import * as fs from 'node:fs';

/**
 * Pause state interface
 */
export interface IPauseState {
  /** Timestamp when pause was activated */
  pausedAt: number;
  /** Who initiated the pause (e.g., 'cli', 'api') */
  pausedBy: string;
  /** Optional reason for pausing */
  reason?: string;
  /** When to auto-resume (null = indefinite, timestamp in ms) */
  resumeAt?: number | null;
}

export type TPauseTransition = 'unchanged' | 'paused' | 'resumed' | 'autoResumed';

export interface IPauseSnapshot {
  isPaused: boolean;
  pauseState: IPauseState | null;
  transition: TPauseTransition;
}

export function loadPauseSnapshot(
  filePath: string,
  wasPaused: boolean,
  now: number = Date.now(),
): IPauseSnapshot {
  try {
    if (!fs.existsSync(filePath)) {
      return {
        isPaused: false,
        pauseState: null,
        transition: wasPaused ? 'resumed' : 'unchanged',
      };
    }

    const data = fs.readFileSync(filePath, 'utf8');
    const pauseState = JSON.parse(data) as IPauseState;

    if (pauseState.resumeAt && now >= pauseState.resumeAt) {
      try {
        fs.unlinkSync(filePath);
      } catch (_error) {
        // Ignore deletion errors and still treat the pause as expired.
      }

      return {
        isPaused: false,
        pauseState: null,
        transition: wasPaused ? 'autoResumed' : 'unchanged',
      };
    }

    return {
      isPaused: true,
      pauseState,
      transition: wasPaused ? 'unchanged' : 'paused',
    };
  } catch (_error) {
    return {
      isPaused: false,
      pauseState: null,
      transition: 'unchanged',
    };
  }
}