from sqlalchemy import Column, Date, DateTime, ForeignKey, String, Text, UniqueConstraint, Index, text
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.sql import func
from backend.app.db.base import Base


class ScheduleItem(Base):
    __tablename__ = "schedule_items"
    __table_args__ = (
        UniqueConstraint("dept_id", "date", "shift_id", "staff_id", name="uq_schedule_unique"),
        Index("idx_schedule_dept_date", "dept_id", "date"),
        Index("idx_schedule_staff_date", "staff_id", "date"),
    )

    id = Column(UUID(as_uuid=True), primary_key=True, server_default=text("gen_random_uuid()"))
    dept_id = Column(UUID(as_uuid=True), ForeignKey("departments.id", ondelete="RESTRICT"), nullable=False)
    date = Column(Date, nullable=False)
    shift_id = Column(UUID(as_uuid=True), ForeignKey("shifts.id", ondelete="RESTRICT"), nullable=True)
    staff_id = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="RESTRICT"), nullable=False)
    tag = Column(String, nullable=False, server_default="normal")
    note = Column(Text)
    original_staff_id = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="SET NULL"))
    substitute_for_id = Column(UUID(as_uuid=True), ForeignKey("schedule_items.id", ondelete="SET NULL"))
    reason = Column(Text)
    created_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False)