add lint and quick-fixes for Money.amount.toString()

cw_custom_lints/lib/main.dart

@@ -3,6 +3,8 @@ import "package:analysis_server_plugin/registry.dart";
 import "package:cw_custom_lints/http_force_proxy/http_force_proxy_rule.dart";
 import "package:cw_custom_lints/modal_top_bar_semantics/modal_top_bar_semantics_rule.dart";
 import "package:cw_custom_lints/modern_button_semantics/modern_button_semantics_rule.dart";
+import "package:cw_custom_lints/money_amount_to_string/money_amount_to_string_fix.dart";
+import "package:cw_custom_lints/money_amount_to_string/money_amount_to_string_rule.dart";
 import "package:cw_custom_lints/print_verbose/print_verbose_fix.dart";
 import "package:cw_custom_lints/print_verbose/print_verbose_rule.dart";
 import "package:cw_custom_lints/restricted_imports/restricted_imports_rule.dart";
@@ -20,7 +22,13 @@ class CwCustomLintsPlugin extends Plugin {
     registry.registerWarningRule(HttpForceProxyRule());
     registry.registerWarningRule(ModernButtonSemanticsRule());
     registry.registerWarningRule(ModalTopBarSemanticsRule());
+    registry.registerWarningRule(MoneyAmountToStringRule());
 
     registry.registerFixForRule(PrintVerboseRule.code, ReplaceWithPrintV.new);
+    registry.registerFixForRule(MoneyAmountToStringRule.code, ReplaceWithMoneyToString.new);
+    registry.registerFixForRule(
+      MoneyAmountToStringRule.code,
+      ReplaceWithMoneyToStringInBaseUnit.new,
+    );
   }
 }

cw_custom_lints/lib/money_amount_to_string/money_amount_to_string_fix.dart

@@ -0,0 +1,66 @@
+import "package:analysis_server_plugin/edit/dart/correction_producer.dart";
+import "package:analysis_server_plugin/edit/dart/dart_fix_kind_priority.dart";
+import "package:analyzer/dart/ast/ast.dart";
+import "package:analyzer_plugin/utilities/change_builder/change_builder_core.dart";
+import "package:analyzer_plugin/utilities/fixes/fixes.dart";
+import "package:analyzer_plugin/utilities/range_factory.dart";
+import "package:cw_custom_lints/money_amount_to_string/money_amount_to_string_rule.dart";
+
+abstract class _ReplaceMoneyAmountToString extends ResolvedCorrectionProducer {
+  _ReplaceMoneyAmountToString({required super.context});
+
+  String get replacement;
+
+  @override
+  CorrectionApplicability get applicability => CorrectionApplicability.singleLocation;
+
+  @override
+  Future<void> compute(ChangeBuilder builder) async {
+    final invocation = node.thisOrAncestorOfType<MethodInvocation>();
+    if (invocation == null) {
+      return;
+    }
+
+    final amount = moneyAmountReference(invocation.realTarget);
+    if (amount == null) {
+      return;
+    }
+
+    await builder.addDartFileEdit(
+      file,
+      (builder) => builder.addSimpleReplacement(range.startEnd(amount, invocation), replacement),
+    );
+  }
+}
+
+class ReplaceWithMoneyToString extends _ReplaceMoneyAmountToString {
+  ReplaceWithMoneyToString({required super.context});
+
+  static const _fixKind = FixKind(
+    "dart.fix.replaceWithMoneyToString",
+    DartFixKindPriority.standard,
+    "Replace with toString() for a decimal amount",
+  );
+
+  @override
+  FixKind get fixKind => _fixKind;
+
+  @override
+  String get replacement => "toString()";
+}
+
+class ReplaceWithMoneyToStringInBaseUnit extends _ReplaceMoneyAmountToString {
+  ReplaceWithMoneyToStringInBaseUnit({required super.context});
+
+  static const _fixKind = FixKind(
+    "dart.fix.replaceWithMoneyToStringInBaseUnit",
+    DartFixKindPriority.standard,
+    "Replace with toStringWithPrecision(useBaseUnit: true) for base units",
+  );
+
+  @override
+  FixKind get fixKind => _fixKind;
+
+  @override
+  String get replacement => "toStringWithPrecision(useBaseUnit: true)";
+}

cw_custom_lints/lib/money_amount_to_string/money_amount_to_string_rule.dart

@@ -0,0 +1,85 @@
+import "package:analyzer/analysis_rule/analysis_rule.dart";
+import "package:analyzer/analysis_rule/rule_context.dart";
+import "package:analyzer/analysis_rule/rule_visitor_registry.dart";
+import "package:analyzer/dart/ast/ast.dart";
+import "package:analyzer/dart/ast/visitor.dart";
+import "package:analyzer/dart/element/element.dart";
+import "package:analyzer/error/error.dart";
+
+class MoneyAmountToStringRule extends AnalysisRule {
+  MoneyAmountToStringRule()
+      : super(
+          name: "no_money_amount_to_string",
+          description:
+              "Money.amount is the internal BigInt, so stringifying it drops the decimal point.",
+        );
+
+  static const LintCode code = LintCode(
+    "no_money_amount_to_string",
+    "This stringifies the internal BigInt of Money instead of the Money itself, so the decimal point is dropped and the amount reads far larger than it is.",
+    correctionMessage:
+        "Call toString() on the Money for a decimal amount, or toStringWithPrecision(useBaseUnit: true) for base units.",
+    severity: DiagnosticSeverity.WARNING,
+  );
+
+  @override
+  LintCode get diagnosticCode => code;
+
+  @override
+  void registerNodeProcessors(RuleVisitorRegistry registry, RuleContext context) =>
+      registry.addMethodInvocation(this, _Visitor(this));
+}
+
+
+SimpleIdentifier? moneyAmountReference(Expression? expression) {
+  final identifier = switch (expression) {
+    PrefixedIdentifier() => expression.identifier,
+    PropertyAccess() => expression.propertyName,
+    SimpleIdentifier() => expression,
+    _ => null,
+  };
+
+  if (identifier == null || identifier.name != "amount") {
+    return null;
+  }
+
+  return _isDeclaredByMoney(identifier.element) ? identifier : null;
+}
+
+bool _isDeclaredByMoney(Element? element) {
+  if (element == null) {
+    return false;
+  }
+
+  final enclosing = element.enclosingElement;
+  if (enclosing is! InterfaceElement || enclosing.name != "Money") {
+    return false;
+  }
+
+  final libraryUri = element.library?.uri;
+  if (libraryUri == null || libraryUri.scheme != "package") {
+    return false;
+  }
+
+  final segments = libraryUri.pathSegments;
+  return segments.isNotEmpty && segments.first == "cw_core";
+}
+
+class _Visitor extends SimpleAstVisitor<void> {
+  _Visitor(this.rule);
+
+  final AnalysisRule rule;
+
+  @override
+  void visitMethodInvocation(MethodInvocation node) {
+    if (node.methodName.name != "toString" || node.argumentList.arguments.isNotEmpty) {
+      return;
+    }
+
+    if (moneyAmountReference(node.realTarget) == null) {
+      return;
+    }
+
+    rule.reportAtNode(node);
+  }
+}