import { Session } from './session.js';

/**
 * Store handles active in-memory sessions indexed by session ID.
 * It also maintains a ride ID mapping to prevent duplicate active sessions per ride.
 */
export class Store {
  constructor() {
    this.sessions = new Map(); // key: sessionID, value: Session
    this.rideToSession = new Map(); // key: rideID, value: Session
  }

  /**
   * Retrieves a session by its session ID.
   * @param {string} sessionID 
   * @returns {Session|undefined}
   */
  getSession(sessionID) {
    return this.sessions.get(sessionID);
  }

  /**
   * Retrieves an active session by its ride ID.
   * @param {string} rideID 
   * @returns {Session|undefined}
   */
  getSessionByRide(rideID) {
    return this.rideToSession.get(rideID);
  }

  /**
   * Registers a new call session, checking for active duplicates.
   * @param {string} rideID 
   * @param {string} driverID 
   * @param {string} passengerID 
   * @param {number} durationMs 
   * @param {string} [driverIP]
   * @param {string} [passengerIP]
   * @returns {Session}
   * @throws {Error} Throws if an active session already exists for the ride
   */
  createSession(rideID, driverID, passengerID, durationMs, driverIP = null, passengerIP = null) {
    const existing = this.rideToSession.get(rideID);
    if (existing && existing.status !== 'ended') {
      throw new Error('session_exists');
    }

    const sess = new Session(rideID, driverID, passengerID, durationMs, driverIP, passengerIP);
    this.sessions.set(sess.sessionID, sess);
    this.rideToSession.set(rideID, sess);
    return sess;
  }

  /**
   * Removes a session from registry mappings.
   * @param {string} sessionID 
   */
  destroySession(sessionID) {
    const sess = this.sessions.get(sessionID);
    if (sess) {
      this.sessions.delete(sessionID);
      this.rideToSession.delete(sess.rideID);
    }
  }

  /**
   * Finds expired active sessions.
   * @returns {Session[]}
   */
  getExpiredSessions() {
    const expired = [];
    const now = Date.now();
    for (const sess of this.sessions.values()) {
      if (sess.status !== 'ended' && now > sess.expiresAt.getTime()) {
        expired.push(sess);
      }
    }
    return expired;
  }

  /**
   * Returns active sessions count.
   * @returns {number}
   */
  getActiveCount() {
    return this.sessions.size;
  }
}