import asyncio
import json
import time
from datetime import datetime, timedelta
from typing import Optional, Dict, Any, List

from app.infra.external import feishu_robot
from app.infra.shared import task_schedule_response
from app.jobs.task_handler import TaskHandler
from app.jobs.task_config import (
    TaskStatus,
    TaskConstants,
    get_task_config,
)
from app.jobs.task_utils import (
    TaskError,
    TaskValidationError,
    TaskConcurrencyError,
    TaskUtils,
)
from app.core.config import GlobalConfigSettings
from app.core.database import DatabaseManager
from app.core.observability import LogService


class TaskScheduler(TaskHandler):
    """
    统一任务调度器

    使用方法：
        scheduler = TaskScheduler(data, log_service, db_client, trace_id)
        result = await scheduler.deal()
    """

    def __init__(
        self,
        data: dict,
        log_service: LogService,
        db_client: DatabaseManager,
        trace_id: str,
        config: GlobalConfigSettings,
    ):
        super().__init__(data, log_service, db_client, trace_id, config)
        self.table = TaskUtils.validate_table_name(TaskConstants.TASK_TABLE)

    # ==================== 数据库操作 ====================

    async def _insert_or_ignore_task(self, task_name: str, date_str: str) -> None:
        """新建任务记录（若同键已存在则忽略）"""
        query = f"""
            INSERT IGNORE INTO {self.table}
            (date_string, task_name, start_timestamp, task_status, trace_id, data)
            VALUES (%s, %s, %s, %s, %s, %s)
        """
        await self.db_client.async_save(
            query=query,
            params=(
                date_str,
                task_name,
                int(time.time()),
                TaskStatus.INIT,
                self.trace_id,
                json.dumps(self.data, ensure_ascii=False),
            ),
        )

    async def _try_lock_task(self) -> bool:
        """
        尝试获取任务锁（CAS 操作）
        返回 True 表示成功获取锁
        """
        query = f"""
            UPDATE {self.table}
            SET task_status = %s
            WHERE trace_id = %s AND task_status = %s
        """
        result = await self.db_client.async_save(
            query=query,
            params=(TaskStatus.PROCESSING, self.trace_id, TaskStatus.INIT),
        )
        return bool(result)

    async def _release_task(self, status: int) -> None:
        """释放任务锁并更新状态"""
        query = f"""
            UPDATE {self.table}
            SET task_status = %s, finish_timestamp = %s
            WHERE trace_id = %s AND task_status = %s
        """
        await self.db_client.async_save(
            query=query,
            params=(
                status,
                int(time.time()),
                self.trace_id,
                TaskStatus.PROCESSING,
            ),
        )

    async def _get_processing_tasks(self, task_name: str) -> List[Dict[str, Any]]:
        """获取正在处理中的任务列表"""
        query = f"""
            SELECT trace_id, start_timestamp, data
            FROM {self.table}
            WHERE task_status = %s AND task_name = %s
        """
        rows = await self.db_client.async_fetch(
            query=query,
            params=(TaskStatus.PROCESSING, task_name),
        )
        return rows or []

    # ==================== 任务检查 ====================

    async def _check_task_concurrency_and_timeout(self, task_name: str) -> None:
        """
        检查任务并发数和超时情况

        优化点：
        1. 真正检查任务是否超时（基于时间）
        2. 分别处理超时和并发限制
        3. 可选择自动释放超时任务

        Raises:
            TaskTimeoutError: 发现超时任务
            TaskConcurrencyError: 超过并发限制
        """
        processing_tasks = await self._get_processing_tasks(task_name)

        if not processing_tasks:
            return

        config = get_task_config(task_name)
        current_time = int(time.time())

