#!/usr/bin/env bash

# This script checks the remote Git repository for changes 
# and triggers a nixos-rebuild if a new commit is found.
# Usage: ./nixos-sync.sh <REPO_URL> <BRANCH>

set -euo pipefail

REPO_URL=${1:-"https://git.depeuter.dev/Bos55/nix-config.git"}
BRANCH=${2:-"main"}

echo "Checking remote hash for $REPO_URL branch $BRANCH..."

# Fetch remote hash, fallback to unknown if it fails
REMOTE_HASH=$(git ls-remote "$REPO_URL" "refs/heads/$BRANCH" | awk '{print $1}' || true)

if [ -z "$REMOTE_HASH" ]; then
  echo "WARNING: Could not fetch remote hash. Forcing rebuild to be safe."
  REMOTE_HASH="unknown_remote"
fi

LOCAL_HASH="unknown_local"
if [ -f /run/current-system/configurationRevision ]; then
  LOCAL_HASH=$(cat /run/current-system/configurationRevision)
fi

echo "Remote hash: $REMOTE_HASH"
echo "Local hash:  $LOCAL_HASH"

if [ "$REMOTE_HASH" = "$LOCAL_HASH" ] && [ "$REMOTE_HASH" != "unknown_remote" ] && [ "$LOCAL_HASH" != "unknown" ]; then
  echo "Hashes match. No update needed."
  exit 0
fi

echo "Hashes differ or unknown. Triggering nixos-rebuild..."

# Trigger the build and switch
nixos-rebuild switch --flake "git+$REPO_URL?dir=nixos&ref=$BRANCH"

echo "Update successful."