Merge "Refactored Field Classification score logic so it can be moved to ExtServices."

13 files changed, 313 insertions, 163 deletions

diff --git a/api/current.txt b/api/current.txt
index 10b5c6785065..32deabb97850 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -37728,18 +37728,12 @@ package android.service.autofill {
     method public android.service.autofill.Dataset.Builder setValue(android.view.autofill.AutofillId, android.view.autofill.AutofillValue, java.util.regex.Pattern, android.widget.RemoteViews);
   }
 
-  public final class EditDistanceScorer implements android.os.Parcelable android.service.autofill.Scorer {
-    method public int describeContents();
-    method public static android.service.autofill.EditDistanceScorer getInstance();
-    method public void writeToParcel(android.os.Parcel, int);
-    field public static final android.os.Parcelable.Creator<android.service.autofill.EditDistanceScorer> CREATOR;
-  }
-
   public final class FieldClassification {
     method public java.util.List<android.service.autofill.FieldClassification.Match> getMatches();
   }
 
   public static final class FieldClassification.Match {
+    method public java.lang.String getAlgorithm();
     method public java.lang.String getRemoteId();
     method public float getScore();
   }
@@ -37891,9 +37885,6 @@ package android.service.autofill {
     field public static final android.os.Parcelable.Creator<android.service.autofill.SaveRequest> CREATOR;
   }
 
-  public abstract interface Scorer {
-  }
-
   public final class TextValueSanitizer implements android.os.Parcelable android.service.autofill.Sanitizer {
     ctor public TextValueSanitizer(java.util.regex.Pattern, java.lang.String);
     method public int describeContents();
@@ -37906,6 +37897,7 @@ package android.service.autofill {
 
   public final class UserData implements android.os.Parcelable {
     method public int describeContents();
+    method public java.lang.String getFieldClassificationAlgorithm();
     method public static int getMaxFieldClassificationIdsSize();
     method public static int getMaxUserDataSize();
     method public static int getMaxValueLength();
@@ -37915,9 +37907,10 @@ package android.service.autofill {
   }
 
   public static final class UserData.Builder {
-    ctor public UserData.Builder(android.service.autofill.Scorer, java.lang.String, java.lang.String);
+    ctor public UserData.Builder(java.lang.String, java.lang.String);
     method public android.service.autofill.UserData.Builder add(java.lang.String, java.lang.String);
     method public android.service.autofill.UserData build();
+    method public android.service.autofill.UserData.Builder setFieldClassificationAlgorithm(java.lang.String, android.os.Bundle);
   }
 
   public abstract interface Validator {
@@ -48550,6 +48543,8 @@ package android.view.autofill {
     method public void commit();
     method public void disableAutofillServices();
     method public android.content.ComponentName getAutofillServiceComponentName();
+    method public java.util.List<java.lang.String> getAvailableFieldClassificationAlgorithms();
+    method public java.lang.String getDefaultFieldClassificationAlgorithm();
     method public android.service.autofill.UserData getUserData();
     method public boolean hasEnabledAutofillServices();
     method public boolean isAutofillSupported();
diff --git a/api/test-current.txt b/api/test-current.txt
index d56b0856c028..a0f981a7b5a9 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -473,7 +473,8 @@ package android.service.autofill {
     method public void apply(android.service.autofill.ValueFinder, android.widget.RemoteViews, int) throws java.lang.Exception;
   }
 
-  public final class EditDistanceScorer extends android.service.autofill.InternalScorer implements android.os.Parcelable android.service.autofill.Scorer {
+  public final class EditDistanceScorer {
+    method public static android.service.autofill.EditDistanceScorer getInstance();
     method public float getScore(android.view.autofill.AutofillValue, java.lang.String);
   }
 
@@ -489,11 +490,6 @@ package android.service.autofill {
     ctor public InternalSanitizer();
   }
 
-  public abstract class InternalScorer implements android.os.Parcelable android.service.autofill.Scorer {
-    ctor public InternalScorer();
-    method public abstract float getScore(android.view.autofill.AutofillValue, java.lang.String);
-  }
-
   public abstract class InternalTransformation implements android.os.Parcelable android.service.autofill.Transformation {
     ctor public InternalTransformation();
   }
diff --git a/core/java/android/service/autofill/EditDistanceScorer.java b/core/java/android/service/autofill/EditDistanceScorer.java
index 0706b377bbe8..97a386866665 100644
--- a/core/java/android/service/autofill/EditDistanceScorer.java
+++ b/core/java/android/service/autofill/EditDistanceScorer.java
@@ -16,8 +16,7 @@
 package android.service.autofill;
 
 import android.annotation.NonNull;
-import android.os.Parcel;
-import android.os.Parcelable;
+import android.annotation.TestApi;
 import android.view.autofill.AutofillValue;
 
 /**
@@ -25,13 +24,20 @@ import android.view.autofill.AutofillValue;
  * by the user and the expected value predicted by an autofill service.
  */
 // TODO(b/70291841): explain algorithm once it's fully implemented
-public final class EditDistanceScorer extends InternalScorer implements Scorer, Parcelable {
+/** @hide */
+@TestApi
+public final class EditDistanceScorer {
 
     private static final EditDistanceScorer sInstance = new EditDistanceScorer();
 
