from __future__ import annotations

from fastapi import APIRouter, Depends, HTTPException
from mousehold_domain import FinancialEventStatus, RelationType
from mousehold_matching import compute_normalized_transaction_fingerprint
from sqlalchemy import or_, select
from sqlalchemy.orm import Session, selectinload

from .. import models
from ..db import get_session
from ..schemas import (
    EventCreate,
    EventDetailRead,
    EventObservationLinkRead,
    EventRead,
    EventRelationCreate,
    EventRelationRead,
    EventTagsUpdate,
    EventUpdate,
    SplitLineCreate,
    SplitLineRead,
    TagRead,
)
from ..services.ingestion import confirm_event

router = APIRouter(tags=["events"])


def _get_event(session: Session, event_id: str) -> models.FinancialEvent:
    event = session.scalars(
        select(models.FinancialEvent)
        .where(models.FinancialEvent.id == event_id)
        .options(selectinload(models.FinancialEvent.split_lines))
    ).first()
    if not event:
        raise HTTPException(status_code=404, detail="Event not found")
    _attach_event_tags(session, [event])
    return event


def _attach_event_tags(session: Session, events: list[models.FinancialEvent]) -> None:
    if not events:
        return
    event_ids = [event.id for event in events]
    rows = session.execute(
        select(models.EventTag.event_id, models.EventTag.tag_id).where(
            models.EventTag.event_id.in_(event_ids)
        )
    ).all()
    tags_by_event: dict[str, list[str]] = {event_id: [] for event_id in event_ids}
    for event_id, tag_id in rows:
        tags_by_event.setdefault(event_id, []).append(tag_id)
    for event in events:
        event.tag_ids = tags_by_event.get(event.id, [])


@router.post("/events", response_model=EventRead)
def create_event(
    payload: EventCreate, session: Session = Depends(get_session)
) -> models.FinancialEvent:
    fingerprint = compute_normalized_transaction_fingerprint(
        amount=payload.amount,
        currency=payload.currency,
        event_date=payload.event_date,
        merchant=payload.merchant,
        counterparty=payload.counterparty,
    )
    event = models.FinancialEvent(
        **payload.model_dump(exclude={"split_lines"}),
        fingerprint=fingerprint,
    )
    session.add(event)
    session.flush()
    for split in payload.split_lines:
        session.add(models.SplitLine(event_id=event.id, **split.model_dump()))
    session.commit()
    return _get_event(session, event.id)


@router.get("/events", response_model=list[EventRead])
def list_events(
    household_id: str,
    status: FinancialEventStatus | None = None,
    hide_related_confirmations: bool = False,
    session: Session = Depends(get_session),
) -> list[models.FinancialEvent]:
    query = (
        select(models.FinancialEvent)
        .where(models.FinancialEvent.household_id == household_id)
        .options(selectinload(models.FinancialEvent.split_lines))
        .order_by(models.FinancialEvent.event_date.desc(), models.FinancialEvent.created_at.desc())
    )
    if status:
        query = query.where(models.FinancialEvent.status == status)
    if hide_related_confirmations:
        household_event_ids = select(models.FinancialEvent.id).where(
            models.FinancialEvent.household_id == household_id
        )
        hidden_ids = select(models.EventRelation.to_event_id).where(
            models.EventRelation.from_event_id.in_(household_event_ids),
            models.EventRelation.relation_type.in_(
                [RelationType.SAME_ECONOMIC_EVENT_AS, RelationType.DUPLICATE_OF]
            ),
        )
        query = query.where(models.FinancialEvent.id.not_in(hidden_ids))
    events = list(session.scalars(query).all())
    _attach_event_tags(session, events)
    return events


@router.get("/events/{event_id}", response_model=EventRead)
def get_event(event_id: str, session: Session = Depends(get_session)) -> models.FinancialEvent:
    return _get_event(session, event_id)


