feat(quality-rails): migrate @mosaic/quality-rails from v0 to v1 (#100)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/quality-rails/src/scaffolder.ts

@@ -0,0 +1,206 @@
+import { spawn } from 'node:child_process';
+import { chmod, mkdir, readFile, writeFile } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+
+import {
+  biomeTemplate,
+  eslintTemplate,
+  prChecklistTemplate,
+  preCommitHookTemplate,
+  pyprojectSection,
+  rustfmtTemplate,
+} from './templates.js';
+import type { RailsConfig, ScaffoldResult } from './types.js';
+
+const PYPROJECT_START_MARKER = '# >>> mosaic-quality-rails >>>';
+const PYPROJECT_END_MARKER = '# <<< mosaic-quality-rails <<<';
+
+async function ensureDirectory(filePath: string): Promise<void> {
+  await mkdir(dirname(filePath), { recursive: true });
+}
+
+async function writeRelativeFile(
+  projectPath: string,
+  relativePath: string,
+  contents: string,
+  result: ScaffoldResult,
+): Promise<void> {
+  const absolutePath = join(projectPath, relativePath);
+  await ensureDirectory(absolutePath);
+  await writeFile(absolutePath, contents, { encoding: 'utf8', mode: 0o644 });
+  result.filesWritten.push(relativePath);
+}
+
+async function upsertPyproject(
+  projectPath: string,
+  profile: RailsConfig['profile'],
+  result: ScaffoldResult,
+): Promise<void> {
+  const pyprojectPath = join(projectPath, 'pyproject.toml');
+  const nextSection = pyprojectSection(profile);
+
+  let previous = '';
+  try {
+    previous = await readFile(pyprojectPath, 'utf8');
+  } catch {
+    previous = '';
+  }
+
+  const existingStart = previous.indexOf(PYPROJECT_START_MARKER);
+  const existingEnd = previous.indexOf(PYPROJECT_END_MARKER);
+
+  if (existingStart >= 0 && existingEnd > existingStart) {
+    const before = previous.slice(0, existingStart).trimEnd();
+    const after = previous.slice(existingEnd + PYPROJECT_END_MARKER.length).trimStart();
+    const rebuilt = [before, nextSection.trim(), after]
+      .filter((segment) => segment.length > 0)
+      .join('\n\n');
+    await writeRelativeFile(projectPath, 'pyproject.toml', `${rebuilt}\n`, result);
+    return;
+  }
+
+  const separator = previous.trim().length > 0 ? '\n\n' : '';
+  await writeRelativeFile(
+    projectPath,
+    'pyproject.toml',
+    `${previous.trimEnd()}${separator}${nextSection}`,
+    result,
+  );
+}
+
+function runCommand(command: string, args: string[], cwd: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(command, args, {
+      cwd,
+      stdio: 'ignore',
+      env: process.env,
+    });
+
+    child.on('error', reject);
+    child.on('exit', (code) => {
+      if (code === 0) {
+        resolve();
+        return;
+      }
+      reject(new Error(`Command failed (${code ?? 'unknown'}): ${command} ${args.join(' ')}`));
+    });
+  });
+}
+
+function buildNodeDevDependencies(config: RailsConfig): string[] {
+  const dependencies = new Set<string>();
+
+  if (config.linters.some((linter) => linter.toLowerCase() === 'eslint')) {
+    dependencies.add('eslint');
+    dependencies.add('@typescript-eslint/parser');
+    dependencies.add('@typescript-eslint/eslint-plugin');
+  }
+
+  if (config.linters.some((linter) => linter.toLowerCase() === 'biome')) {
+    dependencies.add('@biomejs/biome');
+  }
+
+  if (config.formatters.some((formatter) => formatter.toLowerCase() === 'prettier')) {
+    dependencies.add('prettier');
+  }
+
+  if (config.hooks) {
+    dependencies.add('husky');
+  }
+
+  return [...dependencies];
+}
+
+async function installNodeDependencies(config: RailsConfig, result: ScaffoldResult): Promise<void> {
+  const dependencies = buildNodeDevDependencies(config);
+  if (dependencies.length === 0) {
+    return;
+  }
+
+  const commandLine = `pnpm add -D ${dependencies.join(' ')}`;
+
+  if (process.env['MOSAIC_QUALITY_RAILS_SKIP_INSTALL'] === '1') {
+    result.commandsToRun.push(commandLine);
+    return;
+  }
+
+  try {
+    await runCommand('pnpm', ['add', '-D', ...dependencies], config.projectPath);
+  } catch (error) {
+    result.warnings.push(
+      `Failed to auto-install Node dependencies: ${error instanceof Error ? error.message : String(error)}`,
+    );
+    result.commandsToRun.push(commandLine);
+  }
+}
+
+export async function scaffoldQualityRails(config: RailsConfig): Promise<ScaffoldResult> {
+  const result: ScaffoldResult = {
+    filesWritten: [],
+    commandsToRun: [],
+    warnings: [],
+  };
+
+  const normalizedLinters = new Set(config.linters.map((linter) => linter.toLowerCase()));
+
+  if (config.kind === 'node') {
+    if (normalizedLinters.has('eslint')) {
+      await writeRelativeFile(
+        config.projectPath,
+        '.eslintrc',
+        eslintTemplate(config.profile),
+        result,
+      );
+    }
+
+    if (normalizedLinters.has('biome')) {
+      await writeRelativeFile(
+        config.projectPath,
+        'biome.json',
+        biomeTemplate(config.profile),
+        result,
+      );
+    }
+
+    await installNodeDependencies(config, result);
+  }
+
+  if (config.kind === 'python') {
+    await upsertPyproject(config.projectPath, config.profile, result);
+  }
+
+  if (config.kind === 'rust') {
+    await writeRelativeFile(
+      config.projectPath,
+      'rustfmt.toml',
+      rustfmtTemplate(config.profile),
+      result,
+    );
+  }
+
+  if (config.hooks) {
+    await writeRelativeFile(
+      config.projectPath,
+      '.githooks/pre-commit',
+      preCommitHookTemplate(config),
+      result,
+    );
+    await chmod(join(config.projectPath, '.githooks/pre-commit'), 0o755);
+    result.commandsToRun.push('git config core.hooksPath .githooks');
+  }
+
+  await writeRelativeFile(
+    config.projectPath,
+    'PR-CHECKLIST.md',
+    prChecklistTemplate(config.profile),
+    result,
+  );
+
+  if (config.kind === 'unknown') {
+    result.warnings.push(
+      'Unable to detect project kind. Generated generic rails only (hooks + PR checklist).',
+    );
+  }
+
+  return result;
+}