git-wip

#!/usr/bin/env -S uv --quiet run --no-project --script --
# https://peps.python.org/pep-0723/
# https://github.com/astral-sh/uv
# /// script
# # Docopt issues SyntaxWarning in Python 3.12
# requires-python = ">=3.11,<3.12"
# dependencies = [
#   "docopt >=0.6.2",
# ]
# ///

"""
Usage:
	{prog} new NEW_WIP_BRANCH_NAME [UPSTREAM_BRANCH_NAME [STARTING_POINT]]
	{prog} rebase WIP_BRANCH_NAME
"""

import sys, locale, os, subprocess as sp
import docopt


def main(*, args, prog):
	locale.setlocale(locale.LC_ALL, "")

	params = docopt.docopt(
		__doc__.replace("\t", " " * 4).format(prog=os.path.basename(prog)),
		argv=args,
		help=True,
		version=True,
		options_first=False
	)
	verb = None
	if params.pop("new", None):
		verb = "new"
		wip_branch = params.pop("NEW_WIP_BRANCH_NAME")
		upstream_branch = params.pop("UPSTREAM_BRANCH_NAME") or git("config", "--get", "wip.defaultUpstream", stdout=sp.PIPE).stdout.strip()
		starting_point = params.pop("STARTING_POINT") or upstream_branch
		assert params.pop("WIP_BRANCH_NAME") is None
		assert params.pop("rebase") == False
	elif params.pop("rebase", None):
		verb = "rebase"
		wip_branch = params.pop("WIP_BRANCH_NAME")
		assert params.pop("NEW_WIP_BRANCH_NAME") is None
		assert params.pop("UPSTREAM_BRANCH_NAME") is None
		assert params.pop("STARTING_POINT") is None
	assert not params, params

	wip_branch = wip_branch \
		.removeprefix("wip/") \
		.removeprefix("heads/wip/") \
		.removeprefix("refs/heads/wip/")

	if verb == "new":
		try:
			git("update-ref", "--create-reflog", "--stdin", "-z", input=(
				"start\0"
				f"create refs/heads/wip/{wip_branch}/head\0{starting_point}\0"
				f"create refs/heads/wip/{wip_branch}/base\0{upstream_branch}\0"
				f"create refs/heads/wip/{wip_branch}/dest\0{upstream_branch}\0"
				"prepare\0"
				"commit\0"
			))
			git("branch", f"wip/{wip_branch}/head", "--set-upstream-to", f"wip/{wip_branch}/base")
			git("branch", f"wip/{wip_branch}/base", "--set-upstream-to", f"wip/{wip_branch}/dest")
			git("branch", f"wip/{wip_branch}/dest", "--set-upstream-to", f"{upstream_branch}")
		except sp.CalledProcessError as e:
			print(repr(e.cmd), ": ", e.returncode, sep="", file=sys.stderr)
	elif verb == "rebase":
		assert not git("status", "--porcelain=v2", stdout=sp.PIPE).stdout
		print(f"Detaching HEAD from {wip_branch!r}")
		git("switch", "--detach", f"refs/heads/wip/{wip_branch}/head")
		print(f"Rebasing: from base of {wip_branch!r} to HEAD onto dest of {wip_branch!r}.")
		git("rebase", f"refs/heads/wip/{wip_branch}/base", "HEAD", "--onto", f"refs/heads/wip/{wip_branch}/dest") #TODO:vruyr This could fail because of conflicts.
		patchid_old = git("patch-id", input=git("diff", f"refs/heads/wip/{wip_branch}/base", f"refs/heads/wip/{wip_branch}/head", "--", stdout=sp.PIPE).stdout, stdout=sp.PIPE).stdout.strip()
		patchid_new = git("patch-id", input=git("diff", f"refs/heads/wip/{wip_branch}/dest", f"HEAD",                             "--", stdout=sp.PIPE).stdout, stdout=sp.PIPE).stdout.strip()
		assert patchid_old == patchid_new, (patchid_old, patchid_new) #TODO:vruyr This could fail because of conflict resolution.
		print(f"Updating head of {wip_branch!r}")
		git("fetch", ".", f"+HEAD:refs/heads/wip/{wip_branch}/head")
		print(f"Updating base of {wip_branch!r}")
		git("fetch", ".", f"+refs/heads/wip/{wip_branch}/dest:refs/heads/wip/{wip_branch}/base")
		print(f"Switching to branch {wip_branch!r}")
		git("switch", f"wip/{wip_branch}/head")


def git(*args, **kwargs):
	cmd = ["git", *args]
	return sp.run(
		cmd,
		shell=False,
		check=kwargs.pop("check", True),
		encoding=kwargs.pop("encoding", "UTF-8"),
		**kwargs,
	)

def smain(argv=None):
	if argv is None:
		argv = sys.argv

	try:
		return main(
			args=argv[1:],
			prog=argv[0]
		)
	except KeyboardInterrupt:
		print(file=sys.stderr)


if __name__ == "__main__":
	sys.exit(smain())