"""Database connection and session management."""

import uuid, re
from loguru import logger
import traceback
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
from sqlalchemy.orm import sessionmaker
from typing import Optional

from utils.general import gradient_text

from ..core.config import get_settings
from .base import Base
from utils.util_exceptions import DatabaseError

# Custom Session class with desc property and unique ID
class DrSession(AsyncSession):
    """Custom Session class with desc property and unique ID."""
    
    def __init__(self, **kwargs):
        """Initialize DrSession with unique ID."""
        super().__init__(**kwargs)
        self.title = ""
        self.descs = []
        # 确保info属性存在
        if not hasattr(self, 'info'):
            self.info = {}
        self.info['session_id'] = str(uuid.uuid4()).split('-')[0]
        self.stepIndex = 0

    @property
    def title(self) -> Optional[str]:
        """Get work brief from session info."""
        return self.info.get('title')
    
    @title.setter
    def title(self, value: str) -> None:
        """Set work brief in session info."""
        if('title' not in self.info or self.info['title'].strip() == ""):
            self.info['title'] = value  # 确保title属性存在
        else:
            self.info['title'] = value + " >>> " + self.info['title']
        
    @property
    def desc(self) -> Optional[str]:
        """Get work brief from session info."""
        return self.info.get('desc')
    
    @desc.setter
    def desc(self, value: str) -> None:
        """Set work brief in session info."""
        self.stepIndex += 1
        # 统一在这里打印更详细的 session 日志，方便排查问题
        try:
            # level 取 -3，可以拿到触发 desc 设置的上层业务代码位置
            pos = self.parse_source_pos(-3)
        except Exception:
            pos = "unknown"

        logger.info(f"{self.log_prefix()} STEP[{self.stepIndex}] {value} >>> @ {pos}")
        
    def log_prefix(self) -> str:
        """Get log prefix with session ID and desc."""
        return f"〖Session{self.info['session_id']}〗"
    
    def parse_source_pos(self, level: int):
        pos = (traceback.format_stack())[level].strip().split('\n')[0]
        match = re.search(r"File \"(.+?)\", line (\d+), in (\w+)", pos);
        if match:
            file = match.group(1).replace("F:\\DrGraph_Python\\FastAPI\\", "")
            pos = f"{file}:{match.group(2)} in {match.group(3)}"
        return pos
    
    def log_info(self, msg: str, level: int = -2):
        """Log info message with session ID."""
        pos = self.parse_source_pos(level)
        logger.info(f"{self.log_prefix()} {msg} >>> @ {pos}")
    
    def log_success(self, msg: str, level: int = -2):
        """Log success message with session ID."""
        pos = self.parse_source_pos(level)
        logger.success(f"{self.log_prefix()} {msg} >>> @ {pos}")
    
    def log_warning(self, msg: str, level: int = -2):
        """Log warning message with session ID."""
        pos = self.parse_source_pos(level)
        logger.warning(f"{self.log_prefix()} {msg} >>> @ {pos}")
    
    def log_error(self, msg: str, level: int = -2):
        """Log error message with session ID."""      
        pos = self.parse_source_pos(level)
        logger.error(f"{self.log_prefix()} {msg} >>> @ {pos}")
    
    def log_exception(self, msg: str, level: int = -2):
        """Log exception message with session ID."""
        pos = self.parse_source_pos(level)
        logger.exception(f"{self.log_prefix()} {msg} >>> @ {pos}")

engine_async = create_async_engine(
    get_settings().database.url,
    echo=False, # get_settings().database.echo,
    future=True,
    pool_size=get_settings().database.pool_size,
    max_overflow=get_settings().database.max_overflow,
    pool_pre_ping=True,
    pool_recycle=3600,
)
from fastapi import HTTPException, Request

AsyncSessionFactory = sessionmaker(
    bind=engine_async,
    class_=DrSession,
    expire_on_commit=False,
    autoflush=True
)

async def get_session(request: Request = None):    
    url = "无request"
    if request:
        url = f"{request.method} {request.url.path}"# .split("://")[-1]
    # session = AsyncSessionFactory()
    print(url)
    # 取得request的来源IP
    if request:
        client_host = request.client.host
    else:
        client_host = "无request"

    # 使用 AsyncSessionFactory 创建会话，确保 async/greenlet 配置正确
    #（包括 expire_on_commit=False，避免在属性访问时触发隐式 IO，导致 MissingGreenlet / pk_1 参数异常）
    session: DrSession = AsyncSessionFactory()
    
    session.title = f"{url} - {client_host}"
    
    # 设置request属性
    if request:
        session.request = request
    
    try:
        yield session
        
    except Exception as e:
        errMsg = f"数据库 session 异常 >>> {e}"
        # 先打带堆栈的异常日志
        session.log_exception(errMsg)
        # 再通过 desc 打一条结构化的 info 日志（含步骤、调用位置）
        session.desc = f"EXCEPTION: {errMsg}"
        await session.rollback()
        # 重新抛出原始异常，不转换为 HTTPException
        raise e # HTTPException(status_code=e.status_code, detail=errMsg)  # main.py中将捕获本异常
    finally:
        # session.desc = f"数据库 session 关闭"
        session.desc = ""
        await session.close()