android: Use LabelSync plugin

Explicitly setting the "use_labels" setting in the Android code might be
antithetical to "plugins" but since there is no way to plug in or out
modules in runtime in Android we might as well hardcode when needed.

There are a couple of things to fix/investigate:
* Currently the application has to be restarted when the settings have
  changed.
* run_hook is not runned on main thread and a warning is printed. Is
  this a problem here?
* Is a force upload/download option needed?
* Should the 'android' part of the plugin, including the hooks, be more
  generically named? There isn't any Android specific things and other
  clients (iOS?) could use it...

android/app/build.gradle

@@ -67,6 +67,7 @@ android {
                 exclude "electroncash/locale/"
                 include "electroncash_gui/__init__.py"
                 include "electroncash_plugins/__init__.py"
+                include "electroncash_plugins/labels/"
 
                 // From src/main/python
                 include "chaquopy/"

android/app/src/main/java/org/electroncash/electroncash3/Settings.kt

@@ -30,6 +30,9 @@ fun initSettings(): PyObject {
     settings.getBoolean("cashaddr_format").observeForever {
         clsAddress.callAttr("show_cashaddr", it)
     }
+    settings.getBoolean("synchronize_labels").observeForever {
+        settings.getBoolean("use_labels").setValue(it)
+    }
     settings.getString("base_unit").observeForever {
         unitName = it!!
         val places = libUtil.get("base_units")!!.callAttr("get", it)
@@ -70,6 +73,7 @@ fun setDefaultValues(sp: SharedPreferences) {
     // Appearance
     setDefaultValue(sp, "cashaddr_format",
                     clsAddress.get("FMT_UI") == clsAddress.get("FMT_CASHADDR"))
+    setDefaultValue(sp, "use_labels", false)
     setDefaultValue(sp, "base_unit", libUtil.get("DEFAULT_BASE_UNIT")!!.toString())
     setDefaultValue(sp, "block_explorer", libWeb.callAttr("BE_default_explorer")!!.toString())
 

android/app/src/main/python/electroncash_gui/android/console.py

@@ -9,6 +9,7 @@
 
 from electroncash import commands, daemon, interface, keystore, storage, util
 from electroncash.i18n import _
+from electroncash.plugins import Plugins, run_hook
 from electroncash.storage import WalletStorage
 from electroncash.wallet import (ImportedAddressWallet, ImportedPrivkeyWallet, Standard_Wallet,
                                  Wallet)
@@ -80,7 +81,8 @@ def __init__(self, config):
 
         # Create daemon here rather than in start() so the DaemonModel has a chance to register
         # its callback before the daemon threads start.
-        self.daemon = daemon.Daemon(self.config, fd, is_gui=False, plugins=None)
+        plugins = Plugins(config, "android")
+        self.daemon = daemon.Daemon(self.config, fd, is_gui=False, plugins=plugins)
         self.daemon_running = False
 
         self.gui_callback = None
@@ -128,11 +130,14 @@ def load_wallet(self, name, password=None):
             wallet = Wallet(storage)
             wallet.start_threads(self.network)
             self.daemon.add_wallet(wallet)
+            run_hook('start_android_wallet', wallet)
 
     def close_wallet(self, name=None):
         """Close a wallet"""
+        path = self._wallet_path(name)
+        run_hook('stop_android_wallet', self.daemon.get_wallet(path))
         self._assert_daemon_running()
-        self.daemon.stop_wallet(self._wallet_path(name))
+        self.daemon.stop_wallet(path)
 
     def create(self, name, password, seed=None, passphrase="", bip39_derivation=None,
                master=None, addresses=None, privkeys=None):

android/app/src/main/python/electroncash_gui/android/strings.py

@@ -50,6 +50,7 @@
 _("Show seed")
 _("Size")
 _("Signed transaction")
+_("Synchronize labels")
 _("The string you entered has been broadcast. Please check your transactions for confirmation.")
 _("Transaction not found")
 _("%1$d tx (%2$d unverified)")

android/app/src/main/res/xml/settings.xml

@@ -25,6 +25,9 @@
         <SwitchPreference
             android:key="cashaddr_format"
             android:title="@string/cashaddr_address"/>
+        <SwitchPreference
+            android:key="synchronize_labels"
+            android:title="@string/synchronize_labels"/>
         <ListPreference
             android:key="base_unit"
             android:title="@string/base_unit"

electroncash_plugins/labels/__init__.py

@@ -5,4 +5,4 @@
     _("Save your wallet labels on a remote server, and synchronize them across multiple devices where you use Electron Cash."),
     _("Labels, transactions IDs and addresses are encrypted before they are sent to the remote server.")
 ]
-available_for = [ 'qt' ]
+available_for = ['qt', 'android']

electroncash_plugins/labels/android.py

@@ -0,0 +1,15 @@
+from electroncash.plugins import hook
+
+from .labels import LabelsPlugin
+
+class Plugin(LabelsPlugin):
+    def __init__(self, *args):
+        LabelsPlugin.__init__(self, *args)
+
+    @hook
+    def start_android_wallet(self, wallet):
+        self.start_wallet(wallet)
+
+    @hook
+    def stop_android_wallet(self, wallet):
+        self.stop_wallet(wallet)