from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, LargeBinary
from sqlalchemy.orm import relationship
from datetime import datetime
import os

from . import Base

class Attachment(Base):
    """附件模型"""
    __tablename__ = 'attachments'

    id = Column(Integer, primary_key=True)
    email_id = Column(Integer, ForeignKey('emails.id'), nullable=False, index=True)
    filename = Column(String(255), nullable=False)
    content_type = Column(String(100), nullable=True)
    size = Column(Integer, nullable=False, default=0)
    storage_path = Column(String(500), nullable=True)  # 用于文件系统存储
    content = Column(LargeBinary, nullable=True)  # 用于小型附件的直接存储
    created_at = Column(DateTime, default=datetime.utcnow)
    
    # 关联关系
    email = relationship("Email", back_populates="attachments")
    
    @property
    def is_stored_in_fs(self):
        """判断附件是否存储在文件系统中"""
        return bool(self.storage_path and not self.content)
    
    def save_to_filesystem(self, content, base_path):
        """将附件保存到文件系统"""
        # 确保目录存在
        os.makedirs(base_path, exist_ok=True)
        
        # 创建文件路径
        file_path = os.path.join(
            base_path, 
            f"{self.email_id}_{self.id}_{self.filename}"
        )
        
        # 写入文件
        with open(file_path, 'wb') as f:
            f.write(content)
        
        # 更新对象属性
        self.storage_path = file_path
        self.size = len(content)
        self.content = None  # 清空内存中的内容
        
        return file_path
    
    def get_content(self, attachments_dir=None):
        """获取附件内容，无论是从数据库还是文件系统"""
        if self.content:
            return self.content
            
        if self.storage_path and os.path.exists(self.storage_path):
            with open(self.storage_path, 'rb') as f:
                return f.read()
                
        return None
        
    def to_dict(self):
        """转换为字典，用于API响应"""
        return {
            "id": self.id,
            "email_id": self.email_id,
            "filename": self.filename,
            "content_type": self.content_type,
            "size": self.size,
            "created_at": self.created_at.isoformat() if self.created_at else None
        }