Make file suffixes configurable for HTML document discovery

[ascheman]

Background

Currently, file suffix handling is inconsistent across the project:

• Gradle plugin: only searches for .html files
• Maven plugin: searches for .html and .htm files
• CLI: searches for .html and .htm files (configurable via --suffix option)

The logic for discovering source documents is duplicated in each plugin/CLI implementation.

Proposed Enhancement

Make file suffixes a core configuration feature with centralized document discovery logic in AllChecksRunner.

Requirements

1. Core Configuration: Add a suffixes attribute to Configuration

   • Type: Set<String>
   • Default: ["html", "htm"]
   • Represents file extensions to search for (without the dot)

2. Document Discovery in AllChecksRunner:

   • During AllChecksRunner initialization (constructor or performAllChecks())
   • If sourceDocuments is null or empty AND sourceDir is set:
     • Recursively scan sourceDir for files matching configured suffixes
     • Auto-populate the effective source documents for checking
   • If sourceDocuments is explicitly provided: use as-is (no auto-discovery)

3. Plugin/CLI Updates:

   • Gradle plugin: Remove local file scanning (setSourceDir() logic), delegate to core
   • Maven plugin: Remove findHtmlFiles() method, delegate to core
   • CLI: Continue to support --suffix option, pass to core Configuration.suffixes

Implementation Details

Location: Document discovery logic in AllChecksRunner class

• Keeps Configuration as a pure data holder
• Runner already orchestrates the checking process
• Natural place for auto-discovery before checks begin
• Example approach:

  public class AllChecksRunner {
      private Set<File> effectiveSourceDocuments;
      
      public AllChecksRunner(Configuration config) {
          this.effectiveSourceDocuments = config.getSourceDocuments();
          
          if ((effectiveSourceDocuments == null || effectiveSourceDocuments.isEmpty()) 
              && config.getSourceDir() != null) {
              this.effectiveSourceDocuments = discoverSourceDocuments(
                  config.getSourceDir(), 
                  config.getSuffixes()
              );
          }
      }
      
      private Set<File> discoverSourceDocuments(File sourceDir, Set<String> suffixes) {
          // Recursive file scanning logic here
      }
  }

Benefits

• ✅ Consistent behavior across all interfaces (CLI, Maven, Gradle)
• ✅ Single source of truth for file discovery logic
• ✅ User-configurable suffixes (e.g., for .xhtml, .htm5)
• ✅ Reduced code duplication
• ✅ Easier to test and maintain
• ✅ Clean separation: Configuration = data, AllChecksRunner = execution logic

Migration Path

1. Add suffixes to Configuration with default ["html", "htm"]
2. Implement discovery logic in AllChecksRunner
3. Update plugins/CLI to remove local scanning and rely on core
4. Deprecate plugin-specific file discovery mechanisms
5. Update documentation