git-continue

#!/usr/bin/python3

from pathlib import Path
import shlex
import subprocess
import sys


OPERATIONS = (
    ("merge", "MERGE_HEAD"),
    ("rebase", "REBASE_HEAD"),
    ("am", "rebase-apply/applying"),
    ("cherry-pick", "CHERRY_PICK_HEAD"),
    ("revert", "REVERT_HEAD"),
)


def infer_action_from_executable_name():
    executable_name = Path(sys.argv[0]).name
    if not executable_name.startswith("git-"):
        return None

    action = executable_name[len("git-") :]
    if action not in ["continue", "skip", "abort", "quit"]:
        return None

    return action


def infer_active_git_operation():
    git_dir = Path(
        subprocess.check_output(
            ["git", "rev-parse", "--git-dir"], stderr=subprocess.STDOUT
        )
        .decode("utf-8")
        .strip()
    )

    for operation, evidence in OPERATIONS:
        if (git_dir / evidence).exists():
            return operation

    return None


def main():
    action = infer_action_from_executable_name()
    if action is None:
        print("Unknown action.", file=sys.stderr)
        sys.exit(1)

    operation = infer_active_git_operation()
    if operation is None:
        print("Nothing to {}.".format(action), file=sys.stderr)
        sys.exit(0)

    cmd = ["git", operation, "--{}".format(action)] + sys.argv[1:]
    print(">", " ".join(map(shlex.quote, cmd)))
    sys.exit(subprocess.call(cmd))


if __name__ == "__main__":
    try:
        main()
    except subprocess.CalledProcessError as err:
        sys.stderr.write(err.output.decode("utf-8"))
        sys.exit(err.returncode)