        # 检查超时任务
        timeout_tasks = [
            task
            for task in processing_tasks
            if current_time - task["start_timestamp"] > config.timeout
        ]

        if timeout_tasks:
            await self._log_task_event(
                "task_timeout_detected",
                task_name=task_name,
                timeout_count=len(timeout_tasks),
                timeout_tasks=[t["trace_id"] for t in timeout_tasks],
            )

            await feishu_robot.bot(
                title=f"Task Timeout Alert: {task_name}",
                detail={
                    "task_name": task_name,
                    "timeout_count": len(timeout_tasks),
                    "timeout_threshold": config.timeout,
                    "timeout_tasks": [
                        {
                            "trace_id": t["trace_id"],
                            "running_time": current_time - t["start_timestamp"],
                        }
                        for t in timeout_tasks
                    ],
                },
            )

            # 可选：自动释放超时任务（需要谨慎使用）
            for task in timeout_tasks:
                await self._force_release_task(task["trace_id"], TaskStatus.FAILED)

        # 检查并发限制（排除超时任务）
        active_tasks = [
            task
            for task in processing_tasks
            if current_time - task["start_timestamp"] <= config.timeout
        ]

        if len(active_tasks) >= config.max_concurrent:
            await self._log_task_event(
                "task_concurrency_limit",
                task_name=task_name,
                current_count=len(active_tasks),
                max_concurrent=config.max_concurrent,
            )

            await feishu_robot.bot(
                title=f"Task Concurrency Limit: {task_name}",
                detail={
                    "task_name": task_name,
                    "current_count": len(active_tasks),
                    "max_concurrent": config.max_concurrent,
                    "active_tasks": [t["trace_id"] for t in active_tasks],
                },
            )

            raise TaskConcurrencyError(
                f"Task {task_name} has reached max concurrency limit "
                f"({len(active_tasks)}/{config.max_concurrent})",
                task_name=task_name,
            )

    # ==================== 任务执行 ====================

    async def _run_with_guard(
        self,
        task_name: str,
        date_str: str,
        task_handler,
    ) -> dict:
        """
        带保护的任务执行

        优化点：
        1. 更好的错误处理和重试机制
        2. 统一的日志记录
        3. 详细的错误信息
        """
        # 1. 检查并发和超时
        try:
            await self._check_task_concurrency_and_timeout(task_name)
        except TaskConcurrencyError as e:
            return await task_schedule_response.fail_response("5005", str(e))

        # 2. 创建任务记录并尝试获取锁
        await self._insert_or_ignore_task(task_name, date_str)

        if not await self._try_lock_task():
            return await task_schedule_response.fail_response(
                "5001", "Task is already processing"
            )

        # 3. 后台执行任务
        async def _task_wrapper():
            """任务执行包装器 - 处理错误和重试"""
            status = TaskStatus.FAILED
            retry_count = 0
            config = get_task_config(task_name)
            start_time = time.time()

            try:
                await self._log_task_event("task_started", task_name=task_name)

                # 执行任务
                status = await task_handler()

                duration = time.time() - start_time
                await self._log_task_event(
                    "task_completed",
                    task_name=task_name,
                    status=status,
                    duration=duration,
                )

            except TaskError as e:
                # 已知的任务错误
                duration = time.time() - start_time
                error_detail = TaskUtils.format_error_detail(e)

                await self._log_task_event(
                    "task_failed",
                    task_name=task_name,
                    error=error_detail,
                    duration=duration,
                    retry_count=retry_count,
                )

                # 根据错误类型决定是否告警
                if config.alert_on_failure:
                    await feishu_robot.bot(
                        title=f"Task Failed: {task_name}",
                        detail={
                            "task_name": task_name,
                            "trace_id": self.trace_id,
                            "error": error_detail,
                            "duration": duration,
                            "retryable": e.retryable,
                        },
                    )

                # TODO: 实现重试逻辑
                # if e.retryable and retry_count < config.retry_times:
                #     await self._schedule_retry(task_name, retry_count + 1)

            except Exception as e:
                # 未知错误
                duration = time.time() - start_time
                error_detail = TaskUtils.format_error_detail(e)

                await self._log_task_event(
                    "task_error",
                    task_name=task_name,
                    error=error_detail,
                    duration=duration,
                )

                await feishu_robot.bot(
                    title=f"Task Error: {task_name}",
                    detail={
                        "task_name": task_name,
                        "trace_id": self.trace_id,
                        "error": error_detail,
                        "duration": duration,
                    },
                )

            finally:
                await self._release_task(status)

