from __future__ import annotations

from dataclasses import dataclass
from datetime import datetime
import json
from pathlib import Path
import tomllib
from typing import Any


@dataclass(frozen=True)
class RuntimePaths:
    root_dir: Path
    analysis_dir: Path
    output_root: Path
    run_dir: Path


def load_config(root_dir: Path) -> dict[str, Any]:
    config_path = root_dir / "config.toml"
    with config_path.open("rb") as f:
        return tomllib.load(f)


def init_runtime_paths(analysis_dir: Path, run_name: str | None = None) -> RuntimePaths:
    root_dir = analysis_dir.parent
    output_root = root_dir / "analysis_output"
    output_root.mkdir(parents=True, exist_ok=True)

    safe_run_name = run_name or datetime.now().strftime("run_%Y%m%d_%H%M%S")
    run_dir = output_root / safe_run_name
    run_dir.mkdir(parents=True, exist_ok=True)

    return RuntimePaths(
        root_dir=root_dir,
        analysis_dir=analysis_dir,
        output_root=output_root,
        run_dir=run_dir,
    )


def backend_dir(paths: RuntimePaths, backend: str) -> Path:
    out = paths.run_dir / backend
    out.mkdir(parents=True, exist_ok=True)
    return out


def write_json(path: Path, payload: dict[str, Any]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w", encoding="utf-8") as f:
        json.dump(payload, f, indent=2)