#!/bin/bash
set -euo pipefail

if [ $# -ne 1 ]; then
    echo "Usage: git rebase-remote <remote/branch>" >&2
    exit 1
fi

remote_branch="$1"
remote="${remote_branch%%/*}"
branch="${remote_branch#*/}"

if [ "$remote" = "$branch" ]; then
    echo "Error: Could not parse remote/branch from '$remote_branch'" >&2
    exit 1
fi

# Save current branch/commit
current=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || git rev-parse HEAD)

# Fetch both branches
git fetch "$remote" "$branch"
git fetch origin main

# Checkout remote branch in detached HEAD state, rebase, and push
git checkout --detach "$remote/$branch"
git rebase origin/main
git push --force-with-lease "$remote" "HEAD:$branch"

# Return to original branch/commit
git checkout "$current"

echo "✓ Rebased and pushed $remote_branch"