Support associating with an already-paired device

This is required for migration scenario, where device(s) are already
paired(and thus no longer discoverable) but didn't go through companion
flow.
This also fixes a bug with filtering by mac address, which is also relevant to
the use-case of associating a specific device

Test: Pair with a device first, and call associate with a filter with its MAC
address and single device requested. Ensure the device is found.
Ensure only that device is ever returned when filtering by MAC address.
Bug: 62487084
Change-Id: Ic7cc6affc0648ad85b15620e8c3aba4b9fc91aa1

core/java/android/companion/BluetoothDeviceFilterUtils.java

@@ -58,7 +58,7 @@ public class BluetoothDeviceFilterUtils {
 
     static boolean matchesAddress(String deviceAddress, BluetoothDevice device) {
         final boolean result = deviceAddress == null
-                || (device == null || !deviceAddress.equals(device.getAddress()));
+                || (device != null && deviceAddress.equals(device.getAddress()));
         if (DEBUG) debugLogMatchResult(result, device, deviceAddress);
         return result;
     }

core/java/com/android/internal/util/CollectionUtils.java

@@ -25,6 +25,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
@@ -101,7 +102,7 @@ public class CollectionUtils {
     /**
      * Returns the given list, or an immutable empty list if the provided list is null
      *
-     * This can be used to guaranty null-safety without paying the price of extra allocations
+     * This can be used to guarantee null-safety without paying the price of extra allocations
      *
      * @see Collections#emptyList
      */
@@ -109,6 +110,17 @@ public class CollectionUtils {
         return cur == null ? Collections.emptyList() : cur;
     }
 
+    /**
+     * Returns the given set, or an immutable empty set if the provided set is null
+     *
+     * This can be used to guarantee null-safety without paying the price of extra allocations
+     *
+     * @see Collections#emptySet
+     */
+    public static @NonNull <T> Set<T> emptyIfNull(@Nullable Set<T> cur) {
+        return cur == null ? Collections.emptySet() : cur;
+    }
+
     /**
      * Returns the size of the given list, or 0 if the list is null
      */

packages/CompanionDeviceManager/src/com/android/companiondevicemanager/DeviceDiscoveryService.java

@@ -20,6 +20,8 @@ import static android.companion.BluetoothDeviceFilterUtils.getDeviceDisplayNameI
 import static android.companion.BluetoothDeviceFilterUtils.getDeviceMacAddress;
 
 import static com.android.internal.util.ArrayUtils.isEmpty;
+import static com.android.internal.util.CollectionUtils.emptyIfNull;
+import static com.android.internal.util.CollectionUtils.size;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -154,6 +156,25 @@ public class DeviceDiscoveryService extends Service {
             onReadyToShowUI();
         }
 
+        // If filtering to get single device by mac address, also search in the set of already
+        // bonded devices to allow linking those directly
+        String singleMacAddressFilter = null;
+        if (mRequest.isSingleDevice()) {
+            int numFilters = size(mBluetoothFilters);
+            for (int i = 0; i < numFilters; i++) {
+                BluetoothDeviceFilter filter = mBluetoothFilters.get(i);
+                if (!TextUtils.isEmpty(filter.getAddress())) {
+                    singleMacAddressFilter = filter.getAddress();
+                    break;
+                }
+            }
+        }
+        if (singleMacAddressFilter != null) {
+            for (BluetoothDevice dev : emptyIfNull(mBluetoothAdapter.getBondedDevices())) {
+                onDeviceFound(DeviceFilterPair.findMatch(dev, mBluetoothFilters));
+            }
+        }
+
         if (shouldScan(mBluetoothFilters)) {
             final IntentFilter intentFilter = new IntentFilter();
             intentFilter.addAction(BluetoothDevice.ACTION_FOUND);
@@ -211,6 +232,8 @@ public class DeviceDiscoveryService extends Service {
     }
 
     private void onDeviceFound(@Nullable DeviceFilterPair device) {
+        if (device == null) return;
+
         if (mDevicesFound.contains(device)) {
             return;
         }
@@ -444,12 +467,9 @@ public class DeviceDiscoveryService extends Service {
                 }
 
                 for (int i = 0; i < scanResults.size(); i++) {
-                    DeviceFilterPair<android.net.wifi.ScanResult> deviceFilterPair =
-                            DeviceFilterPair.findMatch(scanResults.get(i), mWifiFilters);
-                    if (deviceFilterPair != null) onDeviceFound(deviceFilterPair);
+                    onDeviceFound(DeviceFilterPair.findMatch(scanResults.get(i), mWifiFilters));
                 }
             }
-
         }
     }
 }