import datetime
import logging
from collections import Counter
from typing import Any, Dict, List, Optional, Type, TypeVar
from uuid import UUID

import orjson
from django.core.exceptions import ValidationError
from django.core.validators import URLValidator, validate_email
from django.db import IntegrityError, transaction
from django.db.models import Model
from django.http import HttpRequest, HttpResponse
from django.utils import timezone
from django.utils.crypto import constant_time_compare
from django.utils.translation import gettext as _
from django.utils.translation import gettext as err_
from django.views.decorators.csrf import csrf_exempt

from analytics.lib.counts import COUNT_STATS
from corporate.lib.stripe import do_deactivate_remote_server
from zerver.decorator import require_post
from zerver.lib.exceptions import JsonableError
from zerver.lib.push_notifications import (
    UserPushIdentityCompat,
    send_android_push_notification,
    send_apple_push_notification,
)
from zerver.lib.request import REQ, has_request_variables
from zerver.lib.response import json_success
from zerver.lib.validator import (
    check_bool,
    check_capped_string,
    check_dict,
    check_dict_only,
    check_float,
    check_int,
    check_list,
    check_none_or,
    check_string,
    check_string_fixed_length,
    check_union,
)
from zerver.views.push_notifications import validate_token
from zilencer.auth import InvalidZulipServerKeyError
from zilencer.models import (
    RemoteInstallationCount,
    RemotePushDeviceToken,
    RemoteRealmAuditLog,
    RemoteRealmCount,
    RemoteZulipServer,
    RemoteZulipServerAuditLog,
)

logger = logging.getLogger(__name__)


def validate_uuid(uuid: str) -> None:
    try:
        uuid_object = UUID(uuid, version=4)
        # The UUID initialization under some circumstances will modify the uuid
        # string to create a valid UUIDv4, instead of raising a ValueError.
        # The submitted uuid needing to be modified means it's invalid, so
        # we need to check for that condition.
        if str(uuid_object) != uuid:
            raise ValidationError(err_("Invalid UUID"))
    except ValueError:
        raise ValidationError(err_("Invalid UUID"))


def validate_bouncer_token_request(token: str, kind: int) -> None:
    if kind not in [RemotePushDeviceToken.APNS, RemotePushDeviceToken.GCM]:
        raise JsonableError(err_("Invalid token type"))
    validate_token(token, kind)


@csrf_exempt
@require_post
@has_request_variables
def deactivate_remote_server(
    request: HttpRequest,
    remote_server: RemoteZulipServer,
) -> HttpResponse:
    do_deactivate_remote_server(remote_server)
    return json_success(request)


@csrf_exempt
@require_post
@has_request_variables
def register_remote_server(
    request: HttpRequest,
    zulip_org_id: str = REQ(str_validator=check_string_fixed_length(RemoteZulipServer.UUID_LENGTH)),
    zulip_org_key: str = REQ(
        str_validator=check_string_fixed_length(RemoteZulipServer.API_KEY_LENGTH)
    ),
    hostname: str = REQ(str_validator=check_capped_string(RemoteZulipServer.HOSTNAME_MAX_LENGTH)),
    contact_email: str = REQ(),
    new_org_key: Optional[str] = REQ(
        str_validator=check_string_fixed_length(RemoteZulipServer.API_KEY_LENGTH), default=None
    ),
) -> HttpResponse:
    # REQ validated the the field lengths, but we still need to
    # validate the format of these fields.
    try:
        # TODO: Ideally we'd not abuse the URL validator this way
        url_validator = URLValidator()
        url_validator("http://" + hostname)
    except ValidationError:
        raise JsonableError(_("{hostname} is not a valid hostname").format(hostname=hostname))

    try:
        validate_email(contact_email)
    except ValidationError as e:
        raise JsonableError(e.message)

    try:
        validate_uuid(zulip_org_id)
    except ValidationError as e:
        raise JsonableError(e.message)

    with transaction.atomic():
        remote_server, created = RemoteZulipServer.objects.get_or_create(
            uuid=zulip_org_id,
            defaults={
                "hostname": hostname,
                "contact_email": contact_email,
                "api_key": zulip_org_key,
            },
        )
        if created:
            RemoteZulipServerAuditLog.objects.create(
                event_type=RemoteZulipServerAuditLog.REMOTE_SERVER_CREATED,
                server=remote_server,
                event_time=remote_server.last_updated,
            )
        else:
            if not constant_time_compare(remote_server.api_key, zulip_org_key):
                raise InvalidZulipServerKeyError(zulip_org_id)
            else:
                remote_server.hostname = hostname
                remote_server.contact_email = contact_email
                if new_org_key is not None:
                    remote_server.api_key = new_org_key
                remote_server.save()

    return json_success(request, data={"created": created})


