Hello,

I would like to create an apex class an the EmailMessage object to count the number of Email Feed on a case.
And then use a trigger.
I have done something similar to count the number of text post on a case but I struggle a bit to do the same for EmailMessage 
here is what I have done to count the number of textpost.
Apex class

public class FeedItemTriggerHandler {
    public static void countFeedItem(List<FeedItem> lstFeed){
        if(lstFeed.size() > 0){
            set<Id> setParentIds = new Set<Id>();
            for(FeedItem fd : lstFeed){
                setParentIds.add(fd.ParentId);
            }
            if(setParentIds.size() > 0){
                List<Case> lstCase = [Select caseNumber,All_Users_Feed_Count__c, (Select Id,body,Type,Visibility From Feeds where Type = 'TextPost' OR Type = 'EmailMessageEvent') From Case where Id In : setParentIds];
                if(lstCase.size() > 0){
                    for(Case cs : lstCase){
                        List<CaseFeed> feeds = cs.feeds;
                        Integer count = 0;
                        for(CaseFeed cf : feeds){
                            if(cf.Visibility == 'AllUsers'){
                                count+=1;    
                            }
                        }
                        System.debug(feeds.size());
                        cs.All_Users_Feed_Count__c = count;
                    }
                    update lstCase;
                }    
            }
        }
    }
}

Trigger

trigger FeedItemTrigger on FeedItem (after insert,before delete) {
    if(Trigger.isAfter){
        if(Trigger.isInsert){
          FeedItemTriggerHandler.countFeedItem(Trigger.new);    
        }
    } else if(Trigger.isBefore){
      if(Trigger.isDelete){
          FeedItemTriggerHandler.countFeedItem(Trigger.old);    
        }
    }
}

Could Someone help to do something similar to count the number of Email feed sent on a case.

Thanks