from datetime import datetime
from decimal import Decimal

from sqlalchemy import DateTime, ForeignKey, Integer, Numeric, String
from sqlalchemy.orm import Mapped, mapped_column, relationship

from db import Base


class Customer(Base):
    __tablename__ = "customer"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    name: Mapped[str] = mapped_column(String(120), nullable=False)
    email: Mapped[str] = mapped_column(String(200), nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)

    invoices: Mapped[list["Invoice"]] = relationship(
        back_populates="customer", cascade="all, delete-orphan"
    )


class Invoice(Base):
    __tablename__ = "invoice"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    number: Mapped[str] = mapped_column(String(40), nullable=False, unique=True)
    customer_id: Mapped[int] = mapped_column(ForeignKey("customer.id"), nullable=False)
    issued_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
    due_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    status: Mapped[str] = mapped_column(String(20), default="draft")

    customer: Mapped[Customer] = relationship(back_populates="invoices")
    line_items: Mapped[list["LineItem"]] = relationship(
        back_populates="invoice", cascade="all, delete-orphan"
    )
    payments: Mapped[list["Payment"]] = relationship(
        back_populates="invoice", cascade="all, delete-orphan"
    )


class LineItem(Base):
    __tablename__ = "line_item"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    invoice_id: Mapped[int] = mapped_column(ForeignKey("invoice.id"), nullable=False)
    description: Mapped[str] = mapped_column(String(200), nullable=False)
    quantity: Mapped[int] = mapped_column(Integer, default=1)
    unit_price: Mapped[Decimal] = mapped_column(Numeric(10, 2), default=0)

    invoice: Mapped[Invoice] = relationship(back_populates="line_items")


class Payment(Base):
    __tablename__ = "payment"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    invoice_id: Mapped[int] = mapped_column(ForeignKey("invoice.id"), nullable=False)
    amount: Mapped[Decimal] = mapped_column(Numeric(10, 2), nullable=False)
    method: Mapped[str] = mapped_column(String(20), default="cash")
    paid_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)

    invoice: Mapped[Invoice] = relationship(back_populates="payments")