matches `expected_state_ids`

        Args:
            events (list[FakeEvent])
            edges (list[list[str]]): A list of chains of event edges, e.g.
                `[[A, B, C]]` are edges A->B and B->C.
            expected_state_ids (list[str]): The expected state at END, (excluding
                the keys that haven't changed since START).
        """
        # We want to sort the events into topological order for processing.
        graph = {}

        # node_id -> FakeEvent
        fake_event_map = {}

        for ev in itertools.chain(INITIAL_EVENTS, events):
            graph[ev.node_id] = set()
            fake_event_map[ev.node_id] = ev

        for a, b in pairwise(INITIAL_EDGES):
            graph[a].add(b)

        for edge_list in edges:
            for a, b in pairwise(edge_list):
                graph[a].add(b)

        # event_id -> FrozenEvent
        event_map = {}
        # node_id -> state
        state_at_event = {}

        # We copy the map as the sort consumes the graph
        graph_copy = {k: set(v) for k, v in graph.items()}

        for node_id in lexicographical_topological_sort(graph_copy, key=lambda e: e):
            fake_event = fake_event_map[node_id]
            event_id = fake_event.event_id

            prev_events = list(graph[node_id])

            if len(prev_events) == 0:
                state_before = {}
            elif len(prev_events) == 1:
                state_before = dict(state_at_event[prev_events[0]])
            else:
                state_d = resolve_events_with_store(
                    RoomVersions.V2.identifier,
                    [state_at_event[n] for n in prev_events],
                    event_map=event_map,
                    state_res_store=TestStateResolutionStore(event_map),
                )

                state_before = self.successResultOf(state_d)

            state_after = dict(state_before)
            if fake_event.state_key is not None:
                state_after[(fake_event.type, fake_event.state_key)] = event_id

            auth_types = set(auth_types_for_event(fake_event))

            auth_events = []
            for key in auth_types:
                if key in state_before:
                    auth_events.append(state_before[key])

            event = fake_event.to_event(auth_events, prev_events)

            state_at_event[node_id] = state_after
            event_map[event_id] = event

        expected_state = {}
        for node_id in expected_state_ids:
            # expected_state_ids are node IDs rather than event IDs,
            # so we have to convert
            event_id = EventID(node_id, "example.com").to_string()
            event = event_map[event_id]

            key = (event.type, event.state_key)

            expected_state[key] = event_id

        start_state = state_at_event["START"]
        end_state = {
            key: value
            for key, value in state_at_event["END"].items()
            if key in expected_state or start_state.get(key) != value
        }

        self.assertEqual(expected_state, end_state)


class LexicographicalTestCase(unittest.TestCase):
    def test_simple(self):
        graph = {"l": {"o"}, "m": {"n", "o"}, "n": {"o"}, "o": set(), "p": {"o"}}

        res = list(lexicographical_topological_sort(graph, key=lambda x: x))

        self.assertEqual(["o", "l", "n", "m", "p"], res)


class SimpleParamStateTestCase(unittest.TestCase):
    def setUp(self):
        # We build up a simple DAG.

        event_map = {}

        create_event = FakeEvent(
            id="CREATE",
            sender=ALICE,
            type=EventTypes.Create,
            state_key="",
            content={"creator": ALICE},
        ).to_event([], [])
        event_map[create_event.event_id] = create_event

        alice_member = FakeEvent(
            id="IMA",
            sender=ALICE,
            type=EventTypes.Member,
            state_key=ALICE,
            content=MEMBERSHIP_CONTENT_JOIN,
        ).to_event([create_event.event_id], [create_event.event_id])
        event_map[alice_member.event_id] = alice_member

        join_rules = FakeEvent(
            id="IJR",
            sender=ALICE,
            type=EventTypes.JoinRules,
            state_key="",
            content={"join_rule": JoinRules.PUBLIC},
        ).to_event(
            auth_events=[create_event.event_id, alice_member.event_id],
            prev_events=[alice_member.event_id],
        )
        event_map[join_rules.event_id] = join_rules

        # Bob and Charlie join at the same time, so there is a fork
        bob_member = FakeEvent(
            id="IMB",
            sender=BOB,
            type=EventTypes.Member,
            state_key=BOB,
            content=MEMBERSHIP_CONTENT_JOIN,
        ).to_event(
            auth_events=[create_event.event_id, join_rules.event_id],
            prev_events=[join_rules.event_id],
        )
        event_map[bob_member.event_id] = bob_member

        charlie_member = FakeEvent(
            id="IMC",
            sender=CHARLIE,
            type=EventTypes.Member,
            state_key=CHARLIE,
            content=MEMBERSHIP_CONTENT_JOIN,
        ).to_event(
            auth_events=[create_event.event_id, join_rules.event_id],
            prev_events=[join_rules.event_id],
        )
        event_map[charlie_member.event_id] = charlie_member

        self.event_map = event_map
        self.create_event = create_event
        self.alice_member = alice_member
        self.join_rules = join_rules
        self.bob_member = bob_member
        self.charlie_member = charlie_member

        self.state_at_bob = {
            (e.type, e.state_key): e.event_id
            for e in [create_event, alice_member, join_rules, bob_member]
        }

        self.state_at_charlie = {
            (e.type, e.state_key): e.event_id
            for e in [create_event, alice_member, join_rules, charlie_member]
        }

        self.expected_combined_state = {
            (e.type, e.state_key): e.event_id
            for e in [
                create_event,
                alice_member,
                join_rules,
                bob_member,
                charlie_member,
            ]
        }

    def test_event_map_none(self):
        # Test that we correctly handle passing `None` as the event_map

        state_d = resolve_events_with_store(
            RoomVersions.V2.identifier,
            [self.state_at_bob, self.state_at_charlie],
            event_map=None,
            state_res_store=TestStateResolutionStore(self.event_map),
        )

        state = self.successResultOf(state_d)

        self.assert_dict(self.expected_combined_state, state)


def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = itertools.tee(iterable)
    next(b, None)
    return zip(a, b)


@attr.s
class TestStateResolutionStore(object):
    event_map = attr.ib()

    def get_events(self, event_ids, allow_rejected=False):
        """Get events from the database

        Args:
            event_ids (list): The event_ids of the events to fetch
            allow_rejected (bool): If True return rejected events.

        Returns:
            Deferred[dict[str, FrozenEvent]]: Dict from event_id to event.
        """

        return {eid: self.event_map[eid] for eid in event_ids if eid in self.event_map}

    def get_auth_chain(self, event_ids):
        """Gets the full auth chain for a set of events (including rejected
        events).

        Includes the given event IDs in the result.

        Note that:
            1. All events must be state events.
            2. For v1 rooms this may not have the full auth chain in the
               presence of rejected events

        Args:
            event_ids (list): The event IDs of the events to fetch the auth
                chain for. Must be state events.

        Returns:
            Deferred[list[str]]: List of event IDs of the auth chain.
        """

        # Simple DFS for auth chain
        result = set()
        stack = list(event_ids)
        while stack:
            event_id = stack.pop()
            if event_id in result:
                continue

            result.add(event_id)

            event = self.event_map[event_id]
            for aid in event.auth_event_ids():
                stack.append(aid)

        return list(result)
