Added ability to start a Synchronizer with just a viewing key.

This was a long awaited request from wallet partners who already have keys available when the wallet launches.

src/main/java/cash/z/ecc/android/sdk/jni/RustBackend.kt

@@ -61,8 +61,8 @@ class RustBackend : RustBackendWelding {
 
     override fun initDataDb() = initDataDb(pathDataDb)
 
-//    override fun initAccountsTable(extfvks: Array<String>) =
-//        initAccountsTableWithKeys(dbDataPath, extfvks)
+    override fun initAccountsTable(vararg extfvks: String) =
+        initAccountsTableWithKeys(pathDataDb, extfvks)
 
     override fun initAccountsTable(
         seed: ByteArray,
@@ -207,10 +207,10 @@ class RustBackend : RustBackendWelding {
             accounts: Int
         ): Array<String>
 
-//    @JvmStatic private external fun initAccountsTableWithKeys(
-//        dbDataPath: String,
-//        extfvk: Array<String>
-//    )
+        @JvmStatic private external fun initAccountsTableWithKeys(
+            dbDataPath: String,
+            extfvk: Array<out String>
+        ): Boolean
 
         @JvmStatic private external fun initBlocksTable(
             dbDataPath: String,

src/main/java/cash/z/ecc/android/sdk/jni/RustBackendWelding.kt

@@ -35,7 +35,7 @@ interface RustBackendWelding {
 
     fun initAccountsTable(seed: ByteArray, numberOfAccounts: Int): Array<String>
 
-//    fun initAccountsTable(extfvks: Array<ByteArray>, numberOfAccounts: Int)
+    fun initAccountsTable(vararg extfvks: String): Boolean
 
     fun initBlocksTable(height: Int, hash: String, time: Long, saplingTree: String): Boolean
 

src/main/rust/lib.rs

@@ -172,6 +172,29 @@ pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_initAccount
 
 #[no_mangle]
 pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_deriveExtendedSpendingKeys(
+pub unsafe extern "C" fn Java_cash_z_ecc_android_sdk_jni_RustBackend_initAccountsTableWithKeys(
+    env: JNIEnv<'_>,
+    _: JClass<'_>,
+    db_data: JString<'_>,
+    extfvks_arr: jobjectArray,
+) -> jboolean {
+    let res = panic::catch_unwind(|| {
+        let db_data = utils::java_string_to_rust(&env, db_data);
+        // TODO: avoid all this unwrapping and also surface erros, better
+        let count = env.get_array_length(extfvks_arr).unwrap();
+        let extfvks = (0..count)
+            .map(|i| env.get_object_array_element(extfvks_arr, i))
+            .map(|jstr| utils::java_string_to_rust(&env, jstr.unwrap().into()))
+            .map(|vkstr| decode_extended_full_viewing_key(HRP_SAPLING_EXTENDED_FULL_VIEWING_KEY, &vkstr).unwrap().unwrap())
+            .collect::<Vec<_>>();
+
+        match init_accounts_table(&db_data, &extfvks) {
+            Ok(()) => Ok(JNI_TRUE),
+            Err(e) => Err(format_err!("Error while initializing accounts: {}", e)),
+        }
+    });
+    unwrap_exc_or(&env, res, JNI_FALSE)
+}
     env: JNIEnv<'_>,
     _: JClass<'_>,
     seed: jbyteArray,