"""EC2 user-data template rendering for builder instance bootstrap."""

from __future__ import annotations

import textwrap


def render_userdata(slot_id: str, ssm_param: str = "/nix-builder/ts-authkey") -> str:
    """Render user-data that seeds AMI bootstrap inputs only.

    The AMI's buildbot-ami-bootstrap service consumes this env file and handles
    SSM fetch + tailscale-autoconnect config generation.
    """
    return textwrap.dedent(f"""\
        #!/usr/bin/env bash
        set -euo pipefail

        SLOT_ID="{slot_id}"
        SSM_PARAM="{ssm_param}"

        # Seed AMI bootstrap inputs only; buildbot-ami-bootstrap reads this file.
        cat > /etc/nix-builder-bootstrap-env <<EOF
        SLOT_ID="$SLOT_ID"
        TS_SSM_PARAM="$SSM_PARAM"
        EOF
        chmod 600 /etc/nix-builder-bootstrap-env
    """)