@has_request_variables
def register_remote_push_device(
    request: HttpRequest,
    server: RemoteZulipServer,
    user_id: Optional[int] = REQ(json_validator=check_int, default=None),
    user_uuid: Optional[str] = REQ(default=None),
    token: str = REQ(),
    token_kind: int = REQ(json_validator=check_int),
    ios_app_id: Optional[str] = None,
) -> HttpResponse:
    validate_bouncer_token_request(token, token_kind)

    if user_id is None and user_uuid is None:
        raise JsonableError(_("Missing user_id or user_uuid"))
    if user_id is not None and user_uuid is not None:
        kwargs: Dict[str, object] = {"user_uuid": user_uuid, "user_id": None}
        # Delete pre-existing user_id registration for this user+device to avoid
        # duplication. Further down, uuid registration will be created.
        RemotePushDeviceToken.objects.filter(
            server=server, token=token, kind=token_kind, user_id=user_id
        ).delete()
    else:
        # One of these is None, so these kwargs will lead to a proper registration
        # of either user_id or user_uuid type
        kwargs = {"user_id": user_id, "user_uuid": user_uuid}
    try:
        with transaction.atomic():
            RemotePushDeviceToken.objects.create(
                server=server,
                kind=token_kind,
                token=token,
                ios_app_id=ios_app_id,
                # last_updated is to be renamed to date_created.
                last_updated=timezone.now(),
                **kwargs,
            )
    except IntegrityError:
        pass

    return json_success(request)


@has_request_variables
def unregister_remote_push_device(
    request: HttpRequest,
    server: RemoteZulipServer,
    token: str = REQ(),
    token_kind: int = REQ(json_validator=check_int),
    user_id: Optional[int] = REQ(json_validator=check_int, default=None),
    user_uuid: Optional[str] = REQ(default=None),
    ios_app_id: Optional[str] = None,
) -> HttpResponse:
    validate_bouncer_token_request(token, token_kind)
    user_identity = UserPushIdentityCompat(user_id=user_id, user_uuid=user_uuid)

    (num_deleted, ignored) = RemotePushDeviceToken.objects.filter(
        user_identity.filter_q(), token=token, kind=token_kind, server=server
    ).delete()
    if num_deleted == 0:
        raise JsonableError(err_("Token does not exist"))

    return json_success(request)


@has_request_variables
def unregister_all_remote_push_devices(
    request: HttpRequest,
    server: RemoteZulipServer,
    user_id: Optional[int] = REQ(json_validator=check_int, default=None),
    user_uuid: Optional[str] = REQ(default=None),
) -> HttpResponse:
    user_identity = UserPushIdentityCompat(user_id=user_id, user_uuid=user_uuid)

    RemotePushDeviceToken.objects.filter(user_identity.filter_q(), server=server).delete()
    return json_success(request)


def delete_duplicate_registrations(
    registrations: List[RemotePushDeviceToken], server_id: int, user_id: int, user_uuid: str
) -> List[RemotePushDeviceToken]:
    """
    When migrating to support registration by UUID, we introduced a bug where duplicate
    registrations for the same device+user could be created - one by user_id and one by
    user_uuid. Given no good way of detecting these duplicates at database level, we need to
    take advantage of the fact that when a remote server sends a push notification request
    to us, it sends both user_id and user_uuid of the user.
    See https://github.com/zulip/zulip/issues/24969 for reference.

    This function, knowing the user_id and user_uuid of the user, can detect duplicates
    and delete the legacy user_id registration if appropriate.

    Return the list of registrations with the user_id-based duplicates removed.
    """

    # All registrations passed here should be of the same kind (apple vs android).
    assert len({registration.kind for registration in registrations}) == 1
    kind = registrations[0].kind

    tokens_counter = Counter(device.token for device in registrations)

    tokens_to_deduplicate = []
    for key in tokens_counter:
        if tokens_counter[key] <= 1:
            continue
        if tokens_counter[key] > 2:
            raise AssertionError(
                f"More than two registrations for token {key} for user id:{user_id} uuid:{user_uuid}, shouldn't be possible"
            )
        assert tokens_counter[key] == 2
        tokens_to_deduplicate.append(key)

    if not tokens_to_deduplicate:
        return registrations

    logger.info(
        "Deduplicating push registrations for server id:%s user id:%s uuid:%s and tokens:%s",
        server_id,
        user_id,
        user_uuid,
        sorted(tokens_to_deduplicate),
    )
    RemotePushDeviceToken.objects.filter(
        token__in=tokens_to_deduplicate, kind=kind, server_id=server_id, user_id=user_id
    ).delete()

