from collections.abc import Sequence
from operator import and_
from uuid import UUID

from sqlalchemy import func
from sqlalchemy import select
from sqlalchemy.orm import Session

from danswer.db.models import ConnectorCredentialPair
from danswer.db.models import Document
from danswer.db.models import DocumentByConnectorCredentialPair
from danswer.db.models import User
from danswer.db.models import User__UserGroup
from danswer.db.models import UserGroup
from danswer.db.models import UserGroup__ConnectorCredentialPair
from danswer.server.documents.models import ConnectorCredentialPairIdentifier
from ee.danswer.server.user_group.models import UserGroupCreate
from ee.danswer.server.user_group.models import UserGroupUpdate


def fetch_user_group(db_session: Session, user_group_id: int) -> UserGroup | None:
    stmt = select(UserGroup).where(UserGroup.id == user_group_id)
    return db_session.scalar(stmt)


def fetch_user_groups(
    db_session: Session, only_current: bool = True
) -> Sequence[UserGroup]:
    stmt = select(UserGroup)
    if only_current:
        stmt = stmt.where(UserGroup.is_up_to_date == True)  # noqa: E712
    return db_session.scalars(stmt).all()


def fetch_user_groups_for_user(
    db_session: Session, user_id: UUID
) -> Sequence[UserGroup]:
    stmt = (
        select(UserGroup)
        .join(User__UserGroup, User__UserGroup.user_group_id == UserGroup.id)
        .join(User, User.id == User__UserGroup.user_id)  # type: ignore
        .where(User.id == user_id)  # type: ignore
    )
    return db_session.scalars(stmt).all()


def fetch_documents_for_user_group(
    db_session: Session, user_group_id: int
) -> Sequence[Document]:
    stmt = (
        select(Document)
        .join(
            DocumentByConnectorCredentialPair,
            Document.id == DocumentByConnectorCredentialPair.id,
        )
        .join(
            ConnectorCredentialPair,
            and_(
                DocumentByConnectorCredentialPair.connector_id
                == ConnectorCredentialPair.connector_id,
                DocumentByConnectorCredentialPair.credential_id
                == ConnectorCredentialPair.credential_id,
            ),
        )
        .join(
            UserGroup__ConnectorCredentialPair,
            UserGroup__ConnectorCredentialPair.cc_pair_id == ConnectorCredentialPair.id,
        )
        .join(
            UserGroup,
            UserGroup__ConnectorCredentialPair.user_group_id == UserGroup.id,
        )
        .where(UserGroup.id == user_group_id)
    )
    return db_session.scalars(stmt).all()


def fetch_user_groups_for_documents(
    db_session: Session,
    document_ids: list[str],
    cc_pair_to_delete: ConnectorCredentialPairIdentifier | None = None,
) -> Sequence[tuple[int, list[str]]]:
    stmt = (
        select(Document.id, func.array_agg(UserGroup.name))
        .join(
            UserGroup__ConnectorCredentialPair,
            UserGroup.id == UserGroup__ConnectorCredentialPair.user_group_id,
        )
        .join(
            ConnectorCredentialPair,
            ConnectorCredentialPair.id == UserGroup__ConnectorCredentialPair.cc_pair_id,
        )
        .join(
            DocumentByConnectorCredentialPair,
            and_(
                DocumentByConnectorCredentialPair.connector_id
                == ConnectorCredentialPair.connector_id,
                DocumentByConnectorCredentialPair.credential_id
                == ConnectorCredentialPair.credential_id,
            ),
        )
        .join(Document, Document.id == DocumentByConnectorCredentialPair.id)
        .where(Document.id.in_(document_ids))
        .where(UserGroup__ConnectorCredentialPair.is_current == True)  # noqa: E712
        .group_by(Document.id)
    )

    # pretend that the specified cc pair doesn't exist
    if cc_pair_to_delete is not None:
        stmt = stmt.where(
            and_(
                ConnectorCredentialPair.connector_id != cc_pair_to_delete.connector_id,
                ConnectorCredentialPair.credential_id
                != cc_pair_to_delete.credential_id,
            )
        )

    return db_session.execute(stmt).all()  # type: ignore


def _check_user_group_is_modifiable(user_group: UserGroup) -> None:
    if not user_group.is_up_to_date:
        raise ValueError(
            "Specified user group is currently syncing. Wait until the current "
            "sync has finished before editing."
        )


def _add_user__user_group_relationships__no_commit(
    db_session: Session, user_group_id: int, user_ids: list[UUID]
) -> list[User__UserGroup]:
    """NOTE: does not commit the transaction."""
    relationships = [
        User__UserGroup(user_id=user_id, user_group_id=user_group_id)
        for user_id in user_ids
    ]
    db_session.add_all(relationships)
    return relationships


def _add_user_group__cc_pair_relationships__no_commit(
    db_session: Session, user_group_id: int, cc_pair_ids: list[int]
) -> list[UserGroup__ConnectorCredentialPair]:
    """NOTE: does not commit the transaction."""
    relationships = [
        UserGroup__ConnectorCredentialPair(
            user_group_id=user_group_id, cc_pair_id=cc_pair_id
        )
        for cc_pair_id in cc_pair_ids
    ]
    db_session.add_all(relationships)
    return relationships


def insert_user_group(db_session: Session, user_group: UserGroupCreate) -> UserGroup:
    db_user_group = UserGroup(name=user_group.name)
    db_session.add(db_user_group)
    db_session.flush()  # give the group an ID

