import datetime
from typing import Any, Callable, Dict, List, Optional, Tuple

from django.utils.timezone import now as timezone_now
from sqlalchemy.sql import ClauseElement, and_, column, not_, or_
from sqlalchemy.types import Integer

from zerver.lib.timestamp import datetime_to_timestamp
from zerver.lib.topic import topic_match_sa
from zerver.models import UserProfile, UserTopic, get_stream


def get_topic_mutes(
    user_profile: UserProfile, include_deactivated: bool = False
) -> List[Tuple[str, str, float]]:
    query = UserTopic.objects.filter(user_profile=user_profile, visibility_policy=UserTopic.MUTED)
    # Exclude muted topics that are part of deactivated streams unless
    # explicitly requested.
    if not include_deactivated:
        query = query.filter(stream__deactivated=False)
    rows = query.values(
        "stream__name",
        "topic_name",
        "last_updated",
    )
    return [
        (row["stream__name"], row["topic_name"], datetime_to_timestamp(row["last_updated"]))
        for row in rows
    ]


def set_topic_mutes(
    user_profile: UserProfile,
    muted_topics: List[List[str]],
    date_muted: Optional[datetime.datetime] = None,
) -> None:
    """
    This is only used in tests.
    """

    UserTopic.objects.filter(
        user_profile=user_profile,
        visibility_policy=UserTopic.MUTED,
    ).delete()

    if date_muted is None:
        date_muted = timezone_now()
    for stream_name, topic_name in muted_topics:
        stream = get_stream(stream_name, user_profile.realm)
        recipient_id = stream.recipient_id

        add_topic_mute(
            user_profile=user_profile,
            stream_id=stream.id,
            recipient_id=recipient_id,
            topic_name=topic_name,
            date_muted=date_muted,
        )


def add_topic_mute(
    user_profile: UserProfile,
    stream_id: int,
    recipient_id: int,
    topic_name: str,
    date_muted: Optional[datetime.datetime] = None,
) -> None:
    if date_muted is None:
        date_muted = timezone_now()
    UserTopic.objects.create(
        user_profile=user_profile,
        stream_id=stream_id,
        recipient_id=recipient_id,
        topic_name=topic_name,
        last_updated=date_muted,
        visibility_policy=UserTopic.MUTED,
    )


def remove_topic_mute(user_profile: UserProfile, stream_id: int, topic_name: str) -> None:
    row = UserTopic.objects.get(
        user_profile=user_profile,
        stream_id=stream_id,
        topic_name__iexact=topic_name,
        visibility_policy=UserTopic.MUTED,
    )
    row.delete()


def topic_is_muted(user_profile: UserProfile, stream_id: int, topic_name: str) -> bool:
    is_muted = UserTopic.objects.filter(
        user_profile=user_profile,
        stream_id=stream_id,
        topic_name__iexact=topic_name,
        visibility_policy=UserTopic.MUTED,
    ).exists()
    return is_muted


def exclude_topic_mutes(
    conditions: List[ClauseElement], user_profile: UserProfile, stream_id: Optional[int]
) -> List[ClauseElement]:
    # Note: Unlike get_topic_mutes, here we always want to
    # consider topics in deactivated streams, so they are
    # never filtered from the query in this method.
    query = UserTopic.objects.filter(
        user_profile=user_profile,
        visibility_policy=UserTopic.MUTED,
    )

    if stream_id is not None:
        # If we are narrowed to a stream, we can optimize the query
        # by not considering topic mutes outside the stream.
        query = query.filter(stream_id=stream_id)

    query = query.values(
        "recipient_id",
        "topic_name",
    )
    rows = list(query)

    if not rows:
        return conditions

    def mute_cond(row: Dict[str, Any]) -> ClauseElement:
        recipient_id = row["recipient_id"]
        topic_name = row["topic_name"]
        stream_cond = column("recipient_id", Integer) == recipient_id
        topic_cond = topic_match_sa(topic_name)
        return and_(stream_cond, topic_cond)

    condition = not_(or_(*list(map(mute_cond, rows))))
    return [*conditions, condition]


def build_topic_mute_checker(user_profile: UserProfile) -> Callable[[int, str], bool]:
    rows = UserTopic.objects.filter(
        user_profile=user_profile, visibility_policy=UserTopic.MUTED
    ).values(
        "recipient_id",
        "topic_name",
    )
    rows = list(rows)

    tups = set()
    for row in rows:
        recipient_id = row["recipient_id"]
        topic_name = row["topic_name"]
        tups.add((recipient_id, topic_name.lower()))

    def is_muted(recipient_id: int, topic: str) -> bool:
        return (recipient_id, topic.lower()) in tups

    return is_muted