    deduplicated_registrations_to_return = []
    for registration in registrations:
        if registration.token in tokens_to_deduplicate and registration.user_id is not None:
            # user_id registrations are the ones we deleted
            continue
        deduplicated_registrations_to_return.append(registration)

    return deduplicated_registrations_to_return


@has_request_variables
def remote_server_notify_push(
    request: HttpRequest,
    server: RemoteZulipServer,
    payload: Dict[str, Any] = REQ(argument_type="body"),
) -> HttpResponse:
    user_id = payload.get("user_id")
    user_uuid = payload.get("user_uuid")
    user_identity = UserPushIdentityCompat(user_id, user_uuid)

    gcm_payload = payload["gcm_payload"]
    apns_payload = payload["apns_payload"]
    gcm_options = payload.get("gcm_options", {})

    android_devices = list(
        RemotePushDeviceToken.objects.filter(
            user_identity.filter_q(),
            kind=RemotePushDeviceToken.GCM,
            server=server,
        )
    )
    if android_devices and user_id is not None and user_uuid is not None:
        android_devices = delete_duplicate_registrations(
            android_devices, server.id, user_id, user_uuid
        )

    apple_devices = list(
        RemotePushDeviceToken.objects.filter(
            user_identity.filter_q(),
            kind=RemotePushDeviceToken.APNS,
            server=server,
        )
    )
    if apple_devices and user_id is not None and user_uuid is not None:
        apple_devices = delete_duplicate_registrations(apple_devices, server.id, user_id, user_uuid)

    logger.info(
        "Sending mobile push notifications for remote user %s:%s: %s via FCM devices, %s via APNs devices",
        server.uuid,
        user_identity,
        len(android_devices),
        len(apple_devices),
    )

    # Truncate incoming pushes to 200, due to APNs maximum message
    # sizes; see handle_remove_push_notification for the version of
    # this for notifications generated natively on the server.  We
    # apply this to remote-server pushes in case they predate that
    # commit.
    def truncate_payload(payload: Dict[str, Any]) -> Dict[str, Any]:
        MAX_MESSAGE_IDS = 200
        if payload and payload.get("event") == "remove" and payload.get("zulip_message_ids"):
            ids = [int(id) for id in payload["zulip_message_ids"].split(",")]
            truncated_ids = sorted(ids)[-MAX_MESSAGE_IDS:]
            payload["zulip_message_ids"] = ",".join(str(id) for id in truncated_ids)
        return payload

    # The full request must complete within 30s, the timeout set by
    # Zulip remote hosts for push notification requests (see
    # PushBouncerSession).  The timeouts in the FCM and APNS codepaths
    # must be set accordingly; see send_android_push_notification and
    # send_apple_push_notification.

    gcm_payload = truncate_payload(gcm_payload)
    send_android_push_notification(
        user_identity, android_devices, gcm_payload, gcm_options, remote=server
    )

    if isinstance(apns_payload.get("custom"), dict) and isinstance(
        apns_payload["custom"].get("zulip"), dict
    ):
        apns_payload["custom"]["zulip"] = truncate_payload(apns_payload["custom"]["zulip"])
    send_apple_push_notification(user_identity, apple_devices, apns_payload, remote=server)

    return json_success(
        request,
        data={
            "total_android_devices": len(android_devices),
            "total_apple_devices": len(apple_devices),
        },
    )


def validate_incoming_table_data(
    server: RemoteZulipServer, model: Any, rows: List[Dict[str, Any]], is_count_stat: bool = False
) -> None:
    last_id = get_last_id_from_server(server, model)
    for row in rows:
        if is_count_stat and row["property"] not in COUNT_STATS:
            raise JsonableError(_("Invalid property {property}").format(property=row["property"]))
        if row["id"] <= last_id:
            raise JsonableError(_("Data is out of order."))
        last_id = row["id"]


ModelT = TypeVar("ModelT", bound=Model)


def batch_create_table_data(
    server: RemoteZulipServer,
    model: Type[ModelT],
    row_objects: List[ModelT],
) -> None:
    BATCH_SIZE = 1000
    while len(row_objects) > 0:
        try:
            model._default_manager.bulk_create(row_objects[:BATCH_SIZE])
        except IntegrityError:
            logging.warning(
                "Invalid data saving %s for server %s/%s",
                model._meta.db_table,
                server.hostname,
                server.uuid,
            )
            raise JsonableError(_("Invalid data."))
        row_objects = row_objects[BATCH_SIZE:]


