import asyncio
from datetime import datetime, timedelta
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.database import AsyncSessionLocal
from app.models.emails import VasEmail
from app.services.order_event_service import OrderEventService
from app.schemas.order_event import VasOrderEventCreate
from app.core.biz_exception import BizLogicError

async def sync_recent_emails():
    # 1. 计算 3 周前的时间
    three_weeks_ago = datetime.utcnow() - timedelta(weeks=4)
    
    batch_size = 100
    offset = 0
    total_processed = 0
    total_synced = 0
    total_skipped = 0

    print(f"[*] 开始扫描邮件表，起始时间: {three_weeks_ago}")

    async with AsyncSessionLocal() as db:
        while True:
            # 2. 分批查询 emails 表 (按 created_at 过滤并排序)
            stmt = (
                select(VasEmail)
                .where(VasEmail.created_at >= three_weeks_ago)
                .order_by(VasEmail.created_at.asc())
                .offset(offset)
                .limit(batch_size)
            )
            
            result = await db.execute(stmt)
            batch_emails = result.scalars().all()
            
            if not batch_emails:
                break  # 没有更多数据了

            for email in batch_emails:
                total_processed += 1
                
                # 3. 构造创建参数
                # recipient 映射为 alias_email
                event_in = VasOrderEventCreate(
                    event_title=email.subject or "No Subject",
                    event_message=email.body_text[:2000] if email.body_text else "", # 适当截断防溢出
                    email_uid=email.uid,
                    event_time=email.created_at, # receive_time 是字符串，使用 created_at 更稳妥
                    alias_email=email.recipient,
                    order_no=None # 让 Service 根据 alias_email 自动解析
                )

                try:
                    # 4. 调用之前写好的 Service (它会自动查询 order_id 并写入)
                    await OrderEventService.create(db, event_in)
                    total_synced += 1
                    if total_synced % 10 == 0:
                        print(f"[-] 已处理: {total_processed}, 成功写入: {total_synced}")
                except BizLogicError as e:
                    # 如果 alias_email 找不到对应的 order_id，会抛出这个错，我们记录并跳过
                    total_skipped += 1
                    # print(f"[!] 跳过 UID {email.uid}: {e.message}")
                except Exception as e:
                    print(f"[ERR] 处理 UID {email.uid} 时发生未知错误: {e}")
            
            # 移动偏移量进行下一批次
            offset += batch_size

    print(f"\n[*] 任务完成!")
    print(f"[*] 总扫描数: {total_processed}")
    print(f"[*] 成功写入 OrderEvent: {total_synced}")
    print(f"[*] 被忽略(无对应订单): {total_skipped}")

if __name__ == "__main__":
    asyncio.run(sync_recent_emails())