"""项目成本明细模型

管理项目的耗材成本和设备折旧成本
"""

from typing import Optional, TYPE_CHECKING
from decimal import Decimal

from sqlalchemy import BigInteger, String, DECIMAL, ForeignKey
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import BaseModel

if TYPE_CHECKING:
    from app.models.project import Project


class ProjectCostItem(BaseModel):
    """项目成本明细表（耗材/设备）"""
    
    __tablename__ = "project_cost_items"
    
    project_id: Mapped[int] = mapped_column(
        BigInteger,
        ForeignKey("projects.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
        comment="项目ID"
    )
    item_type: Mapped[str] = mapped_column(
        String(20),
        nullable=False,
        index=True,
        comment="类型：material-耗材, equipment-设备"
    )
    item_id: Mapped[int] = mapped_column(
        BigInteger,
        nullable=False,
        comment="耗材/设备ID"
    )
    quantity: Mapped[Decimal] = mapped_column(
        DECIMAL(10, 4),
        nullable=False,
        comment="用量"
    )
    unit_cost: Mapped[Decimal] = mapped_column(
        DECIMAL(12, 4),
        nullable=False,
        comment="单位成本"
    )
    total_cost: Mapped[Decimal] = mapped_column(
        DECIMAL(12, 2),
        nullable=False,
        comment="总成本 = quantity * unit_cost"
    )
    remark: Mapped[Optional[str]] = mapped_column(
        String(200),
        nullable=True,
        comment="备注"
    )
    
    # 关系
    project: Mapped["Project"] = relationship(
        "Project",
        back_populates="cost_items"
    )