@has_request_variables
def remote_server_post_analytics(
    request: HttpRequest,
    server: RemoteZulipServer,
    realm_counts: List[Dict[str, Any]] = REQ(
        json_validator=check_list(
            check_dict_only(
                [
                    ("property", check_string),
                    ("realm", check_int),
                    ("id", check_int),
                    ("end_time", check_float),
                    ("subgroup", check_none_or(check_string)),
                    ("value", check_int),
                ]
            )
        )
    ),
    installation_counts: List[Dict[str, Any]] = REQ(
        json_validator=check_list(
            check_dict_only(
                [
                    ("property", check_string),
                    ("id", check_int),
                    ("end_time", check_float),
                    ("subgroup", check_none_or(check_string)),
                    ("value", check_int),
                ]
            )
        )
    ),
    realmauditlog_rows: Optional[List[Dict[str, Any]]] = REQ(
        json_validator=check_list(
            check_dict_only(
                [
                    ("id", check_int),
                    ("realm", check_int),
                    ("event_time", check_float),
                    ("backfilled", check_bool),
                    ("extra_data", check_none_or(check_union([check_string, check_dict()]))),
                    ("event_type", check_int),
                ]
            )
        ),
        default=None,
    ),
) -> HttpResponse:
    validate_incoming_table_data(server, RemoteRealmCount, realm_counts, True)
    validate_incoming_table_data(server, RemoteInstallationCount, installation_counts, True)
    if realmauditlog_rows is not None:
        validate_incoming_table_data(server, RemoteRealmAuditLog, realmauditlog_rows)

    remote_realm_counts = [
        RemoteRealmCount(
            property=row["property"],
            realm_id=row["realm"],
            remote_id=row["id"],
            server=server,
            end_time=datetime.datetime.fromtimestamp(row["end_time"], tz=datetime.timezone.utc),
            subgroup=row["subgroup"],
            value=row["value"],
        )
        for row in realm_counts
    ]
    batch_create_table_data(server, RemoteRealmCount, remote_realm_counts)

    remote_installation_counts = [
        RemoteInstallationCount(
            property=row["property"],
            remote_id=row["id"],
            server=server,
            end_time=datetime.datetime.fromtimestamp(row["end_time"], tz=datetime.timezone.utc),
            subgroup=row["subgroup"],
            value=row["value"],
        )
        for row in installation_counts
    ]
    batch_create_table_data(server, RemoteInstallationCount, remote_installation_counts)

    if realmauditlog_rows is not None:
        remote_realm_audit_logs = []
        for row in realmauditlog_rows:
            extra_data = {}
            # Remote servers that do support JSONField will pass extra_data
            # as a dict. Otherwise, extra_data will be either a string or None.
            if isinstance(row["extra_data"], str):
                # A valid "extra_data" as a str, if present, should always be generated from
                # orjson.dumps because the POSTed analytics data for RealmAuditLog is restricted
                # to event types in SYNC_BILLING_EVENTS.
                # For these event types, we don't create extra_data that requires special
                # handling to fit into the JSONField.
                try:
                    extra_data = orjson.loads(row["extra_data"])
                except orjson.JSONDecodeError:
                    raise JsonableError(_("Malformed audit log data"))
            elif row["extra_data"] is not None:
                # This is guaranteed to succeed because row["extra_data"] would be parsed
                # from JSON with our json validator and validated with check_dict if it
                # is not a str or None.
                assert isinstance(row["extra_data"], dict)
                extra_data = row["extra_data"]
            remote_realm_audit_logs.append(
                RemoteRealmAuditLog(
                    realm_id=row["realm"],
                    remote_id=row["id"],
                    server=server,
                    event_time=datetime.datetime.fromtimestamp(
                        row["event_time"], tz=datetime.timezone.utc
                    ),
                    backfilled=row["backfilled"],
                    extra_data=extra_data,
                    event_type=row["event_type"],
                )
            )
        batch_create_table_data(server, RemoteRealmAuditLog, remote_realm_audit_logs)

    return json_success(request)


def get_last_id_from_server(server: RemoteZulipServer, model: Any) -> int:
    last_count = model.objects.filter(server=server).order_by("remote_id").last()
    if last_count is not None:
        return last_count.remote_id
    return 0


@has_request_variables
def remote_server_check_analytics(request: HttpRequest, server: RemoteZulipServer) -> HttpResponse:
    result = {
        "last_realm_count_id": get_last_id_from_server(server, RemoteRealmCount),
        "last_installation_count_id": get_last_id_from_server(server, RemoteInstallationCount),
        "last_realmauditlog_id": get_last_id_from_server(server, RemoteRealmAuditLog),
    }
    return json_success(request, data=result)