add ReceivePage UI for the demo wallet

bdk_demo/lib/core/router/app_router.dart

@@ -1,6 +1,7 @@
 import 'package:flutter_riverpod/misc.dart';
 import 'package:go_router/go_router.dart';
 import 'package:bdk_demo/features/home/home_page.dart';
+import 'package:bdk_demo/features/receive/receive_page.dart';
 import 'package:bdk_demo/features/transactions/transaction_detail_page.dart';
 import 'package:bdk_demo/features/transactions/transactions_list_page.dart';
 import 'package:bdk_demo/features/shared/widgets/placeholder_page.dart';
@@ -71,7 +72,7 @@ GoRouter createRouter(RouterRead read) => GoRouter(
     GoRoute(
       path: AppRoutes.receive,
       name: 'receive',
-      builder: (context, state) => const PlaceholderPage(title: 'Receive'),
+      builder: (context, state) => const ReceivePage(),
     ),
     GoRoute(
       path: AppRoutes.send,

bdk_demo/lib/features/receive/receive_page.dart

@@ -0,0 +1,227 @@
+import 'package:bdk_demo/core/theme/app_theme.dart';
+import 'package:bdk_demo/core/utils/clipboard_util.dart';
+import 'package:bdk_demo/core/utils/formatters.dart';
+import 'package:bdk_demo/features/shared/widgets/neutral_button.dart';
+import 'package:bdk_demo/features/shared/widgets/secondary_app_bar.dart';
+import 'package:bdk_demo/features/shared/widgets/wallet_ui_helpers.dart';
+import 'package:bdk_demo/providers/address_providers.dart';
+import 'package:bdk_demo/providers/wallet_providers.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:pretty_qr_code/pretty_qr_code.dart';
+
+class ReceivePage extends ConsumerWidget {
+  const ReceivePage({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final record = ref.watch(activeWalletRecordProvider);
+    final wallet = ref.watch(activeWalletProvider);
+    final receiveState = ref.watch(currentReceiveAddressProvider);
+
+    return Scaffold(
+      appBar: const SecondaryAppBar(title: 'Receive'),
+      body: SafeArea(
+        child: record == null || wallet == null
+            ? const WalletStateCard(
+                icon: Icons.account_balance_wallet_outlined,
+                title: 'No active wallet',
+                message:
+                    'Create or load a wallet before generating a receive address.',
+                centered: true,
+              )
+            : ListView(
+                padding: const EdgeInsets.all(24),
+                children: [
+                  _IntroCard(walletName: record.name),
+                  const SizedBox(height: 16),
+                  _ReceiveAddressCard(state: receiveState),
+                ],
+              ),
+      ),
+    );
+  }
+}
+
+class _IntroCard extends StatelessWidget {
+  const _IntroCard({required this.walletName});
+
+  final String walletName;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(20),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Icon(Icons.call_received, color: theme.colorScheme.primary),
+            const SizedBox(width: 12),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    'Receive bitcoin',
+                    style: theme.textTheme.titleMedium?.copyWith(
+                      fontWeight: FontWeight.w600,
+                    ),
+                  ),
+                  const SizedBox(height: 6),
+                  Text(
+                    'Generate an address for $walletName and share it with the sender.',
+                    style: theme.textTheme.bodyMedium,
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _ReceiveAddressCard extends ConsumerWidget {
+  const _ReceiveAddressCard({required this.state});
+
+  final ReceiveAddressState state;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final theme = Theme.of(context);
+    final address = state.address;
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(20),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            if (state.isGenerating)
+              const WalletStateCard(
+                icon: Icons.qr_code_2,
+                title: 'Generating address',
+                message: 'Revealing and saving the next receive address...',
+                showSpinner: true,
+              )
+            else if (address != null) ...[
+              _GeneratedAddressDetails(address: address, index: state.index),
+              if (state.errorMessage != null) ...[
+                const SizedBox(height: 16),
+                WalletStateCard(
+                  icon: Icons.error_outline,
+                  title: 'Could not generate new address',
+                  message: state.errorMessage!,
+                  accentColor: theme.colorScheme.error,
+                ),
+              ],
+            ] else if (state.errorMessage != null)
+              WalletStateCard(
+                icon: Icons.error_outline,
+                title: 'Could not generate address',
+                message: state.errorMessage!,
+                accentColor: theme.colorScheme.error,
+              )
+            else if (address == null)
+              const WalletStateCard(
+                icon: Icons.qr_code_2,
+                title: 'No receive address yet',
+                message:
+                    'Generate a new address when you are ready to receive funds.',
+              )
+            else
+              const SizedBox.shrink(),
+            const SizedBox(height: 20),
+            FilledButton.icon(
+              onPressed: state.isGenerating
+                  ? null
+                  : () => ref
+                        .read(currentReceiveAddressProvider.notifier)
+                        .generateForActiveWallet(),
+              icon: state.isGenerating
+                  ? const SizedBox(
+                      width: 18,
+                      height: 18,
+                      child: CircularProgressIndicator(strokeWidth: 2),
+                    )
+                  : const Icon(Icons.add),
+              label: const Text('Generate New Address'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _GeneratedAddressDetails extends StatelessWidget {
+  const _GeneratedAddressDetails({required this.address, required this.index});
+
+  final String address;
+  final int? index;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final formattedAddress = Formatters.formatAddress(address);
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.stretch,
+      children: [
+        Text(
+          'Current receive address',
+          style: theme.textTheme.titleMedium?.copyWith(
+            fontWeight: FontWeight.w600,
+          ),
+        ),
+        const SizedBox(height: 16),
+        Center(
+          child: Container(
+            padding: const EdgeInsets.all(16),
+            decoration: BoxDecoration(
+              color: Colors.white,
+              borderRadius: BorderRadius.circular(16),
+            ),
+            child: SizedBox(
+              width: 220,
+              height: 220,
+              child: PrettyQrView.data(data: address),
+            ),
+          ),
+        ),
+        const SizedBox(height: 16),
+        Text(
+          formattedAddress,
+          textAlign: TextAlign.center,
+          style: AppTheme.monoStyle.copyWith(
+            fontSize: 13,
+            color: theme.colorScheme.onSurface,
+            height: 1.5,
+          ),
+        ),
+        const SizedBox(height: 12),
+        Text(
+          index == null ? 'Address index unavailable' : 'Address index #$index',
+          textAlign: TextAlign.center,
+          style: theme.textTheme.labelLarge?.copyWith(
+            color: theme.colorScheme.onSurface.withAlpha(170),
+          ),
+        ),
+        const SizedBox(height: 20),
+        NeutralButton(
+          label: 'Copy Address',
+          icon: Icons.copy,
+          onPressed: () => ClipboardUtil.copyAndNotify(
+            context,
+            address,
+            message: 'Address copied',
+          ),
+        ),
+      ],
+    );
+  }
+}