+    /** @hide */
+    public static final String NAME = "EDIT_DISTANCE";
+
     /**
      * Gets the singleton instance.
      */
+    @TestApi
+    /** @hide */
     public static EditDistanceScorer getInstance() {
         return sInstance;
     }
@@ -39,59 +45,32 @@ public final class EditDistanceScorer extends InternalScorer implements Scorer,
     private EditDistanceScorer() {
     }
 
-    /** @hide */
-    @Override
-    public float getScore(@NonNull AutofillValue actualValue, @NonNull String userData) {
-        if (actualValue == null || !actualValue.isText() || userData == null) return 0;
+    /**
+     * Returns the classification score between an actual {@link AutofillValue} filled
+     * by the user and the expected value predicted by an autofill service.
+     *
+     * <p>A full-match is {@code 1.0} (representing 100%), a full mismatch is {@code 0.0} and
+     * partial mathces are something in between, typically using edit-distance algorithms.
+     *
+     * @hide
+     */
+    @TestApi
+    public float getScore(@NonNull AutofillValue actualValue, @NonNull String userDataValue) {
+        if (actualValue == null || !actualValue.isText() || userDataValue == null) return 0;
         // TODO(b/70291841): implement edit distance - currently it's returning either 0, 100%, or
         // partial match when number of chars match
         final String textValue = actualValue.getTextValue().toString();
         final int total = textValue.length();
-        if (total != userData.length()) return 0F;
+        if (total != userDataValue.length()) return 0F;
 
         int matches = 0;
         for (int i = 0; i < total; i++) {
             if (Character.toLowerCase(textValue.charAt(i)) == Character
-                    .toLowerCase(userData.charAt(i))) {
+                    .toLowerCase(userDataValue.charAt(i))) {
                 matches++;
             }
         }
 
         return ((float) matches) / total;
     }
-
-    /////////////////////////////////////
-    // Object "contract" methods. //
-    /////////////////////////////////////
-    @Override
-    public String toString() {
-        return "EditDistanceScorer";
-    }
-
-    /////////////////////////////////////
-    // Parcelable "contract" methods. //
-    /////////////////////////////////////
-
-    @Override
-    public int describeContents() {
-        return 0;
-    }
-
-    @Override
-    public void writeToParcel(Parcel parcel, int flags) {
-        // Do nothing
-    }
-
-    public static final Parcelable.Creator<EditDistanceScorer> CREATOR =
-            new Parcelable.Creator<EditDistanceScorer>() {
-        @Override
-        public EditDistanceScorer createFromParcel(Parcel parcel) {
-            return EditDistanceScorer.getInstance();
-        }
-
-        @Override
-        public EditDistanceScorer[] newArray(int size) {
-            return new EditDistanceScorer[size];
-        }
-    };
 }
diff --git a/core/java/android/service/autofill/Scorer.java b/core/java/android/service/autofill/FieldClassification.aidl
index c4018558b3ed..42f7f0252d6d 100644
--- a/core/java/android/service/autofill/Scorer.java
+++ b/core/java/android/service/autofill/FieldClassification.aidl
@@ -1,11 +1,11 @@
-/*
- * Copyright (C) 2017 The Android Open Source Project
+/**
+ * Copyright (c) 2017, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
- *      http://www.apache.org/licenses/LICENSE-2.0
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
@@ -13,16 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package android.service.autofill;
 
-/**
- * Helper class used to calculate a score.
- *
- * <p>Typically used to calculate the
- * <a href="AutofillService.html#FieldClassification">field classification</a> score between an
- * actual {@link android.view.autofill.AutofillValue} filled by the user and the expected value
- * predicted by an autofill service.
- */
-public interface Scorer {
+package android.service.autofill;
 
-}
+parcelable FieldClassification.AlgorithmInfo;
diff --git a/core/java/android/service/autofill/FieldClassification.java b/core/java/android/service/autofill/FieldClassification.java
index 001b2917aadf..536180335a83 100644
--- a/core/java/android/service/autofill/FieldClassification.java
+++ b/core/java/android/service/autofill/FieldClassification.java
@@ -106,18 +106,20 @@ public final class FieldClassification {
     /**
      * Represents the score of a {@link UserData} entry for the field.
      *
-     * <p>The score is defined by {@link #getScore()} and the entry is identified by
-     * {@link #getRemoteId()}.
+     * <p>The score is calculated by the given {@link #getAlgorithm() algorithm} and
+     * the entry is identified by {@link #getRemoteId()}.
      */
     public static final class Match {
 
         private final String mRemoteId;
         private final float mScore;
+        private final String mAlgorithm;
 
         /** @hide */
-        public Match(String remoteId, float score) {
+        public Match(String remoteId, float score, String algorithm) {
             mRemoteId = Preconditions.checkNotNull(remoteId);
             mScore = score;
+            mAlgorithm = algorithm;
         }
 
