feat: modularize flattener tool into separate components with improved project root detection (#417)

tools/flattener/ignoreRules.js

@@ -0,0 +1,176 @@
+const fs = require("fs-extra");
+const path = require("node:path");
+const ignore = require("ignore");
+
+// Central default ignore patterns for discovery and filtering.
+// These complement .gitignore and are applied regardless of VCS presence.
+const DEFAULT_PATTERNS = [
+  // Project/VCS
+  "**/.bmad-core/**",
+  "**/.git/**",
+  "**/.svn/**",
+  "**/.hg/**",
+  "**/.bzr/**",
+  // Package/build outputs
+  "**/node_modules/**",
+  "**/bower_components/**",
+  "**/vendor/**",
+  "**/packages/**",
+  "**/build/**",
+  "**/dist/**",
+  "**/out/**",
+  "**/target/**",
+  "**/bin/**",
+  "**/obj/**",
+  "**/release/**",
+  "**/debug/**",
+  // Environments
+  "**/.venv/**",
+  "**/venv/**",
+  "**/.virtualenv/**",
+  "**/virtualenv/**",
+  "**/env/**",
+  // Logs & coverage
+  "**/*.log",
+  "**/npm-debug.log*",
+  "**/yarn-debug.log*",
+  "**/yarn-error.log*",
+  "**/lerna-debug.log*",
+  "**/coverage/**",
+  "**/.nyc_output/**",
+  "**/.coverage/**",
+  "**/test-results/**",
+  // Caches & temp
+  "**/.cache/**",
+  "**/.tmp/**",
+  "**/.temp/**",
+  "**/tmp/**",
+  "**/temp/**",
+  "**/.sass-cache/**",
+  // IDE/editor
+  "**/.vscode/**",
+  "**/.idea/**",
+  "**/*.swp",
+  "**/*.swo",
+  "**/*~",
+  "**/.project",
+  "**/.classpath",
+  "**/.settings/**",
+  "**/*.sublime-project",
+  "**/*.sublime-workspace",
+  // Lockfiles
+  "**/package-lock.json",
+  "**/yarn.lock",
+  "**/pnpm-lock.yaml",
+  "**/composer.lock",
+  "**/Pipfile.lock",
+  // Python/Java/compiled artifacts
+  "**/*.pyc",
+  "**/*.pyo",
+  "**/*.pyd",
+  "**/__pycache__/**",
+  "**/*.class",
+  "**/*.jar",
+  "**/*.war",
+  "**/*.ear",
+  "**/*.o",
+  "**/*.so",
+  "**/*.dll",
+  "**/*.exe",
+  // System junk
+  "**/lib64/**",
+  "**/.venv/lib64/**",
+  "**/venv/lib64/**",
+  "**/_site/**",
+  "**/.jekyll-cache/**",
+  "**/.jekyll-metadata",
+  "**/.DS_Store",
+  "**/.DS_Store?",
+  "**/._*",
+  "**/.Spotlight-V100/**",
+  "**/.Trashes/**",
+  "**/ehthumbs.db",
+  "**/Thumbs.db",
+  "**/desktop.ini",
+  // XML outputs
+  "**/flattened-codebase.xml",
+  "**/repomix-output.xml",
+  // Images, media, fonts, archives, docs, dylibs
+  "**/*.jpg",
+  "**/*.jpeg",
+  "**/*.png",
+  "**/*.gif",
+  "**/*.bmp",
+  "**/*.ico",
+  "**/*.svg",
+  "**/*.pdf",
+  "**/*.doc",
+  "**/*.docx",
+  "**/*.xls",
+  "**/*.xlsx",
+  "**/*.ppt",
+  "**/*.pptx",
+  "**/*.zip",
+  "**/*.tar",
+  "**/*.gz",
+  "**/*.rar",
+  "**/*.7z",
+  "**/*.dylib",
+  "**/*.mp3",
+  "**/*.mp4",
+  "**/*.avi",
+  "**/*.mov",
+  "**/*.wav",
+  "**/*.ttf",
+  "**/*.otf",
+  "**/*.woff",
+  "**/*.woff2",
+  // Env files
+  "**/.env",
+  "**/.env.*",
+  "**/*.env",
+  // Misc
+  "**/junit.xml",
+];
+
+async function readIgnoreFile(filePath) {
+  try {
+    if (!await fs.pathExists(filePath)) return [];
+    const content = await fs.readFile(filePath, "utf8");
+    return content
+      .split("\n")
+      .map((l) => l.trim())
+      .filter((l) => l && !l.startsWith("#"));
+  } catch (err) {
+    return [];
+  }
+}
+
+// Backward compatible export matching previous signature
+async function parseGitignore(gitignorePath) {
+  return readIgnoreFile(gitignorePath);
+}
+
+async function loadIgnore(rootDir, extraPatterns = []) {
+  const ig = ignore();
+  const gitignorePath = path.join(rootDir, ".gitignore");
+  const patterns = [
+    ...await readIgnoreFile(gitignorePath),
+    ...DEFAULT_PATTERNS,
+    ...extraPatterns,
+  ];
+  // De-duplicate
+  const unique = Array.from(new Set(patterns.map((p) => String(p))));
+  ig.add(unique);
+
+  // Include-only filter: return true if path should be included
+  const filter = (relativePath) => !ig.ignores(relativePath.replace(/\\/g, "/"));
+
+  return { ig, filter, patterns: unique };
+}
+
+module.exports = {
+  DEFAULT_PATTERNS,
+  parseGitignore,
+  loadIgnore,
+};