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      1 /*
      2  * Copyright 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.server.wifi;
     18 
     19 import android.content.Context;
     20 import android.net.wifi.ScanResult;
     21 
     22 import com.android.internal.annotations.VisibleForTesting;
     23 
     24 import java.util.Collection;
     25 
     26 /**
     27  * Evaluates ScanResults for Wifi Wake.
     28  */
     29 public class WakeupEvaluator {
     30 
     31     private final int mThresholdMinimumRssi24;
     32     private final int mThresholdMinimumRssi5;
     33 
     34     /**
     35      * Constructs a {@link WakeupEvaluator} using the given context.
     36      */
     37     public static WakeupEvaluator fromContext(Context context) {
     38         ScoringParams scoringParams = new ScoringParams(context); // TODO(b/74793980) - replumb
     39         return new WakeupEvaluator(scoringParams.getEntryRssi(ScoringParams.BAND2),
     40                                    scoringParams.getEntryRssi(ScoringParams.BAND5));
     41     }
     42 
     43     @VisibleForTesting
     44     WakeupEvaluator(int minimumRssi24, int minimumRssi5) {
     45         mThresholdMinimumRssi24 = minimumRssi24;
     46         mThresholdMinimumRssi5 = minimumRssi5;
     47     }
     48 
     49     /**
     50      * Searches ScanResults to find a connectable network.
     51      *
     52      * <p>This method searches the given ScanResults for one that is present in the given
     53      * ScanResultMatchInfos and has a sufficiently high RSSI. If there is no such ScanResult, it
     54      * returns null. If there are multiple, it returns the one with the highest RSSI.
     55      *
     56      * @param scanResults ScanResults to search
     57      * @param savedNetworks Network list to compare against
     58      * @return The {@link ScanResult} representing an in-range connectable network, or {@code null}
     59      *         signifying there is no viable network
     60      */
     61     public ScanResult findViableNetwork(Collection<ScanResult> scanResults,
     62                                         Collection<ScanResultMatchInfo> savedNetworks) {
     63         ScanResult selectedScanResult = null;
     64 
     65         for (ScanResult scanResult : scanResults) {
     66             if (isBelowThreshold(scanResult)) {
     67                 continue;
     68             }
     69             if (savedNetworks.contains(ScanResultMatchInfo.fromScanResult(scanResult))) {
     70                 if (selectedScanResult == null || selectedScanResult.level < scanResult.level) {
     71                     selectedScanResult = scanResult;
     72                 }
     73             }
     74         }
     75 
     76         return selectedScanResult;
     77     }
     78 
     79     /**
     80      * Returns whether the given ScanResult's signal strength is below the selection threshold.
     81      */
     82     public boolean isBelowThreshold(ScanResult scanResult) {
     83         return ((scanResult.is24GHz() && scanResult.level < mThresholdMinimumRssi24)
     84                 || (scanResult.is5GHz() && scanResult.level < mThresholdMinimumRssi5));
     85     }
     86 }
     87