"""示例 3：重试与超时。

运行::

    uv run python examples/03_retry_and_timeout.py
"""

from __future__ import annotations

import time

from chongming_task.policies import ExponentialBackoff, RetryPolicy, Timeout
from chongming_task.run import run_task

_attempts = 0


def flaky(ctx, succeed_on_attempt: int) -> str:
    """前几次故意失败，用来演示重试与退避。"""
    global _attempts
    _attempts += 1
    if _attempts < succeed_on_attempt:
        raise RuntimeError(f"第 {_attempts} 次尝试遇到暂时性故障")
    return f"第 {_attempts} 次尝试成功"


def slow(ctx) -> str:
    """跑得很慢，用来演示超时后会被请求停止。"""
    for _ in range(10_000):
        ctx.checkpoint()
        time.sleep(0.01)
    return "跑完了"


def demo_retry() -> None:
    print("== 重试：失败两次后成功 ==")
    _attempts = 0
    outcome = run_task(
        flaky,
        3,
        retry=RetryPolicy(max_attempts=5, backoff=ExponentialBackoff(base=0.05, factor=2)),
        task_id="demo-retry",
        name="会抖的任务",
    )
    print(f"  终态      ：{outcome.status.value}")
    print(f"  返回值    ：{outcome.value}")
    print(f"  尝试次数  ：{outcome.snapshot.attempt}/{outcome.snapshot.max_attempts}")


def demo_retry_exhausted() -> None:
    print("\n== 重试：预算耗尽 ==")
    global _attempts
    _attempts = 0
    outcome = run_task(
        flaky,
        99,  # 永远不会成功
        retry=RetryPolicy(max_attempts=2, backoff=ExponentialBackoff(base=0.05, factor=1)),
        task_id="demo-exhausted",
        name="必定失败",
    )
    print(f"  终态      ：{outcome.status.value}")
    print(f"  尝试次数  ：{outcome.snapshot.attempt}/{outcome.snapshot.max_attempts}")
    print(f"  失败归类  ：{outcome.failure.kind.value if outcome.failure else '-'}")


def demo_timeout() -> None:
    print("\n== 超时：单次尝试不超过 0.5 秒 ==")
    outcome = run_task(
        slow,
        timeout=Timeout(per_attempt=0.5),
        task_id="demo-timeout",
        name="慢任务",
    )
    print(f"  终态      ：{outcome.status.value}")
    print(f"  失败归类  ：{outcome.failure.kind.value if outcome.failure else '-'}")
    print(f"  可重试    ：{outcome.failure.retryable if outcome.failure else '-'}")


def main() -> None:
    demo_retry()
    demo_retry_exhausted()
    demo_timeout()


if __name__ == "__main__":
    main()