[Unit]
Description=Check and restart KCG Backend if JAR updated

[Service]
Type=oneshot
ExecStart=/bin/bash -c '\
  DEPLOY_DIR=/devdata/services/kcg/backend; \
  JAR=$DEPLOY_DIR/kcg.jar; \
  MARKER=$DEPLOY_DIR/.last-restart; \
  [ ! -f "$JAR" ] && exit 0; \
  if [ "$JAR" -nt "$MARKER" ] 2>/dev/null || [ ! -f "$MARKER" ]; then \
    SYSTEMD_DIR=/etc/systemd/system; \
    CHANGED=0; \
    for f in kcg-backend.service kcg-backend-deploy.service kcg-backend-deploy.timer; do \
      if [ -f "$DEPLOY_DIR/$f" ] && ! diff -q "$DEPLOY_DIR/$f" "$SYSTEMD_DIR/$f" >/dev/null 2>&1; then \
        cp "$DEPLOY_DIR/$f" "$SYSTEMD_DIR/$f"; \
        CHANGED=1; \
      fi; \
    done; \
    [ "$CHANGED" = "1" ] && systemctl daemon-reload; \
    systemctl restart kcg-backend; \
    touch "$MARKER"; \
  fi'