#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 2016 OpenMarket 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 synapse

from synapse.api.constants import EventTypes, PresenceState
from synapse.config._base import ConfigError
from synapse.config.homeserver import HomeServerConfig
from synapse.config.logger import setup_logging
from synapse.events import FrozenEvent
from synapse.handlers.presence import PresenceHandler
from synapse.http.site import SynapseSite
from synapse.http.server import JsonResource
from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
from synapse.rest.client.v2_alpha import sync
from synapse.replication.slave.storage._base import BaseSlavedStore
from synapse.replication.slave.storage.events import SlavedEventStore
from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
from synapse.replication.slave.storage.appservice import SlavedApplicationServiceStore
from synapse.replication.slave.storage.registration import SlavedRegistrationStore
from synapse.replication.slave.storage.filtering import SlavedFilteringStore
from synapse.replication.slave.storage.push_rule import SlavedPushRuleStore
from synapse.replication.slave.storage.presence import SlavedPresenceStore
from synapse.server import HomeServer
from synapse.storage.client_ips import ClientIpStore
from synapse.storage.engines import create_engine
from synapse.storage.presence import PresenceStore, UserPresenceState
from synapse.storage.roommember import RoomMemberStore
from synapse.util.async import sleep
from synapse.util.httpresourcetree import create_resource_tree
from synapse.util.logcontext import LoggingContext, preserve_fn
from synapse.util.manhole import manhole
from synapse.util.rlimit import change_resource_limit
from synapse.util.stringutils import random_string
from synapse.util.versionstring import get_version_string

from twisted.internet import reactor, defer
from twisted.web.resource import Resource

from daemonize import Daemonize

import sys
import logging
import contextlib
import gc
import ujson as json

logger = logging.getLogger("synapse.app.synchrotron")


class SynchrotronSlavedStore(
    SlavedPushRuleStore,
    SlavedEventStore,
    SlavedReceiptsStore,
    SlavedAccountDataStore,
    SlavedApplicationServiceStore,
    SlavedRegistrationStore,
    SlavedFilteringStore,
    SlavedPresenceStore,
    BaseSlavedStore,
    ClientIpStore,  # After BaseSlavedStore because the constructor is different
):
    # XXX: This is a bit broken because we don't persist forgotten rooms
    # in a way that they can be streamed. This means that we don't have a
    # way to invalidate the forgotten rooms cache correctly.
    # For now we expire the cache every 10 minutes.
    BROKEN_CACHE_EXPIRY_MS = 60 * 60 * 1000
    who_forgot_in_room = (
        RoomMemberStore.__dict__["who_forgot_in_room"]
    )

    # XXX: This is a bit broken because we don't persist the accepted list in a
    # way that can be replicated. This means that we don't have a way to
    # invalidate the cache correctly.
    get_presence_list_accepted = PresenceStore.__dict__[
        "get_presence_list_accepted"
    ]

UPDATE_SYNCING_USERS_MS = 10 * 1000


class SynchrotronPresence(object):
    def __init__(self, hs):
        self.http_client = hs.get_simple_http_client()
        self.store = hs.get_datastore()
        self.user_to_num_current_syncs = {}
        self.syncing_users_url = hs.config.worker_replication_url + "/syncing_users"
        self.clock = hs.get_clock()

        active_presence = self.store.take_presence_startup_info()
        self.user_to_current_state = {
            state.user_id: state
            for state in active_presence
        }

        self.process_id = random_string(16)
        logger.info("Presence process_id is %r", self.process_id)

        self._sending_sync = False
        self._need_to_send_sync = False
        self.clock.looping_call(
            self._send_syncing_users_regularly,
            UPDATE_SYNCING_USERS_MS,
        )

        reactor.addSystemEventTrigger("before", "shutdown", self._on_shutdown)

    def set_state(self, user, state, ignore_status_msg=False):
        # TODO Hows this supposed to work?
        pass

    get_states = PresenceHandler.get_states.__func__
    current_state_for_users = PresenceHandler.current_state_for_users.__func__

    @defer.inlineCallbacks
    def user_syncing(self, user_id, affect_presence):
        if affect_presence:
            curr_sync = self.user_to_num_current_syncs.get(user_id, 0)
            self.user_to_num_current_syncs[user_id] = curr_sync + 1
            prev_states = yield self.current_state_for_users([user_id])
            if prev_states[user_id].state == PresenceState.OFFLINE:
                # TODO: Don't block the sync request on this HTTP hit.
                yield self._send_syncing_users_now()

        def _end():
            # We check that the user_id is in user_to_num_current_syncs because
            # user_to_num_current_syncs may have been cleared if we are
            # shutting down.
            if affect_presence and user_id in self.user_to_num_current_syncs:
                self.user_to_num_current_syncs[user_id] -= 1

