"""
`rich.progress` decorator for iterators.

Usage:
>>> from tqdm.rich import trange, tqdm
>>> for i in trange(10):
...     ...
"""
from __future__ import absolute_import

from warnings import warn

from rich.progress import (
    BarColumn, Progress, ProgressColumn, Text, TimeElapsedColumn, TimeRemainingColumn, filesize)

from .std import TqdmExperimentalWarning
from .std import tqdm as std_tqdm
from .utils import _range

__author__ = {"github.com/": ["casperdcl"]}
__all__ = ['tqdm_rich', 'trrange', 'tqdm', 'trange']


class FractionColumn(ProgressColumn):
    """Renders completed/total, e.g. '0.5/2.3 G'."""
    def __init__(self, unit_scale=False, unit_divisor=1000):
        self.unit_scale = unit_scale
        self.unit_divisor = unit_divisor
        super().__init__()

    def render(self, task):
        """Calculate common unit for completed and total."""
        completed = int(task.completed)
        total = int(task.total)
        if self.unit_scale:
            unit, suffix = filesize.pick_unit_and_suffix(
                total,
                ["", "K", "M", "G", "T", "P", "E", "Z", "Y"],
                self.unit_divisor,
            )
        else:
            unit, suffix = filesize.pick_unit_and_suffix(total, [""], 1)
        precision = 0 if unit == 1 else 1
        return Text(
            f"{completed/unit:,.{precision}f}/{total/unit:,.{precision}f} {suffix}",
            style="progress.download")


class RateColumn(ProgressColumn):
    """Renders human readable transfer speed."""
    def __init__(self, unit="", unit_scale=False, unit_divisor=1000):
        self.unit = unit
        self.unit_scale = unit_scale
        self.unit_divisor = unit_divisor
        super().__init__()

    def render(self, task):
        """Show data transfer speed."""
        speed = task.speed
        if speed is None:
            return Text(f"? {self.unit}/s", style="progress.data.speed")
        if self.unit_scale:
            unit, suffix = filesize.pick_unit_and_suffix(
                speed,
                ["", "K", "M", "G", "T", "P", "E", "Z", "Y"],
                self.unit_divisor,
            )
        else:
            unit, suffix = filesize.pick_unit_and_suffix(speed, [""], 1)
        precision = 0 if unit == 1 else 1
        return Text(f"{speed/unit:,.{precision}f} {suffix}{self.unit}/s",
                    style="progress.data.speed")


class tqdm_rich(std_tqdm):  # pragma: no cover
    """Experimental rich.progress GUI version of tqdm!"""
    # TODO: @classmethod: write()?
    def __init__(self, *args, **kwargs):
        """
        This class accepts the following parameters *in addition* to
        the parameters accepted by `tqdm`.

        Parameters
        ----------
        progress  : tuple, optional
            arguments for `rich.progress.Progress()`.
        """
        kwargs = kwargs.copy()
        kwargs['gui'] = True
        # convert disable = None to False
        kwargs['disable'] = bool(kwargs.get('disable', False))
        progress = kwargs.pop('progress', None)
        super(tqdm_rich, self).__init__(*args, **kwargs)

        if self.disable:
            return

        warn("rich is experimental/alpha", TqdmExperimentalWarning, stacklevel=2)
        d = self.format_dict
        if progress is None:
            progress = (
                "[progress.description]{task.description}"
                "[progress.percentage]{task.percentage:>4.0f}%",
                BarColumn(bar_width=None),
                FractionColumn(
                    unit_scale=d['unit_scale'], unit_divisor=d['unit_divisor']),
                "[", TimeElapsedColumn(), "<", TimeRemainingColumn(),
                ",", RateColumn(unit=d['unit'], unit_scale=d['unit_scale'],
                                unit_divisor=d['unit_divisor']), "]"
            )
        self._prog = Progress(*progress, transient=not self.leave)
        self._prog.__enter__()
        self._task_id = self._prog.add_task(self.desc or "", **d)

    def close(self):
        if self.disable:
            return
        super(tqdm_rich, self).close()
        self._prog.__exit__(None, None, None)

    def clear(self, *_, **__):
        pass

    def display(self, *_, **__):
        if not hasattr(self, '_prog'):
            return
        self._prog.update(self._task_id, completed=self.n, description=self.desc)

    def reset(self, total=None):
        """
        Resets to 0 iterations for repeated use.

        Parameters
        ----------
        total  : int or float, optional. Total to use for the new bar.
        """
        if hasattr(self, '_prog'):
            self._prog.reset(total=total)
        super(tqdm_rich, self).reset(total=total)


def trrange(*args, **kwargs):
    """
    A shortcut for `tqdm.rich.tqdm(xrange(*args), **kwargs)`.
    On Python3+, `range` is used instead of `xrange`.
    """
    return tqdm_rich(_range(*args), **kwargs)


# Aliases
tqdm = tqdm_rich
trange = trrange
