import { DyNTS_SingletonService } from '../../_services/base/singleton.service';

/**
 * In-memory ring buffer a szerver console kimenethez.
 * Interceptalja a console.log/error/warn/info hivasokat es eltarolja az utolso N sort.
 *
 * Hasznalat:
 *   DyNTS_LogBuffer_Service.getInstance().install();  // app startup-nal
 *   DyNTS_LogBuffer_Service.getInstance().getLines(100);  // utolso 100 sor
 */
export class DyNTS_LogBuffer_Service extends DyNTS_SingletonService {

  static getInstance(): DyNTS_LogBuffer_Service {
    return DyNTS_LogBuffer_Service.getSingletonInstance();
  }

  private readonly maxLines: number = 2000;
  private readonly buffer: string[] = [];
  private installed: boolean = false;

  /**
   * Interceptalja a console.log/error/warn/info kimeneteket es a bufferbe irja.
   * Egyszer kell hivni, a szerver indulasakor (lehetoleg a legelso muvelet).
   */
  install(): void {
    if (this.installed) { return; }
    this.installed = true;

    const self: DyNTS_LogBuffer_Service = this;

    const originalLog: typeof console.log = console.log.bind(console);
    const originalError: typeof console.error = console.error.bind(console);
    const originalWarn: typeof console.warn = console.warn.bind(console);
    const originalInfo: typeof console.info = console.info.bind(console);

    console.log = (...args: any[]): void => {
      self.addLine('LOG', args);
      originalLog(...args);
    };

    console.error = (...args: any[]): void => {
      self.addLine('ERR', args);
      originalError(...args);
    };

    console.warn = (...args: any[]): void => {
      self.addLine('WRN', args);
      originalWarn(...args);
    };

    console.info = (...args: any[]): void => {
      self.addLine('INF', args);
      originalInfo(...args);
    };
  }

  /**
   * A log buffer be van-e kapcsolva (install megtortent-e).
   */
  isInstalled(): boolean {
    return this.installed;
  }

  /**
   * Az utolso N sor lekerdezese.
   */
  getLines(count: number = 200): string[] {
    const start: number = Math.max(0, this.buffer.length - count);
    return this.buffer.slice(start);
  }

  /**
   * Az osszes buffered sor szama.
   */
  getLineCount(): number {
    return this.buffer.length;
  }

  /**
   * Buffer uritese.
   */
  clear(): void {
    this.buffer.length = 0;
  }

  private addLine(level: string, args: any[]): void {
    const timestamp: string = new Date().toISOString();
    const message: string = args.map(formatArg).join(' ');
    this.buffer.push(`${timestamp} [${level}] ${message}`);

    if (this.buffer.length > this.maxLines) {
      this.buffer.shift();
    }
  }
}

function formatArg(arg: any): string {
  if (typeof arg === 'string') { return arg; }
  try { return JSON.stringify(arg); } catch { return String(arg); }
}