        @contextlib.contextmanager
        def _user_syncing():
            try:
                yield
            finally:
                _end()

        defer.returnValue(_user_syncing())

    @defer.inlineCallbacks
    def _on_shutdown(self):
        # When the synchrotron is shutdown tell the master to clear the in
        # progress syncs for this process
        self.user_to_num_current_syncs.clear()
        yield self._send_syncing_users_now()

    def _send_syncing_users_regularly(self):
        # Only send an update if we aren't in the middle of sending one.
        if not self._sending_sync:
            preserve_fn(self._send_syncing_users_now)()

    @defer.inlineCallbacks
    def _send_syncing_users_now(self):
        if self._sending_sync:
            # We don't want to race with sending another update.
            # Instead we wait for that update to finish and send another
            # update afterwards.
            self._need_to_send_sync = True
            return

        # Flag that we are sending an update.
        self._sending_sync = True

        yield self.http_client.post_json_get_json(self.syncing_users_url, {
            "process_id": self.process_id,
            "syncing_users": [
                user_id for user_id, count in self.user_to_num_current_syncs.items()
                if count > 0
            ],
        })

        # Unset the flag as we are no longer sending an update.
        self._sending_sync = False
        if self._need_to_send_sync:
            # If something happened while we were sending the update then
            # we might need to send another update.
            # TODO: Check if the update that was sent matches the current state
            # as we only need to send an update if they are different.
            self._need_to_send_sync = False
            yield self._send_syncing_users_now()

    def process_replication(self, result):
        stream = result.get("presence", {"rows": []})
        for row in stream["rows"]:
            (
                position, user_id, state, last_active_ts,
                last_federation_update_ts, last_user_sync_ts, status_msg,
                currently_active
            ) = row
            self.user_to_current_state[user_id] = UserPresenceState(
                user_id, state, last_active_ts,
                last_federation_update_ts, last_user_sync_ts, status_msg,
                currently_active
            )


class SynchrotronTyping(object):
    def __init__(self, hs):
        self._latest_room_serial = 0
        self._room_serials = {}
        self._room_typing = {}

    def stream_positions(self):
        return {"typing": self._latest_room_serial}

    def process_replication(self, result):
        stream = result.get("typing")
        if stream:
            self._latest_room_serial = int(stream["position"])

            for row in stream["rows"]:
                position, room_id, typing_json = row
                typing = json.loads(typing_json)
                self._room_serials[room_id] = position
                self._room_typing[room_id] = typing


class SynchrotronApplicationService(object):
    def notify_interested_services(self, event):
        pass


class SynchrotronServer(HomeServer):
    def get_db_conn(self, run_new_connection=True):
        # Any param beginning with cp_ is a parameter for adbapi, and should
        # not be passed to the database engine.
        db_params = {
            k: v for k, v in self.db_config.get("args", {}).items()
            if not k.startswith("cp_")
        }
        db_conn = self.database_engine.module.connect(**db_params)

        if run_new_connection:
            self.database_engine.on_new_connection(db_conn)
        return db_conn

    def setup(self):
        logger.info("Setting up.")
        self.datastore = SynchrotronSlavedStore(self.get_db_conn(), self)
        logger.info("Finished setting up.")

    def _listen_http(self, listener_config):
        port = listener_config["port"]
        bind_address = listener_config.get("bind_address", "")
        site_tag = listener_config.get("tag", port)
        resources = {}
        for res in listener_config["resources"]:
            for name in res["names"]:
                if name == "metrics":
                    resources[METRICS_PREFIX] = MetricsResource(self)
                elif name == "client":
                    resource = JsonResource(self, canonical_json=False)
                    sync.register_servlets(self, resource)
                    resources.update({
                        "/_matrix/client/r0": resource,
                        "/_matrix/client/unstable": resource,
                        "/_matrix/client/v2_alpha": resource,
                    })

        root_resource = create_resource_tree(resources, Resource())
        reactor.listenTCP(
            port,
            SynapseSite(
                "synapse.access.http.%s" % (site_tag,),
                site_tag,
                listener_config,
                root_resource,
            ),
            interface=bind_address
        )
        logger.info("Synapse synchrotron now listening on port %d", port)

    def start_listening(self, listeners):
        for listener in listeners:
            if listener["type"] == "http":
                self._listen_http(listener)
            elif listener["type"] == "manhole":
                reactor.listenTCP(
                    listener["port"],
                    manhole(
                        username="matrix",
                        password="rabbithole",
                        globals={"hs": self},
                    ),
                    interface=listener.get("bind_address", '127.0.0.1')
                )
            else:
                logger.warn("Unrecognized listener type: %s", listener["type"])

