import path from 'path';
import fs from 'fs';

class PathManager {
  private static instance: PathManager;
  private readonly baseDir: string;

  private constructor() {
    this.baseDir = path.join(__dirname, '../..');
  }

  /**
   * 获取单例实例
   */
  public static getInstance(): PathManager {
    if (!PathManager.instance) {
      PathManager.instance = new PathManager();
    }
    return PathManager.instance;
  }

  /**
   * 获取预定义路径
   * @param type 路径类型
   */
  public get(type?: PathType): string {
    const mappings: Record<PathType, string> = {
      root: this.baseDir,
      public: path.join(this.baseDir, 'public'),
      images: path.join(this.baseDir, 'public/images'),
      log: path.join(this.baseDir, 'logs'),
      config: path.join(this.baseDir, 'config'),
      temp: path.join(this.baseDir, 'temp'),
    };

    return type ? mappings[type] : this.baseDir;
  }

  /**
   * 解析相对路径（基于项目根目录）
   * @param segments 路径片段
   */
  public resolve(...segments: string[]): string {
    return path.join(this.baseDir, ...segments);
  }

  /**
   * 检查路径是否存在（同步）
   */
  public existsSync(targetPath: string): boolean {
    try {
      return fs.existsSync(targetPath);
    } catch {
      return false;
    }
  }
}

type PathType = 'root' | 'public' | 'images' | 'log' | 'config' | 'temp';

const paths = PathManager.getInstance();
export default paths;