bitwindow: bid for FreeBank blocks

bitwindow/lib/dialogs/freebank_bid_dialog.dart

@@ -0,0 +1,165 @@
+import 'dart:io';
+
+import 'package:bitwindow/utils/freebank_conf.dart';
+import 'package:flutter/material.dart';
+import 'package:get_it/get_it.dart';
+import 'package:logger/logger.dart';
+import 'package:sail_ui/pages/sidechains/bmm_tab.dart';
+import 'package:sail_ui/sail_ui.dart';
+
+// The BMM tab scrolls on its own, so the dialog gives it a fixed slot.
+const _bmmTabHeight = 420.0;
+
+// The tab's control row holds two buttons and three fields, with a 44 px gap
+// between them, and it does not wrap. Below this width Flutter clips the
+// max-bid field and the manual-bid button.
+const _bmmTabWidth = 1160.0;
+
+/// Bidding for FreeBank blocks from BitWindow: the name the node writes into the
+/// blocks it wins, then the BMM engine's own controls. FreeBank has no app of its
+/// own, so BitWindow is where a user starts it.
+class FreeBankBidDialog extends StatefulWidget {
+  const FreeBankBidDialog({super.key});
+
+  @override
+  State<FreeBankBidDialog> createState() => _FreeBankBidDialogState();
+}
+
+class _FreeBankBidDialogState extends State<FreeBankBidDialog> {
+  final FreeBankRPC _rpc = GetIt.I.get<FreeBankRPC>();
+  final TextEditingController _name = TextEditingController();
+  String? _saved;
+  String? _error;
+  bool _saving = false;
+
+  bool get _hasName => _saved != null && _saved!.isNotEmpty;
+
+  File get _conf => File(filePath([_rpc.binary.datadirNetwork(), 'freebank.conf']));
+
+  @override
+  void initState() {
+    super.initState();
+    _load();
+  }
+
+  Future<void> _load() async {
+    try {
+      final conf = await _conf.exists() ? await _conf.readAsString() : '';
+      final tag = readCoinbaseTag(conf);
+      if (!mounted) {
+        return;
+      }
+      setState(() {
+        _saved = tag;
+        // A name is required before the first bid, so offer one to change.
+        _name.text = (tag == null || tag.isEmpty) ? suggestCoinbaseTag() : tag;
+      });
+    } catch (e) {
+      GetIt.I.get<Logger>().w('FreeBank: could not read freebank.conf: $e');
+      if (!mounted) {
+        return;
+      }
+      setState(() => _error = 'Could not read the name: $e');
+    }
+  }
+
+  Future<void> _save() async {
+    final problem = coinbaseTagProblem(_name.text);
+    if (problem != null) {
+      setState(() => _error = problem);
+      return;
+    }
+    setState(() {
+      _error = null;
+      _saving = true;
+    });
+    try {
+      final conf = await _conf.exists() ? await _conf.readAsString() : '';
+      await _conf.parent.create(recursive: true);
+      await _conf.writeAsString(setCoinbaseTag(conf, _name.text));
+      // freebankd reads the name at startup only.
+      await GetIt.I.get<BinaryProvider>().restart(_rpc.binary);
+      if (!mounted) {
+        return;
+      }
+      setState(() => _saved = _name.text.trim());
+    } catch (e) {
+      if (!mounted) {
+        return;
+      }
+      setState(() => _error = 'Could not save the name: $e');
+    } finally {
+      if (mounted) {
+        setState(() => _saving = false);
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    _name.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return SailDialog(
+      title: 'Bid for FreeBank blocks',
+      subtitle:
+          'For each eCash block, your node offers a small fee to have its next FreeBank block included. '
+          'A bid is paid from your BitWindow wallet, and only when it wins.',
+      error: _error,
+      maxWidth: _bmmTabWidth + 80,
+      maxHeight: 720,
+      withCloseButton: true,
+      child: SailColumn(
+        spacing: SailStyleValues.padding16,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          SailText.primary13('Name on your blocks', bold: true),
+          SailRow(
+            spacing: SailStyleValues.padding08,
+            children: [
+              Expanded(
+                child: SailTextField(
+                  controller: _name,
+                  hintText: "Your name, or your pool's name",
+                  enabled: !_saving,
+                ),
+              ),
+              SailButton(
+                label: 'Save',
+                loading: _saving,
+                onPressed: _save,
+              ),
+            ],
+          ),
+          SailText.secondary12(
+            _hasName
+                ? 'Blocks you win show "$_saved" on the explorer. Saving a new name restarts your FreeBank node.'
+                : 'Blocks you win show this name on the explorer. Change it if you like, then save. '
+                      'Saving restarts your FreeBank node.',
+          ),
+          SizedBox(
+            height: _bmmTabHeight,
+            child: SingleChildScrollView(
+              scrollDirection: Axis.horizontal,
+              child: SizedBox(
+                width: _bmmTabWidth,
+                // Every block a bid wins carries the name, so bidding waits for one.
+                child: _hasName
+                    ? const BMMTab()
+                    : Stack(
+                        children: [
+                          const IgnorePointer(child: Opacity(opacity: 0.35, child: BMMTab())),
+                          Center(child: SailText.primary15('Save a name above to start bidding.')),
+                        ],
+                      ),
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}

