# This file is part of beets.
# Copyright 2015, Philippe Mongeau.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

"""Get a random song or album from the library.
"""
from __future__ import (division, absolute_import, print_function,
                        unicode_literals)

from beets.plugins import BeetsPlugin
from beets.ui import Subcommand, decargs, print_
import random
from operator import attrgetter
from itertools import groupby


def random_item(lib, opts, args):
    query = decargs(args)

    if opts.album:
        objs = list(lib.albums(query))
    else:
        objs = list(lib.items(query))

    if opts.equal_chance:
        # Group the objects by artist so we can sample from them.
        key = attrgetter('albumartist')
        objs.sort(key=key)
        objs_by_artists = {}
        for artist, v in groupby(objs, key):
            objs_by_artists[artist] = list(v)

        objs = []
        for _ in range(opts.number):
            # Terminate early if we're out of objects to select.
            if not objs_by_artists:
                break

            # Choose an artist and an object for that artist, removing
            # this choice from the pool.
            artist = random.choice(objs_by_artists.keys())
            objs_from_artist = objs_by_artists[artist]
            i = random.randint(0, len(objs_from_artist) - 1)
            objs.append(objs_from_artist.pop(i))

            # Remove the artist if we've used up all of its objects.
            if not objs_from_artist:
                del objs_by_artists[artist]

    else:
        number = min(len(objs), opts.number)
        objs = random.sample(objs, number)

    for item in objs:
        print_(format(item))

random_cmd = Subcommand('random',
                        help='chose a random track or album')
random_cmd.parser.add_option('-n', '--number', action='store', type="int",
                             help='number of objects to choose', default=1)
random_cmd.parser.add_option('-e', '--equal-chance', action='store_true',
                             help='each artist has the same chance')
random_cmd.parser.add_all_common_options()
random_cmd.func = random_item


class Random(BeetsPlugin):
    def commands(self):
        return [random_cmd]
