app/models/bill_sequence.py

"""
Bill Number Sequence Model
Manages bill numbering with batch system (A1-A500, B1-B500, etc.)
"""

from sqlalchemy import String, Integer, Boolean, DateTime, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.sql import func
from typing import Optional
import uuid

from app.core.database import Base


class BillNumberSequence(Base):
    """
    Bill number sequence tracking
    Format: {PREFIX}{YEAR}{BATCH}{NUMBER}
    Example: A2025A001, A2025A500, A2025B001
    """
    __tablename__ = "bill_number_sequences"
    __table_args__ = (
        UniqueConstraint('bill_type', 'year', 'batch', name='uq_bill_sequence'),
    )

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    bill_type: Mapped[str] = mapped_column(String(20), nullable=False)  # 'awaak', 'jawaak', 'patti_awaak', 'patti_jawaak'
    year: Mapped[int] = mapped_column(Integer, nullable=False)
    batch: Mapped[str] = mapped_column(String(1), nullable=False)  # 'A' to 'Z'
    current_number: Mapped[int] = mapped_column(Integer, default=0)  # 0 to 500
    is_full: Mapped[bool] = mapped_column(Boolean, default=False)  # True when reaches 500
    
    created_at: Mapped[DateTime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[DateTime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

    def __repr__(self) -> str:
        return f"<BillNumberSequence(type={self.bill_type}, year={self.year}, batch={self.batch}, num={self.current_number})>"