/**
 * Global config singleton.
 *
 * Initialized exactly once in main.js from the JSON files in /data,
 * then any module in the game can import it and read values:
 *
 *   import { config } from '../config/Config.js';
 *   const thrust = config.get('ship.thrust', 900);
 *   const menu   = config.section('menu', {});
 *
 * Conventions (see docs/PROJECT_NOTES.md):
 *  - tunable values live in data/*.json, never hardcoded in code;
 *  - add a new data file by listing it in data/manifest.json.
 */
class Config {
  constructor() {
    this.data = {};
  }

  /** @param {Record<string, any>} data keyed by config file name (no .json) */
  init(data) {
    this.data = data ?? {};
    return this;
  }

  /** @returns {boolean} true if a top-level section (a file in /data) exists */
  has(name) {
    return Object.prototype.hasOwnProperty.call(this.data, name);
  }

  /**
   * @returns {object} the value at `name` if it's an object — dotted
   * paths allowed (`section('systems.types')` works) — else `fallback`.
   */
  section(name, fallback = {}) {
    const value = this.get(name, undefined);
    return (value && typeof value === 'object') ? value : fallback;
  }

  /**
   * Dotted-path getter: config.get('menu.buttons.newGame.label', 'New Game')
   * @returns {*} the value at `path`, or `fallback` if any segment is missing
   */
  get(path, fallback = undefined) {
    if (!path) return fallback;
    let node = this.data;
    for (const part of String(path).split('.')) {
      if (node == null || typeof node !== 'object') return fallback;
      node = node[part];
    }
    return node === undefined ? fallback : node;
  }
}

export const config = new Config();