from pathlib import Path
from typing import Callable

from l4d2host.spec import load_spec
from l4d2host.systemd_user import daemon_reload, ensure_template_unit


DEFAULT_ROOT = Path("/opt/l4d2")


def initialize_instance(
    name: str,
    spec_path: Path,
    *,
    root: Path = DEFAULT_ROOT,
    on_stdout: Callable[[str], None] | None = None,
    on_stderr: Callable[[str], None] | None = None,
    passthrough: bool = False,
) -> None:
    spec = load_spec(spec_path)

    instance_dir = root / "instances" / name
    runtime_dir = root / "runtime" / name
    (runtime_dir / "upper").mkdir(parents=True, exist_ok=True)
    (runtime_dir / "work").mkdir(parents=True, exist_ok=True)
    (runtime_dir / "merged").mkdir(parents=True, exist_ok=True)
    instance_dir.mkdir(parents=True, exist_ok=True)

    lowerdirs = [str(root / "overlays" / overlay) for overlay in spec.overlays]
    lowerdirs.append(str(root / "installation"))

    instance_env = "\n".join(
        [
            f"L4D2_PORT={spec.port}",
            f"L4D2_ARGS={' '.join(spec.arguments)}",
            f"L4D2_LOWERDIRS={':'.join(lowerdirs)}",
        ]
    ) + "\n"
    (instance_dir / "instance.env").write_text(instance_env)

    server_cfg = "\n".join(spec.config) if spec.config else ""
    (instance_dir / "server.cfg").write_text(server_cfg)

    if root.resolve() == DEFAULT_ROOT:
        ensure_template_unit()
        daemon_reload(on_stdout=on_stdout, on_stderr=on_stderr, passthrough=passthrough)