bitwindow/lib/main.dart

@@ -233,6 +233,9 @@ Future<(Directory, File, Logger)> init(String arguments) async {
   GetIt.I.registerSingleton<PhotonRPC>(PhotonLive());
   GetIt.I.registerSingleton<TruthcoinRPC>(TruthcoinLive());
   GetIt.I.registerSingleton<FreeBankRPC>(FreeBankLive());
+  // FreeBank has no app of its own, so its BMM controls live in BitWindow. Lazy:
+  // the provider only starts watching the engine once the bid dialog opens.
+  GetIt.I.registerLazySingleton<BMMProvider>(() => BMMProvider(sidechainRPC: GetIt.I.get<FreeBankRPC>()));
 
   registerNodeMode();
 

bitwindow/lib/pages/sidechains_page.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:math';
 
 import 'package:auto_route/auto_route.dart';
+import 'package:bitwindow/dialogs/freebank_bid_dialog.dart';
 import 'package:bitwindow/log_window.dart';
 import 'package:bitwindow/utils/deposit_fee.dart';
 import 'package:bitwindow/pages/explorer/block_explorer_dialog.dart';
@@ -615,6 +616,23 @@ class _SidechainActions extends StatelessWidget {
           ],
           _depositButton(context),
           const SizedBox(width: SailStyleValues.padding08),
+          if (viewModel.sidechainForSlot(slot) is FreeBank && settingsConnection != null) ...[
+            SizedBox.square(
+              dimension: 32,
+              child: SailTooltip(
+                message: 'Bid for FreeBank blocks',
+                child: SailButton(
+                  variant: ButtonVariant.icon,
+                  icon: SailSVGAsset.iconTabBmm,
+                  small: true,
+                  onPressed: () async {
+                    await showThemedDialog(context: context, builder: (context) => const FreeBankBidDialog());
+                  },
+                ),
+              ),
+            ),
+            const SizedBox(width: SailStyleValues.padding08),
+          ],
           SizedBox.square(
             dimension: 32,
             child: settingsConnection == null

