Add WifiOemConfigStoreMigrationHook class for OEM migration

Add a helper class (not part of the wifi mainline module) to migrate
config store data from existing OEM devices. This will be used when the
device upgrades from a build containing OEM impl of wifi to a
build containing wifi mainline module. OEM should implement this
class if they had any non-AOSP changes in the config store
format/field names on their devices.

Bug: 142394776
Test: Compiles
Change-Id: Ie11e0ffe8e4b8f1edcaa23d35284c3b564dc97f4
diff --git a/wifi/Android.bp b/wifi/Android.bp
index 180368c..286be0b 100644
--- a/wifi/Android.bp
+++ b/wifi/Android.bp
@@ -32,6 +32,7 @@
         // framework-wifi.jar. This is not a good idea, should move WifiNetworkScoreCache
         // to a separate package.
         "java/android/net/wifi/WifiNetworkScoreCache.java",
+        "java/android/net/wifi/WifiOemConfigStoreMigrationHook.java",
         "java/android/net/wifi/wificond/*.java",
         ":libwificond_ipc_aidl",
     ],
diff --git a/wifi/java/android/net/wifi/WifiOemConfigStoreMigrationHook.java b/wifi/java/android/net/wifi/WifiOemConfigStoreMigrationHook.java
new file mode 100755
index 0000000..642dcb9
--- /dev/null
+++ b/wifi/java/android/net/wifi/WifiOemConfigStoreMigrationHook.java
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2020 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.net.wifi;
+
+import static com.android.internal.util.Preconditions.checkNotNull;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import java.util.List;
+
+/**
+ * Class used to provide one time hooks for existing OEM devices to migrate their config store
+ * data to the wifi mainline module.
+ * <p>
+ * Note:
+ * <li> OEM's need to implement {@link #load()} only if their
+ * existing config store format or file locations differs from the vanilla AOSP implementation (
+ * which is what the wifi mainline module understands).
+ * </li>
+ * <li> The wifi mainline module will invoke {@link #load()}  method on every bootup, its
+ * the responsibility of the OEM implementation to ensure that this method returns non-null data
+ * only on the first bootup. Once the migration is done, the OEM can safely delete their config
+ * store files and then return null on any subsequent reboots. The first & only relevant invocation
+ * of {@link #load()} occurs when a previously released device upgrades to the wifi
+ * mainline module from an OEM implementation of the wifi stack.
+ * </li>
+ * @hide
+ */
+@SystemApi
+public final class WifiOemConfigStoreMigrationHook {
+    /**
+     * Container for all the wifi config data to migrate.
+     */
+    public static final class MigrationData implements Parcelable {
+        /**
+         * Builder to create instance of {@link MigrationData}.
+         */
+        public static final class Builder {
+            private List<WifiConfiguration> mUserSavedNetworkConfigurations;
+            private SoftApConfiguration mUserSoftApConfiguration;
+
+            public Builder() {
+                mUserSavedNetworkConfigurations = null;
+                mUserSoftApConfiguration = null;
+            }
+
+            /**
+             * Sets the list of all user's saved network configurations parsed from OEM config
+             * store files.
+             *
+             * @param userSavedNetworkConfigurations List of {@link WifiConfiguration} representing
+             *                                       the list of user's saved networks
+             * @return Instance of {@link Builder} to enable chaining of the builder method.
+             */
+            public @NonNull Builder setUserSavedNetworkConfigurations(
+                    @NonNull List<WifiConfiguration> userSavedNetworkConfigurations) {
+                checkNotNull(userSavedNetworkConfigurations);
+                mUserSavedNetworkConfigurations = userSavedNetworkConfigurations;
+                return this;
+            }
+
+            /**
+             * Sets the user's softap configuration parsed from OEM config store files.
+             *
+             * @param userSoftApConfiguration {@link SoftApConfiguration} representing user's
+             *                                SoftAp configuration
+             * @return Instance of {@link Builder} to enable chaining of the builder method.
+             */
+            public @NonNull Builder setUserSoftApConfiguration(
+                    @NonNull SoftApConfiguration userSoftApConfiguration) {
+                checkNotNull(userSoftApConfiguration);
+                mUserSoftApConfiguration  = userSoftApConfiguration;
+                return this;
+            }
+
+            /**
+             * Build an instance of {@link MigrationData}.
+             *
+             * @return Instance of {@link MigrationData}.
+             */
+            public @NonNull MigrationData build() {
+                return new MigrationData(mUserSavedNetworkConfigurations, mUserSoftApConfiguration);
+            }
+        }
+
+        private final List<WifiConfiguration> mUserSavedNetworkConfigurations;
+        private final SoftApConfiguration mUserSoftApConfiguration;
+
+        private MigrationData(
+                @Nullable List<WifiConfiguration> userSavedNetworkConfigurations,
+                @Nullable SoftApConfiguration userSoftApConfiguration) {
+            mUserSavedNetworkConfigurations = userSavedNetworkConfigurations;
+            mUserSoftApConfiguration = userSoftApConfiguration;
+        }
+
+        public static final @NonNull Parcelable.Creator<MigrationData> CREATOR =
+                new Parcelable.Creator<MigrationData>() {
+                    @Override
+                    public MigrationData createFromParcel(Parcel in) {
+                        List<WifiConfiguration> userSavedNetworkConfigurations =
+                                in.readArrayList(null);
+                        SoftApConfiguration userSoftApConfiguration = in.readParcelable(null);
+                        return new MigrationData(
+                                userSavedNetworkConfigurations, userSoftApConfiguration);
+                    }
+
+                    @Override
+                    public MigrationData[] newArray(int size) {
+                        return new MigrationData[size];
+                    }
+                };
+
+        @Override
+        public int describeContents() {
+            return 0;
+        }
+
+        @Override
+        public void writeToParcel(@NonNull Parcel dest, int flags) {
+            dest.writeList(mUserSavedNetworkConfigurations);
+            dest.writeParcelable(mUserSoftApConfiguration, flags);
+        }
+
+        /**
+         * Returns list of all user's saved network configurations.
+         *
+         * Note: Only to be returned if there is any format change in how OEM persisted this info.
+         * @return List of {@link WifiConfiguration} representing the list of user's saved networks,
+         * or null if no migration necessary.
+         */
+        @Nullable
+        public List<WifiConfiguration> getUserSavedNetworkConfigurations() {
+            return mUserSavedNetworkConfigurations;
+        }
+
+        /**
+         * Returns user's softap configuration.
+         *
+         * Note: Only to be returned if there is any format change in how OEM persisted this info.
+         * @return {@link SoftApConfiguration} representing user's SoftAp configuration,
+         * or null if no migration necessary.
+         */
+        @Nullable
+        public SoftApConfiguration getUserSoftApConfiguration() {
+            return mUserSoftApConfiguration;
+        }
+    }
+
+    private WifiOemConfigStoreMigrationHook() { }
+
+    /**
+     * Load data from OEM's config store.
+     *
+     * @return Instance of {@link MigrationData} for migrating data, null if no
+     * migration is necessary.
+     */
+    @Nullable
+    public static MigrationData load() {
+        // Note: OEM's should add code to parse data from their config store format here!
+        return null;
+    }
+}