@router.get("/events/{event_id}/details", response_model=EventDetailRead)
def get_event_details(event_id: str, session: Session = Depends(get_session)) -> EventDetailRead:
    event = _get_event(session, event_id)
    observation_links = list(
        session.scalars(
            select(models.EventObservationLink)
            .where(models.EventObservationLink.event_id == event_id)
            .order_by(models.EventObservationLink.created_at)
        ).all()
    )
    observations: list[models.RawObservation] = []
    if observation_links:
        observations = list(
            session.scalars(
                select(models.RawObservation).where(
                    models.RawObservation.id.in_([link.observation_id for link in observation_links])
                )
            ).all()
        )
    relations = list(
        session.scalars(
            select(models.EventRelation)
            .where(
                or_(
                    models.EventRelation.from_event_id == event_id,
                    models.EventRelation.to_event_id == event_id,
                )
            )
            .order_by(models.EventRelation.created_at)
        ).all()
    )
    related_event_ids = {
        relation.to_event_id if relation.from_event_id == event_id else relation.from_event_id
        for relation in relations
    }
    related_events: list[models.FinancialEvent] = []
    if related_event_ids:
        related_events = list(
            session.scalars(
                select(models.FinancialEvent)
                .where(models.FinancialEvent.id.in_(related_event_ids))
                .options(selectinload(models.FinancialEvent.split_lines))
                .order_by(models.FinancialEvent.event_date.desc())
            ).all()
        )
        _attach_event_tags(session, related_events)
    category = session.get(models.Category, event.category_id) if event.category_id else None
    tags = (
        list(session.scalars(select(models.Tag).where(models.Tag.id.in_(event.tag_ids))).all())
        if event.tag_ids
        else []
    )
    return EventDetailRead(
        event=event,
        category=category,
        tags=tags,
        observation_links=[EventObservationLinkRead.model_validate(link) for link in observation_links],
        observations=observations,
        relations=[EventRelationRead.model_validate(relation) for relation in relations],
        related_events=related_events,
    )


@router.patch("/events/{event_id}", response_model=EventRead)
def update_event(
    event_id: str,
    payload: EventUpdate,
    session: Session = Depends(get_session),
) -> models.FinancialEvent:
    event = _get_event(session, event_id)
    for field, value in payload.model_dump(exclude_unset=True).items():
        setattr(event, field, value)
    event.fingerprint = compute_normalized_transaction_fingerprint(
        amount=event.amount,
        currency=event.currency,
        event_date=event.event_date,
        merchant=event.merchant,
        counterparty=event.counterparty,
    )
    session.add(event)
    session.commit()
    return _get_event(session, event_id)


@router.patch("/events/{event_id}/tags", response_model=list[TagRead])
def update_event_tags(
    event_id: str,
    payload: EventTagsUpdate,
    session: Session = Depends(get_session),
) -> list[models.Tag]:
    event = _get_event(session, event_id)
    tags = (
        list(
            session.scalars(
                select(models.Tag).where(
                    models.Tag.id.in_(payload.tag_ids),
                    models.Tag.household_id == event.household_id,
                )
            ).all()
        )
        if payload.tag_ids
        else []
    )
    if len(tags) != len(set(payload.tag_ids)):
        raise HTTPException(status_code=400, detail="One or more tags do not belong to this household")
    session.query(models.EventTag).filter(models.EventTag.event_id == event_id).delete(
        synchronize_session=False
    )
    session.add_all([models.EventTag(event_id=event_id, tag_id=tag.id) for tag in tags])
    session.commit()
    return tags


@router.post("/events/{event_id}/confirm", response_model=EventRead)
def confirm_event_endpoint(
    event_id: str, session: Session = Depends(get_session)
) -> models.FinancialEvent:
    event = confirm_event(session, _get_event(session, event_id))
    session.commit()
    return _get_event(session, event.id)


@router.post("/events/{event_id}/relations", response_model=EventRelationRead)
def add_event_relation(
    event_id: str,
    payload: EventRelationCreate,
    session: Session = Depends(get_session),
) -> models.EventRelation:
    if not session.get(models.FinancialEvent, event_id) or not session.get(
        models.FinancialEvent, payload.to_event_id
    ):
        raise HTTPException(status_code=404, detail="Event not found")
    relation = models.EventRelation(from_event_id=event_id, **payload.model_dump())
    session.add(relation)
    session.commit()
    session.refresh(relation)
    return relation


@router.post("/events/{event_id}/splits", response_model=list[SplitLineRead])
def replace_event_splits(
    event_id: str,
    payload: list[SplitLineCreate],
    session: Session = Depends(get_session),
) -> list[models.SplitLine]:
    event = _get_event(session, event_id)
    for split in list(event.split_lines):
        session.delete(split)
    session.flush()
    new_splits = [models.SplitLine(event_id=event_id, **split.model_dump()) for split in payload]
    session.add_all(new_splits)
    session.commit()
    return list(
        session.scalars(select(models.SplitLine).where(models.SplitLine.event_id == event_id)).all()
    )