         /**
@@ -140,29 +142,46 @@ public final class FieldClassification {
          *   <li>Any other value is a partial match.
          * </ul>
          *
-         * <p>How the score is calculated depends on the algorithm used by the {@link Scorer}
-         * implementation.
+         * <p>How the score is calculated depends on the
+         * {@link UserData.Builder#setFieldClassificationAlgorithm(String, android.os.Bundle)
+         * algorithm} used.
          */
         public float getScore() {
             return mScore;
         }
 
+        /**
+         * Gets the algorithm used to calculate this score.
+         *
+         * <p>Typically, this is either the algorithm set by
+         * {@link UserData.Builder#setFieldClassificationAlgorithm(String, android.os.Bundle)},
+         * or the
+         * {@link android.view.autofill.AutofillManager#getDefaultFieldClassificationAlgorithm()}.
+         */
+        @NonNull
+        public String getAlgorithm() {
+            return mAlgorithm;
+        }
+
         @Override
         public String toString() {
             if (!sDebug) return super.toString();
 
             final StringBuilder string = new StringBuilder("Match: remoteId=");
             Helper.appendRedacted(string, mRemoteId);
-            return string.append(", score=").append(mScore).toString();
+            return string.append(", score=").append(mScore)
+                    .append(", algorithm=").append(mAlgorithm)
+                    .toString();
         }
 
         private void writeToParcel(@NonNull Parcel parcel) {
             parcel.writeString(mRemoteId);
             parcel.writeFloat(mScore);
+            parcel.writeString(mAlgorithm);
         }
 
         private static Match readFromParcel(@NonNull Parcel parcel) {
-            return new Match(parcel.readString(), parcel.readFloat());
+            return new Match(parcel.readString(), parcel.readFloat(), parcel.readString());
         }
     }
 }
diff --git a/core/java/android/service/autofill/InternalScorer.java b/core/java/android/service/autofill/InternalScorer.java
deleted file mode 100644
index 0da5afc2331d..000000000000
--- a/core/java/android/service/autofill/InternalScorer.java
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright (C) 2017 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package android.service.autofill;
-
-import android.annotation.NonNull;
-import android.annotation.TestApi;
-import android.os.Parcelable;
-import android.view.autofill.AutofillValue;
-
-/**
- * Superclass of all scorer the system understands. As this is not public all
- * subclasses have to implement {@link Scorer} again.
- *
- * @hide
- */
-@TestApi
-public abstract class InternalScorer implements Scorer, Parcelable {
-
-    /**
-     * Returns the classification score between an actual {@link AutofillValue} filled
-     * by the user and the expected value predicted by an autofill service.
-     *
-     * <p>A full-match is {@code 1.0} (representing 100%), a full mismatch is {@code 0.0} and
-     * partial mathces are something in between, typically using edit-distance algorithms.
-     */
-    public abstract float getScore(@NonNull AutofillValue actualValue, @NonNull String userData);
-}
diff --git a/core/java/android/service/autofill/UserData.aidl b/core/java/android/service/autofill/UserData.aidl
index 76016ded424a..19282e0e7c85 100644
--- a/core/java/android/service/autofill/UserData.aidl
+++ b/core/java/android/service/autofill/UserData.aidl
@@ -17,4 +17,3 @@
 package android.service.autofill;
 
 parcelable UserData;
-parcelable UserData.Constraints;
diff --git a/core/java/android/service/autofill/UserData.java b/core/java/android/service/autofill/UserData.java
index f0cc360fe075..2f9225acc520 100644
--- a/core/java/android/service/autofill/UserData.java
+++ b/core/java/android/service/autofill/UserData.java
@@ -25,10 +25,13 @@ import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.app.ActivityThread;
 import android.content.ContentResolver;
+import android.os.Bundle;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.provider.Settings;
+import android.service.autofill.FieldClassification.Match;
 import android.util.Log;
+import android.view.autofill.AutofillManager;
 import android.view.autofill.Helper;
 
 import com.android.internal.util.Preconditions;
@@ -49,21 +52,32 @@ public final class UserData implements Parcelable {
     private static final int DEFAULT_MIN_VALUE_LENGTH = 5;
     private static final int DEFAULT_MAX_VALUE_LENGTH = 100;
 
-    private final InternalScorer mScorer;
+    private final String mAlgorithm;
+    private final Bundle mAlgorithmArgs;
     private final String[] mRemoteIds;
     private final String[] mValues;
 
     private UserData(Builder builder) {
-        mScorer = builder.mScorer;
+        mAlgorithm = builder.mAlgorithm;
+        mAlgorithmArgs = builder.mAlgorithmArgs;
         mRemoteIds = new String[builder.mRemoteIds.size()];
         builder.mRemoteIds.toArray(mRemoteIds);
         mValues = new String[builder.mValues.size()];
         builder.mValues.toArray(mValues);
     }
 
