from datetime import datetime
import time

from api.metrics import record_db_query
from models.decision import ListingDecision
from sqlalchemy import Engine
from sqlmodel import Session, select


class DecisionRepository:
    engine: Engine

    def __init__(self, engine: Engine) -> None:
        self.engine = engine

    def upsert_decision(
        self,
        user_id: int,
        listing_id: int,
        listing_type: str,
        decision: str,
        price_at_decision: float | None = None,
    ) -> ListingDecision:
        """Create or update a decision. Uses dialect-specific upsert."""
        t0 = time.monotonic()
        with Session(self.engine) as session:
            now = datetime.utcnow()
            values = {
                "user_id": user_id,
                "listing_id": listing_id,
                "listing_type": listing_type,
                "decision": decision,
                "price_at_decision": price_at_decision,
                "created_at": now,
                "updated_at": now,
            }
            dialect = self.engine.dialect.name
            if dialect == "mysql":
                from sqlalchemy.dialects.mysql import insert as mysql_insert
                stmt = mysql_insert(ListingDecision).values(**values)
                stmt = stmt.on_duplicate_key_update(
                    decision=stmt.inserted.decision,
                    price_at_decision=stmt.inserted.price_at_decision,
                    updated_at=stmt.inserted.updated_at,
                )
            else:
                from sqlalchemy.dialects.sqlite import insert as sqlite_insert
                stmt = sqlite_insert(ListingDecision).values(**values)
                stmt = stmt.on_conflict_do_update(
                    index_elements=["user_id", "listing_id", "listing_type"],
                    set_={
                        "decision": stmt.excluded.decision,
                        "price_at_decision": stmt.excluded.price_at_decision,
                        "updated_at": stmt.excluded.updated_at,
                    },
                )
            session.execute(stmt)
            session.commit()
            # Fetch the result
            result = session.exec(
                select(ListingDecision).where(
                    ListingDecision.user_id == user_id,
                    ListingDecision.listing_id == listing_id,
                    ListingDecision.listing_type == listing_type,
                )
            ).first()
            assert result is not None
        record_db_query("upsert_decision", "decision", time.monotonic() - t0)
        return result

    def get_decisions_for_user(self, user_id: int) -> list[ListingDecision]:
        t0 = time.monotonic()
        with Session(self.engine) as session:
            statement = select(ListingDecision).where(
                ListingDecision.user_id == user_id
            )
            results = list(session.exec(statement).all())
        record_db_query("get_decisions_for_user", "decision", time.monotonic() - t0, len(results))
        return results

    def delete_decision(
        self,
        user_id: int,
        listing_id: int,
        listing_type: str,
    ) -> bool:
        with Session(self.engine) as session:
            result = session.exec(
                select(ListingDecision).where(
                    ListingDecision.user_id == user_id,
                    ListingDecision.listing_id == listing_id,
                    ListingDecision.listing_type == listing_type,
                )
            ).first()
            if result is None:
                return False
            session.delete(result)
            session.commit()
            return True

    def get_disliked_listing_ids(
        self,
        user_id: int,
        listing_type: str,
    ) -> set[int]:
        t0 = time.monotonic()
        with Session(self.engine) as session:
            statement = select(ListingDecision.listing_id).where(
                ListingDecision.user_id == user_id,
                ListingDecision.listing_type == listing_type,
                ListingDecision.decision == "disliked",
            )
            ids = {row for row in session.exec(statement).all()}
        record_db_query("get_disliked_listing_ids", "decision", time.monotonic() - t0, len(ids))
        return ids

    def get_liked_listing_ids(
        self,
        user_id: int,
        listing_type: str,
    ) -> set[int]:
        with Session(self.engine) as session:
            statement = select(ListingDecision.listing_id).where(
                ListingDecision.user_id == user_id,
                ListingDecision.listing_type == listing_type,
                ListingDecision.decision == "liked",
            )
            return {row for row in session.exec(statement).all()}