# Source code for dask.diagnostics.progress

    from __future__ import annotations

    import contextlib
    import sys
    import threading
    import time
    from timeit import default_timer

    from dask.callbacks import Callback
    from dask.utils import _deprecated

    @_deprecated(after_version="2022.6.0", use_instead="dask.utils.format_time")
    def format_time(t):
        """Format seconds into a human readable form.

        >>> format_time(10.4)  # doctest: +SKIP
        '10.4s'
        >>> format_time(1000.4)  # doctest: +SKIP
        '16min 40.4s'
        """
        m, s = divmod(t, 60)
        h, m = divmod(m, 60)
        if h:
            return f"{h:2.0f}hr {m:2.0f}min {s:4.1f}s"
        elif m:
            return f"{m:2.0f}min {s:4.1f}s"
        else:
            return f"{s:4.1f}s"

    class ProgressBar(Callback):
        """A progress bar for dask.

        Parameters
        ----------
        minimum : int, optional
            Minimum time threshold in seconds before displaying a progress bar.
            Default is 0 (always display)
        width : int, optional
            Width of the bar
        dt : float, optional
            Update resolution in seconds, default is 0.1 seconds
        out : file object, optional
            File object to which the progress bar will be written
            It can be ``sys.stdout``, ``sys.stderr`` or any other file object able to write ``str`` objects
            Default is ``sys.stdout``

        Examples
        --------

        Below we create a progress bar with a minimum threshold of 1 second before
        displaying. For cheap computations nothing is shown:

        >>> with ProgressBar(minimum=1.0):      # doctest: +SKIP
        ...     out = some_fast_computation.compute()

        But for expensive computations a full progress bar is displayed:

        >>> with ProgressBar(minimum=1.0):      # doctest: +SKIP
        ...     out = some_slow_computation.compute()
        [########################################] | 100% Completed | 10.4 s

        The duration of the last computation is available as an attribute

        >>> pbar = ProgressBar()                # doctest: +SKIP
        >>> with pbar:                          # doctest: +SKIP
        ...     out = some_computation.compute()
        [########################################] | 100% Completed | 10.4 s
        >>> pbar.last_duration                  # doctest: +SKIP
        10.4

        You can also register a progress bar so that it displays for all
        computations:

        >>> pbar = ProgressBar()                # doctest: +SKIP
        >>> pbar.register()                     # doctest: +SKIP
        >>> some_slow_computation.compute()     # doctest: +SKIP
        [########################################] | 100% Completed | 10.4 s
        """

        def __init__(self, minimum=0, width=40, dt=0.1, out=None):
            if out is None:
                # Warning, on windows, stdout can still be None if
                # an application is started as GUI Application
                # https://docs.python.org/3/library/sys.html#sys.__stderr__
                out = sys.stdout
            self._minimum = minimum
            self._width = width
            self._dt = dt
            self._file = out
            self.last_duration = 0

        def _start(self, dsk):
            self._state = None
            self._start_time = default_timer()
            # Start background thread
            self._running = True
            self._timer = threading.Thread(target=self._timer_func)
            self._timer.daemon = True
            self._timer.start()

        def _pretask(self, key, dsk, state):
            self._state = state
            if self._file is not None:
                self._file.flush()

        def _finish(self, dsk, state, errored):
            self._running = False
            self._timer.join()
            elapsed = default_timer() - self._start_time
            self.last_duration = elapsed
            if elapsed < self._minimum:
                return
            if not errored:
                self._draw_bar(1, elapsed)
            else:
                self._update_bar(elapsed)
            if self._file is not None:
                self._file.write("\n")
                self._file.flush()

        def _timer_func(self):
            """Background thread for updating the progress bar"""
            while self._running:
                elapsed = default_timer() - self._start_time
                if elapsed > self._minimum:
                    self._update_bar(elapsed)
                time.sleep(self._dt)

        def _update_bar(self, elapsed):
            s = self._state
            if not s:
                self._draw_bar(0, elapsed)
                return
            ndone = len(s["finished"])
            ntasks = sum(len(s[k]) for k in ["ready", "waiting", "running"]) + ndone
            if ndone < ntasks:
                self._draw_bar(ndone / ntasks if ntasks else 0, elapsed)

        def _draw_bar(self, frac, elapsed):
            from dask.utils import format_time

            bar = "#" * int(self._width * frac)
            percent = int(100 * frac)
            elapsed = format_time(elapsed)
            msg = "\r[{0:<{1}}] | {2}% Completed | {3}".format(
                bar, self._width, percent, elapsed
            )
            with contextlib.suppress(ValueError):
                if self._file is not None:
                    self._file.write(msg)
                    self._file.flush()