Don’t download DeviceSQL DBs for SQLite hardware

Author: brunchboy

src/main/java/org/deepsymmetry/beatlink/DeviceAnnouncement.java

@@ -58,6 +58,7 @@ public DeviceAnnouncement(DatagramPacket packet) {
         name = new String(packetBytes, 0x0c, 20).trim();
         isOpusQuad = name.equals(OpusProvider.OPUS_NAME);
         isXdjAz = name.equals(OpusProvider.XDJ_AZ_NAME);
+        isUsingDeviceLibraryPlus = isOpusQuad || isXdjAz;
         number = Util.unsign(packetBytes[0x24]);
     }
 
@@ -80,6 +81,7 @@ public DeviceAnnouncement(DatagramPacket packet, int deviceNumber) {
         name = new String(packetBytes, 0x0c, 20).trim();
         isOpusQuad = name.equals(OpusProvider.OPUS_NAME);
         isXdjAz = name.equals(OpusProvider.XDJ_AZ_NAME);
+        isUsingDeviceLibraryPlus = isOpusQuad || isXdjAz;
         number = deviceNumber;
     }
 
@@ -184,17 +186,23 @@ public byte[] getPacketBytes() {
     }
 
     /**
-     * Check whether a device update came from an Opus Quad, which behaves very differently from true Pro DJ Link hardware.
+     * Indicates whether a device update came from an Opus Quad, which behaves very differently from true Pro DJ Link hardware.
      */
     @API(status = API.Status.EXPERIMENTAL)
     public final boolean isOpusQuad;
 
     /**
-     * Check whether a device update came from an XDJ-AZ, which can also be in a weird, non-Pro DJ Link mode.
+     * Indicates whether a device update came from an XDJ-AZ, which can also be in a weird, non-Pro DJ Link mode.
      */
     @API(status = API.Status.EXPERIMENTAL)
     public final boolean isXdjAz;
 
+    /**
+     * Indicates whether the device that sent this update uses Device Library Plus (SQLite) track IDs rather than DeviceSQL IDs.
+     */
+    @API(status = API.Status.EXPERIMENTAL)
+    public final boolean isUsingDeviceLibraryPlus;
+
     @Override
     public String toString() {
         return "DeviceAnnouncement[device:" + number + ", name:" + name + ", address:" + address.getHostAddress() +

src/main/java/org/deepsymmetry/beatlink/data/CrateDigger.java

@@ -225,6 +225,21 @@ public static String humanReadableByteCount(long bytes, boolean si) {
         return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
     }
 
+    /**
+     * Check whether we would be able to use a database read from the specified slot. Makes sure the device that
+     * owns the slot uses DeviceSQL track IDs, or that we know how to access SQLite databases if it doesn’t.
+     *
+     * @param slot the slot from which a track was loaded
+     *
+     * @return {@code true} if we will be able to read track metadata from a database downloaded from that slot
+     */
+    @API(status = API.Status.EXPERIMENTAL)
+    public boolean canUseDatabase(SlotReference slot) {
+        final DeviceAnnouncement owner = DeviceFinder.getInstance().getLatestAnnouncementFrom(slot.player);
+        // TODO: Implement reading SQLite, and check if we have the key.
+        return !owner.isUsingDeviceLibraryPlus;
+    }
+
     /**
      * Whenever we learn media details about a newly-mounted media slot, if it is rekordbox media, start the process
      * of fetching and parsing the database, so we can offer metadata for that slot.
@@ -235,7 +250,8 @@ public void detailsAvailable(final MediaDetails details) {
             if (isRunning() && details.mediaType == CdjStatus.TrackType.REKORDBOX &&
                     !VirtualCdj.getInstance().inOpusQuadCompatibilityMode() &&  // If we are dealing with an Opus Quad, we can’t download files.
                     details.slotReference.slot != CdjStatus.TrackSourceSlot.COLLECTION &&  // We always use dbserver to talk to rekordbox.
-                    !databases.containsKey(details.slotReference) &&
+                    !databases.containsKey(details.slotReference) &&  // We haven’t already downloaded it.
+                    canUseDatabase(details.slotReference) &&  // The player uses a database format we can read.
                     activeRequests.add(details.slotReference)) {
                 new Thread(() -> {
                     File file = null;