        # 创建后台任务
        asyncio.create_task(_task_wrapper(), name=f"{task_name}_{self.trace_id}")

        return await task_schedule_response.success_response(
            task_name=task_name,
            data={
                "code": 0,
                "message": "Task started successfully",
                "trace_id": self.trace_id,
            },
        )

    # ==================== 任务管理接口 ====================

    async def get_task_status(
        self, trace_id: Optional[str] = None
    ) -> Optional[Dict[str, Any]]:
        """
        查询任务状态

        Args:
            trace_id: 任务追踪 ID，默认使用当前实例的 trace_id

        Returns:
            任务信息字典，如果不存在返回 None
        """
        trace_id = trace_id or self.trace_id
        query = f"SELECT * FROM {self.table} WHERE trace_id = %s"
        result = await self.db_client.async_fetch_one(query, (trace_id,))
        return result

    async def cancel_task(self, trace_id: Optional[str] = None) -> bool:
        """
        取消任务（将状态设置为失败）

        Args:
            trace_id: 任务追踪 ID，默认使用当前实例的 trace_id

        Returns:
            是否成功取消
        """
        trace_id = trace_id or self.trace_id
        query = f"""
            UPDATE {self.table}
            SET task_status = %s, finish_timestamp = %s
            WHERE trace_id = %s AND task_status IN (%s, %s)
        """
        result = await self.db_client.async_save(
            query,
            (
                TaskStatus.FAILED,
                int(time.time()),
                trace_id,
                TaskStatus.INIT,
                TaskStatus.PROCESSING,
            ),
        )

        if result:
            await self._log_task_event("task_cancelled", trace_id=trace_id)

        return bool(result)

    async def retry_task(self, trace_id: Optional[str] = None) -> bool:
        """
        重试任务（将状态重置为初始化）

        Args:
            trace_id: 任务追踪 ID，默认使用当前实例的 trace_id

        Returns:
            是否成功重置
        """
        trace_id = trace_id or self.trace_id
        query = f"""
            UPDATE {self.table}
            SET task_status = %s, start_timestamp = %s, finish_timestamp = NULL
            WHERE trace_id = %s
        """
        result = await self.db_client.async_save(
            query,
            (TaskStatus.INIT, int(time.time()), trace_id),
        )

        if result:
            await self._log_task_event("task_retried", trace_id=trace_id)

        return bool(result)

    async def _force_release_task(self, trace_id: str, status: int) -> None:
        """强制释放任务（用于超时任务清理）"""
        query = f"""
            UPDATE {self.table}
            SET task_status = %s, finish_timestamp = %s
            WHERE trace_id = %s
        """
        await self.db_client.async_save(
            query,
            (status, int(time.time()), trace_id),
        )
        await self._log_task_event(
            "task_force_released", trace_id=trace_id, status=status
        )

    # ==================== 主入口 ====================

    async def deal(self) -> dict:
        """
        任务调度主入口

        Returns:
            调度结果字典
        """
        # 验证任务名
        task_name = self.data.get("task_name")
        if not task_name:
            return await task_schedule_response.fail_response(
                "4003", "task_name is required"
            )

        try:
            task_name = TaskUtils.validate_task_name(task_name)
        except TaskValidationError as e:
            return await task_schedule_response.fail_response("4003", str(e))

        # 获取日期
        date_str = self.data.get("date_string") or (
            datetime.utcnow() + timedelta(hours=8)
        ).strftime("%Y-%m-%d")

        # 获取任务处理器
        handler = self.get_handler(task_name)
        if not handler:
            return await task_schedule_response.fail_response(
                "4001",
                f"Unknown task: {task_name}. "
                f"Available tasks: {', '.join(self.list_registered_tasks())}",
            )

        # 执行任务
        return await self._run_with_guard(
            task_name,
            date_str,
            lambda: handler(self),
        )


__all__ = ["TaskScheduler"]