#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright 2015, 2016 OpenMarket Ltd
# Copyright (C) 2023 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
import logging
import random
import urllib.parse
from typing import TYPE_CHECKING

from prometheus_client import Counter

from twisted.internet.error import AlreadyCalled, AlreadyCancelled
from twisted.internet.interfaces import IDelayedCall

from synapse.api.constants import EventTypes
from synapse.events import EventBase
from synapse.logging import opentracing
from synapse.metrics import SERVER_NAME_LABEL
from synapse.push import Pusher, PusherConfig, PusherConfigException
from synapse.storage.databases.main.event_push_actions import HttpPushAction
from synapse.types import JsonDict, JsonMapping

from . import push_tools

if TYPE_CHECKING:
    from synapse.server import HomeServer

logger = logging.getLogger(__name__)

http_push_processed_counter = Counter(
    "synapse_http_httppusher_http_pushes_processed",
    "Number of push notifications successfully sent",
    labelnames=[SERVER_NAME_LABEL],
)

http_push_failed_counter = Counter(
    "synapse_http_httppusher_http_pushes_failed",
    "Number of push notifications which failed",
    labelnames=[SERVER_NAME_LABEL],
)

http_badges_processed_counter = Counter(
    "synapse_http_httppusher_badge_updates_processed",
    "Number of badge updates successfully sent",
    labelnames=[SERVER_NAME_LABEL],
)

http_badges_failed_counter = Counter(
    "synapse_http_httppusher_badge_updates_failed",
    "Number of badge updates which failed",
    labelnames=[SERVER_NAME_LABEL],
)


def tweaks_for_actions(actions: list[str | dict]) -> JsonMapping:
    """
    Converts a list of actions into a `tweaks` dict (which can then be passed to
        the push gateway).

    This function ignores all actions other than `set_tweak` actions, and treats
    absent `value`s as `True`, which agrees with the only spec-defined treatment
    of absent `value`s (namely, for `highlight` tweaks).

    Args:
        actions: list of actions
            e.g. [
                {"set_tweak": "a", "value": "AAA"},
                {"set_tweak": "b", "value": "BBB"},
                {"set_tweak": "highlight"},
                "notify"
            ]

    Returns:
        dictionary of tweaks for those actions
            e.g. {"a": "AAA", "b": "BBB", "highlight": True}
    """
    tweaks = {}
    for a in actions:
        if not isinstance(a, dict):
            continue
        if "set_tweak" in a:
            # value is allowed to be absent in which case the value assumed
            # should be True.
            tweaks[a["set_tweak"]] = a.get("value", True)
    return tweaks


class HttpPusher(Pusher):
    INITIAL_BACKOFF_SEC = 1  # in seconds because that's what Twisted takes
    MAX_BACKOFF_SEC = 60 * 60

    # This one's in ms because we compare it against the clock
    GIVE_UP_AFTER_MS = 24 * 60 * 60 * 1000

    def __init__(self, hs: "HomeServer", pusher_config: PusherConfig):
        super().__init__(hs, pusher_config)
        self.server_name = hs.hostname
        self._storage_controllers = self.hs.get_storage_controllers()
        self.app_display_name = pusher_config.app_display_name
        self.device_display_name = pusher_config.device_display_name
        self.device_id = pusher_config.device_id
        self.pushkey_ts = pusher_config.ts
        self.data = pusher_config.data
        self.backoff_delay = HttpPusher.INITIAL_BACKOFF_SEC
        self.failing_since = pusher_config.failing_since
        self.timed_call: IDelayedCall | None = None
        self._is_processing = False
        self._group_unread_count_by_room = (
            hs.config.push.push_group_unread_count_by_room
        )
        self._pusherpool = hs.get_pusherpool()

        self.push_jitter_delay_ms = hs.config.push.push_jitter_delay_ms

        self.data = pusher_config.data
        if self.data is None:
            raise PusherConfigException("'data' key can not be null for HTTP pusher")

        # Check if badge counts should be disabled for this push gateway
        self.disable_badge_count = self.hs.config.experimental.msc4076_enabled and bool(
            self.data.get("org.matrix.msc4076.disable_badge_count", False)
        )

        self.name = "%s/%s/%s" % (
            pusher_config.user_name,
            pusher_config.app_id,
            pusher_config.pushkey,
        )

