<apex:page controller="AssignSlabs" tabstyle="Orders__c">
<apex:form id="assignSlabs">
<apex:pageBlock mode="edit">
<p>This is a list of all available {!orderline.slab_color__r.Name} slabs for 
{!orderline.order__r.Name}. This order line requires {!quantityRemaining}  
more slabs to complete the order of {!orderQuantity} slabs.</p>
<p/>
<br/>
<apex:pageblockSection id="Slabs">
   <apex:pageblocktable align="center" value="{!slabs}" var="slab" title="Slabs" width="100%">
         <apex:column headerValue="Slab" width="15%"><apex:outputLink value="/{!slab.ID}">{!slab.Name}</apex:outputlink></apex:column>
         <apex:column headerValue="Status" width="15%" value="{!slab.Status__c}"/>
         <apex:column headerValue="Quality Rating" width="20%" value="{!slab.Quality_Rating__c}"/>
         <apex:column headerValue="Finished Date" width="10%" value="{!slab.Finished_Date__c}"/>
         <apex:column headerValue="Comments" width="30%" value="{!slab.Comments__c}"/>
         <apex:column headerValue="Assign Slab—" width="10%"><apex:inputfield value="{!slab.Assigned__c}"/></apex:column>
   </apex:pageblockTable>
</apex:pageblockSection>
<p/>
<apex:pageBlockSection id="Status">
   <apex:commandButton action="{!assign}" value="Assign Slabs" rerender="Status" id="assignSlabsButton"/>
   <apex:commandButton action="{!cancel}" value="Cancel" id="cancelButton"/>
   <apex:outputLabel value="{!errormessage}"></apex:outputLabel>
</apex:pageblockSection>
</apex:pageBlock>
</apex:form>
</apex:page>

global class AssignSlabs {
    List<Slab__c> slabs;
    Order_Line__c orderline;
    Integer orderQuantity;
    Integer quantityRemaining;
    String errormessage;
    String testMessage;
    List<String> headers;
    
    public AssignSlabs() {
        slabs = getSlabs();
        orderline = getOrderLine();
        quantityRemaining = getQuantityRemaining();
        orderQuantity = getOrderQuantity();
        headers = getHeaders();
    }
    
    public List<Slab__c> getSlabs() {
        List <Slab__c> slabs = [
            select Name, comments__c, slab_color__c, status__c, 
                finished_date__c, assigned__c, order_line__c, 
                quality_rating__c from slab__c
            where slab_color__c = :ApexPages.currentPage().getParameters().get('slabcolor') 
                AND Order_Line__c = NULL 
            order by slab_color__c, finished_date__c];
        return slabs;
    }

    public Order_Line__c getOrderLine() {
        Order_Line__c orderline = [
            select id, slab_color__r.Name, Order__r.Name, quantity__c, assigned__c 
            from order_line__c 
            where id = :ApexPages.currentPage().getParameters().get('olid')]; 
        return orderLine;
    }
    
    public Integer getQuantityRemaining() {
        Integer QuantityRemaining = 0;
        orderline.assigned__c = [select count() 
            from slab__c 
            where order_line__c = :ApexPages.currentPage().getParameters().get('olid')];
        quantityRemaining = orderLine.quantity__c.intValue() - orderline.assigned__c.intValue();
        return quantityRemaining;
    }
    
    public Integer getOrderQuantity() {
        Integer OrderQuantity = 0;
        orderQuantity = orderline.quantity__c.intValue();
        return orderQuantity;
    }
    
    public string[] getheaders() { 
         return new string [] 
              {'Slab','Status','Quality Rating','Finished Date', 
               'Comments', 'Assign Slab —'} ; 
    }    

    public String geterrorMessage() {
        return errormessage;
    }

    public PageReference assign(){ 
        Integer entries = slabs.size();
        Integer assigned = 0; // integer must be initialized or it will be null
        Boolean isError = false;
        PageReference orderlinepage = new PageReference('/' + orderLine.id);
        PageReference assignSlabs = new PageReference('/apex/AssignSlabs');                
        
        for (Integer e = 0; e < entries; e++){
            if (slabs[e].assigned__c) {
                slabs[e].order_line__c = orderline.ID;
                assigned++;
            }
        }
        if (assigned <= quantityremaining) {
                // update slab records
            try {
                update slabs;
            } catch(System.DMLException e) {
                isError = true;
                ApexPages.addMessages(e);
            }
                // update assigned count in orderline record
            orderline.assigned__c = [select count() 
                from slab__c 
                where order_line__c = :ApexPages.currentPage().getParameters().get('olid')];
            try {
                update orderline;
            } catch(System.DMLException e) {
                isError = true;
                ApexPages.addMessages(e);
                
            }
            
            return (isError) – assignSlabs:orderlinepage;
        }
        else {
            errormessage = 'You have selected too many slabs for assignment.  Your selections would assign ' + assigned + ' slabs to this order, which only requires ' + quantityRemaining + ' slabs.';
            return assignSlabs;
        }
 
    } 
        

    public PageReference cancel() {
        PageReference orderlinepage = new PageReference('/' + orderline.id);
        return orderlinepage;
    }
}