ChatGPT's suggestion for implementing `cherry-pick` in `isomorphic-git`

cherry-pick.ts

import { RepoPath, CommitObject, GitError, MergeOptions, MergeReport } from 'isomorphic-git';
import { getCommit, listCommits, merge } from 'isomorphic-git';

// The cherryPick function takes a repository path and a commit SHA as input, and applies the
// changes made in the specified commit to the current branch. The function first gets the commit
// object for the specified commit, and then finds the parent commit(s) to use as the merge base(s).
// It then sets up the merge options, with ours set to the current HEAD commit and theirs set to the
// specified commit. The fastForwardOnly and noUpdateBranch options are used to ensure that the
// merge only applies changes from the specified commit, and does not change the branch reference
// or allow non-fast-forward merges. The merge function is then called to perform the merge and
// generate a merge report, which is used to check for merge conflicts. If there are conflicts,
// a GitError is thrown with an appropriate error message. If the merge succeeds without conflicts,
// the commit function is called to create a new commit with the merged changes. The commit message
// is set to cherry-pick: <original commit message>, and the author and committer are set to the same
// as the original commit. The parents are set to the current HEAD commit and the specified commit,
// and the tree is set to the merge result returned by the merge report.
async function cherryPick(repoPath: RepoPath, commitSha: string): Promise<void> {
  // Get the commit object to apply changes from
  const commit: CommitObject = await getCommit({ fs, dir: repoPath, oid: commitSha });

  // Find the parent commit(s) to use as the merge base(s)
  const parentCommits = await listCommits({ fs, dir: repoPath, ref: 'HEAD' });

  // Set up the merge options
  const mergeOptions: MergeOptions = {
    dir: repoPath,
    ours: parentCommits[0],
    theirs: commitSha,
    fastForwardOnly: true,
    noUpdateBranch: true,
  };

  // Merge the changes from the specified commit
  const mergeReport: MergeReport = await merge({ fs, ...mergeOptions });

  // Check for merge conflicts
  if (mergeReport.conflicts.length > 0) {
    throw new GitError(E.MergeNotSupportedFail, {
      message: 'Cherry-pick failed due to merge conflicts.',
    });
  }

  // Commit the merge changes with the cherry-pick message
  const message = `cherry-pick: ${commit.message}`;
  const author = { ...commit.author, timestamp: Math.floor(new Date().getTime() / 1000) };
  await commit({
    fs,
    dir: repoPath,
    message,
    author,
    committer: author,
    parents: [parentCommits[0], commitSha],
    tree: mergeReport.oid,
  });
}