        # Validate that there's a URL and it is of the proper form.
        if "url" not in self.data:
            raise PusherConfigException("'url' required in data for HTTP pusher")

        url = self.data["url"]
        if not isinstance(url, str):
            raise PusherConfigException("'url' must be a string")
        url_parts = urllib.parse.urlparse(url)
        # Note that the specification also says the scheme must be HTTPS, but
        # it isn't up to the homeserver to verify that.
        if url_parts.path != "/_matrix/push/v1/notify":
            raise PusherConfigException(
                "'url' must have a path of '/_matrix/push/v1/notify'"
            )

        self.url = url
        self.http_client = hs.get_proxied_blocklisted_http_client()
        self.data_minus_url = {}
        self.data_minus_url.update(self.data)
        del self.data_minus_url["url"]
        self.badge_count_last_call: int | None = None

    def on_started(self, should_check_for_notifs: bool) -> None:
        """Called when this pusher has been started.

        Args:
            should_check_for_notifs: Whether we should immediately
                check for push to send. Set to False only if it's known there
                is nothing to send
        """
        if should_check_for_notifs:
            self._start_processing()

    def on_new_receipts(self) -> None:
        # Note that the min here shouldn't be relied upon to be accurate.

        # We could check the receipts are actually m.read receipts here,
        # but currently that's the only type of receipt anyway...
        self.hs.run_as_background_process(
            "http_pusher.on_new_receipts", self._update_badge
        )

    async def _update_badge(self) -> None:
        # XXX as per https://github.com/matrix-org/matrix-doc/issues/2627, this seems
        # to be largely redundant. perhaps we can remove it.
        badge = await push_tools.get_badge_count(
            self.hs.get_datastores().main,
            self.user_id,
            group_by_room=self._group_unread_count_by_room,
        )
        if self.badge_count_last_call is None or self.badge_count_last_call != badge:
            self.badge_count_last_call = badge
            await self._send_badge(badge)

    def on_timer(self) -> None:
        self._start_processing()

    def on_stop(self) -> None:
        if self.timed_call:
            try:
                self.timed_call.cancel()
            except (AlreadyCalled, AlreadyCancelled):
                pass
            self.timed_call = None

    def _start_processing(self) -> None:
        if self._is_processing:
            return

        # Check if we are trying, but failing, to contact the pusher. If so, we
        # don't try and start processing immediately and instead wait for the
        # retry loop to try again later (which is controlled by the timer).
        if self.failing_since and self.timed_call and self.timed_call.active():
            return

        self.hs.run_as_background_process("httppush.process", self._process)

    async def _process(self) -> None:
        # we should never get here if we are already processing
        assert not self._is_processing

        try:
            self._is_processing = True
            # if the max ordering changes while we're running _unsafe_process,
            # call it again, and so on until we've caught up.
            while True:
                starting_max_ordering = self.max_stream_ordering
                try:
                    await self._unsafe_process()
                except Exception:
                    logger.exception("Exception processing notifs")
                if self.max_stream_ordering == starting_max_ordering:
                    break
        finally:
            self._is_processing = False

    async def _unsafe_process(self) -> None:
        """
        Looks for unset notifications and dispatch them, in order
        Never call this directly: use _process which will only allow this to
        run once per pusher.
        """
        unprocessed = (
            await self.store.get_unread_push_actions_for_user_in_range_for_http(
                self.user_id, self.last_stream_ordering, self.max_stream_ordering
            )
        )

        logger.info(
            "Processing %i unprocessed push actions for %s starting at "
            "stream_ordering %s",
            len(unprocessed),
            self.name,
            self.last_stream_ordering,
        )

        for push_action in unprocessed:
            with opentracing.start_active_span(
                "http-push",
                tags={
                    "authenticated_entity": self.user_id,
                    "event_id": push_action.event_id,
                    "app_id": self.app_id,
                    "app_display_name": self.app_display_name,
                },
            ):
                processed = await self._process_one(push_action)

            if processed:
                http_push_processed_counter.labels(
                    **{SERVER_NAME_LABEL: self.server_name}
                ).inc()
                self.backoff_delay = HttpPusher.INITIAL_BACKOFF_SEC
                self.last_stream_ordering = push_action.stream_ordering
                pusher_still_exists = (
                    await self.store.update_pusher_last_stream_ordering_and_success(
                        self.app_id,
                        self.pushkey,
                        self.user_id,
                        self.last_stream_ordering,
                        self.clock.time_msec(),
                    )
                )
                if not pusher_still_exists:
                    # The pusher has been deleted while we were processing, so
                    # lets just stop and return.
                    self.on_stop()
                    return

