from typing import Optional

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.company import Company, CompanyStatus
from app.schemas.company import CompanyCreate, CompanyUpdate


class CompanyService:
    """企业服务"""

    @staticmethod
    async def create_company(
        db: AsyncSession,
        company_data: CompanyCreate,
    ) -> Company:
        """
        创建企业
        
        Args:
            db: 数据库会话
            company_data: 企业数据
            
        Returns:
            创建的企业对象
        """
        company = Company(**company_data.model_dump())
        db.add(company)
        await db.commit()
        await db.refresh(company)
        return company

    @staticmethod
    async def get_company(
        db: AsyncSession,
        company_id: int,
    ) -> Optional[Company]:
        """
        获取企业信息
        
        Args:
            db: 数据库会话
            company_id: 企业 ID
            
        Returns:
            企业对象，不存在则返回 None
        """
        result = await db.execute(
            select(Company).where(
                Company.id == company_id,
                Company.status != CompanyStatus.DELETED.value,
            )
        )
        return result.scalar_one_or_none()

    @staticmethod
    async def update_company(
        db: AsyncSession,
        company_id: int,
        company_data: CompanyUpdate,
    ) -> Optional[Company]:
        """
        更新企业信息
        
        Args:
            db: 数据库会话
            company_id: 企业 ID
            company_data: 更新数据
            
        Returns:
            更新后的企业对象，不存在则返回 None
        """
        company = await CompanyService.get_company(db, company_id)
        if not company:
            return None

        update_data = company_data.model_dump(exclude_unset=True)
        for field, value in update_data.items():
            setattr(company, field, value)

        await db.commit()
        await db.refresh(company)
        return company

    @staticmethod
    async def list_companies(
        db: AsyncSession,
        skip: int = 0,
        limit: int = 100,
    ) -> list[Company]:
        """
        获取企业列表
        
        Args:
            db: 数据库会话
            skip: 跳过数量
            limit: 返回数量
            
        Returns:
            企业列表
        """
        result = await db.execute(
            select(Company)
            .where(Company.status != CompanyStatus.DELETED.value)
            .offset(skip)
            .limit(limit)
        )
        return list(result.scalars().all())


# 单例实例
company_service = CompanyService()