Adding volume fade in/out for volume change and stop functions

src/main/java/net/dirtydeeds/discordsoundboard/ChatSoundBoardListener.java

@@ -104,21 +104,31 @@ public void onMessageReceived(MessageReceivedEvent event) {
 	                            "\n" + commandCharacter + "stop             - Stops the sound that is currently playing." +
 	                            "\n" + commandCharacter + "info             - Returns info about the bot.```");
 	                } else if (message.startsWith(commandCharacter + "volume")) {
-	                    int newVol = Integer.parseInt(message.substring(8));
+		                int fadeoutIndex = message.indexOf('~');
+	                    int newVol = Integer.parseInt(message.substring(8, (fadeoutIndex > -1) ? fadeoutIndex - 1 : message.length()));
+	                    int fadeoutTimeout =  0;
+	                    if (fadeoutIndex > -1) {
+	                    	fadeoutTimeout = Integer.parseInt(message.substring(fadeoutIndex + 1, message.length()));
+	                    }
 	                    if (newVol >= 1 && newVol <= 100) {
 	                        muted = false;
-	                        soundPlayer.setSoundPlayerVolume(newVol);
+	                        soundPlayer.setSoundPlayerVolume(newVol, fadeoutTimeout * 1000);
 	                        replyByPrivateMessage(event, "*Volume set to " + newVol + "%*");
 	                        LOG.info("Volume set to " + newVol + "% by " + requestingUser + ".");
 	                    } else if (newVol == 0) {
 	                        muted = true;
-	                        soundPlayer.setSoundPlayerVolume(newVol);
+	                        soundPlayer.setSoundPlayerVolume(newVol, fadeoutTimeout * 1000);
 	                        replyByPrivateMessage(event, requestingUser + " muted me.");
 	                        LOG.info("Bot muted by " + requestingUser + ".");
 	                    }
 	                } else if (message.startsWith(commandCharacter + "stop")) {
-	                    LOG.info("Stop requested by " + requestingUser + ".");
-	                    if (soundPlayer.stop()) {
+		                int fadeoutIndex = message.indexOf('~');
+	                    int fadeoutTimeout =  0;
+	                    if (fadeoutIndex > -1) {
+	                    	fadeoutTimeout = Integer.parseInt(message.substring(fadeoutIndex + 1, message.length()));
+	                    }
+	                    LOG.info("Stop requested by " + requestingUser + " with a fadeout of " + fadeoutTimeout + " seconds");
+	                    if (soundPlayer.stop(fadeoutTimeout * 1000)) {
 	                        replyByPrivateMessage(event, "Playback stopped.");
 	                    } else {
 	                        replyByPrivateMessage(event, "Nothing was playing.");

src/main/java/net/dirtydeeds/discordsoundboard/service/SoundPlayerImpl.java

@@ -22,6 +22,8 @@
 import net.dv8tion.jda.utils.PermissionUtil;
 import net.dv8tion.jda.utils.SimpleLog;
 import org.springframework.stereotype.Service;
+import java.util.concurrent.TimeUnit;
+import java.lang.InterruptedException;
 
 import javax.annotation.PreDestroy;
 import javax.inject.Inject;
@@ -54,6 +56,7 @@ public class SoundPlayerImpl implements Observer {
     private float playerVolume = (float) .75;
     private final MainWatch mainWatch;
     private boolean initialized = false;
+    private boolean isFading = false;
     private MusicPlayer musicPlayer;
     private FilePlayer player;
     private String playerSetting;
@@ -105,15 +108,47 @@ public Map<String, SoundFile> getAvailableSoundFiles() {
         }
         return returnFiles;
     }
-    
+
     /**
      * Sets volume of the player.
      * @param volume - The volume value to set.
      */
     public void setSoundPlayerVolume(int volume) {
-        playerVolume = (float) volume / 100;
-        if (isMusicPlayer()) {
-            musicPlayer.setVolume(playerVolume);
+	    setSoundPlayerVolume(volume, 1000);
+    }
+
+    /**
+     * Sets volume of the player.
+     * @param volume - The volume value to set.
+     */
+    public void setSoundPlayerVolume(int volume, int timeout) {
+	    int currentVolume = Math.round(playerVolume * 100);
+
+        int volumeDiff = currentVolume - volume;
+        if (volumeDiff < 0) {
+	        volumeDiff = volumeDiff * -1;
+        }
+
+        if (volumeDiff != 0 && isFading == false) {
+	        boolean isFading = true;
+	        int microInterval = Math.round(timeout / volumeDiff);
+	        while (currentVolume != volume) {
+		        if (currentVolume < volume) {
+			        currentVolume++;
+		        } else {
+			        currentVolume--;
+		        }
+				playerVolume = (float) currentVolume / 100;
+		        if (isMusicPlayer()) {
+		            musicPlayer.setVolume(playerVolume);
+		        }
+		        try {
+			        TimeUnit.MILLISECONDS.sleep(microInterval);
+		        } catch (InterruptedException e) {
+			        // mute...
+		        }
+	        }
+	        isFading = false;
         }
     }
 
@@ -299,16 +334,32 @@ public void playFileForDisconnect(String fileName, VoiceLeaveEvent event) throws
      * @return boolean representing whether playback was stopped.
      */
     public boolean stop() {
+	    return stop(0);
+    }
+
+    /**
+     * Stops sound playback and returns true or false depending on if playback was stopped.
+     * @return boolean representing whether playback was stopped.
+     */
+    public boolean stop(int timeout) {
+	    boolean result = false;
+	    float originalVolume = playerVolume;
+
+
         if (isMusicPlayer()) {
             if (musicPlayer != null && musicPlayer.isPlaying()) {
+          	    setSoundPlayerVolume(0, timeout);
                 musicPlayer.stop();
+                playerVolume = originalVolume;
                 return true;
             } else {
                 return false;
             }
         } else {
             if (player != null && player.isPlaying()) {
+          	    setSoundPlayerVolume(0, timeout);
                 player.stop();
+                playerVolume = originalVolume;
                 return true;
             } else {
                 return false;