from datetime import datetime, timezone
from decimal import Decimal

from fastapi import HTTPException, status
from sqlalchemy import func
from sqlalchemy.orm import Session

from ..accounts.models import Account
from ..service_requests.models import ServiceRequest
from ..suppliers.models import Supplier
from .dto import QuoteCreate, QuoteItemCreate, QuoteItemUpdate, QuoteUpdate
from .models import Quote, QuoteItem


def _exists(db: Session, model, _id: int | None, tenant_id: int, company_id: int) -> bool:
    if _id is None:
        return True
    return (
        db.query(model.id)
        .filter(
            model.id == _id,
            model.tenant_id == tenant_id,
            model.company_id == company_id,
            model.deleted_at.is_(None),
        )
        .first()
        is not None
    )


def _validate_refs(db: Session, data: dict, tenant_id: int, company_id: int) -> None:
    if not _exists(db, Account, data.get("account_id"), tenant_id, company_id):
        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="El cliente asociado no existe")
    if not _exists(db, ServiceRequest, data.get("service_request_id"), tenant_id, company_id):
        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="La solicitud asociada no existe")


def _recompute_totals(db: Session, quote: Quote) -> None:
    """Recalcula total_cost/total_sale a partir de los conceptos vigentes."""
    cost, sale = (
        db.query(
            func.coalesce(func.sum(QuoteItem.quantity * QuoteItem.unit_cost), 0),
            func.coalesce(func.sum(QuoteItem.quantity * QuoteItem.unit_sale), 0),
        )
        .filter(QuoteItem.quote_id == quote.id, QuoteItem.deleted_at.is_(None))
        .one()
    )
    quote.total_cost = Decimal(cost or 0)
    quote.total_sale = Decimal(sale or 0)


# ----- Quotes -----

def get_quotes(
    db: Session,
    tenant_id: int,
    company_id: int,
    search: str | None = None,
    quote_status: str | None = None,
    account_id: int | None = None,
) -> list[Quote]:
    query = db.query(Quote).filter(
        Quote.tenant_id == tenant_id,
        Quote.company_id == company_id,
        Quote.deleted_at.is_(None),
    )
    if quote_status:
        query = query.filter(Quote.status == quote_status)
    if account_id is not None:
        query = query.filter(Quote.account_id == account_id)
    if search:
        query = query.filter(Quote.reference.ilike(f"%{search}%"))
    return query.order_by(Quote.created_at.desc()).all()


def get_quote(db: Session, quote_id: int, tenant_id: int, company_id: int) -> Quote:
    obj = (
        db.query(Quote)
        .filter(
            Quote.id == quote_id,
            Quote.tenant_id == tenant_id,
            Quote.company_id == company_id,
            Quote.deleted_at.is_(None),
        )
        .first()
    )
    if not obj:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Cotización no encontrada")
    return obj


def create_quote(
    db: Session, payload: QuoteCreate, tenant_id: int, company_id: int, user_id: str | None = None
) -> Quote:
    data = payload.model_dump()
    _validate_refs(db, data, tenant_id, company_id)
    obj = Quote(**data, tenant_id=tenant_id, company_id=company_id, created_by=user_id, updated_by=user_id)
    db.add(obj)
    db.commit()
    db.refresh(obj)
    return obj


def update_quote(
    db: Session, quote_id: int, payload: QuoteUpdate, tenant_id: int, company_id: int, user_id: str | None = None
) -> Quote:
    obj = get_quote(db, quote_id, tenant_id, company_id)
    data = payload.model_dump(exclude_unset=True)
    _validate_refs(db, data, tenant_id, company_id)
    for field, value in data.items():
        setattr(obj, field, value)
    obj.updated_by = user_id
    db.commit()
    db.refresh(obj)
    return obj


def delete_quote(db: Session, quote_id: int, tenant_id: int, company_id: int) -> None:
    obj = get_quote(db, quote_id, tenant_id, company_id)
    obj.deleted_at = datetime.now(timezone.utc)
    db.commit()


