"""Database base model."""

from datetime import datetime
from sqlalchemy import Integer, DateTime, event
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, Session
from sqlalchemy.sql import func
from typing import Optional
from sqlalchemy import MetaData

class Base(DeclarativeBase):
    metadata = MetaData(
        naming_convention={
            # ix: index, 索引
            "ix": "ix_%(column_0_label)s",
            # uq: unique, 唯一约束
            "uq": "uq_%(table_name)s_%(column_0_name)s",
            # ck: check, 检查约束
            "ck": "ck_%(table_name)s_%(constraint_name)s",
            # fk: foreign key, 外键约束
            "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
            # pk: primary key, 主键约束
            "pk": "pk_%(table_name)s"
        }
    )


class BaseModel(Base):
    """Base model with common fields."""
    
    __abstract__ = True
    
    id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=func.now(), nullable=False)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=func.now(), onupdate=func.now(), nullable=False)
    created_by: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
    updated_by: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
    
    def to_dict(self):
        """Convert model to dictionary."""
        return {
            column.name: getattr(self, column.name).isoformat() if hasattr(getattr(self, column.name), 'isoformat') else getattr(self, column.name)
            for column in self.__table__.columns
        }
    
    @classmethod
    def from_dict(cls, data: dict):
        """Create model instance from dictionary.
        
        Args:
            data: Dictionary containing model field values
            
        Returns:
            Model instance created from the dictionary
        """
        # Filter out fields that don't exist in the model
        model_fields = {column.name for column in cls.__table__.columns}
        filtered_data = {key: value for key, value in data.items() if key in model_fields}
        
        # Create and return the instance
        return cls(**filtered_data)

    def set_audit_fields(self, user_id: Optional[int] = None, is_update: bool = False):
        """对创建/更新操作设置created_by/updated_by字段。

        Args:
            user_id: 用户ID，用于设置创建/更新操作的审计字段（可选，默认从上下文获取）
            is_update: True 表示更新操作，False 表示创建操作
        """
        # 如果未提供user_id，则从上下文获取
        if user_id is None:
            from ..core.context import UserContext
            try:
                user_id = UserContext.get_current_user_id()
            except Exception:
                # 如果上下文没有用户ID，则跳过设置审计字段
                return

        # 如果仍未提供user_id，则跳过设置审计字段
        if user_id is None:
            return

        if not is_update:
            # 对于创建操作，同时设置created_by和updated_by
            self.created_by = user_id
            self.updated_by = user_id
        else:
            # 对于更新操作，仅设置updated_by
            self.updated_by = user_id
    
# @event.listens_for(Session, 'before_flush')
# def set_audit_fields_before_flush(session, flush_context, instances):
#     """Automatically set audit fields before flush."""
#     try:
#         from th_agenter.core.context import UserContext
#         user_id = UserContext.get_current_user_id()
#     except Exception:
#         user_id = None
    
#     # 处理新增对象
#     for instance in session.new:
#         if isinstance(instance, BaseModel) and user_id:
#             instance.created_by = user_id
#             instance.updated_by = user_id
    
#     # 处理修改对象
#     for instance in session.dirty:
#         if isinstance(instance, BaseModel) and user_id:
#             instance.updated_by = user_id

#     # def __init__(self, **kwargs):
#     #     """Initialize model with automatic audit fields setting."""
#     #     super().__init__(**kwargs)
#     #     # Set audit fields for new instances
#     #     self.set_audit_fields()

#     # def set_audit_fields(self, user_id: Optional[int] = None, is_update: bool = False):
#     #     """Set audit fields for create/update operations.

#     #     Args:
#     #         user_id: ID of the user performing the operation (optional, will use context if not provided)
#     #         is_update: True for update operations, False for create operations
#     #     """
#     #     # Get user_id from context if not provided
#     #     if user_id is None:
#     #         from ..core.context import UserContext
#     #         try:
#     #             user_id = UserContext.get_current_user_id()
#     #         except Exception:
#     #             # If no user in context, skip setting audit fields
#     #             return

#     #     # Skip if still no user_id
#     #     if user_id is None:
#     #         return

#     #     if not is_update:
#     #         # For create operations, set both create_by and update_by
#     #         self.created_by = user_id
#     #         self.updated_by = user_id
#     #     else:
#     #         # For update operations, only set update_by
#     #         self.updated_by = user_id