Codelab rebuild to markdown

tooling/codelab_rebuild/bin/codelab_rebuild.dart

@@ -21,5 +21,7 @@ void main(List<String> arguments) {
 
   final source = arguments.single;
   final blueprint = Blueprint.load(File(source));
-  blueprint.rebuild(File(source).parent);
+  var basedir = File(source).parent;
+  blueprint.rebuild(basedir);
+  blueprint.regenerateCodelabRebuildMd(basedir);
 }

tooling/codelab_rebuild/lib/src/blueprint.dart

@@ -9,19 +9,29 @@ import 'package:json_annotation/json_annotation.dart';
 import 'package:logging/logging.dart';
 
 import 'rebuild_blueprint.dart';
+import 'regenerate_codelab_rebuild_md.dart';
 
 part 'blueprint.g.dart';
 
 final _logger = Logger('blueprint');
 
 @JsonSerializable(anyMap: true, checked: true, disallowUnrecognizedKeys: true)
 class Blueprint {
+  /// The name of the codelab.
   @JsonKey(required: true)
   final String name;
+
+  @JsonKey(name: 'generate-markdown')
+  final bool generateMarkdown;
+
   @JsonKey(required: true)
   final List<BlueprintStep> steps;
 
-  Blueprint({required this.name, required this.steps}) {
+  Blueprint({
+    required this.name,
+    required this.steps,
+    this.generateMarkdown = false,
+  }) {
     if (name.isEmpty) {
       throw ArgumentError.value(name, 'name', 'Cannot be empty.');
     }
@@ -64,6 +74,10 @@ class Blueprint {
   /// Rebuild a blueprint in a target directory.
   Future<void> rebuild(Directory cwd) => rebuildFromBlueprint(cwd, this);
 
+  /// Regenerate the `codelab_rebuild.md` from the blueprint.
+  Future<void> regenerateCodelabRebuildMd(Directory cwd) =>
+      regenerateCodelabRebuildMdFromBlueprint(cwd, this);
+
   Map<String, dynamic> toJson() => _$BlueprintToJson(this);
 
   @override
@@ -76,6 +90,11 @@ class BlueprintStep {
   final String name;
   final List<BlueprintStep> steps;
 
+  @JsonKey(name: 'markdown-content')
+  final String? markdownContent;
+  @JsonKey(name: 'markdown-ignore')
+  final bool markdownIgnore;
+
   final String? path;
 
   @JsonKey(name: 'base64-contents')
@@ -175,6 +194,8 @@ class BlueprintStep {
     this.iphoneosDeploymentTarget,
     this.macosxDeploymentTarget,
     this.protoc,
+    this.markdownContent,
+    this.markdownIgnore = false,
   }) {
     if (name.isEmpty) {
       throw ArgumentError.value(name, 'name', 'Cannot be empty.');
@@ -190,6 +211,9 @@ class BlueprintStep {
     // Stop is for debugging only.
     if (stop != null && stop == true) return true;
 
+    // Markdown content is stand alone valid
+    if (markdownContent != null) return true;
+
     // If there aren't sub-steps, then there should be something else to do.
     if (steps.isEmpty &&
         patch == null &&

tooling/codelab_rebuild/lib/src/rebuild_blueprint.dart

@@ -37,6 +37,11 @@ Future<void> _buildBlueprintStep(Directory cwd, BlueprintStep step) async {
     exit(0);
   }
 
+  final markdownContent = step.markdownContent;
+  if (markdownContent != null) {
+    return;
+  }
+
   final platforms = step.platforms;
   if (platforms != null) {
     if (!platforms.contains(Platform.operatingSystem)) {

tooling/codelab_rebuild/lib/src/regenerate_codelab_rebuild_md.dart

@@ -0,0 +1,63 @@
+import 'dart:io';
+
+import 'package:path/path.dart' as path;
+
+import 'blueprint.dart';
+
+Future<void> regenerateCodelabRebuildMdFromBlueprint(
+  Directory cwd,
+  Blueprint blueprint,
+) async {
+  if (blueprint.generateMarkdown != true) return;
+
+  final buff = StringBuffer();
+
+  buff.writeln('# ${blueprint.name}');
+  buff.writeln();
+
+  for (final step in blueprint.steps) {
+    _handleStep(step, buff, 2);
+  }
+
+  await File(
+    path.join(cwd.path, 'codelab_rebuild.md'),
+  ).writeAsString(buff.toString(), flush: true);
+}
+
+void _handleStep(BlueprintStep step, StringBuffer buff, int depth) {
+  // Skip certain steps
+  if (step.rmdir != null || step.stripLinesContaining != null) return;
+
+  buff.writeln('${'#' * depth} ${step.name}');
+
+  if (step.steps.length > 1) {
+    for (final subStep in step.steps) {
+      _handleStep(subStep, buff, depth + 1);
+    }
+    return;
+  }
+
+  final flutter = step.flutter;
+  if (flutter != null) {
+    buff.write('''
+Run the following Flutter command:
+
+```console
+\$ flutter $flutter
+```
+      ''');
+    return;
+  }
+
+  final dart = step.dart;
+  if (dart != null) {
+    buff.write('''
+Run the following Dart command:
+
+```console
+\$ dart $dart
+```
+      ''');
+    return;
+  }
+}