# -*- coding: utf-8 -*-
# Copyright 2015, 2016 OpenMarket Ltd
# 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 logging
import re

from canonicaljson import json

from twisted.internet import defer

from synapse.appservice import AppServiceTransaction
from synapse.config.appservice import load_appservices
from synapse.storage.events_worker import EventsWorkerStore

from ._base import SQLBaseStore

logger = logging.getLogger(__name__)


def _make_exclusive_regex(services_cache):
    # We precompie a regex constructed from all the regexes that the AS's
    # have registered for exclusive users.
    exclusive_user_regexes = [
        regex.pattern
        for service in services_cache
        for regex in service.get_exclusive_user_regexes()
    ]
    if exclusive_user_regexes:
        exclusive_user_regex = "|".join("(" + r + ")" for r in exclusive_user_regexes)
        exclusive_user_regex = re.compile(exclusive_user_regex)
    else:
        # We handle this case specially otherwise the constructed regex
        # will always match
        exclusive_user_regex = None

    return exclusive_user_regex


class ApplicationServiceWorkerStore(SQLBaseStore):
    def __init__(self, db_conn, hs):
        self.services_cache = load_appservices(
            hs.hostname,
            hs.config.app_service_config_files
        )
        self.exclusive_user_regex = _make_exclusive_regex(self.services_cache)

        super(ApplicationServiceWorkerStore, self).__init__(db_conn, hs)

    def get_app_services(self):
        return self.services_cache

    def get_if_app_services_interested_in_user(self, user_id):
        """Check if the user is one associated with an app service (exclusively)
        """
        if self.exclusive_user_regex:
            return bool(self.exclusive_user_regex.match(user_id))
        else:
            return False

    def get_app_service_by_user_id(self, user_id):
        """Retrieve an application service from their user ID.

        All application services have associated with them a particular user ID.
        There is no distinguishing feature on the user ID which indicates it
        represents an application service. This function allows you to map from
        a user ID to an application service.

        Args:
            user_id(str): The user ID to see if it is an application service.
        Returns:
            synapse.appservice.ApplicationService or None.
        """
        for service in self.services_cache:
            if service.sender == user_id:
                return service
        return None

    def get_app_service_by_token(self, token):
        """Get the application service with the given appservice token.

        Args:
            token (str): The application service token.
        Returns:
            synapse.appservice.ApplicationService or None.
        """
        for service in self.services_cache:
            if service.token == token:
                return service
        return None

    def get_app_service_by_id(self, as_id):
        """Get the application service with the given appservice ID.

        Args:
            as_id (str): The application service ID.
        Returns:
            synapse.appservice.ApplicationService or None.
        """
        for service in self.services_cache:
            if service.id == as_id:
                return service
        return None


class ApplicationServiceStore(ApplicationServiceWorkerStore):
    # This is currently empty due to there not being any AS storage functions
    # that can't be run on the workers. Since this may change in future, and
    # to keep consistency with the other stores, we keep this empty class for
    # now.
    pass


class ApplicationServiceTransactionWorkerStore(ApplicationServiceWorkerStore,
                                               EventsWorkerStore):
    @defer.inlineCallbacks
    def get_appservices_by_state(self, state):
        """Get a list of application services based on their state.

        Args:
            state(ApplicationServiceState): The state to filter on.
        Returns:
            A Deferred which resolves to a list of ApplicationServices, which
            may be empty.
        """
        results = yield self._simple_select_list(
            "application_services_state",
            dict(state=state),
            ["as_id"]
        )
        # NB: This assumes this class is linked with ApplicationServiceStore
        as_list = self.get_app_services()
        services = []

        for res in results:
            for service in as_list:
                if service.id == res["as_id"]:
                    services.append(service)
        defer.returnValue(services)

    @defer.inlineCallbacks
    def get_appservice_state(self, service):
        """Get the application service state.

        Args:
            service(ApplicationService): The service whose state to set.
        Returns:
            A Deferred which resolves to ApplicationServiceState.
        """
        result = yield self._simple_select_one(
            "application_services_state",
            dict(as_id=service.id),
            ["state"],
            allow_none=True,
            desc="get_appservice_state",
        )
        if result:
            defer.returnValue(result.get("state"))
            return
        defer.returnValue(None)

    def set_appservice_state(self, service, state):
        """Set the application service state.

        Args:
            service(ApplicationService): The service whose state to set.
            state(ApplicationServiceState): The connectivity state to apply.
        Returns:
            A Deferred which resolves when the state was set successfully.
        """
        return self._simple_upsert(
            "application_services_state",
            dict(as_id=service.id),
            dict(state=state)
        )

    def create_appservice_txn(self, service, events):
        """Atomically creates a new transaction for this application service
        with the given list of events.

