jj_github_pr.py

#!/usr/bin/env python

# jj-github-pr: Create Github PRs from jujutsu changes
# Each change will be one PR. Relations between changes will be preserved by setting the PR base branch.
# The commit title/message will be used for the PR title/body.
# The command can be used multiple times to update the stack of PRs, titles and commits.
# A "Relation chain" which shows the relation between the submitted PRs will be added to the PR body.
# Usage: Run jj-github-pr <revision> to submit each jj change as a PR.
# 
# Example usage:
# $ jj-github-pr
# Fix prod email configuration. » https://github.com/pelme/reko/pull/46
# Set proper noreply+reply-to addresses. » https://github.com/pelme/reko/pull/47
# Use fail_silently=True to make it possible to place an order when SMTP is not working. » https://github.com/pelme/reko/pull/48
#
# Requires jj, git and gh to be available on path. Tested with Python 3.12 with pygithub and click installed.

import itertools
import os
import subprocess

import click
import github


def pr_branch(change_id):
    if change_id == "main":
        return "main"
    return f"push-{change_id[:8]}"


def run(*args):
    res = subprocess.run(args, capture_output=True)

    if res.returncode == 0:
        return res.stdout.decode("utf8").strip()

    print("  > " + (" ".join(args)))

    raise Exception(res.stderr.decode("utf8"))


def make_pr(*, commit, change, target_change, repo):
    head = pr_branch(change)
    base = pr_branch(target_change)
    title = run("git", "log", "-1", "--pretty=format:%s", commit)
    body = run("git", "log", "-1", "--pretty=format:%b", commit)

    print(f"{title}", end="")
    run("git", "push", "origin", "--force", f"{commit}:refs/heads/{pr_branch(change)}")

    prs = list(repo.get_pulls(head=f"{repo.owner.login}:{head}"))
    if len(prs) == 0:
        pr = repo.create_pull(title=title, body=body, head=head, base=base)
    elif len(prs) == 1:
        pr = prs[0]
        pr.edit(title=title, body=body, base=base)
    else:
        raise AssertionError(prs)
    print(f" » {pr.html_url}")
    return pr


def get_github_repo():
    remote_url = run("git", "config", "--get", "remote.origin.url")
    _, _, result = remote_url.partition("github.com:")
    return result.removesuffix(".git")


def body_with_relation_chain(*, prs, current_pr):
    relation_chain = "\n".join(
        f"- {'👉' if pr == current_pr else ''} #{pr.number}" for pr in prs
    )

    return f"{current_pr.body or ''}\n\n### Relation chain\n{relation_chain}"


@click.command()
@click.argument("revision", default="@-")
def main(revision):
    auth = github.Auth.Token(run("gh", "auth", "token"))
    g = github.Github(auth=auth)
    g_repo = g.get_repo(get_github_repo())

    res = run(
        "jj",
        "log",
        "-r",
        f"::{revision} & mutable()",
        "--no-graph",
        "--color",
        "never",
        "-T",
        """commit_id ++ " " ++ change_id ++ "\n" """,
    )
    commit_change_ids = list(reversed([x.split() for x in res.splitlines()]))
    commit_change_ids.insert(0, (None, "main"))

    prs = []
    for (_target_commit, target_change), (commit, change) in itertools.pairwise(
        commit_change_ids
    ):
        prs.append(
            make_pr(
                commit=commit,
                change=change,
                target_change=target_change,
                repo=g_repo,
            )
        )

    if len(prs) >= 2:
        print("Updating descriptions...", end="")
        for pr in prs:
            pr.edit(body=body_with_relation_chain(prs=prs, current_pr=pr))
        print("done.")


if __name__ == "__main__":
    main()