Hi all , Apex Trigger on Account which adds all the Closed won Opportunity amounts of that Account and shows it on the Account record. , can any one help me writing the trigger for updating account field

B: Update Method  if Already Created Opportunity Is Updated With Diff Account or Any Change in Amount  Total Amount Updated

trigger SumAmountOpp on Opportunity (After Insert,After Update,After Delete) {
 List<Account> accList=new List<Account>();
    Set<Id> setAccIds = new Set<Id>();
    if(Trigger.isInsert){
         if(trigger.isAfter){
        for(Opportunity con : Trigger.new){
            if(con.AccountId != null && Con.StageName == 'Closed Won' && con.Amount != null){
            setAccIds.add(con.AccountId);
            	}
			}
		}
    } 
    system.debug('setAccIds ==> '+setAccIds);
    if(Trigger.isUpdate){
         if(trigger.isAfter){
        for(Opportunity con : Trigger.new){ 
            if(con.AccountId!=Trigger.oldMap.get(con.Id).AccountId && Con.StageName == 'Closed Won' && con.Amount != null){
               	setAccIds.add(con.AccountId);
                setAccIds.add(Trigger.oldMap.get(con.Id).AccountId);
            	}
            else if(Con.StageName == 'Closed Won' && con.Amount!=Trigger.oldMap.get(con.Id).Amount && con.AccountId != null){
                setAccIds.add(con.AccountId);
                }
			}        
        }
    }
    if(Trigger.isDelete){
        if(trigger.isAfter){
        for(Opportunity con : Trigger.old) { 
            if(con.AccountId != null && Con.StageName == 'Closed Won'){
            setAccIds.add(con.AccountId);
            	}
        	}
        }
    }    
    for(Account acc :[Select id,Total_Amount__c ,(Select id,Name,Amount from Opportunities where StageName = 'Closed Won') from Account where Id in : setAccIds]){
			integer val = 0;
        for(Opportunity con : acc.Opportunities){
            val += integer.valueOf(con.Amount);
            system.debug('====> ' +val);
        }
        system.debug(val);
        acc.Total_Amount__c = string.valueOf(val);
        acclist.add(acc);
    }
    if(acclist.size()>0){
        update accList;     
    }
}