+    /**
+     * Gets the name of the algorithm that is used to calculate
+     * {@link Match#getScore() match scores}.
+     */
+    @Nullable
+    public String getFieldClassificationAlgorithm() {
+        return mAlgorithm;
+    }
+
     /** @hide */
-    public InternalScorer getScorer() {
-        return mScorer;
+    public Bundle getAlgorithmArgs() {
+        return mAlgorithmArgs;
     }
 
     /** @hide */
@@ -78,7 +92,9 @@ public final class UserData implements Parcelable {
 
     /** @hide */
     public void dump(String prefix, PrintWriter pw) {
-        pw.print(prefix); pw.print("Scorer: "); pw.println(mScorer);
+        pw.print(prefix); pw.print("Algorithm: "); pw.print(mAlgorithm);
+        pw.print(" Args: "); pw.println(mAlgorithmArgs);
+
         // Cannot disclose remote ids or values because they could contain PII
         pw.print(prefix); pw.print("Remote ids size: "); pw.println(mRemoteIds.length);
         for (int i = 0; i < mRemoteIds.length; i++) {
@@ -105,9 +121,10 @@ public final class UserData implements Parcelable {
      * A builder for {@link UserData} objects.
      */
     public static final class Builder {
-        private final InternalScorer mScorer;
         private final ArrayList<String> mRemoteIds;
         private final ArrayList<String> mValues;
+        private String mAlgorithm;
+        private Bundle mAlgorithmArgs;
         private boolean mDestroyed;
 
         /**
@@ -120,13 +137,9 @@ public final class UserData implements Parcelable {
          *   <li>{@code value} is empty
          *   <li>the length of {@code value} is lower than {@link UserData#getMinValueLength()}
          *   <li>the length of {@code value} is higher than {@link UserData#getMaxValueLength()}
-         *   <li>{@code scorer} is not instance of a class provided by the Android System.
          * </ol>
          */
-        public Builder(@NonNull Scorer scorer, @NonNull String remoteId, @NonNull String value) {
-            Preconditions.checkArgument((scorer instanceof InternalScorer),
-                    "not provided by Android System: " + scorer);
-            mScorer = (InternalScorer) scorer;
+        public Builder(@NonNull String remoteId, @NonNull String value) {
             checkValidRemoteId(remoteId);
             checkValidValue(value);
             final int capacity = getMaxUserDataSize();
@@ -137,6 +150,31 @@ public final class UserData implements Parcelable {
         }
 
         /**
+         * Sets the algorithm used for <a href="#FieldClassification">field classification</a>.
+         *
+         * <p>The currently available algorithms can be retrieve through
+         * {@link AutofillManager#getAvailableFieldClassificationAlgorithms()}.
+         *
+         * <p><b>Note: </b>The available algorithms in the Android System can change dinamically,
+         * so it's not guaranteed that the algorithm set here is the one that will be effectually
+         * used. If the algorithm set here is not available at runtime, the
+         * {@link AutofillManager#getDefaultFieldClassificationAlgorithm()} is used instead.
+         * You can verify which algorithm was used by calling
+         * {@link FieldClassification.Match#getAlgorithm()}.
+         *
+         * @param name name of the algorithm or {@code null} to used default.
+         * @param args optional arguments to the algorithm.
+         *
+         * @return this builder
+         */
+        public Builder setFieldClassificationAlgorithm(@Nullable String name,
+                @Nullable Bundle args) {
+            mAlgorithm = name;
+            mAlgorithmArgs = args;
+            return this;
+        }
+
+        /**
          * Adds a new value for user data.
          *
          * @param remoteId unique string used to identify the user data.
@@ -211,7 +249,7 @@ public final class UserData implements Parcelable {
     public String toString() {
         if (!sDebug) return super.toString();
 
-        final StringBuilder builder = new StringBuilder("UserData: [scorer=").append(mScorer);
+        final StringBuilder builder = new StringBuilder("UserData: [algorithm=").append(mAlgorithm);
         // Cannot disclose remote ids or values because they could contain PII
         builder.append(", remoteIds=");
         Helper.appendRedacted(builder, mRemoteIds);
@@ -231,9 +269,10 @@ public final class UserData implements Parcelable {
 
     @Override
     public void writeToParcel(Parcel parcel, int flags) {
-        parcel.writeParcelable(mScorer, flags);
         parcel.writeStringArray(mRemoteIds);
         parcel.writeStringArray(mValues);
+        parcel.writeString(mAlgorithm);
+        parcel.writeBundle(mAlgorithmArgs);
     }
 
