1#!/usr/bin/env python3
2
3import subprocess
4import webbrowser
5
6
7def git(*args: str) -> str:
8    """
9    Run a Git command and return the output.
10    """
11    cmd = ["git"] + list(args)
12    return subprocess.check_output(cmd, text=True).strip()
13
14
15def get_parent(commit_id: str) -> str:
16    """
17    Return the commit ID of the parent of this commit.
18    """
19    return git("log", "--pretty=%P", "-n", "1", commit_id)
20
21
22def get_remote_branches(commit_id: str) -> list[str]:
23    """
24    Return a list of remote branches where this commit is the tip.
25    """
26    branches = git(
27        "for-each-ref",
28        "--format=%(refname:short)",
29        "refs/remotes/",
30        "--points-at",
31        commit_id,
32    ).splitlines()
33    return [b for b in branches if b != "origin"]
34
35
36def get_local_branches(commit_id: str) -> list[str]:
37    """
38    Return a list of local branches where this commit is the tip.
39    """
40    return git(
41        "for-each-ref",
42        "--format=%(refname:short)",
43        "refs/heads/",
44        "--points-at",
45        commit_id,
46    ).splitlines
47
48
49if __name__ == "__main__":
50    current_branch = git("rev-parse", "--abbrev-ref", "HEAD")
51    base_branch = "main"
52
53    commit = git("rev-parse", "HEAD")
54    for _ in range(5):
55        parent = get_parent(commit)
56
57        if rb := get_remote_branches(parent):
58            base_branch = rb[0].replace("origin/", "")
59            break
60
61        if lb := get_local_branches(parent):
62            if lb[0] == "main":
63                break
64
65    github_url = subprocess.check_output("_get_github_url", text=True).strip()
66
67    url = f"{github_url}/compare/{base_branch}...{current_branch}?expand=1"
68    webbrowser.open(url)