mobile-session-promise/index.js

The modules creates a promise that resolves an existing or creates a brand new session

"use strict";

/*
 * ATTENTION: IF YOU USE THIS MODULE PLEASE MAKE SURE TO POPULATE THE ENV VARIABLES:
   TABLE_NAME (Mandatory) - Dynamo table name see ./cloudformation/dynamo-mobile-session
   TTL_LENGTH_DAYS (default: 7) - Time to live after which the record gets erased by DynamoDB
   SESSION_EXPIRATION_TIMEOUT (default: 1800000) - the period of time the same session is reused within

 * The modules creates a promise that resolves existing or creates a new
 * session in the format as follows:
   {"schema":"iglu:com.nordstrom/client_session/jsonschema/1-2-4",
    "user_id":[[DOMAIN_USER_ID_SUPPLIED]],
    "session_id": [[NEW_OR_EXISTING_SESSION_ID]],
    "session_index": [[SESSION_SEQUENTIAL_NUMBER]],
    "storage_mechanism": "DYNAMO",
    "previous_session_id": [[EXISTING_SESSION_ID_OR_ZZZZZZ]], //nulls disallowed in dynamoDB
    "orig_event_id": [[EVENT_ID_SUPPLIED]],
    "first_event_id":[[FIRST_EVENT_OF_CURRENT_SESSION]]}}`
 *
 * Copyright(c) Nordstrom,Inc. All Rights reserved. This software is the confidential and
 * proprietary information of Nordstrom, Inc. ("Confidential Information"). You shall not disclose
 * such Confidential Information and shall use it only in accordance with the terms of the license
 * agreement you entered into with Nordstrom, Inc.
 */

const calc_derived_tstamp = require('./utils/calc_derived_tstamp');

const DEBUG = process.env.SNOWPLOW_DEBUG === 'true';

/** The function produces a Promise that eventually delivers the information
    about new or re-used session. Whether the session is created anew or
    retrieved and re-used from the Dynamo DB is based on three main
    decision points:
    * No previous events for the given domain_userid is found in DB then the
      new Session Id is created (USER_ID_NOT_FOUND)
    * The previous most recent event is found and it happened less than 30 minutes ago
      then the Session Id is reused from the event found (<30_MINUTES)
    * The previous most recent event is found and it happened earlier than 30 minutes
      ago then the new Session Id is generated and the previous_session_id is populated
      from the event found (>30_MINUTES)

    @orig_event_id event id
    @domain_userid user id or cookie id
    @body the payload body, containing all of the necessary timestamps
*/

module.exports = function(orig_event_id, domain_userid, collector_tstamp, device_created_tstamp, device_sent_tstamp) {
  const derived_tstamp = calc_derived_tstamp(collector_tstamp, device_created_tstamp, device_sent_tstamp);

  if(DEBUG)
  {console.log(orig_event_id);
  console.log(domain_userid);
  console.log(derived_tstamp);
  }
  var promise = new Promise(function(resolve, reject) {
    // do a thing, possibly async, then…
  
    const coElement = {"schema":"iglu:com.nordstrom/client_session/jsonschema/1-2-4",
                       "user_id": domain_userid,
                       "session_id": "ZZZZZZ",
                       "session_index": 0,
                       "storage_mechanism": "",
                       "previous_session_id": "ZZZZZZ",
                       "orig_event_id": orig_event_id,
                       "first_event_id": orig_event_id};
  
   // if(DEBUG)console.log(coElement);
  
    if (true) {
       resolve(coElement);
    }
    else {
       reject(coElement);
    }
  });
  if(DEBUG) console.log("before return",promise);
  return promise;
 };