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/restore-commit-message/cli.ts

@@ -0,0 +1,51 @@
+/**
+ * @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 {Arguments, Argv, CommandModule} from 'yargs';
+
+import {CommitMsgSource} from '../commit-message-source';
+
+import {restoreCommitMessage} from './restore-commit-message';
+
+export interface RestoreCommitMessageOptions {
+  fileEnvVariable: string[];
+}
+
+/** Builds the command. */
+function builder(yargs: Argv) {
+  return yargs.option('file-env-variable' as 'fileEnvVariable', {
+    type: 'string',
+    array: true,
+    demandOption: true,
+    description: 'The key for the environment variable which holds the arguments for the\n' +
+        'prepare-commit-msg hook as described here:\n' +
+        'https://git-scm.com/docs/githooks#_prepare_commit_msg',
+    coerce: arg => {
+      const [file, source] = (process.env[arg] || '').split(' ');
+      if (!file) {
+        throw new Error(`Provided environment variable "${arg}" was not found.`);
+      }
+      return [file, source];
+    },
+  });
+}
+
+/** Handles the command. */
+async function handler({fileEnvVariable}: Arguments<RestoreCommitMessageOptions>) {
+  restoreCommitMessage(fileEnvVariable[0], fileEnvVariable[1] as CommitMsgSource);
+}
+
+/** yargs command module describing the command.  */
+export const RestoreCommitMessageModule: CommandModule<{}, RestoreCommitMessageOptions> = {
+  handler,
+  builder,
+  command: 'restore-commit-message-draft',
+  // Description: Restore a commit message draft if one has been saved from a failed commit attempt.
+  // No describe is defiend to hide the command from the --help.
+  describe: false,
+};

dev-infra/commit-message/restore-commit-message/restore-commit-message.ts

@@ -0,0 +1,49 @@
+/**
+ * @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 {writeFileSync} from 'fs';
+
+import {debug, log} from '../../utils/console';
+
+import {loadCommitMessageDraft} from '../commit-message-draft';
+import {CommitMsgSource} from '../commit-message-source';
+
+/**
+ * Restore the commit message draft to the git to be used as the default commit message.
+ *
+ * The source provided may be one of the sources described in
+ *   https://git-scm.com/docs/githooks#_prepare_commit_msg
+ */
+export function restoreCommitMessage(filePath: string, source?: CommitMsgSource) {
+  if (!!source) {
+    log('Skipping commit message restoration attempt');
+    if (source === 'message') {
+      debug('A commit message was already provided via the command with a -m or -F flag');
+    }
+    if (source === 'template') {
+      debug('A commit message was already provided via the -t flag or config.template setting');
+    }
+    if (source === 'squash') {
+      debug('A commit message was already provided as a merge action or via .git/MERGE_MSG');
+    }
+    if (source === 'commit') {
+      debug('A commit message was already provided through a revision specified via --fixup, -c,');
+      debug('-C or --amend flag');
+    }
+    process.exit(0);
+  }
+  /** A draft of a commit message. */
+  const commitMessage = loadCommitMessageDraft(filePath);
+
+  // If the commit message draft has content, restore it into the provided filepath.
+  if (commitMessage) {
+    writeFileSync(filePath, commitMessage);
+  }
+  // Exit the process
+  process.exit(0);
+}