public class extCaseClusters {
 public string CurrentAction;
 public Case lCase;
 public List<ClusterSelect> ClusterSelects;

 public String newUrl;
 public String setUrl(string pInit){
  this.newUrl = pInit;
  return this.newUrl;
 }

 public Map<Id, Case_Clusters__c> CaseClusters {
  public get{
   if (CaseClusters==null) {
          List<Case_Clusters__c> lClusters = [select cluster__r.Name, cluster__c, Case__c,Id from Case_Clusters__c where case__c =: this.lCase.Id order by cluster__r.Name];
          this.CaseClusters = new Map<Id, Case_Clusters__c>();
          for(Case_Clusters__c cc : lClusters) {
           if (cc.Cluster__c!=null)
           CaseClusters.put(cc.Cluster__c,cc );
          }
          //return CaseClusters;
   } 
   return CaseClusters;
  } private set;
 }
 
 public Set<Id> SelectedClusterIds { 
  get {
   Set <Id> SelectedClusterIds = new Set<Id>();
   SelectedClusterIds = CaseClusters.keySet();
   return SelectedClusterIds;
  }
 }
 
 public extCaseClusters(ApexPages.StandardController controller) {
  Case lTmpCase = (Case)controller.getRecord();
  // Retrieve all necessary attributes
  if (lTmpCase!=null) {
   this.lCase = [select ID, Account.ClusterCount__c, Account.Name, AccountId, Cluster__c, Cluster__r.Name from Case where ID=:lTmpCase.Id limit 1];
  }
  this.CurrentAction = ApexPages.currentPage().getParameters().get('a');
 }

   public ApexPages.StandardSetController setCon {
        get {
           if(setCon == null) {
             //List<Case_Clusters__c> lClusters = [select cluster__c, Id from Case_Clusters__c where case__c =: this.lCase.Id order by cluster__r.Name];
             //List<Id> lClusterIds = new List<Id>{};
             //for(Case_Clusters__c cc : lClusters) {
             // lClusterIds.add(lClusters.cluster__c);
             //}
    setCon = new ApexPages.StandardSetController(Database.getQueryLocator(
    [select Id, Name, Location__c, Federation__c, Release__c, Release__r.Name, Primary_Contact__c, Leader_Node__c from Cluster__c Where Account__c=:this.lCase.AccountId or Id in : SelectedClusterIds]));               
            }
           return setCon;
          }
        set;
   }  
 
 public Id AddedId {
  public get {
   if (AddedId==null) {
    AddedId = (Id)ApexPages.currentPage().getParameters().get('newid');
   }
   return AddedId;
  } private set;
 }

 public List<ClusterSelect> getClusterSelects() {
     // Add new cluster if one was created
     String newId = ApexPages.currentPage().getParameters().get('newid');
  if(ClusterSelects == null) {
         ClusterSelects = new List<ClusterSelect>();
         List<Cluster__c> Clusters = (List<Cluster__c>) setCon.getRecords();
         for(Cluster__c c:Clusters) {
             ClusterSelect cs = new ClusterSelect(c, (CaseClusters.containsKey(c.Id) || this.AddedId==c.Id));
             ClusterSelects.add(cs);                   
         }
     }
     return ClusterSelects;
 }
   
    public class ClusterSelect {
        public Cluster__c cc { get; private set; }
        public boolean selected { get; set; }
       
        public ClusterSelect(Cluster__c c, boolean IsSelected) {
            this.cc = c;
            this.selected = IsSelected;
        }
    }

   
    public PageReference saveClusters() {
     // Locate cluster to add/drop
     List<Case_Clusters__c> lAddLinks = new List<Case_Clusters__c>{};
     List<Id> lDropLinks = new List<Id>{};
     for (ClusterSelect cs: ClusterSelects) {
      if (cs.selected) {
       // Add if necessary
       if (!CaseClusters.containsKey(cs.cc.Id)) {
        Case_Clusters__c lCl = new Case_Clusters__c();
        lCl.Cluster__c = cs.cc.Id;
        lCl.Case__c = this.lCase.Id;
        lAddLinks.add(lCl);
       }
      } else {
       if (CaseClusters.containsKey(cs.cc.Id)) {
        // Drop if necessary
        lDropLinks.add(CaseClusters.get(cs.cc.Id).Id);
       }
      }
     }
     // Perform add
     if (lAddLinks.size()>0) {
      insert lAddLinks;
     }
     // Perform drop
     if (lDropLinks.size()>0) {
      List<Case_Clusters__c> lDropLinksCC = [select Id from Case_Clusters__c where Id in : lDropLinks];
      delete lDropLinksCC;
     }
     // Redirect to primary Cluster case assignment page
        //PageReference lPr = new PageReference('/'+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
        PageReference lPr = new PageReference('/apex/CaseCluster—id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
        lPr.setRedirect(true);
        return lPr;
    }
    
    public PageReference cancel() {
        PageReference lPr = new PageReference('/'+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
        lPr.setRedirect(true);
        return lPr;
    } 
    public PageReference createNew(){
        PageReference lPr = new PageReference('/a0F/e–CF00N30000002qbnG='+EncodingUtil.urlEncode(this.lCase.Account.Name,'UTF-8')+'&CF00N30000002qbnG_lkid='+EncodingUtil.urlEncode(this.lCase.AccountId,'UTF-8')+'&saveURL='+EncodingUtil.urlEncode('/apex/CaseClusters˜id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8')+'&retURL='+EncodingUtil.urlEncode('/apex/CaseClusters™id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8'));
        lPr.setRedirect(true);
        return lPr;
    }
    
