#264 gdtest_skill_complex

"""A task-orchestration framework."""

__version__ = "3.1.0"
__all__ = [
    "Scheduler",
    "Task",
    "CronExpr",
    "TaskResult",
    "every",
    "cron",
    "once",
    "chain",
]


class Scheduler:
    """
    Central task scheduler with worker pool.

    Parameters
    ----------
    workers
        Number of concurrent worker threads.
    name
        Scheduler instance identifier.
    """

    def __init__(self, workers: int = 1, name: str = "default"):
        self.workers = workers
        self.name = name
        self._tasks: list = []

    def every(self, seconds: int, fn=None, name: str = "") -> "Task":
        """
        Schedule a recurring task at a fixed interval.

        Parameters
        ----------
        seconds
            Interval in seconds between executions.
        fn
            Callable to execute.
        name
            Task identifier.

        Returns
        -------
        Task
            The registered task.
        """
        t = Task(name=name or "interval", fn=fn)
        self._tasks.append(t)
        return t

    def cron(self, expr: str, fn=None, name: str = "") -> "Task":
        """
        Schedule a task using a cron expression.

        Parameters
        ----------
        expr
            Cron expression (e.g., ``*/5 * * * *``).
        fn
            Callable to execute.
        name
            Task identifier.

        Returns
        -------
        Task
            The registered task.
        """
        CronExpr(expr)  # validate
        t = Task(name=name or "cron", fn=fn)
        self._tasks.append(t)
        return t

    def once(self, delay: int, fn=None, name: str = "") -> "Task":
        """
        Schedule a one-shot task after a delay.

        Parameters
        ----------
        delay
            Delay in seconds before execution.
        fn
            Callable to execute.
        name
            Task identifier.

        Returns
        -------
        Task
            The registered task.
        """
        t = Task(name=name or "once", fn=fn)
        self._tasks.append(t)
        return t

    def chain(self, *tasks: "Task") -> list["TaskResult"]:
        """
        Execute tasks sequentially, passing each result to the next.

        Parameters
        ----------
        *tasks
            Tasks to chain in order.

        Returns
        -------
        list[TaskResult]
            Results from each task in the chain.
        """
        return [TaskResult(task=t, status="pending") for t in tasks]

    def submit(self, fn=None, name: str = "") -> "Task":
        """
        Submit a fire-and-forget task.

        Parameters
        ----------
        fn
            Callable to execute.
        name
            Task identifier.

        Returns
        -------
        Task
            The submitted task.
        """
        t = Task(name=name or "submitted", fn=fn)
        self._tasks.append(t)
        return t

    def run(self) -> list["TaskResult"]:
        """
        Start the scheduler and block until stopped.

        Returns
        -------
        list[TaskResult]
            Results of all completed tasks.
        """
        return []

    def stop(self) -> None:
        """Stop the scheduler gracefully."""
        pass


class Task:
    """
    A unit of work managed by a Scheduler.

    Parameters
    ----------
    name
        Task identifier (must be unique within a scheduler).
    fn
        Callable to execute.
    timeout
        Maximum execution time in seconds (None = no limit).
    """

    def __init__(self, name: str, fn=None, timeout: int | None = None):
        self.name = name
        self.fn = fn
        self.timeout = timeout


class CronExpr:
    """
    A parsed cron expression.

    Parameters
    ----------
    expr
        Cron expression string (5 fields: min hour dom month dow).

    Raises
    ------
    ValueError
        If the expression is malformed.
    """

    def __init__(self, expr: str):
        parts = expr.strip().split()
        if len(parts) != 5:
            raise ValueError(
                f"Cron expression must have 5 fields, got {len(parts)}: {expr!r}"
            )
        self.expr = expr

    def matches(self, dt) -> bool:
        """
        Check if a datetime matches this cron expression.

        Parameters
        ----------
        dt
            A datetime to test.

        Returns
        -------
        bool
            True if the datetime matches.
        """
        return True


class TaskResult:
    """
    The result of a completed task.

    Parameters
    ----------
    task
        The task that produced this result.
    status
        Execution status (pending, success, failed, timeout).
    value
        Return value from the task callable.
    error
        Exception if the task failed.
    """

    def __init__(
        self,
        task: Task,
        status: str = "pending",
        value=None,
        error: Exception | None = None,
    ):
        self.task = task
        self.status = status
        self.value = value
        self.error = error


def every(seconds: int, fn=None) -> Task:
    """
    Module-level shortcut: schedule a recurring task.

    Parameters
    ----------
    seconds
        Interval between executions.
    fn
        Callable to execute.

    Returns
    -------
    Task
        The registered task.
    """
    return Scheduler().every(seconds, fn)


def cron(expr: str, fn=None) -> Task:
    """
    Module-level shortcut: schedule a cron task.

    Parameters
    ----------
    expr
        Cron expression.
    fn
        Callable to execute.

    Returns
    -------
    Task
        The registered task.
    """
    return Scheduler().cron(expr, fn)


def once(delay: int, fn=None) -> Task:
    """
    Module-level shortcut: schedule a one-shot task.

    Parameters
    ----------
    delay
        Seconds before execution.
    fn
        Callable to execute.

    Returns
    -------
    Task
        The registered task.
    """
    return Scheduler().once(delay, fn)


def chain(*tasks: Task) -> list[TaskResult]:
    """
    Module-level shortcut: chain tasks sequentially.

    Parameters
    ----------
    *tasks
        Tasks to chain.

    Returns
    -------
    list[TaskResult]
        Results from each task.
    """
    return Scheduler().chain(*tasks)