    @defer.inlineCallbacks
    def replicate(self):
        http_client = self.get_simple_http_client()
        store = self.get_datastore()
        replication_url = self.config.worker_replication_url
        clock = self.get_clock()
        notifier = self.get_notifier()
        presence_handler = self.get_presence_handler()
        typing_handler = self.get_typing_handler()

        def expire_broken_caches():
            store.who_forgot_in_room.invalidate_all()
            store.get_presence_list_accepted.invalidate_all()

        def notify_from_stream(
            result, stream_name, stream_key, room=None, user=None
        ):
            stream = result.get(stream_name)
            if stream:
                position_index = stream["field_names"].index("position")
                if room:
                    room_index = stream["field_names"].index(room)
                if user:
                    user_index = stream["field_names"].index(user)

                users = ()
                rooms = ()
                for row in stream["rows"]:
                    position = row[position_index]

                    if user:
                        users = (row[user_index],)

                    if room:
                        rooms = (row[room_index],)

                    notifier.on_new_event(
                        stream_key, position, users=users, rooms=rooms
                    )

        def notify(result):
            stream = result.get("events")
            if stream:
                max_position = stream["position"]
                for row in stream["rows"]:
                    position = row[0]
                    internal = json.loads(row[1])
                    event_json = json.loads(row[2])
                    event = FrozenEvent(event_json, internal_metadata_dict=internal)
                    extra_users = ()
                    if event.type == EventTypes.Member:
                        extra_users = (event.state_key,)
                    notifier.on_new_room_event(
                        event, position, max_position, extra_users
                    )

            notify_from_stream(
                result, "push_rules", "push_rules_key", user="user_id"
            )
            notify_from_stream(
                result, "user_account_data", "account_data_key", user="user_id"
            )
            notify_from_stream(
                result, "room_account_data", "account_data_key", user="user_id"
            )
            notify_from_stream(
                result, "tag_account_data", "account_data_key", user="user_id"
            )
            notify_from_stream(
                result, "receipts", "receipt_key", room="room_id"
            )
            notify_from_stream(
                result, "typing", "typing_key", room="room_id"
            )

        next_expire_broken_caches_ms = 0
        while True:
            try:
                args = store.stream_positions()
                args.update(typing_handler.stream_positions())
                args["timeout"] = 30000
                result = yield http_client.get_json(replication_url, args=args)
                now_ms = clock.time_msec()
                if now_ms > next_expire_broken_caches_ms:
                    expire_broken_caches()
                    next_expire_broken_caches_ms = (
                        now_ms + store.BROKEN_CACHE_EXPIRY_MS
                    )
                yield store.process_replication(result)
                typing_handler.process_replication(result)
                presence_handler.process_replication(result)
                notify(result)
            except:
                logger.exception("Error replicating from %r", replication_url)
                yield sleep(5)

    def build_presence_handler(self):
        return SynchrotronPresence(self)

    def build_typing_handler(self):
        return SynchrotronTyping(self)


def start(config_options):
    try:
        config = HomeServerConfig.load_config(
            "Synapse synchrotron", config_options
        )
    except ConfigError as e:
        sys.stderr.write("\n" + e.message + "\n")
        sys.exit(1)

    assert config.worker_app == "synapse.app.synchrotron"

    setup_logging(config.worker_log_config, config.worker_log_file)

    database_engine = create_engine(config.database_config)

    ss = SynchrotronServer(
        config.server_name,
        db_config=config.database_config,
        config=config,
        version_string="Synapse/" + get_version_string(synapse),
        database_engine=database_engine,
        application_service_handler=SynchrotronApplicationService(),
    )

    ss.setup()
    ss.start_listening(config.worker_listeners)

    def run():
        with LoggingContext("run"):
            logger.info("Running")
            change_resource_limit(config.soft_file_limit)
            if config.gc_thresholds:
                gc.set_threshold(*config.gc_thresholds)
            reactor.run()

    def start():
        ss.get_datastore().start_profiling()
        ss.replicate()

    reactor.callWhenRunning(start)

    if config.worker_daemonize:
        daemon = Daemonize(
            app="synapse-synchrotron",
            pid=config.worker_pid_file,
            action=run,
            auto_close_fds=False,
            verbose=True,
            logger=logger,
        )
        daemon.start()
    else:
        run()


if __name__ == '__main__':
    with LoggingContext("main"):
        start(sys.argv[1:])