public with sharing class CampaignHandler {

  public static void manageEBCourse(List<Campaign> newList, Map<id, Campaign> oldMap)
  {
    Set<String> EBIDSet = new Set<String>();
    Map<String, Course__c> EBCourseMap = new Map<String, Course__c>();
    List<Course__c> courseList = new List<Course__c>();
    Map<String, Opportunity> oppMap = new Map<String, Opportunity>();

    List<Account> vtAccounts = [Select Id, Name from Account where Name = 'VitalTalk' limit 1];
    Account vtAccount = null;

    if (vtAccounts.isEmpty())
    {
      vtAccount = new Account();
      vtAccount.Name = 'VitalTalk';
      insert vtAccount;
    }
    else
      vtAccount = vtAccounts[0];

    if (vtAccount != null)
    {
      for (Campaign c : newList)
      {
        if (c.EventbriteSync__EventbriteId__c != null && (Trigger.isInsert || oldMap.get(c.Id).EventbriteSync__EventbriteId__c != c.EventbriteSync__EventbriteId__c || oldMap.get(c.Id).StartDate != c.StartDate || oldMap.get(c.Id).EndDate != c.EndDate))
        {
          EBIDSet.add(c.EventbriteSync__EventbriteId__c);
        }
      }

      if (!EBIDSet.isEmpty())
      {
        for (Course__c course : [Select Id, EventBrite_ID__c, Opportunity__c from Course__c where EventBrite_ID__c in :EBIDSet])
        {
          EBCourseMap.put(course.EventBrite_ID__c, course);
        }

        for (Campaign c : newList)
        {
          if (c.EventbriteSync__EventbriteId__c != null && (Trigger.isInsert || oldMap.get(c.Id).EventbriteSync__EventbriteId__c != c.EventbriteSync__EventbriteId__c || oldMap.get(c.Id).StartDate != c.StartDate || oldMap.get(c.Id).EndDate != c.EndDate))
          {
            Course__c existingCourse = EBCourseMap.get(c.EventbriteSync__EventbriteId__c);
            if (existingCourse == null)
            {
              Course__c course = new Course__c();
              course.Name = c.Name;
              course.EventBrite_ID__c = c.EventbriteSync__EventbriteId__c;
              course.Start_Date__c = c.StartDate;
              course.End_Date__c = c.EndDate;
              courseList.add(course);

              Opportunity o = new Opportunity();
              o.Name = c.Name;
              o.AccountId = vtAccount.Id;
              o.CloseDate = System.today();
              o.StageName = 'Closed Won';
              o.EventBrite_Event_ID__c = c.EventbriteSync__EventbriteId__c;
              oppMap.put(o.EventBrite_Event_ID__c, o);
            }
            else
            {
              System.debug('@@@Found course: ' + existingCourse);
              Course__c course = new Course__c();
              course.Id = existingCourse.Id;
              course.Name = c.Name;
              course.Start_Date__c = c.StartDate;
              course.End_Date__c = c.EndDate;
              courseList.add(course);

              if (existingCourse.Opportunity__c == null)
              {
                Opportunity o = new Opportunity();
                o.Name = c.Name;
                o.AccountId = vtAccount.Id;
                o.CloseDate = System.today();
                o.StageName = 'Closed Won';
                o.EventBrite_Event_ID__c = c.EventbriteSync__EventbriteId__c;
                oppMap.put(o.EventBrite_Event_ID__c, o);
              }
            }
          }
        }

        if (!oppMap.isEmpty())
          upsert oppMap.values();

        for (Course__c course : courseList)
        {
          Opportunity o = oppMap.get(course.EventBrite_ID__c);
          if (course != null && o != null)
            course.Opportunity__c = o.Id;
        }

        if (!courseList.isEmpty())
          upsert courseList;
      }
    }
  }

}