     public static final Parcelable.Creator<UserData> CREATOR =
@@ -243,10 +282,10 @@ public final class UserData implements Parcelable {
             // Always go through the builder to ensure the data ingested by
             // the system obeys the contract of the builder to avoid attacks
             // using specially crafted parcels.
-            final InternalScorer scorer = parcel.readParcelable(null);
             final String[] remoteIds = parcel.readStringArray();
             final String[] values = parcel.readStringArray();
-            final Builder builder = new Builder(scorer, remoteIds[0], values[0]);
+            final Builder builder = new Builder(remoteIds[0], values[0])
+                    .setFieldClassificationAlgorithm(parcel.readString(), parcel.readBundle());
             for (int i = 1; i < remoteIds.length; i++) {
                 builder.add(remoteIds[i], values[i]);
             }
diff --git a/core/java/android/view/autofill/AutofillManager.java b/core/java/android/view/autofill/AutofillManager.java
index 269745455517..78b41c6f4c7b 100644
--- a/core/java/android/view/autofill/AutofillManager.java
+++ b/core/java/android/view/autofill/AutofillManager.java
@@ -53,6 +53,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
@@ -1027,7 +1028,9 @@ public final class AutofillManager {
      * Gets the user data used for
      * <a href="AutofillService.html#FieldClassification">field classification</a>.
      *
-     * <p><b>Note:</b> This method should only be called by an app providing an autofill service.
+     * <p><b>Note:</b> This method should only be called by an app providing an autofill service,
+     * and it's ignored if the caller currently doesn't have an enabled autofill service for
+     * the user.
      *
      * @return value previously set by {@link #setUserData(UserData)} or {@code null} if it was
      * reset or if the caller currently does not have an enabled autofill service for the user.
@@ -1079,6 +1082,49 @@ public final class AutofillManager {
     }
 
     /**
+     * Gets the name of the default algorithm used for
+     * <a href="AutofillService.html#FieldClassification">field classification</a>.
+     *
+     * <p>The default algorithm is used when the algorithm on {@link UserData} is invalid or not
+     * set.
+     *
+     * <p><b>Note:</b> This method should only be called by an app providing an autofill service,
+     * and it's ignored if the caller currently doesn't have an enabled autofill service for
+     * the user.
+     */
+    @Nullable
+    public String getDefaultFieldClassificationAlgorithm() {
+        try {
+            return mService.getDefaultFieldClassificationAlgorithm();
+        } catch (RemoteException e) {
+            e.rethrowFromSystemServer();
+            return null;
+        }
+    }
+
+    /**
+     * Gets the name of all algorithms currently available for
+     * <a href="AutofillService.html#FieldClassification">field classification</a>.
+     *
+     * <p><b>Note:</b> This method should only be called by an app providing an autofill service,
+     * and it's ignored if the caller currently doesn't have an enabled autofill service for
+     * the user.
+     *
+     * @return list of all algorithms currently available, or an empty list if the caller currently
+     * does not have an enabled autofill service for the user.
+     */
+    @NonNull
+    public List<String> getAvailableFieldClassificationAlgorithms() {
+        try {
+            final List<String> names = mService.getAvailableFieldClassificationAlgorithms();
+            return names != null ? names : Collections.emptyList();
+        } catch (RemoteException e) {
+            e.rethrowFromSystemServer();
+            return null;
+        }
+    }
+
+    /**
      * Returns {@code true} if autofill is supported by the current device and
      * is supported for this user.
      *
diff --git a/core/java/android/view/autofill/IAutoFillManager.aidl b/core/java/android/view/autofill/IAutoFillManager.aidl
index 38bb311986e8..1afa35e80a26 100644
--- a/core/java/android/view/autofill/IAutoFillManager.aidl
+++ b/core/java/android/view/autofill/IAutoFillManager.aidl
@@ -58,4 +58,6 @@ interface IAutoFillManager {
     void setUserData(in UserData userData);
     boolean isFieldClassificationEnabled();
     ComponentName getAutofillServiceComponentName();
+    List<String> getAvailableFieldClassificationAlgorithms();
+    String getDefaultFieldClassificationAlgorithm();
 }
diff --git a/services/autofill/java/com/android/server/autofill/AutofillManagerService.java b/services/autofill/java/com/android/server/autofill/AutofillManagerService.java
index e1cb154c88f5..cac7fedd0b00 100644
--- a/services/autofill/java/com/android/server/autofill/AutofillManagerService.java
+++ b/services/autofill/java/com/android/server/autofill/AutofillManagerService.java
@@ -479,7 +479,7 @@ public final class AutofillManagerService extends SystemService {
         if (service != null) {
             service.destroySessionsLocked();
             service.updateLocked(disabled);
-            if (!service.isEnabled()) {
+            if (!service.isEnabledLocked()) {
                 removeCachedServiceLocked(userId);
             }
         }
@@ -621,6 +621,34 @@ public final class AutofillManagerService extends SystemService {
         }
 
