# Copyright 2015 Adafruit Industries.
# Author: Tony DiCola
# License: GNU GPLv2, see LICENSE.txt
class Playlist(object):
    """Representation of a playlist of movies."""

    def __init__(self, movies):
        """Create a playlist from the provided list of movies."""
        self._movies = movies
        self._index = None

    def get_next(self):
        """Get the next movie in the playlist. Will loop to start of playlist
        after reaching end.
        """
        # Check if no movies are in the playlist and return nothing.
        if len(self._movies) == 0:
            return None
        # Start at the first movie and increment through them in order.
        if self._index is None:
            self._index = 0
        else:
            self._index += 1
        # Wrap around to the start after finishing.
        if self._index >= len(self._movies):
            self._index = 0
        return self._movies[self._index]

    def length(self):
        """Return the number of movies in the playlist."""
        return len(self._movies)