refactor(dev-infra): refactor commit-message files (#38845)

Refactor the commit-message files to be consistent with how other ng-dev tooling
is structured.

PR Close #38845

dev-infra/commit-message/validate-file/validate-file.ts

@@ -0,0 +1,47 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {readFileSync} from 'fs';
+import {resolve} from 'path';
+
+import {getRepoBaseDir} from '../../utils/config';
+import {error, green, info, log, red, yellow} from '../../utils/console';
+
+import {deleteCommitMessageDraft, saveCommitMessageDraft} from '../commit-message-draft';
+import {printValidationErrors, validateCommitMessage} from '../validate';
+
+/** Validate commit message at the provided file path. */
+export function validateFile(filePath: string, isErrorMode: boolean) {
+  const commitMessage = readFileSync(resolve(getRepoBaseDir(), filePath), 'utf8');
+  const {valid, errors} = validateCommitMessage(commitMessage);
+  if (valid) {
+    info(`${green('√')}  Valid commit message`);
+    deleteCommitMessageDraft(filePath);
+    process.exitCode = 0;
+    return;
+  }
+
+  /** Function used to print to the console log. */
+  let printFn = isErrorMode ? error : log;
+
+  printFn(`${isErrorMode ? red('✘') : yellow('!')}  Invalid commit message`);
+  printValidationErrors(errors, printFn);
+  if (isErrorMode) {
+    printFn(red('Aborting commit attempt due to invalid commit message.'));
+    printFn(
+        red('Commit message aborted as failure rather than warning due to local configuration.'));
+  } else {
+    printFn(yellow('Before this commit can be merged into the upstream repository, it must be'));
+    printFn(yellow('amended to follow commit message guidelines.'));
+  }
+
+  // On all invalid commit messages, the commit message should be saved as a draft to be
+  // restored on the next commit attempt.
+  saveCommitMessageDraft(filePath, commitMessage);
+  // Set the correct exit code based on if invalid commit message is an error.
+  process.exitCode = isErrorMode ? 1 : 0;
+}