# Topydo - A todo.txt client written in Python.
# Copyright (C) 2014 - 2015 Bram Schoenmakers <bram@topydo.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Various utility functions.
"""

import re
from collections import namedtuple
from datetime import date

import arrow


def date_string_to_date(p_date):
    """
    Given a date in YYYY-MM-DD, returns a Python date object. Throws a
    ValueError if the date is invalid.
    """
    result = None

    if p_date:
        parsed_date = re.match(r'(\d{4})-(\d{2})-(\d{2})', p_date)
        if parsed_date:
            result = date(
                int(parsed_date.group(1)),  # year
                int(parsed_date.group(2)),  # month
                int(parsed_date.group(3))   # day
            )
        else:
            raise ValueError

    return result


def is_valid_priority(p_priority):
    return p_priority is not None and re.match(r'^[A-Z]$', p_priority) is not None


def escape_ansi(p_string):
    return escape_ansi.pattern.sub('', p_string)

escape_ansi.pattern = re.compile(r'\x1b[^m]*m')


def get_terminal_size(p_getter=None):
    """
    Try to determine terminal size at run time. If that is not possible,
    returns the default size of 80x24.

    By default, the size is determined with provided get_terminal_size by
    shutil. Sometimes an UI may want to specify the desired width, then it can
    provide a getter that returns a named tuple (columns, lines) with the size.
    """

    try:
        return get_terminal_size.getter()
    except AttributeError:
        if p_getter:
            get_terminal_size.getter = p_getter
        else:
            def inner():
                try:
                    # shutil.get_terminal_size was added to the standard
                    # library in Python 3.3
                    try:
                        from shutil import \
                            get_terminal_size as \
                            _get_terminal_size  # pylint: disable=no-name-in-module
                    except ImportError:
                        from backports.shutil_get_terminal_size import \
                            get_terminal_size as \
                            _get_terminal_size  # pylint: disable=import-error

                    size = _get_terminal_size()
                except ValueError:
                    # This can result from the 'underlying buffer being detached', which
                    # occurs during running the unittest on Windows (but not on Linux?)
                    terminal_size = namedtuple('Terminal_Size', 'columns lines')
                    size = terminal_size(80, 24)

                return size

            get_terminal_size.getter = inner

        return get_terminal_size.getter()


def translate_key_to_config(p_key):
    """
    Translates urwid key event to form understandable by topydo config parser.
    """
    if len(p_key) > 1:
        key = p_key.capitalize()
        if key.startswith('Ctrl') or key.startswith('Meta'):
            key = key[0] + '-' + key[5:]
        key = '<' + key + '>'
    else:
        key = p_key

    return key

def humanize_date(p_datetime):
    """ Returns a relative date string from a datetime object. """
    now = arrow.now()
    _date = now.replace(day=p_datetime.day, month=p_datetime.month, year=p_datetime.year)
    return _date.humanize(now).replace('just now', 'today')
