multi: hide decred rescan page if it's not ready

-  move hasRescan method to WalletBase and implement for decred

Signed-off-by: Philemon Ukane <ukanephilemon@gmail.com>

cw_core/lib/wallet_base.dart

@@ -60,6 +60,14 @@ abstract class WalletBase<BalanceType extends Balance, HistoryType extends Trans
 
   bool get isHardwareWallet => walletInfo.isHardwareWallet;
 
+  bool get hasRescan =>
+      walletInfo.type == WalletType.bitcoin ||
+      walletInfo.type == WalletType.litecoin ||
+      walletInfo.type == WalletType.monero ||
+      walletInfo.type == WalletType.wownero ||
+      walletInfo.type == WalletType.decred ||
+      walletInfo.type == WalletType.haven;
+
   Future<void> connectToNode({required Node node});
 
   // there is a default definition here because only coins with a pow node (nano based) need to override this

cw_decred/lib/wallet.dart

@@ -426,6 +426,9 @@ abstract class DecredWalletBase extends WalletBase<DecredBalance,
   @override
   Future<void> save() async {}
 
+  @override
+  bool get hasRescan => walletBirthdayBlockHeight() != -1;
+
   @override
   Future<void> rescan({required int height}) async {
     // The required height is not used. A birthday time is recorded in the
@@ -433,12 +436,10 @@ abstract class DecredWalletBase extends WalletBase<DecredBalance,
     // can always rescan from there.
     var rescanHeight = 0;
     if (!watchingOnly) {
-      final res = libdcrwallet.birthState(walletInfo.name);
-      final decoded = json.decode(res);
-      if (decoded["setfromheight"] == true || decoded["setfromtime"] == true) {
+      rescanHeight = walletBirthdayBlockHeight();
+      if (rescanHeight == -1) {
         throw "cannot rescan before the birthday block has been set";
       }
-      rescanHeight = decoded["height"] ?? 0;
     }
     libdcrwallet.rescanFromHeight(walletInfo.name, rescanHeight.toString());
   }
@@ -502,7 +503,7 @@ abstract class DecredWalletBase extends WalletBase<DecredBalance,
       throw "unable to get an address from unsynced wallet";
     }
     return libdcrwallet.signMessageAsync(
-        walletInfo.name, message, addr!, _password);
+        walletInfo.name, message, addr, _password);
   }
 
   List<Unspent> unspents() {
@@ -582,6 +583,17 @@ abstract class DecredWalletBase extends WalletBase<DecredBalance,
     unspentCoinsInfo.add(newInfo);
   }
 
+  // walletBirthdayBlockHeight checks if the wallet birthday is set and returns
+  // it. Returns -1 if not.
+  int walletBirthdayBlockHeight() {
+    final res = libdcrwallet.birthState(walletInfo.name);
+    final decoded = json.decode(res);
+    if (decoded["setfromheight"] == true || decoded["setfromtime"] == true) {
+      return -1;
+    }
+    return decoded["height"] ?? 0;
+  }
+
   @override
   Future<bool> verifyMessage(String message, String signature, {String? address = null}) {
     return true;