                if self.failing_since:
                    self.failing_since = None
                    await self.store.update_pusher_failing_since(
                        self.app_id, self.pushkey, self.user_id, self.failing_since
                    )
            else:
                http_push_failed_counter.labels(
                    **{SERVER_NAME_LABEL: self.server_name}
                ).inc()
                if not self.failing_since:
                    self.failing_since = self.clock.time_msec()
                    await self.store.update_pusher_failing_since(
                        self.app_id, self.pushkey, self.user_id, self.failing_since
                    )

                if (
                    self.failing_since
                    and self.failing_since
                    < self.clock.time_msec() - HttpPusher.GIVE_UP_AFTER_MS
                ):
                    # we really only give up so that if the URL gets
                    # fixed, we don't suddenly deliver a load
                    # of old notifications.
                    logger.warning(
                        "Giving up on a notification to user %s, pushkey %s",
                        self.user_id,
                        self.pushkey,
                    )
                    self.backoff_delay = HttpPusher.INITIAL_BACKOFF_SEC
                    self.last_stream_ordering = push_action.stream_ordering
                    await self.store.update_pusher_last_stream_ordering(
                        self.app_id,
                        self.pushkey,
                        self.user_id,
                        self.last_stream_ordering,
                    )

                    self.failing_since = None
                    await self.store.update_pusher_failing_since(
                        self.app_id, self.pushkey, self.user_id, self.failing_since
                    )
                else:
                    logger.info("Push failed: delaying for %ds", self.backoff_delay)
                    self.timed_call = self.hs.get_clock().call_later(
                        self.backoff_delay,
                        self.on_timer,
                    )
                    self.backoff_delay = min(
                        self.backoff_delay * 2, self.MAX_BACKOFF_SEC
                    )
                    break

    async def _process_one(self, push_action: HttpPushAction) -> bool:
        if "notify" not in push_action.actions:
            return True

        tweaks = tweaks_for_actions(push_action.actions)
        badge = await push_tools.get_badge_count(
            self.hs.get_datastores().main,
            self.user_id,
            group_by_room=self._group_unread_count_by_room,
        )

        event = await self.store.get_event(push_action.event_id, allow_none=True)
        if event is None:
            return True  # It's been redacted

        # Check if we should delay sending out the notification by a random
        # amount.
        #
        # Note: we base the delay off of when the event was sent, rather than
        # now, to handle the case where we need to send out many notifications
        # at once. If we just slept the random amount each loop then the last
        # push notification in the set could be delayed by many times the max
        # delay.
        if self.push_jitter_delay_ms:
            delay_ms = random.randint(1, self.push_jitter_delay_ms)
            diff_ms = event.origin_server_ts + delay_ms - self.clock.time_msec()
            if diff_ms > 0:
                await self.clock.sleep(diff_ms / 1000)

        rejected = await self.dispatch_push_event(event, tweaks, badge)
        if rejected is False:
            return False

        if isinstance(rejected, (list, tuple)):
            for pk in rejected:
                if pk != self.pushkey:
                    # for sanity, we only remove the pushkey if it
                    # was the one we actually sent...
                    logger.warning(
                        ("Ignoring rejected pushkey %s because we didn't send it"),
                        pk,
                    )
                else:
                    logger.info("Pushkey %s was rejected: removing", pk)
                    await self._pusherpool.remove_pusher(self.app_id, pk, self.user_id)
        return True

    async def dispatch_push(
        self,
        content: JsonDict,
        tweaks: JsonMapping | None = None,
        default_payload: JsonMapping | None = None,
    ) -> bool | list[str]:
        """Send a notification to the registered push gateway, with `content` being
        the content of the `notification` top property specified in the spec.
        Note that the `devices` property will be added with device-specific
        information for this pusher.

        Args:
            content: the content
            tweaks: tweaks to add into the `devices` section
            default_payload: default payload to add in `devices[0].data.default_payload`.
                This will be merged (and override if some matching values already exist there)
                with existing `default_payload`.

