CIHelper: offer a convenient method to parse a PR comment URL

This will be used in the upcoming `handle-pr-comment` GitHub Action.

Note that the reason why this information needs to be passed to the
respective GitHub Action is that the corresponding GitHub workflows will
not run inside `gitgitgadget/git` and will therefore not automatically
receive the comment ID and PR number as part of the `github` context.
GitGitGadget's GitHub App will need to pass that information along when
receiving the webhook event that a PR comment has been created or
modified.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

lib/ci-helper.ts

@@ -152,6 +152,16 @@ export class CIHelper {
         await unshallow(this.workDir);
     }
 
+    public parsePRCommentURLInput(): { owner: string; repo: string; prNumber: number; commentId: number } {
+        const prCommentUrl = core.getInput("pr-comment-url");
+        const [, owner, repo, prNumber, commentId] =
+            prCommentUrl.match(/^https:\/\/github\.com\/([^/]+)\/([^/]+)\/pull\/(\d+)#issuecomment-(\d+)$/) || [];
+        if (!this.config.repo.owners.includes(owner) || repo !== this.config.repo.name) {
+            throw new Error(`Invalid PR comment URL: ${prCommentUrl}`);
+        }
+        return { owner, repo, prNumber: parseInt(prNumber, 10), commentId: parseInt(commentId, 10) };
+    }
+
     public setAccessToken(repositoryOwner: string, token: string): void {
         this.github.setAccessToken(repositoryOwner, token);
         if (this.config.repo.owner === repositoryOwner) {