        Args:
            service(ApplicationService): The service who the transaction is for.
            events(list<Event>): A list of events to put in the transaction.
        Returns:
            AppServiceTransaction: A new transaction.
        """
        def _create_appservice_txn(txn):
            # work out new txn id (highest txn id for this service += 1)
            # The highest id may be the last one sent (in which case it is last_txn)
            # or it may be the highest in the txns list (which are waiting to be/are
            # being sent)
            last_txn_id = self._get_last_txn(txn, service.id)

            txn.execute(
                "SELECT MAX(txn_id) FROM application_services_txns WHERE as_id=?",
                (service.id,)
            )
            highest_txn_id = txn.fetchone()[0]
            if highest_txn_id is None:
                highest_txn_id = 0

            new_txn_id = max(highest_txn_id, last_txn_id) + 1

            # Insert new txn into txn table
            event_ids = json.dumps([e.event_id for e in events])
            txn.execute(
                "INSERT INTO application_services_txns(as_id, txn_id, event_ids) "
                "VALUES(?,?,?)",
                (service.id, new_txn_id, event_ids)
            )
            return AppServiceTransaction(
                service=service, id=new_txn_id, events=events
            )

        return self.runInteraction(
            "create_appservice_txn",
            _create_appservice_txn,
        )

    def complete_appservice_txn(self, txn_id, service):
        """Completes an application service transaction.

        Args:
            txn_id(str): The transaction ID being completed.
            service(ApplicationService): The application service which was sent
            this transaction.
        Returns:
            A Deferred which resolves if this transaction was stored
            successfully.
        """
        txn_id = int(txn_id)

        def _complete_appservice_txn(txn):
            # Debugging query: Make sure the txn being completed is EXACTLY +1 from
            # what was there before. If it isn't, we've got problems (e.g. the AS
            # has probably missed some events), so whine loudly but still continue,
            # since it shouldn't fail completion of the transaction.
            last_txn_id = self._get_last_txn(txn, service.id)
            if (last_txn_id + 1) != txn_id:
                logger.error(
                    "appservice: Completing a transaction which has an ID > 1 from "
                    "the last ID sent to this AS. We've either dropped events or "
                    "sent it to the AS out of order. FIX ME. last_txn=%s "
                    "completing_txn=%s service_id=%s", last_txn_id, txn_id,
                    service.id
                )

            # Set current txn_id for AS to 'txn_id'
            self._simple_upsert_txn(
                txn, "application_services_state", dict(as_id=service.id),
                dict(last_txn=txn_id)
            )

            # Delete txn
            self._simple_delete_txn(
                txn, "application_services_txns",
                dict(txn_id=txn_id, as_id=service.id)
            )

        return self.runInteraction(
            "complete_appservice_txn",
            _complete_appservice_txn,
        )

    @defer.inlineCallbacks
    def get_oldest_unsent_txn(self, service):
        """Get the oldest transaction which has not been sent for this
        service.

        Args:
            service(ApplicationService): The app service to get the oldest txn.
        Returns:
            A Deferred which resolves to an AppServiceTransaction or
            None.
        """
        def _get_oldest_unsent_txn(txn):
            # Monotonically increasing txn ids, so just select the smallest
            # one in the txns table (we delete them when they are sent)
            txn.execute(
                "SELECT * FROM application_services_txns WHERE as_id=?"
                " ORDER BY txn_id ASC LIMIT 1",
                (service.id,)
            )
            rows = self.cursor_to_dict(txn)
            if not rows:
                return None

            entry = rows[0]

            return entry

        entry = yield self.runInteraction(
            "get_oldest_unsent_appservice_txn",
            _get_oldest_unsent_txn,
        )

        if not entry:
            defer.returnValue(None)

        event_ids = json.loads(entry["event_ids"])

        events = yield self._get_events(event_ids)

        defer.returnValue(AppServiceTransaction(
            service=service, id=entry["txn_id"], events=events
        ))

    def _get_last_txn(self, txn, service_id):
        txn.execute(
            "SELECT last_txn FROM application_services_state WHERE as_id=?",
            (service_id,)
        )
        last_txn_id = txn.fetchone()
        if last_txn_id is None or last_txn_id[0] is None:  # no row exists
            return 0
        else:
            return int(last_txn_id[0])  # select 'last_txn' col

    def set_appservice_last_pos(self, pos):
        def set_appservice_last_pos_txn(txn):
            txn.execute(
                "UPDATE appservice_stream_position SET stream_ordering = ?", (pos,)
            )
        return self.runInteraction(
            "set_appservice_last_pos", set_appservice_last_pos_txn
        )

    @defer.inlineCallbacks
    def get_new_events_for_appservice(self, current_id, limit):
        """Get all new evnets"""

        def get_new_events_for_appservice_txn(txn):
            sql = (
                "SELECT e.stream_ordering, e.event_id"
                " FROM events AS e"
                " WHERE"
                " (SELECT stream_ordering FROM appservice_stream_position)"
                "     < e.stream_ordering"
                " AND e.stream_ordering <= ?"
                " ORDER BY e.stream_ordering ASC"
                " LIMIT ?"
            )

            txn.execute(sql, (current_id, limit))
            rows = txn.fetchall()

            upper_bound = current_id
            if len(rows) == limit:
                upper_bound = rows[-1][0]

            return upper_bound, [row[1] for row in rows]

        upper_bound, event_ids = yield self.runInteraction(
            "get_new_events_for_appservice", get_new_events_for_appservice_txn,
        )

        events = yield self._get_events(event_ids)

        defer.returnValue((upper_bound, events))


class ApplicationServiceTransactionStore(ApplicationServiceTransactionWorkerStore):
    # This is currently empty due to there not being any AS storage functions
    # that can't be run on the workers. Since this may change in future, and
    # to keep consistency with the other stores, we keep this empty class for
    # now.
    pass