        Returns:
            False if an error occured when calling the push gateway, or an array of
            rejected push keys otherwise. If this array is empty, the push fully
            succeeded.
        """
        content = content.copy()

        data = self.data_minus_url.copy()
        if default_payload:
            data.setdefault("default_payload", {}).update(default_payload)

        device = {
            "app_id": self.app_id,
            "pushkey": self.pushkey,
            "pushkey_ts": int(self.pushkey_ts / 1000),
            "data": data,
        }
        if tweaks:
            device["tweaks"] = tweaks

        content["devices"] = [device]

        try:
            resp = await self.http_client.post_json_get_json(
                self.url, {"notification": content}
            )
        except Exception as e:
            logger.warning(
                "Failed to push data to %s: %s %s",
                self.name,
                type(e),
                e,
            )
            return False
        rejected = []
        if "rejected" in resp:
            rejected = resp["rejected"]
        return rejected

    async def dispatch_push_event(
        self,
        event: EventBase,
        tweaks: JsonMapping,
        badge: int,
    ) -> bool | list[str]:
        """Send a notification to the registered push gateway by building it
        from an event.

        Args:
            event: the event
            tweaks: tweaks to add into the `devices` section, used to decide the
                push priority
            badge: unread count to send with the push notification

        Returns:
            False if an error occured when calling the push gateway, or an array of
            rejected push keys otherwise. If this array is empty, the push fully
            succeeded.
        """
        priority = "low"
        if (
            event.type == EventTypes.Encrypted
            or tweaks.get("highlight")
            or tweaks.get("sound")
        ):
            # HACK send our push as high priority only if it generates a sound, highlight
            #  or may do so (i.e. is encrypted so has unknown effects).
            priority = "high"

        # This was checked in the __init__, but mypy doesn't seem to know that.
        assert self.data is not None
        if self.data.get("format") == "event_id_only":
            content: JsonDict = {
                "event_id": event.event_id,
                "room_id": event.room_id,
                "prio": priority,
            }
            if not self.disable_badge_count:
                content["counts"] = {"unread": badge}
            # event_id_only doesn't include the tweaks, so override them.
            tweaks = {}
        else:
            ctx = await push_tools.get_context_for_event(
                self._storage_controllers, event, self.user_id
            )

            content = {
                "id": event.event_id,  # deprecated: remove soon
                "event_id": event.event_id,
                "room_id": event.room_id,
                "type": event.type,
                "sender": event.user_id,
                "prio": priority,
            }
            if not self.disable_badge_count:
                content["counts"] = {
                    "unread": badge,
                }
            if event.type == "m.room.member" and event.is_state():
                content["membership"] = event.content["membership"]
                content["user_is_target"] = event.state_key == self.user_id
            if self.hs.config.push.push_include_content and event.content:
                content["content"] = event.content

            # We no longer send aliases separately, instead, we send the human
            # readable name of the room, which may be an alias.
            if "sender_display_name" in ctx and len(ctx["sender_display_name"]) > 0:
                content["sender_display_name"] = ctx["sender_display_name"]
            if "name" in ctx and len(ctx["name"]) > 0:
                content["room_name"] = ctx["name"]

        res = await self.dispatch_push(content, tweaks)

        # If the push is successful and none are rejected, update the badge count.
        if res is not False and not res:
            self.badge_count_last_call = badge

        return res

    async def _send_badge(self, badge: int) -> None:
        """
        Args:
            badge: number of unread messages
        """
        logger.debug("Sending updated badge count %d to %s", badge, self.name)
        d = {
            "notification": {
                "id": "",
                "type": None,
                "sender": "",
                "counts": {"unread": badge},
                "devices": [
                    {
                        "app_id": self.app_id,
                        "pushkey": self.pushkey,
                        "pushkey_ts": int(self.pushkey_ts / 1000),
                        "data": self.data_minus_url,
                    }
                ],
            }
        }
        try:
            await self.http_client.post_json_get_json(self.url, d)
            http_badges_processed_counter.labels(
                **{SERVER_NAME_LABEL: self.server_name}
            ).inc()
        except Exception as e:
            logger.warning(
                "Failed to send badge count to %s: %s %s", self.name, type(e), e
            )
            http_badges_failed_counter.labels(
                **{SERVER_NAME_LABEL: self.server_name}
            ).inc()