bitwindow/lib/utils/freebank_conf.dart

@@ -0,0 +1,131 @@
+/// The one line of freebank.conf that BitWindow edits: `coinbasetag=`, the name
+/// a FreeBank node writes into the coinbase of every block it makes, so block
+/// explorers can credit the block to it. freebankd reads it at startup only.
+library;
+
+import 'dart:math';
+
+const coinbaseTagKey = 'coinbasetag';
+const coinbaseTagMaxBytes = 64;
+
+/// A Core-style network header, for example `[regtest]`. Every line after one
+/// belongs to that network only.
+final _sectionHeader = RegExp(r'^\[[^\]]*\]$');
+
+/// The network section freebankd reads. BitWindow starts the node with no chain
+/// flag, so it runs its default main chain.
+const activeNetworkSection = 'main';
+
+/// The name the node takes, or null when the conf sets none. A `[main]` entry
+/// beats the global part, and any other network section counts for nothing. The
+/// last line of a scope wins, as in Core.
+String? readCoinbaseTag(String conf) {
+  String? global;
+  String? active;
+  String? section;
+  for (final line in conf.split('\n')) {
+    final trimmed = line.trim();
+    if (_sectionHeader.hasMatch(trimmed)) {
+      section = trimmed.substring(1, trimmed.length - 1);
+      continue;
+    }
+    if (!trimmed.startsWith('$coinbaseTagKey=')) {
+      continue;
+    }
+    final value = trimmed.substring(coinbaseTagKey.length + 1).trim();
+    if (section == null) {
+      global = value;
+    } else if (section == activeNetworkSection) {
+      active = value;
+    }
+  }
+  return active ?? global;
+}
+
+/// Why freebankd would refuse this name, or null if it takes it. It mirrors the
+/// node's own check (1 to 64 printable ASCII bytes), plus the two things the conf
+/// file itself would bend: a `#` starts a comment, and quotes become part of the
+/// name.
+String? coinbaseTagProblem(String name) {
+  final tag = name.trim();
+  if (tag.isEmpty) {
+    return 'Give a name.';
+  }
+  if (tag.length > coinbaseTagMaxBytes) {
+    return 'Use at most $coinbaseTagMaxBytes characters.';
+  }
+  for (final unit in tag.codeUnits) {
+    if (unit < 0x20 || unit > 0x7e) {
+      return 'Use plain letters, digits, punctuation and spaces.';
+    }
+  }
+  if (tag.contains('#')) {
+    return 'Leave out #: it starts a comment in freebank.conf.';
+  }
+  if (tag.startsWith('"') || tag.startsWith("'") || tag.endsWith('"') || tag.endsWith("'")) {
+    return 'Leave out the quotes: they would become part of the name.';
+  }
+  return null;
+}
+
+/// The conf with the name the node takes set to [name]. A `[main]` entry beats
+/// the global part, so the change goes there when one exists. Otherwise the line
+/// goes in the global part, before the first network header. Every other line
+/// stays as it was.
+String setCoinbaseTag(String conf, String name) {
+  final line = '$coinbaseTagKey=${name.trim()}';
+  final lines = conf.isEmpty ? <String>[] : conf.split('\n');
+  final target = _tagInActiveSection(lines) ? activeNetworkSection : null;
+
+  final kept = <String>[];
+  var written = false;
+  String? section;
+  for (final l in lines) {
+    final trimmed = l.trim();
+    if (_sectionHeader.hasMatch(trimmed)) {
+      if (!written && target == null) {
+        kept.add(line);
+        written = true;
+      }
+      section = trimmed.substring(1, trimmed.length - 1);
+    } else if (section == target && trimmed.startsWith('$coinbaseTagKey=')) {
+      if (!written) {
+        kept.add(line);
+        written = true;
+      }
+      continue;
+    }
+    kept.add(l);
+  }
+  if (!written) {
+    if (kept.isNotEmpty && kept.last.isEmpty) {
+      kept.insert(kept.length - 1, line);
+    } else {
+      kept.add(line);
+    }
+  }
+  final out = kept.join('\n');
+  return out.endsWith('\n') ? out : '$out\n';
+}
+
+bool _tagInActiveSection(List<String> lines) {
+  String? section;
+  for (final l in lines) {
+    final trimmed = l.trim();
+    if (_sectionHeader.hasMatch(trimmed)) {
+      section = trimmed.substring(1, trimmed.length - 1);
+    } else if (section == activeNetworkSection && trimmed.startsWith('$coinbaseTagKey=')) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/// A name to offer a user who has none yet: unique enough to spot their own
+/// blocks, it says where they came from, and it carries nothing personal.
+String suggestCoinbaseTag([Random? random]) {
+  const letters = 'abcdefghjkmnpqrstuvwxyz23456789';
+  final rng = random ?? Random.secure();
+  final suffix = List.generate(4, (_) => letters[rng.nextInt(letters.length)]).join();
+  return 'bitwindow-$suffix';
+}