# -*- coding: utf-8 -*-
"""This module implements features for printing additional information and
for modifying how information is printed."""
# import...
# ...from standard library
import os
import sys
import tempfile
import time
from typing import IO
from typing import *
# ...from site-packages
import wrapt
# ...from HydPy
import hydpy


T = TypeVar('T')


class PrintStyle:
    """Context manager for changing the colour and font of printed
    output temporarilly."""

    color: int
    font: int
    file: IO

    def __init__(self, color: int, font: int, file: Optional[IO] = None) \
            -> None:
        self.color = color
        self.font = font
        self.file = sys.stdout if file is None else file

    def __enter__(self) -> None:
        if hydpy.pub.options.printincolor:
            print(end=f'\x1B[{self.font};30;{self.color}m', file=self.file)

    def __exit__(self, exception, message, traceback_) -> None:
        if hydpy.pub.options.printincolor:
            print(end='\x1B[0m', file=self.file)


_printprogress_indentation = -4


@wrapt.decorator
def print_progress(wrapped, _=None, args=None, kwargs=None):
    """Add print commands time to the given function informing about
     execution time.

    To show how the |print_progress| decorator works, we need to modify the
    functions used by |print_progress| to gain system time information
    available in module |time|.

    First, we mock the functions |time.strftime| and |time.perf_counter|:

    >>> import time
    >>> from unittest import mock
    >>> strftime = time.strftime
    >>> perf_counter = time.perf_counter
    >>> strftime_mock = mock.MagicMock()
    >>> time.strftime = strftime_mock
    >>> time.perf_counter = mock.MagicMock()

    The mock of |time.strftime| shall respond to two calls, as if the first
    call to a decorated function occurs at quarter past eight, and the second
    one two seconds later:

    >>> time.strftime.side_effect = '20:15:00', '20:15:02'

    The mock of |time.perf_counter| shall respond to four calls, as if the
    subsequent calls by decorated functions occur at second 1, 3, 4, and 7:

    >>> time.perf_counter.side_effect = 1, 3, 4, 7

    Now we decorate two test functions.  The first one does nothing; the
    second one only calls the first one:

    >>> from hydpy.core.printtools import print_progress
    >>> @print_progress
    ... def test1():
    ...     pass
    >>> @print_progress
    ... def test2():
    ...     test1()

    The first example shows that the output is appropriately indented,
    tat the returned times are at the right place, that the calculated
    execution the is correct, and that the mock of |time.strftime|
    received a valid format string:

    >>> from hydpy import pub
    >>> pub.options.printprogress = True
    >>> test2()
    method test2 started at 20:15:00
        method test1 started at 20:15:02
            seconds elapsed: 1
        seconds elapsed: 6
    >>> strftime_mock.call_args
    call('%H:%M:%S')

    The second example verifies that resetting the indentation works:

    >>> time.strftime.side_effect = '20:15:00', '20:15:02'
    >>> time.perf_counter.side_effect = 1, 3, 4, 7
    >>> test2()
    method test2 started at 20:15:00
        method test1 started at 20:15:02
            seconds elapsed: 1
        seconds elapsed: 6

    The last example shows that disabling the |Options.printprogress|
    option works as expected:

    >>> pub.options.printprogress = False
    >>> test2()

    >>> time.strftime = strftime
    >>> time.perf_counter = perf_counter
    """
    global _printprogress_indentation
    _printprogress_indentation += 4
    try:
        if hydpy.pub.options.printprogress:
            blanks = ' ' * _printprogress_indentation
            name = wrapped.__name__
            time_ = time.strftime('%H:%M:%S')
            with PrintStyle(color=34, font=1):
                print(f'{blanks}method {name} started at {time_}')
            seconds = time.perf_counter()
            sys.stdout.flush()
            wrapped(*args, **kwargs)
            blanks = ' ' * (_printprogress_indentation+4)
            seconds = time.perf_counter()-seconds
            with PrintStyle(color=34, font=1):
                print(f'{blanks}seconds elapsed: {seconds}')
            sys.stdout.flush()
        else:
            wrapped(*args, **kwargs)
    finally:
        _printprogress_indentation -= 4


def progressbar(iterable: Iterable[T], length: int = 23) -> Iterator[T]:
    """Print a simple progress bar while processing the given iterable.

    Function |progressbar| does print the progress bar when option
    `printprogress` is activted:

    >>> from hydpy import pub
    >>> pub.options.printprogress = True

    You can pass an iterable object.  Say you want to calculate the the sum
    of all integer values from 1 to 100 and print the progress of the
    calculation.  Using function |range| (which returns a list in Python 2
    and an iterator in Python3, but both are fine), one just has to
    interpose function |progressbar|:

    >>> from hydpy.core.printtools import progressbar
    >>> x_sum = 0
    >>> for x in progressbar(range(1, 101)):
    ...     x_sum += x
        |---------------------|
        ***********************
    >>> x_sum
    5050

    To prevent possible interim print commands from dismembering the status
    bar, they are delayed until the status bar is complete.  For intermediate
    print outs of each fiftieth calculation, the result looks as follows:

    >>> x_sum = 0
    >>> for x in progressbar(range(1, 101)):
    ...     x_sum += x
    ...     if not x % 50:
    ...         print(x, x_sum)
        |---------------------|
        ***********************
    50 1275
    100 5050


    The number of characters of the progress bar can be changed:

    >>> for i in progressbar(range(100), length=50):
    ...     continue
        |------------------------------------------------|
        **************************************************

    But its maximum number of characters is restricted by the length of the
    given iterable:

    >>> for i in progressbar(range(10), length=50):
    ...     continue
        |--------|
        **********

    The smallest possible progress bar has two characters:

    >>> for i in progressbar(range(2)):
    ...     continue
        ||
        **

    For iterables of length one or zero, no progress bar is plottet:

    >>> for i in progressbar(range(1)):
    ...     continue

    The same is True when the |Options.printprogress| option is inactivated:

    >>> pub.options.printprogress = False
    >>> for i in progressbar(range(100)):
    ...     continue
    """
    nmbitems = len(tuple(iterable))
    if hydpy.pub.options.printprogress and (nmbitems > 1):
        temp_name = os.path.join(tempfile.gettempdir(),
                                 'HydPy_progressbar_stdout')
        temp_stdout = open(temp_name, 'w')
        real_stdout = sys.stdout
        try:
            sys.stdout = temp_stdout
            nmbstars = min(nmbitems, length)
            nmbcounts = nmbitems/nmbstars
            indentation = ' '*max(_printprogress_indentation, 0)
            with PrintStyle(color=36, font=1, file=real_stdout):
                print('    %s|%s|\n%s    ' % (indentation,
                                              '-'*(nmbstars-2),
                                              indentation),
                      end='',
                      file=real_stdout)
                counts = 1.
                for next_ in iterable:
                    counts += 1.
                    if counts >= nmbcounts:
                        print(end='*', file=real_stdout)
                        counts -= nmbcounts
                    yield next_
        finally:
            temp_stdout.close()
            sys.stdout = real_stdout
            print()
            with open(temp_name, 'r') as temp_stdout:
                sys.stdout.write(temp_stdout.read())
            sys.stdout.flush()
    else:
        for next_ in iterable:
            yield next_
