def main()

in dev/merge_spark_pr.py [0:0]
94 lines of code
21 McCabe index (conditional complexity)

def main():
    initialize_jira()
    global original_head

    os.chdir(SPARK_HOME)
    original_head = get_current_ref()

    branches = get_json("%s/branches" % GITHUB_API_BASE)
    branch_names = list(filter(lambda x: x.startswith("branch-"), [x["name"] for x in branches]))
    # Assumes branch names can be sorted lexicographically
    branch_names = sorted(branch_names, reverse=True)
    branch_iter = iter(branch_names)

    pr_num = bold_input("Which pull request would you like to merge? (e.g. 34): ")
    pr = get_json("%s/pulls/%s" % (GITHUB_API_BASE, pr_num))
    pr_events = get_json("%s/issues/%s/events" % (GITHUB_API_BASE, pr_num))

    url = pr["url"]

    # Warn if the PR is WIP
    if "[WIP]" in pr["title"]:
        msg = "The PR title has `[WIP]`:\n%s\nContinue?" % pr["title"]
        continue_maybe(msg)

    # Decide whether to use the modified title or not
    modified_title = standardize_jira_ref(pr["title"]).rstrip(".")
    if modified_title != pr["title"]:
        print("I've re-written the title as follows to match the standard format:")
        print("Original: %s" % pr["title"])
        print("Modified: %s" % modified_title)
        result = bold_input("Would you like to use the modified title? (y/N): ")
        if result.lower() == "y":
            title = modified_title
            print("Using modified title:")
        else:
            title = pr["title"]
            print("Using original title:")
        print(title)
    else:
        title = pr["title"]

    body = pr["body"]
    if body is None:
        body = ""
    modified_body = re.sub(re.compile(r"<!--[^>]*-->\n?", re.DOTALL), "", body).lstrip()
    if modified_body != body:
        print("=" * 80)
        print(modified_body)
        print("=" * 80)
        print("I've removed the comments from PR template like the above:")
        result = bold_input("Would you like to use the modified body? (y/N): ")
        if result.lower() == "y":
            body = modified_body
            print("Using modified body:")
        else:
            print("Using original body:")
        print("=" * 80)
        print(body)
        print("=" * 80)
    target_ref = pr["base"]["ref"]
    user_login = pr["user"]["login"]
    base_ref = pr["head"]["ref"]
    pr_repo_desc = "%s/%s" % (user_login, base_ref)

    # Merged pull requests don't appear as merged in the GitHub API;
    # Instead, they're closed by committers.
    merge_commits = [e for e in pr_events if e["event"] == "closed" and e["commit_id"] is not None]

    if merge_commits and pr["state"] == "closed":
        # A PR might have multiple merge commits, if it's reopened and merged again. We shall
        # cherry-pick PRs in closed state with the latest merge hash.
        # If the PR is still open(reopened), we shall not cherry-pick it but perform the normal
        # merge as it could have been reverted earlier.
        merge_commits = sorted(merge_commits, key=lambda x: x["created_at"])
        merge_hash = merge_commits[-1]["commit_id"]
        message = get_json("%s/commits/%s" % (GITHUB_API_BASE, merge_hash))["commit"]["message"]

        print("Pull request %s has already been merged, assuming you want to backport" % pr_num)
        commit_is_downloaded = (
            run_cmd(["git", "rev-parse", "--quiet", "--verify", "%s^{commit}" % merge_hash]).strip()
            != ""
        )
        if not commit_is_downloaded:
            fail("Couldn't find any merge commit for #%s, you may need to update HEAD." % pr_num)

        print("Found commit %s:\n%s" % (merge_hash, message))
        cherry_pick(pr_num, merge_hash, next(branch_iter, branch_names[0]))
        sys.exit(0)

    if not bool(pr["mergeable"]):
        msg = (
            "Pull request %s is not mergeable in its current form.\n" % pr_num
            + "Continue? (experts only!)"
        )
        continue_maybe(msg)

    print("\n=== Pull Request #%s ===" % pr_num)
    print("title\t%s\nsource\t%s\ntarget\t%s\nurl\t%s" % (title, pr_repo_desc, target_ref, url))
    continue_maybe("Proceed with merging pull request #%s?" % pr_num)

    merged_refs = [target_ref]

    merge_hash = merge_pr(pr_num, target_ref, title, body, pr_repo_desc)

    pick_prompt = "Would you like to pick %s into another branch?" % merge_hash
    while bold_input("\n%s (y/N): " % pick_prompt).lower() == "y":
        merged_refs = merged_refs + [
            cherry_pick(pr_num, merge_hash, next(branch_iter, branch_names[0]))
        ]

    if asf_jira is not None:
        continue_maybe("Would you like to update an associated JIRA?")
        jira_comment = "Issue resolved by pull request %s\n[%s/%s]" % (
            pr_num,
            GITHUB_BASE,
            pr_num,
        )
        resolve_jira_issues(title, merged_refs, jira_comment)
    else:
        print("Exiting without trying to close the associated JIRA.")