def _set_service_request_status(db: Session, quote: Quote, new_status: str) -> None:
    if quote.service_request_id:
        sr = db.query(ServiceRequest).filter(ServiceRequest.id == quote.service_request_id).first()
        if sr:
            sr.status = new_status


def send_quote(db: Session, quote_id: int, tenant_id: int, company_id: int) -> Quote:
    quote = get_quote(db, quote_id, tenant_id, company_id)
    quote.status = "enviada"
    quote.sent_at = datetime.now(timezone.utc)
    _set_service_request_status(db, quote, "cotizada")
    db.commit()
    db.refresh(quote)
    return quote


def accept_quote(db: Session, quote_id: int, tenant_id: int, company_id: int) -> Quote:
    quote = get_quote(db, quote_id, tenant_id, company_id)
    quote.status = "aceptada"
    quote.accepted_at = datetime.now(timezone.utc)
    _set_service_request_status(db, quote, "aceptada")
    db.commit()
    db.refresh(quote)
    return quote


def reject_quote(db: Session, quote_id: int, tenant_id: int, company_id: int) -> Quote:
    quote = get_quote(db, quote_id, tenant_id, company_id)
    quote.status = "rechazada"
    quote.rejected_at = datetime.now(timezone.utc)
    _set_service_request_status(db, quote, "rechazada")
    db.commit()
    db.refresh(quote)
    return quote


# ----- Quote items -----

def get_quote_items(db: Session, quote_id: int, tenant_id: int, company_id: int) -> list[QuoteItem]:
    get_quote(db, quote_id, tenant_id, company_id)  # valida scope
    return (
        db.query(QuoteItem)
        .filter(
            QuoteItem.quote_id == quote_id,
            QuoteItem.tenant_id == tenant_id,
            QuoteItem.company_id == company_id,
            QuoteItem.deleted_at.is_(None),
        )
        .order_by(QuoteItem.id.asc())
        .all()
    )


def _get_item(db: Session, item_id: int, tenant_id: int, company_id: int) -> QuoteItem:
    item = (
        db.query(QuoteItem)
        .filter(
            QuoteItem.id == item_id,
            QuoteItem.tenant_id == tenant_id,
            QuoteItem.company_id == company_id,
            QuoteItem.deleted_at.is_(None),
        )
        .first()
    )
    if not item:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Concepto no encontrado")
    return item


def create_quote_item(db: Session, payload: QuoteItemCreate, tenant_id: int, company_id: int) -> QuoteItem:
    quote = get_quote(db, payload.quote_id, tenant_id, company_id)
    if not _exists(db, Supplier, payload.supplier_id, tenant_id, company_id):
        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="El proveedor no existe")
    item = QuoteItem(**payload.model_dump(), tenant_id=tenant_id, company_id=company_id)
    db.add(item)
    db.flush()
    _recompute_totals(db, quote)
    db.commit()
    db.refresh(item)
    return item


def update_quote_item(
    db: Session, item_id: int, payload: QuoteItemUpdate, tenant_id: int, company_id: int
) -> QuoteItem:
    item = _get_item(db, item_id, tenant_id, company_id)
    data = payload.model_dump(exclude_unset=True)
    if "supplier_id" in data and not _exists(db, Supplier, data["supplier_id"], tenant_id, company_id):
        raise HTTPException(status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail="El proveedor no existe")
    for field, value in data.items():
        setattr(item, field, value)
    db.flush()
    quote = get_quote(db, item.quote_id, tenant_id, company_id)
    _recompute_totals(db, quote)
    db.commit()
    db.refresh(item)
    return item


def delete_quote_item(db: Session, item_id: int, tenant_id: int, company_id: int) -> None:
    item = _get_item(db, item_id, tenant_id, company_id)
    quote_id = item.quote_id
    item.deleted_at = datetime.now(timezone.utc)
    db.flush()
    quote = get_quote(db, quote_id, tenant_id, company_id)
    _recompute_totals(db, quote)
    db.commit()