         @Override
+        public String getDefaultFieldClassificationAlgorithm() throws RemoteException {
+            final int userId = UserHandle.getCallingUserId();
+
+            synchronized (mLock) {
+                final AutofillManagerServiceImpl service = peekServiceForUserLocked(userId);
+                if (service != null) {
+                    return service.getDefaultFieldClassificationAlgorithm(getCallingUid());
+                }
+            }
+
+            return null;
+        }
+
+        @Override
+        public List<String> getAvailableFieldClassificationAlgorithms() throws RemoteException {
+            final int userId = UserHandle.getCallingUserId();
+
+            synchronized (mLock) {
+                final AutofillManagerServiceImpl service = peekServiceForUserLocked(userId);
+                if (service != null) {
+                    return service.getAvailableFieldClassificationAlgorithms(getCallingUid());
+                }
+            }
+
+            return null;
+        }
+
+        @Override
         public ComponentName getAutofillServiceComponentName() throws RemoteException {
             final int userId = UserHandle.getCallingUserId();
 
diff --git a/services/autofill/java/com/android/server/autofill/AutofillManagerServiceImpl.java b/services/autofill/java/com/android/server/autofill/AutofillManagerServiceImpl.java
index 4cdfd625a8f0..65984dd5fdbe 100644
--- a/services/autofill/java/com/android/server/autofill/AutofillManagerServiceImpl.java
+++ b/services/autofill/java/com/android/server/autofill/AutofillManagerServiceImpl.java
@@ -51,6 +51,7 @@ import android.os.UserManager;
 import android.provider.Settings;
 import android.service.autofill.AutofillService;
 import android.service.autofill.AutofillServiceInfo;
+import android.service.autofill.EditDistanceScorer;
 import android.service.autofill.FieldClassification;
 import android.service.autofill.FieldClassification.Match;
 import android.service.autofill.FillEventHistory;
@@ -63,6 +64,8 @@ import android.util.ArrayMap;
 import android.util.ArraySet;
 import android.util.DebugUtils;
 import android.util.LocalLog;
+import android.util.Log;
+import android.util.Pair;
 import android.util.Slog;
 import android.util.SparseArray;
 import android.util.TimeUtils;
@@ -81,6 +84,7 @@ import com.android.server.autofill.ui.AutoFillUI;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Random;
 
@@ -105,7 +109,10 @@ final class AutofillManagerServiceImpl {
     private final AutoFillUI mUi;
     private final MetricsLogger mMetricsLogger = new MetricsLogger();
 
+    @GuardedBy("mLock")
     private RemoteCallbackList<IAutoFillManagerClient> mClients;
+
+    @GuardedBy("mLock")
     private AutofillServiceInfo mInfo;
 
     private static final Random sRandom = new Random();
@@ -113,25 +120,74 @@ final class AutofillManagerServiceImpl {
     private final LocalLog mRequestsHistory;
     private final LocalLog mUiLatencyHistory;
 
+    // TODO(b/70939974): temporary, will be moved to ExtServices
+    static final class FieldClassificationAlgorithmService {
+
+        /**
+         * Gets the name of all available algorithms.
+         */
+        @NonNull
+        public List<String> getAvailableAlgorithms() {
+            return Arrays.asList(EditDistanceScorer.NAME);
+        }
+
+        /**
+         * Gets the default algorithm that's used when an algorithm is not specified or is invalid.
+         */
+        @NonNull
+        public String getDefaultAlgorithm() {
+            return EditDistanceScorer.NAME;
+        }
+
+        /**
+         * Gets a field classification score.
+         *
+         * @param algorithmName algorithm to be used. If invalid, the default algorithm will be used
+         * instead.
+         * @param algorithmArgs optional arguments to be passed to the algorithm.
+         * @param actualValue value entered by the user.
+         * @param userDataValue value from the user data.
+         *
+         * @return pair containing the algorithm used and the score.
+         */
+        // TODO(b/70939974): use parcelable instead of pair
+        Pair<String, Float> getScore(@NonNull String algorithmName, @Nullable Bundle algorithmArgs,
+                @NonNull AutofillValue actualValue, @NonNull String userDataValue) {
+            if (!EditDistanceScorer.NAME.equals(algorithmName)) {
+                Log.w(TAG, "Ignoring invalid algorithm (" + algorithmName + ") and using "
+                        + EditDistanceScorer.NAME + " instead");
+            }
+            return new Pair<>(EditDistanceScorer.NAME,
+                    EditDistanceScorer.getInstance().getScore(actualValue, userDataValue));
+        }
+    }
+
+    private final FieldClassificationAlgorithmService mFcService =
+            new FieldClassificationAlgorithmService();
+
     /**
      * Apps disabled by the service; key is package name, value is when they will be enabled again.
      */
+    @GuardedBy("mLock")
     private ArrayMap<String, Long> mDisabledApps;
 
     /**
      * Activities disabled by the service; key is component name, value is when they will be enabled
      * again.
      */
+    @GuardedBy("mLock")
     private ArrayMap<ComponentName, Long> mDisabledActivities;
 
     /**
      * Whether service was disabled for user due to {@link UserManager} restrictions.
      */
+    @GuardedBy("mLock")
     private boolean mDisabled;
 
     /**
      * Data used for field classification.
      */
+    @GuardedBy("mLock")
     private UserData mUserData;
 