lib/src/screens/rescan/rescan_page.dart

@@ -25,52 +25,55 @@ class RescanPage extends BasePage {
 
   @override
   Widget body(BuildContext context) {
-    var child = Padding(
-      padding: EdgeInsets.only(left: 24, right: 24, bottom: 24),
-      child:
-          Column(mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [
-        Observer(
-            builder: (_) => BlockchainHeightWidget(
-                  type: this.type,
-                  key: _blockchainHeightWidgetKey,
-                  onHeightOrDateEntered: (value) =>
-                      _rescanViewModel.isButtonEnabled = value,
-                  isSilentPaymentsScan: _rescanViewModel.isSilentPaymentsScan,
-                  isMwebScan: _rescanViewModel.isMwebScan,
-                  doSingleScan: _rescanViewModel.doSingleScan,
-                  hasDatePicker: !_rescanViewModel
-                      .isMwebScan, // disable date picker for mweb for now
-                  toggleSingleScan: () => _rescanViewModel.doSingleScan =
-                      !_rescanViewModel.doSingleScan,
-                  walletType: _rescanViewModel.wallet.type,
-                  bitcoinMempoolAPIEnabled:
-                      _rescanViewModel.isBitcoinMempoolAPIEnabled,
-                )),
-        Observer(
-            builder: (_) => LoadingPrimaryButton(
-                  isLoading:
-                      _rescanViewModel.state == RescanWalletState.rescaning,
-                  text: S.of(context).rescan,
-                  onPressed: () async {
-                    if (_rescanViewModel.isSilentPaymentsScan) {
-                      return _toggleSilentPaymentsScanning(context);
-                    }
-
-                    _rescanViewModel.rescanCurrentWallet(
-                        restoreHeight:
-                            _blockchainHeightWidgetKey.currentState!.height);
-
-                    Navigator.of(context).pop();
-                  },
-                  color: Theme.of(context).primaryColor,
-                  textColor: Colors.white,
-                  isDisabled: !_rescanViewModel.isButtonEnabled,
-                ))
-      ]),
-    );
-    if (type == WalletType.decred) {
+    var child;
+    if (type != WalletType.decred) {
       child = Padding(
         padding: EdgeInsets.only(left: 24, right: 24, bottom: 24),
+        child:
+            Column(mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [
+          Observer(
+              builder: (_) => BlockchainHeightWidget(
+                    type: this.type,
+                    key: _blockchainHeightWidgetKey,
+                    onHeightOrDateEntered: (value) =>
+                        _rescanViewModel.isButtonEnabled = value,
+                    isSilentPaymentsScan: _rescanViewModel.isSilentPaymentsScan,
+                    isMwebScan: _rescanViewModel.isMwebScan,
+                    doSingleScan: _rescanViewModel.doSingleScan,
+                    hasDatePicker: !_rescanViewModel
+                        .isMwebScan, // disable date picker for mweb for now
+                    toggleSingleScan: () => _rescanViewModel.doSingleScan =
+                        !_rescanViewModel.doSingleScan,
+                    walletType: _rescanViewModel.wallet.type,
+                    bitcoinMempoolAPIEnabled:
+                        _rescanViewModel.isBitcoinMempoolAPIEnabled,
+                  )),
+          Observer(
+              builder: (_) => LoadingPrimaryButton(
+                    isLoading:
+                        _rescanViewModel.state == RescanWalletState.rescaning,
+                    text: S.of(context).rescan,
+                    onPressed: () async {
+                      if (_rescanViewModel.isSilentPaymentsScan) {
+                        return _toggleSilentPaymentsScanning(context);
+                      }
+
+                      _rescanViewModel.rescanCurrentWallet(
+                          restoreHeight:
+                              _blockchainHeightWidgetKey.currentState!.height);
+
+                      Navigator.of(context).pop();
+                    },
+                    color: Theme.of(context).primaryColor,
+                    textColor: Colors.white,
+                    isDisabled: !_rescanViewModel.isButtonEnabled,
+                  ))
+        ]),
+      );
+    } else {
+      child = Center(
+          child: Padding(
+        padding: EdgeInsets.only(left: 24, right: 24, bottom: 24),
         child: Column(
             mainAxisAlignment: MainAxisAlignment.spaceBetween,
             children: [
@@ -89,7 +92,7 @@ class RescanPage extends BasePage {
                         textColor: Colors.white,
                       ))
             ]),
-      );
+      ));
     }
     return GestureDetector(
       behavior: HitTestBehavior.opaque,

lib/view_model/dashboard/dashboard_view_model.dart

@@ -383,13 +383,7 @@ abstract class DashboardViewModelBase with Store {
   bool get isTestnet => wallet.type == WalletType.bitcoin && bitcoin!.isTestnet(wallet);
 
   @computed
-  bool get hasRescan =>
-      wallet.type == WalletType.bitcoin ||
-      wallet.type == WalletType.monero ||
-      wallet.type == WalletType.litecoin ||
-      wallet.type == WalletType.wownero ||
-      wallet.type == WalletType.decred ||
-      wallet.type == WalletType.haven;
+  bool get hasRescan => wallet.hasRescan;
 
   @computed
   bool get isMoneroViewOnly {