from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session

from db import get_session
from models import Invoice, Payment
from schemas import PaymentIn, PaymentOut

router = APIRouter()


@router.get("", response_model=list[PaymentOut])
def list_payments(
    invoice_id: int | None = None, session: Session = Depends(get_session)
):
    query = session.query(Payment).order_by(Payment.paid_at.desc())
    if invoice_id:
        query = query.filter(Payment.invoice_id == invoice_id)
    return query.all()


@router.post("/invoices/{invoice_id}", response_model=PaymentOut, status_code=201)
def record_payment(
    invoice_id: int, payload: PaymentIn, session: Session = Depends(get_session)
):
    invoice = session.get(Invoice, invoice_id)
    if not invoice:
        raise HTTPException(404, "invoice not found")
    payment = Payment(invoice_id=invoice_id, **payload.model_dump())
    session.add(payment)

    total_paid = sum(
        (p.amount for p in invoice.payments), start=payment.amount
    )
    total_owed = sum((li.unit_price * li.quantity for li in invoice.line_items), start=0)
    if total_owed > 0 and total_paid >= total_owed:
        invoice.status = "paid"

    session.commit()
    session.refresh(payment)
    return payment


@router.delete("/{payment_id}", status_code=204)
def delete_payment(payment_id: int, session: Session = Depends(get_session)):
    payment = session.get(Payment, payment_id)
    if not payment:
        raise HTTPException(404, "payment not found")
    session.delete(payment)
    session.commit()