refactor(git): prepare support for commit signing with other key formats

lib/util/git/private-key.ts

@@ -8,56 +8,69 @@ import { exec } from '../exec';
 import { newlineRegex } from '../regex';
 import { addSecretForSanitizing } from '../sanitize';
 
-let gitPrivateKey: string | undefined;
-let keyId: string | undefined;
+let gitPrivateKey: PrivateKey | undefined;
 
-export function setPrivateKey(key: string | undefined): void {
-  if (!is.nonEmptyStringAndNotWhitespace(key)) {
-    return;
+abstract class PrivateKey {
+  protected readonly key: string;
+  protected keyId: string | undefined;
+
+  constructor(key: string) {
+    this.key = key.trim();
+    addSecretForSanitizing(this.key, 'global');
+    logger.debug(
+      'gitPrivateKey: successfully set (but not yet written/configured)',
+    );
+  }
+
+  async writeKey(): Promise<void> {
+    try {
+      if (!this.keyId) {
+        this.keyId = await this.importKey();
+      }
+      logger.debug('gitPrivateKey: imported');
+    } catch (err) {
+      logger.warn({ err }, 'gitPrivateKey: error importing');
+      throw new Error(PLATFORM_GPG_FAILED);
+    }
+  }
+
+  async configSigningKey(cwd: string): Promise<void> {
+    logger.debug('gitPrivateKey: configuring commit signing');
+    // TODO: types (#22198)
+    await exec(`git config user.signingkey ${this.keyId!}`, { cwd });
+    await exec(`git config commit.gpgsign true`, { cwd });
   }
-  addSecretForSanitizing(key.trim(), 'global');
-  logger.debug(
-    'gitPrivateKey: successfully set (but not yet written/configured)',
-  );
-  gitPrivateKey = key.trim();
+
+  protected abstract importKey(): Promise<string | undefined>;
 }
 
-async function importKey(): Promise<void> {
-  if (keyId) {
-    return;
+class GPGKey extends PrivateKey {
+  protected async importKey(): Promise<string | undefined> {
+    const keyFileName = upath.join(os.tmpdir() + '/git-private-gpg.key');
+    await fs.outputFile(keyFileName, this.key);
+    const { stdout, stderr } = await exec(`gpg --import ${keyFileName}`);
+    logger.debug({ stdout, stderr }, 'Private key import result');
+    await fs.remove(keyFileName);
+    return `${stdout}${stderr}`
+      .split(newlineRegex)
+      .find((line) => line.includes('secret key imported'))
+      ?.replace('gpg: key ', '')
+      .split(':')
+      .shift();
   }
-  const keyFileName = upath.join(os.tmpdir() + '/git-private.key');
-  await fs.outputFile(keyFileName, gitPrivateKey!);
-  const { stdout, stderr } = await exec(`gpg --import ${keyFileName}`);
-  logger.debug({ stdout, stderr }, 'Private key import result');
-  keyId = `${stdout}${stderr}`
-    .split(newlineRegex)
-    .find((line) => line.includes('secret key imported'))
-    ?.replace('gpg: key ', '')
-    .split(':')
-    .shift();
-  await fs.remove(keyFileName);
 }
 
-export async function writePrivateKey(): Promise<void> {
-  if (!gitPrivateKey) {
+export function setPrivateKey(key: string | undefined): void {
+  if (!is.nonEmptyStringAndNotWhitespace(key)) {
     return;
   }
-  try {
-    await importKey();
-    logger.debug('gitPrivateKey: imported');
-  } catch (err) {
-    logger.warn({ err }, 'gitPrivateKey: error importing');
-    throw new Error(PLATFORM_GPG_FAILED);
-  }
+  gitPrivateKey = new GPGKey(key);
+}
+
+export async function writePrivateKey(): Promise<void> {
+  await gitPrivateKey?.writeKey();
 }
 
 export async function configSigningKey(cwd: string): Promise<void> {
-  if (!gitPrivateKey) {
-    return;
-  }
-  logger.debug('gitPrivateKey: configuring commit signing');
-  // TODO: types (#22198)
-  await exec(`git config user.signingkey ${keyId!}`, { cwd });
-  await exec(`git config commit.gpgsign true`, { cwd });
+  await gitPrivateKey?.configSigningKey(cwd);
 }