copy-git-permalink

#!/usr/bin/env python3
import argparse
import subprocess
import re
from pathlib import Path


def get_revision() -> str:
    return subprocess.check_output(
        ("git", "rev-parse", "HEAD"), text=True, stderr=subprocess.DEVNULL
    ).strip()


def lookup_hostname(hostname: str) -> str:
    ssh_config = (Path.home() / ".ssh" / "config").read_text()
    current_host: str | None = None
    hostname_map: dict[str, str] = {}
    for line in ssh_config.splitlines():
        if line.startswith("Host"):
            current_host = line.split(" ")[1].strip()
        elif not line.startswith(" "):
            # We're at the end of a block,
            # and so whatever `Host` we've found
            # is now invalid.
            current_host = None

        if not current_host:
            continue

        line = line.strip()
        if line.startswith("HostName"):
            hostname_map[current_host] = line.split(" ")[1].strip()
    return hostname_map[hostname]


SSH_URL_RE = re.compile(r"^git@(?P<url>[^:]+):(?P<repo_name>.+?)(\.git)?$")


def get_remote_url() -> str:
    url = subprocess.check_output(
        ("git", "remote", "get-url", "origin"), text=True, stderr=subprocess.DEVNULL
    ).strip()
    if url.startswith("http://") or url.startswith("https://"):
        return url

    match = SSH_URL_RE.match(url)
    if match is None:
        raise ValueError(f"Invalid SSH URL: {url}")

    match_url = lookup_hostname(match["url"])
    match_repo_name = match["repo_name"]
    return f"https://{match_url}/{match_repo_name}"


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("buffer_name")
    parser.add_argument("selection_start")
    parser.add_argument("selection_end")
    namespace = parser.parse_args()

    buffer_name: str = namespace.buffer_name
    selection_end = int(namespace.selection_end)
    selection_start = int(namespace.selection_start)
    remote_url = get_remote_url()
    revision = get_revision()

    if selection_start == selection_end:
        selection = f"L{selection_start}"
    else:
        selection = f"L{selection_start}-L{selection_end}"

    permalink = f"{remote_url}/blob/{revision}/{buffer_name}#{selection}"
    copy = subprocess.Popen(("pbcopy"), stdin=subprocess.PIPE, text=True)
    _ = copy.communicate(permalink)


if __name__ == "__main__":
    main()