"""回滚 SQL API 路由 — 提供回滚 SQL 生成和预览功能。"""
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.database import get_db
from app.core.security import get_current_user, require_role
from app.core.crypto import decrypt_password
from app.models.user import User
from app.models.instance import Instance
from app.models.ticket import Ticket
from app.schemas.rollback import (
    RollbackPreviewRequest,
    RollbackPreviewResponse,
    RollbackGenerateResponse,
    RollbackGenerateRequest,
)
from app.services.rollback_generator import RollbackGenerator, RollbackGeneratorError

router = APIRouter(tags=["回滚 SQL"])


async def _get_ticket(db: AsyncSession, ticket_id: int) -> Ticket:
    """获取工单并检查是否存在。

    Args:
        db: 数据库会话
        ticket_id: 工单ID

    Returns:
        工单对象

    Raises:
        HTTPException: 工单不存在
    """
    result = await db.execute(select(Ticket).where(Ticket.id == ticket_id))
    ticket = result.scalar_one_or_none()
    if not ticket:
        raise HTTPException(status_code=404, detail="工单不存在")
    return ticket


async def _get_instance(db: AsyncSession, instance_id: int) -> Instance:
    """获取实例并检查是否存在。

    Args:
        db: 数据库会话
        instance_id: 实例ID

    Returns:
        实例对象

    Raises:
        HTTPException: 实例不存在
    """
    result = await db.execute(select(Instance).where(Instance.id == instance_id))
    instance = result.scalar_one_or_none()
    if not instance:
        raise HTTPException(status_code=404, detail="数据源不存在")
    return instance


@router.post("/tickets/{ticket_id}/generate-rollback", response_model=RollbackGenerateResponse)
async def generate_rollback_sql(
    ticket_id: int,
    data: RollbackGenerateRequest,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin", "dba")),
):
    """为工单生成回滚 SQL。

    根据工单中的 SQL 内容，自动生成对应的回滚 SQL。
    支持 INSERT/UPDATE/DELETE 三种 DML 操作。

    Args:
        ticket_id: 工单ID
        data: 生成选项（是否自动保存）
        db: 数据库会话
        current_user: 当前用户

    Returns:
        生成的回滚 SQL 信息

    Raises:
        HTTPException: 工单不存在、无权访问或生成失败
    """
    ticket = await _get_ticket(db, ticket_id)

    # 获取关联的数据源实例
    instance = await _get_instance(db, ticket.instance_id)
    instance.password = decrypt_password(instance.password)

    # 生成回滚 SQL
    generator = RollbackGenerator()
    try:
        rollback_sql = await generator.generate(
            instance, ticket.target_database, ticket.sql_content
        )
    except RollbackGeneratorError as e:
        raise HTTPException(status_code=400, detail=str(e))
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"回滚 SQL 生成失败: {str(e)}")

    # 自动保存到工单
    saved = False
    if data.auto_save:
        ticket.rollback_sql = rollback_sql
        await db.commit()
        saved = True

    # 检测 SQL 类型
    from app.services.sql_analyzer import SQLAnalyzer
    analyzer = SQLAnalyzer()
    sql_type = analyzer._detect_sql_type(ticket.sql_content)

    return RollbackGenerateResponse(
        ticket_id=ticket_id,
        original_sql=ticket.sql_content,
        rollback_sql=rollback_sql,
        sql_type=sql_type.value if sql_type else None,
        saved=saved,
    )


@router.post("/rollback/preview", response_model=RollbackPreviewResponse)
async def preview_rollback_sql(
    req: RollbackPreviewRequest,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """预览回滚 SQL（不保存）。

    为给定的 SQL 语句生成回滚 SQL 预览，不执行实际数据库操作，
    也不保存到任何工单。

    Args:
        req: 预览请求（实例ID、数据库、SQL）
        db: 数据库会话
        current_user: 当前用户

    Returns:
        回滚 SQL 预览

    Raises:
        HTTPException: 实例不存在或无权限
    """
    instance = await _get_instance(db, req.instance_id)
    instance.password = decrypt_password(instance.password)

    generator = RollbackGenerator()
    try:
        rollback_sql = await generator.preview(instance, req.database, req.sql)
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"回滚 SQL 预览失败: {str(e)}")

    # 检测 SQL 类型
    from app.services.sql_analyzer import SQLAnalyzer
    analyzer = SQLAnalyzer()
    sql_type = analyzer._detect_sql_type(req.sql)

    warning = None
    if rollback_sql.startswith("--"):
        # 提取警告信息
        lines = rollback_sql.split("\n")
        warning_lines = [l for l in lines if l.startswith("--") and "无法" in l]
        if warning_lines:
            warning = warning_lines[0].replace("-- ", "")

    return RollbackPreviewResponse(
        original_sql=req.sql,
        rollback_sql=rollback_sql,
        sql_type=sql_type.value if sql_type else None,
        warning=warning,
    )