# -*- coding: utf-8 -*-
# This file is part of beets.
# Copyright 2016, 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

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


def _length(obj, album):
    """Get the duration of an item or album.
    """
    if album:
        return sum(i.length for i in obj.items())
    else:
        return obj.length


def random_objs(objs, album, number=1, time=None, equal_chance=False):
    """Get a random subset of the provided `objs`.

    If `number` is provided, produce that many matches. Otherwise, if
    `time` is provided, instead select a list whose total time is close
    to that number of minutes. If `equal_chance` is true, give each
    artist an equal chance of being included so that artists with more
    songs are not represented disproportionately.
    """
    if time:
        total_time = 0.0
        time_sec = (time * 60)
        objs_shuffled = objs
        random.shuffle(objs_shuffled)

        if not equal_chance:
            objs = []

            for obj in objs_shuffled:
                length = _length(obj, album)
                if (total_time + length) <= time_sec:
                    objs.append(obj)
                    total_time += length

                else:
                    pass

    if 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 = []

        if time:
            for obj in objs_shuffled:
                if not objs_by_artists:
                    break

                length = _length(obj, album)
                if (total_time + length) <= time_sec:
                    artist = random.choice(list(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))
                    total_time += length

                    if not objs_from_artist:
                        del objs_by_artists[artist]

                else:
                    pass

        else:
            for _ in range(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(list(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]

    elif not time:
        number = min(len(objs), number)
        objs = random.sample(objs, number)

    return objs


def random_func(lib, opts, args):
    """Select some random items or albums and print the results.
    """
    # Fetch all the objects matching the query into a list.
    query = decargs(args)
    if opts.album:
        objs = list(lib.albums(query))
    else:
        objs = list(lib.items(query))

    # Print a random subset.
    objs = random_objs(objs, opts.album, opts.number, opts.time,
                       opts.equal_chance)
    for obj in objs:
        print_(format(obj))


random_cmd = Subcommand('random',
                        help=u'choose a random track or album')
random_cmd.parser.add_option(
    u'-n', u'--number', action='store', type="int",
    help=u'number of objects to choose', default=1)
random_cmd.parser.add_option(
    u'-e', u'--equal-chance', action='store_true',
    help=u'each artist has the same chance')
random_cmd.parser.add_option(
    u'-t', u'--time', action='store', type="float",
    help=u'total length in minutes of objects to choose')
random_cmd.parser.add_all_common_options()
random_cmd.func = random_func


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