    _add_user__user_group_relationships__no_commit(
        db_session=db_session,
        user_group_id=db_user_group.id,
        user_ids=user_group.user_ids,
    )
    _add_user_group__cc_pair_relationships__no_commit(
        db_session=db_session,
        user_group_id=db_user_group.id,
        cc_pair_ids=user_group.cc_pair_ids,
    )

    db_session.commit()
    return db_user_group


def _cleanup_user__user_group_relationships__no_commit(
    db_session: Session, user_group_id: int
) -> None:
    """NOTE: does not commit the transaction."""
    user__user_group_relationships = db_session.scalars(
        select(User__UserGroup).where(User__UserGroup.user_group_id == user_group_id)
    ).all()
    for user__user_group_relationship in user__user_group_relationships:
        db_session.delete(user__user_group_relationship)


def _mark_user_group__cc_pair_relationships_outdated__no_commit(
    db_session: Session, user_group_id: int
) -> None:
    """NOTE: does not commit the transaction."""
    user_group__cc_pair_relationships = db_session.scalars(
        select(UserGroup__ConnectorCredentialPair).where(
            UserGroup__ConnectorCredentialPair.user_group_id == user_group_id
        )
    )
    for user_group__cc_pair_relationship in user_group__cc_pair_relationships:
        user_group__cc_pair_relationship.is_current = False


def update_user_group(
    db_session: Session, user_group_id: int, user_group: UserGroupUpdate
) -> UserGroup:
    stmt = select(UserGroup).where(UserGroup.id == user_group_id)
    db_user_group = db_session.scalar(stmt)
    if db_user_group is None:
        raise ValueError(f"UserGroup with id '{user_group_id}' not found")

    _check_user_group_is_modifiable(db_user_group)

    existing_cc_pairs = db_user_group.cc_pairs
    cc_pairs_updated = set([cc_pair.id for cc_pair in existing_cc_pairs]) != set(
        user_group.cc_pair_ids
    )
    users_updated = set([user.id for user in db_user_group.users]) != set(
        user_group.user_ids
    )

    if users_updated:
        _cleanup_user__user_group_relationships__no_commit(
            db_session=db_session, user_group_id=user_group_id
        )
        _add_user__user_group_relationships__no_commit(
            db_session=db_session,
            user_group_id=user_group_id,
            user_ids=user_group.user_ids,
        )
    if cc_pairs_updated:
        _mark_user_group__cc_pair_relationships_outdated__no_commit(
            db_session=db_session, user_group_id=user_group_id
        )
        _add_user_group__cc_pair_relationships__no_commit(
            db_session=db_session,
            user_group_id=db_user_group.id,
            cc_pair_ids=user_group.cc_pair_ids,
        )

    # only needs to sync with Vespa if the cc_pairs have been updated
    if cc_pairs_updated:
        db_user_group.is_up_to_date = False

    db_session.commit()
    return db_user_group


def prepare_user_group_for_deletion(db_session: Session, user_group_id: int) -> None:
    stmt = select(UserGroup).where(UserGroup.id == user_group_id)
    db_user_group = db_session.scalar(stmt)
    if db_user_group is None:
        raise ValueError(f"UserGroup with id '{user_group_id}' not found")

    _check_user_group_is_modifiable(db_user_group)

    _cleanup_user__user_group_relationships__no_commit(
        db_session=db_session, user_group_id=user_group_id
    )
    _mark_user_group__cc_pair_relationships_outdated__no_commit(
        db_session=db_session, user_group_id=user_group_id
    )
    db_user_group.is_up_to_date = False
    db_user_group.is_up_for_deletion = True
    db_session.commit()


def _cleanup_user_group__cc_pair_relationships__no_commit(
    db_session: Session, user_group_id: int, outdated_only: bool
) -> None:
    """NOTE: does not commit the transaction."""
    stmt = select(UserGroup__ConnectorCredentialPair).where(
        UserGroup__ConnectorCredentialPair.user_group_id == user_group_id
    )
    if outdated_only:
        stmt = stmt.where(
            UserGroup__ConnectorCredentialPair.is_current == False  # noqa: E712
        )
    user_group__cc_pair_relationships = db_session.scalars(stmt)
    for user_group__cc_pair_relationship in user_group__cc_pair_relationships:
        db_session.delete(user_group__cc_pair_relationship)


def mark_user_group_as_synced(db_session: Session, user_group: UserGroup) -> None:
    # cleanup outdated relationships
    _cleanup_user_group__cc_pair_relationships__no_commit(
        db_session=db_session, user_group_id=user_group.id, outdated_only=True
    )
    user_group.is_up_to_date = True
    db_session.commit()


def delete_user_group(db_session: Session, user_group: UserGroup) -> None:
    _cleanup_user__user_group_relationships__no_commit(
        db_session=db_session, user_group_id=user_group.id
    )
    _cleanup_user_group__cc_pair_relationships__no_commit(
        db_session=db_session,
        user_group_id=user_group.id,
        outdated_only=False,
    )

    # need to flush so that we don't get a foreign key error when deleting the user group row
    db_session.flush()

    db_session.delete(user_group)
    db_session.commit()
