Add some initial backupV2 network infrastructure.

app/src/main/java/org/thoughtcrime/securesms/keyvalue/BackupValues.kt

@@ -0,0 +1,76 @@
+package org.thoughtcrime.securesms.keyvalue
+
+import com.fasterxml.jackson.annotation.JsonProperty
+import org.signal.core.util.logging.Log
+import org.whispersystems.signalservice.api.archive.ArchiveServiceCredential
+import org.whispersystems.signalservice.internal.util.JsonUtil
+import java.io.IOException
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.days
+
+internal class BackupValues(store: KeyValueStore) : SignalStoreValues(store) {
+  companion object {
+    val TAG = Log.tag(BackupValues::class.java)
+    val KEY_CREDENTIALS = "backup.credentials"
+  }
+
+  override fun onFirstEverAppLaunch() = Unit
+  override fun getKeysToIncludeInBackup(): List<String> = emptyList()
+
+  /**
+   * Retrieves the stored credentials, mapped by the day they're valid. The day is represented as
+   * the unix time (in seconds) of the start of the day. Wrapped in a [ArchiveServiceCredentials]
+   * type to make it easier to use. See [ArchiveServiceCredentials.getForCurrentTime].
+   */
+  val credentialsByDay: ArchiveServiceCredentials
+    get() {
+      val serialized = store.getString(KEY_CREDENTIALS, null) ?: return ArchiveServiceCredentials()
+
+      return try {
+        val map = JsonUtil.fromJson(serialized, SerializedCredentials::class.java).credentialsByDay
+        ArchiveServiceCredentials(map)
+      } catch (e: IOException) {
+        Log.w(TAG, "Invalid JSON! Clearing.", e)
+        putString(KEY_CREDENTIALS, null)
+        ArchiveServiceCredentials()
+      }
+    }
+
+  /**
+   * Adds the given credentials to the existing list of stored credentials.
+   */
+  fun addCredentials(credentials: List<ArchiveServiceCredential>) {
+    val current: MutableMap<Long, ArchiveServiceCredential> = credentialsByDay.toMutableMap()
+    current.putAll(credentials.associateBy { it.redemptionTime })
+    putString(KEY_CREDENTIALS, JsonUtil.toJson(SerializedCredentials(current)))
+  }
+
+  /**
+   * Trims out any credentials that are for days older than the given timestamp.
+   */
+  fun clearCredentialsOlderThan(startOfDayInSeconds: Long) {
+    val current: MutableMap<Long, ArchiveServiceCredential> = credentialsByDay.toMutableMap()
+    val updated = current.filterKeys { it < startOfDayInSeconds }
+    putString(KEY_CREDENTIALS, JsonUtil.toJson(SerializedCredentials(updated)))
+  }
+
+  class SerializedCredentials(
+    @JsonProperty
+    val credentialsByDay: Map<Long, ArchiveServiceCredential>
+  )
+
+  /**
+   * A [Map] wrapper that makes it easier to get the credential for the current time.
+   */
+  class ArchiveServiceCredentials(map: Map<Long, ArchiveServiceCredential>) : Map<Long, ArchiveServiceCredential> by map {
+    constructor() : this(mapOf())
+
+    /**
+     * Retrieves a credential that is valid for the current time, otherwise null.
+     */
+    fun getForCurrentTime(currentTime: Duration): ArchiveServiceCredential? {
+      val startOfDayInSeconds: Long = currentTime.inWholeDays.days.inWholeSeconds
+      return this[startOfDayInSeconds]
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/keyvalue/SignalStore.java

@@ -44,6 +44,7 @@ public final class SignalStore {
   private final ReleaseChannelValues      releaseChannelValues;
   private final StoryValues               storyValues;
   private final ApkUpdateValues           apkUpdate;
+  private final BackupValues              backupValues;
 
   private final PlainTextSharedPrefsDataStore plainTextValues;
 
@@ -89,6 +90,7 @@ public final class SignalStore {
     this.releaseChannelValues      = new ReleaseChannelValues(store);
     this.storyValues               = new StoryValues(store);
     this.apkUpdate                 = new ApkUpdateValues(store);
+    this.backupValues              = new BackupValues(store);
     this.plainTextValues           = new PlainTextSharedPrefsDataStore(ApplicationDependencies.getApplication());
   }
 
@@ -270,6 +272,10 @@ public final class SignalStore {
     return getInstance().apkUpdate;
   }
 
+  public static @NonNull BackupValues backup() {
+    return getInstance().backupValues;
+  }
+
   public static @NonNull GroupsV2AuthorizationSignalStoreCache groupsV2AciAuthorizationCache() {
     return GroupsV2AuthorizationSignalStoreCache.createAciCache(getStore());
   }