public with sharing class ContactRoleOnOppo {
    //class with sharing rule of context user
    
    public static void  checkContactRole(list<Contact> con){
        
        //set For  store accountIds of current contacts
        set<id>accId=new set<id>();
		
		//list of Contacts not in  OpportunityContactRole
		List<Contact> contaListNotInOCR = new List<Contact>();
        
        //set for store contact ids from current contac list
        set<id>ConId=new set<id>();
        
        //iterate loop for add accountId and contact Id in set
        for(contact co:con){
            accId.add(co.AccountId);
            conId.add(co.Id);
             }
        
        //list of opportunity related account list
        list<Opportunity>opp=[select Id,Name from opportunity where AccountId=:accId];
        
        //set to store ids of opportunity of contact account
        set<id>oppId=new set<id>();
        for(Opportunity op:opp){
            oppId.add(op.ID);
            }
       //list of OpportunityContactRole related contact list
       list<OpportunityContactRole> roleList=[select Id,contactId from OpportunityContactRole where contactId in :ConId AND opportunityId in :oppId];
        //set to store ids of OpportunityContactRole of contact 
       set<id>cId=new set<id>();
        for(OpportunityContactRole R: roleList){
           cId.add(R.contactId);
            }
        //list of all opportunity contact role of current opportunity and contact
      
       list<contact>cont=[select id,name from contact where id=:cId];
        
        //system.debug(cont);
        //itrate over opportunity contact role list
        for(contact cnt:con){
            if(cId.Contains(cnt.Id)){
             //check if is there any opportunity contact role in list
              //dont allow to delete contact
				cnt.addError('contact cant be deleted');
            }
            else{
				contaListNotInOCR.add(cnt);
			}
        }
		if(!contaListNotInOCR.isEmpty())	delete contaListNotInOCR;
    }
}