Requirement 2 final project (draft) line 41 onwards

requirement2draft.cls

trigger StockItemTrigger on Stock_Item__c (before insert, after delete) {

	
	//*DATA SET UP*created sample records using DML via the execute annonymous window
	//stock_item__c stock = new stock_item__c (); 
    //stock.Item_Name__c = 'chocolate';
	//stock.description__c = 'i love chocolate';
    //stock.minimum_stock_level__c = 10;
	//stock.stock_on_hand__c = 10;
	//stock.list_price__c = 50;
    //insert stock;

    //*REQUIREMENT 1* Before a Stock Item can be created, check that there is not already
    // a stock item record with a matching name.
    
    //the below creates the new stockitems in a set that 
    //doesn't allow for duplicates. Trigger.new to ensure all new records created
    //for this object get added to this Set
    
    set <string> stockitems = new set <string> ();
    for (stock_item__c stock : trigger.new) {
        stockitems.add(stock.Item_Name__c);      
    }
    
    
//here we are checking for duplicates in the existing records to ensure
//we don't enter new stock items with the same name

    //SOQL query to get a list of existing stock items from the org calling for the stock name
    list <stock_item__c> stocklist = new list <stock_item__c> (
    [select id, Item_Name__c from stock_item__c where Item_Name__c in : stockitems]);
    
    
    for(stock_item__c newstock : trigger.new) {
        
        //checking if the list has a duplicate item then add the below words to the new stock item name
        if(stocklist.size() > 0)
            newstock.adderror('duplicate item' + newstock.Item_Name__c);
    }

	//*REQUIREMENT 2*Before a Stock Item is deleted, make sure that the stock on 
	//hand is at 0.  If it is not, Create a case so that someone is alerted.
	
    //checking if the record is deleted
    if(trigger.isdelete) {
     
    for (stock_item__c stockdelete : trigger.old) 
    {
      if (stockdelete.Stock_on_Hand__c <> 0) //check if stock on hand is not 0 then create a case to alert
      {
 		case c = new case ();
		c.subject = 'stock item being deleted';
        c.OwnerId = '0050Y000001lnHx';
        c.Description= 'Item_Name__c , stock_on_hand__c';
        c.Status = 'new';
        c.Origin = 'email';
        
            	    //not sure how to get the record id for the
            	    //record that's being deleted 
       insert c;     	    
      }