from sqlalchemy import event, text
from sqlalchemy import Column, Integer, Float, String, ForeignKey
from sqlalchemy.orm import relationship
from config.database import Base


class Capex(Base):
    __tablename__ = "capex"

    id = Column(Integer, primary_key=True, index=True)
    scenario_id = Column(Integer, ForeignKey("scenario.id"), nullable=False)
    amount = Column(Float, nullable=False)
    description = Column(String, nullable=True)
    currency_id = Column(Integer, ForeignKey("currency.id"), nullable=False)

    scenario = relationship("Scenario", back_populates="capex_items")
    currency = relationship("Currency", back_populates="capex_items")

    def __repr__(self):
        return (
            f"<Capex id={self.id} scenario_id={self.scenario_id} "
            f"amount={self.amount} currency_id={self.currency_id}>"
        )

    @property
    def currency_code(self) -> str:
        return self.currency.code if self.currency else None

    @currency_code.setter
    def currency_code(self, value: str) -> None:
        # store pending code so application code or migrations can pick it up
        setattr(self, "_currency_code_pending",
                (value or "USD").strip().upper())


# SQLAlchemy event handlers to ensure currency_id is set before insert/update


def _resolve_currency(mapper, connection, target):
    # If currency_id already set, nothing to do
    if getattr(target, "currency_id", None):
        return
    code = getattr(target, "_currency_code_pending", None) or "USD"
    # Try to find existing currency id
    row = connection.execute(text("SELECT id FROM currency WHERE code = :code"), {
                             "code": code}).fetchone()
    if row:
        cid = row[0]
    else:
        # Insert new currency and attempt to get lastrowid
        res = connection.execute(
            text("INSERT INTO currency (code, name, symbol, is_active) VALUES (:code, :name, :symbol, :active)"),
            {"code": code, "name": code, "symbol": None, "active": True},
        )
        try:
            cid = res.lastrowid
        except Exception:
            # fallback: select after insert
            cid = connection.execute(text("SELECT id FROM currency WHERE code = :code"), {
                                     "code": code}).scalar()
    target.currency_id = cid


event.listen(Capex, "before_insert", _resolve_currency)
event.listen(Capex, "before_update", _resolve_currency)