from datetime import datetime
from decimal import Decimal
from enum import Enum
from typing import TYPE_CHECKING, List, Optional

from sqlalchemy import CheckConstraint, Column
from sqlalchemy import Enum as SAEnum
from sqlmodel import Field, Relationship, SQLModel

if TYPE_CHECKING:
    from app.models.order import Order
    from app.models.route import Route
    from app.models.wine_offering import WineOffering


class PurchaseRoundStatus(str, Enum):
    DRAFT = "draft"
    OPEN = "open"
    CLOSED = "closed"


class PurchaseRoundBase(SQLModel):
    name: str
    status: PurchaseRoundStatus = Field(
        default=PurchaseRoundStatus.DRAFT,
        sa_column=Column(
            SAEnum(
                PurchaseRoundStatus,
                name="purchase_round_status",
                native_enum=False,
                values_callable=lambda enum_cls: [member.value for member in enum_cls],
            ),
            nullable=False,
        ),
    )
    opens_at: Optional[datetime] = Field(default=None)
    order_deadline_at: Optional[datetime] = Field(default=None)
    pickup_at: Optional[datetime] = Field(default=None)
    eur_dkk_rate: Optional[Decimal] = Field(default=None, max_digits=10, decimal_places=4)
    intro_text: Optional[str] = Field(default=None)
    pickup_info_text: Optional[str] = Field(default=None)


class PurchaseRound(PurchaseRoundBase, table=True):
    __tablename__ = "purchase_round"
    __table_args__ = (
        CheckConstraint(
            "status = 'draft' OR "
            "(opens_at IS NOT NULL AND order_deadline_at IS NOT NULL AND pickup_at IS NOT NULL)",
            name="ck_purchase_round_dates_required_unless_draft",
        ),
    )

    id: Optional[int] = Field(default=None, primary_key=True)
    route_id: int = Field(foreign_key="route.id", ondelete="CASCADE")

    route: "Route" = Relationship(back_populates="purchase_rounds")
    wine_offerings: List["WineOffering"] = Relationship(
        back_populates="purchase_round", sa_relationship_kwargs={"cascade": "all, delete-orphan"}
    )
    orders: List["Order"] = Relationship(
        back_populates="purchase_round", sa_relationship_kwargs={"cascade": "all, delete-orphan"}
    )