Moves player logic to its own class, away from Interface

In the future, this will make testing and a CLI environment easier.

interface/src/main/java/edu/regis/universeplayer/player/Player.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2021 William Hubbard. All Rights Reserved.
+ */
+
+package edu.regis.universeplayer.player;
+
+import edu.regis.universeplayer.PlaybackListener;
+import edu.regis.universeplayer.PlaybackStatus;
+import edu.regis.universeplayer.browserCommands.QueryFuture;
+import edu.regis.universeplayer.data.Song;
+
+import java.util.HashMap;
+
+/**
+ * This interface serves as the connection to a music player of some sort, whether it be
+ * browser-based or from a file.
+ *
+ * @param <T> - The type of songs supported.
+ * @author William Hubbard
+ * @since 0.1
+ */
+public interface Player<T extends Song>
+{
+    /**
+     * Obtains the song currently playing.
+     *
+     * @return The current song, or null if none is playing.
+     */
+    Song getCurrentSong();
+    
+    /**
+     * Loads up a song
+     *
+     * @param song - The song to load.
+     * @return A confirmation of whether the command was successful or not.
+     */
+    QueryFuture<Void> loadSong(T song);
+    
+    /**
+     * Enables playback of the current song, if one is active.
+     *
+     * @return A confirmation of whether the command was successful or not.
+     */
+    QueryFuture<Void> play();
+    
+    /**
+     * Pauses playback of the current song.
+     *
+     * @return A confirmation of whether the command was successful or not.
+     */
+    QueryFuture<Void> pause();
+    
+    /**
+     * Toggles between playing and pausing the current song.
+     *
+     * @return A confirmation of whether the command was successful or not.
+     */
+    QueryFuture<Void> togglePlayback();
+    
+    /**
+     * Stops playback of the current song.
+     */
+    QueryFuture<Void> stopSong();
+    
+    /**
+     * Sets the current song time to the specified position.
+     *
+     * @param time - The specified time in the song, in seconds.
+     * @return A confirmation of whether the command was successful or not.
+     */
+    QueryFuture<Void> seek(float time);
+    
+    /**
+     * Obtains the player's current playback status.
+     * @return A future for the request.
+     */
+    QueryFuture<PlaybackStatus> getStatus();
+    
+    /**
+     * Obtains the time we are currently at in the current song.
+     *
+     * @return - The current song position in seconds, or -1 if no song is playing.
+     */
+    QueryFuture<Float> getCurrentTime();
+    
+    /**
+     * Gets the length of the current song.
+     *
+     * @return The song length, in seconds.
+     */
+    QueryFuture<Float> getLength();
+    
+    /**
+     * Closes the player.
+     *
+     * @return A confirmation of whether the player was successfully closed.
+     */
+    QueryFuture<Void> close();
+    
+    /**
+     * Adds a listener for playback status updates.
+     *
+     * @param listener - The listener to add.
+     */
+    void addPlaybackListener(PlaybackListener listener);
+    
+    /**
+     * Checks to see if a listener has been added.
+     *
+     * @param listener - The listener to look for.
+     * @return True if the provided listener has been added, false otherwise.
+     */
+    boolean hasPlaybackListener(PlaybackListener listener);
+    
+    /**
+     * Removes a listener for playback status updates.
+     *
+     * @param listener - The listener to remove.
+     */
+    void removePlaybackListener(PlaybackListener listener);
+}