     /**
@@ -235,7 +291,7 @@ final class AutofillManagerServiceImpl {
     }
 
     void updateLocked(boolean disabled) {
-        final boolean wasEnabled = isEnabled();
+        final boolean wasEnabled = isEnabledLocked();
         if (sVerbose) {
             Slog.v(TAG, "updateLocked(u=" + mUserId + "): wasEnabled=" + wasEnabled
                     + ", mSetupComplete= " + mSetupComplete
@@ -274,7 +330,7 @@ final class AutofillManagerServiceImpl {
             Slog.e(TAG, "Bad AutofillServiceInfo for '" + componentName + "': " + e);
             mInfo = null;
         }
-        final boolean isEnabled = isEnabled();
+        final boolean isEnabled = isEnabledLocked();
         if (wasEnabled != isEnabled) {
             if (!isEnabled) {
                 final int sessionCount = mSessions.size();
@@ -292,7 +348,7 @@ final class AutofillManagerServiceImpl {
             mClients = new RemoteCallbackList<>();
         }
         mClients.register(client);
-        return isEnabled();
+        return isEnabledLocked();
     }
 
     void removeClientLocked(IAutoFillManagerClient client) {
@@ -302,7 +358,7 @@ final class AutofillManagerServiceImpl {
     }
 
     void setAuthenticationResultLocked(Bundle data, int sessionId, int authenticationId, int uid) {
-        if (!isEnabled()) {
+        if (!isEnabledLocked()) {
             return;
         }
         final Session session = mSessions.get(sessionId);
@@ -312,7 +368,7 @@ final class AutofillManagerServiceImpl {
     }
 
     void setHasCallback(int sessionId, int uid, boolean hasIt) {
-        if (!isEnabled()) {
+        if (!isEnabledLocked()) {
             return;
         }
         final Session session = mSessions.get(sessionId);
@@ -327,7 +383,7 @@ final class AutofillManagerServiceImpl {
             @NonNull IBinder appCallbackToken, @NonNull AutofillId autofillId,
             @NonNull Rect virtualBounds, @Nullable AutofillValue value, boolean hasCallback,
             int flags, @NonNull ComponentName componentName) {
-        if (!isEnabled()) {
+        if (!isEnabledLocked()) {
             return 0;
         }
 
@@ -388,7 +444,7 @@ final class AutofillManagerServiceImpl {
     }
 
     void finishSessionLocked(int sessionId, int uid) {
-        if (!isEnabled()) {
+        if (!isEnabledLocked()) {
             return;
         }
 
@@ -411,7 +467,7 @@ final class AutofillManagerServiceImpl {
     }
 
     void cancelSessionLocked(int sessionId, int uid) {
-        if (!isEnabled()) {
+        if (!isEnabledLocked()) {
             return;
         }
 
@@ -799,14 +855,15 @@ final class AutofillManagerServiceImpl {
     // Called by AutofillManager
     void setUserData(int callingUid, UserData userData) {
         synchronized (mLock) {
-            if (isCalledByServiceLocked("setUserData", callingUid)) {
-                mUserData = userData;
-                // Log it
-                int numberFields = mUserData == null ? 0: mUserData.getRemoteIds().length;
-                mMetricsLogger.write(Helper.newLogMaker(MetricsEvent.AUTOFILL_USERDATA_UPDATED,
-                        getServicePackageName(), null)
-                        .setCounterValue(numberFields));
+            if (!isCalledByServiceLocked("setUserData", callingUid)) {
+                return;
             }
+            mUserData = userData;
+            // Log it
+            int numberFields = mUserData == null ? 0: mUserData.getRemoteIds().length;
+            mMetricsLogger.write(Helper.newLogMaker(MetricsEvent.AUTOFILL_USERDATA_UPDATED,
+                    getServicePackageName(), null)
+                    .setCounterValue(numberFields));
         }
     }
 
@@ -917,6 +974,11 @@ final class AutofillManagerServiceImpl {
             pw.println();
             mUserData.dump(prefix2, pw);
         }
+
+        pw.print(prefix); pw.print("Available Field Classification algorithms: ");
+        pw.println(mFcService.getAvailableAlgorithms());
+        pw.print(prefix); pw.print("Default Field Classification algorithm: ");
+        pw.println(mFcService.getDefaultAlgorithm());
     }
 
     void destroySessionsLocked() {
@@ -964,11 +1026,13 @@ final class AutofillManagerServiceImpl {
                 final IAutoFillManagerClient client = clients.getBroadcastItem(i);
                 try {
                     final boolean resetSession;
+                    final boolean isEnabled;
                     synchronized (mLock) {
                         resetSession = resetClient || isClientSessionDestroyedLocked(client);
+                        isEnabled = isEnabledLocked();
                     }
                     int flags = 0;
-                    if (isEnabled()) {
+                    if (isEnabled) {
                         flags |= AutofillManager.SET_STATE_FLAG_ENABLED;
                     }
                     if (resetSession) {
@@ -1004,7 +1068,7 @@ final class AutofillManagerServiceImpl {
         return true;
     }
 
-    boolean isEnabled() {
+    boolean isEnabledLocked() {
         return mSetupComplete && mInfo != null && !mDisabled;
     }
 
@@ -1093,9 +1157,9 @@ final class AutofillManagerServiceImpl {
     }
 
     // Called by AutofillManager, checks UID.
-    boolean isFieldClassificationEnabled(int uid) {
+    boolean isFieldClassificationEnabled(int callingUid) {
         synchronized (mLock) {
-            if (!isCalledByServiceLocked("isFieldClassificationEnabled", uid)) {
+            if (!isCalledByServiceLocked("isFieldClassificationEnabled", callingUid)) {
                 return false;
             }
             return isFieldClassificationEnabledLocked();
@@ -1110,6 +1174,28 @@ final class AutofillManagerServiceImpl {
                 mUserId) == 1;
     }
 
+    FieldClassificationAlgorithmService getFieldClassificationService() {
+        return mFcService;
+    }
+
+    List<String> getAvailableFieldClassificationAlgorithms(int callingUid) {
+        synchronized (mLock) {
+            if (!isCalledByServiceLocked("getFCAlgorithms()", callingUid)) {
+                return null;
+            }
+        }
+        return mFcService.getAvailableAlgorithms();
+    }
+
+    String getDefaultFieldClassificationAlgorithm(int callingUid) {
+        synchronized (mLock) {
+            if (!isCalledByServiceLocked("getDefaultFCAlgorithm()", callingUid)) {
+                return null;
+            }
+        }
+        return mFcService.getDefaultAlgorithm();
+    }
+
     @Override
     public String toString() {
         return "AutofillManagerServiceImpl: [userId=" + mUserId
diff --git a/services/autofill/java/com/android/server/autofill/Session.java b/services/autofill/java/com/android/server/autofill/Session.java
index 01f908407691..96296907b2c5 100644
--- a/services/autofill/java/com/android/server/autofill/Session.java
+++ b/services/autofill/java/com/android/server/autofill/Session.java
@@ -69,6 +69,7 @@ import android.service.autofill.FieldClassification;
 import android.util.ArrayMap;
 import android.util.ArraySet;
 import android.util.LocalLog;
+import android.util.Pair;
 import android.util.Slog;
 import android.util.SparseArray;
 import android.util.TimeUtils;
@@ -84,6 +85,7 @@ import com.android.internal.logging.MetricsLogger;
 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
 import com.android.internal.os.HandlerCaller;
 import com.android.internal.util.ArrayUtils;
+import com.android.server.autofill.AutofillManagerServiceImpl.FieldClassificationAlgorithmService;
 import com.android.server.autofill.ui.AutoFillUI;
 import com.android.server.autofill.ui.PendingUi;
 
@@ -1088,7 +1090,8 @@ final class Session implements RemoteFillService.FillServiceCallbacks, ViewState
 
                     // Sets field classification score for field
                     if (userData!= null) {
-                        setScore(detectedFieldIds, detectedFieldClassifications, userData,
+                        setFieldClassificationScore(mService.getFieldClassificationService(),
+                                detectedFieldIds, detectedFieldClassifications, userData,
                                 viewState.id, currentValue);
                     }
                 } // else
@@ -1133,7 +1136,9 @@ final class Session implements RemoteFillService.FillServiceCallbacks, ViewState
      * Adds the matches to {@code detectedFieldsIds} and {@code detectedFieldClassifications} for
      * {@code fieldId} based on its {@code currentValue} and {@code userData}.
      */
-    private static void setScore(@NonNull ArrayList<AutofillId> detectedFieldIds,
+    private static void setFieldClassificationScore(
+            @NonNull AutofillManagerServiceImpl.FieldClassificationAlgorithmService  service,
+            @NonNull ArrayList<AutofillId> detectedFieldIds,
             @NonNull ArrayList<FieldClassification> detectedFieldClassifications,
             @NonNull UserData userData, @NonNull AutofillId fieldId,
             @NonNull AutofillValue currentValue) {
@@ -1150,11 +1155,16 @@ final class Session implements RemoteFillService.FillServiceCallbacks, ViewState
             return;
         }
 
+        final String algorithm = userData.getFieldClassificationAlgorithm();
+        final Bundle algorithmArgs = userData.getAlgorithmArgs();
         ArrayList<Match> matches = null;
         for (int i = 0; i < userValues.length; i++) {
             String remoteId = remoteIds[i];
             final String value = userValues[i];
-            final float score = userData.getScorer().getScore(currentValue, value);
+            final Pair<String, Float> result = service.getScore(algorithm, algorithmArgs,
+                    currentValue, value);
+            final String actualAlgorithm = result.first;
+            final float score = result.second;
             if (score > 0) {
                 if (sVerbose) {
                     Slog.v(TAG, "adding score " + score + " at index " + i + " and id " + fieldId);
@@ -1162,7 +1172,7 @@ final class Session implements RemoteFillService.FillServiceCallbacks, ViewState
                 if (matches == null) {
                     matches = new ArrayList<>(userValues.length);
                 }
-                matches.add(new Match(remoteId, score));
+                matches.add(new Match(remoteId, score, actualAlgorithm));
             }
             else if (sVerbose) Slog.v(TAG, "skipping score 0 at index " + i + " and id " + fieldId);
         }