    public boolean CaseHasValidCluster{
     get { return (this.lCase.AccountId!=null) ;}
    }
        
    public PageReference validateCaseAccount(){
     PageReference lPr = null;
     if (this.CaseHasValidCluster) {
      
      if(this.AccountClusterCount == 0) {
          lPr = new PageReference('/a0F/e?CF00N30000002qbnG='+EncodingUtil.urlEncode(this.lCase.Account.Name,'UTF-8')+'&CF00N30000002qbnG_lkid='+EncodingUtil.urlEncode(this.lCase.AccountId,'UTF-8')+'&saveURL='+EncodingUtil.urlEncode('/apex/CaseClusters?id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8')+'&retURL='+EncodingUtil.urlEncode('/apex/CaseClusters?id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8'));
          lPr.setRedirect(true);
      }
     }
        return lPr;
    }
    
    public integer AccountClusterCount {
     get {
   if (AccountClusterCount==null) {
    AccountClusterCount = [select count() from Cluster__c Where Account__c=:this.lCase.AccountId or Id in : SelectedClusterIds];
   }
   return AccountClusterCount;      
     }
     set;
    }

    // Return currently selected clusters
 public List<SelectOption> getCaseClustersSelect() {
  List<SelectOption> options = new List<SelectOption>();
  List<Case_Clusters__c> cc = this.CaseClusters.Values();
  for (Case_Clusters__c c:cc) {
   options.add(new SelectOption(c.Cluster__c,c.cluster__r.Name));
  }
  return options;
 }
 // Case primary cluster attribute
 public Id primaryCaseCluster {
  get {
   if (primaryCaseCluster==null) {
    primaryCaseCluster = this.lCase.Cluster__c;
   }
   return primaryCaseCluster;
  }
  set;
 }
 
 public PageReference savePrimaryCluster() {
  if (this.primaryCaseCluster != this.lCase.Cluster__c) {
   this.lCase.Cluster__c = this.primaryCaseCluster;
   update this.lCase;
  }
     // Redirect to primary Cluster case assignment page
        PageReference lPr = new PageReference('/'+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
        lPr.setRedirect(true);
        return lPr; 
 }
 
    public PageReference editClusters(){
        PageReference lPr = new PageReference('/apex/CaseClusters?Id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
        lPr.setRedirect(true);
        return lPr;
    }
    
    public PageReference validatePrimaryCluster() {
     PageReference lPr = null;
     integer selectedClusterCount = this.CaseClusters.size();
     if (selectedClusterCount==0) {
      // If no clusters are available for account, create a cluster, otherwise go to cluste selection
      //integer AccountClusterCount = [select count() from Cluster__c Where Account__c=:this.lCase.AccountId or Id in : SelectedClusterIds];
      if (AccountClusterCount > 0) {
          lPr = new PageReference('/apex/CaseClusters?Id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
      } else {
          lPr = new PageReference('/a0F/e?CF00N30000002qbnG='+EncodingUtil.urlEncode(this.lCase.Account.Name,'UTF-8')+'&CF00N30000002qbnG_lkid='+EncodingUtil.urlEncode(this.lCase.AccountId,'UTF-8')+'&saveURL='+EncodingUtil.urlEncode('/apex/CaseClusters?id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8')+'&retURL='+EncodingUtil.urlEncode('/apex/CaseClusters?id='+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'),'UTF-8'));
         }
         lPr.setRedirect(true);
     } else if (selectedClusterCount==1) {
      Case_Clusters__c c = this.CaseClusters.Values()[0];
      // If the primary case cluster is different from the avaiable cluster, change the primary on the case
      if (c.Cluster__c != this.lCase.Cluster__c) {
       this.lCase.Cluster__c = c.Cluster__c;
       update this.lCase; 
      }
      // in either case go back to case
      lPr = new PageReference('/'+EncodingUtil.urlEncode(this.lCase.Id,'UTF-8'));
      lPr.setRedirect(true);
     }
     return lPr;
    }
 
 // Test this object
    static testMethod void testCaseClusters() {
        // Test registration creation
        // Create an account
        Account a = new Account();
        a.Name = 'Test Cluster Account';
        insert a;
        //Create a contact
        Contact c = new Contact();
        c.AccountId = a.Id;
        c.FirstName = 'John';
        c.LastName = 'Doe'; 
        insert c;
        // Create a case
        Case theCase = new Case();
        theCase.AccountId = a.Id;
        theCase.Subject = 'Testing clusters';
        theCase.contactid = c.id;
        insert theCase;
        
  // Check validity before cluster exists for account
        ApexPages.StandardController sc = new ApexPages.StandardController(theCase);
        extCaseClusters cc = new extCaseClusters(sc);
  cc.validatePrimaryCluster();
  
        // Create a cluster
        Cluster__c theCLuster = new Cluster__c();
        theCluster.Name = 'New Prod Cluster';
        theCluster.account__c = a.Id;
        insert theCluster;
        
  // Check validity after cluster exists for account
  cc.validatePrimaryCluster();
        // Reset the session
        cc = null;
        sc = null;
        
        // Start the extension page
        sc = new ApexPages.StandardController(theCase);
        cc = new extCaseClusters(sc);
        // Set the cluster new ID
        ApexPages.currentPage().getParameters().put('newid',(String)theCluster.Id);
        // Get the list of clusters for account
        List<ClusterSelect> csel = cc.getClusterSelects();
        System.assertEquals(csel[0].selected,true);
        // Save the case cluster record, adding a case cluster record
        PageReference pr = cc.saveClusters();
        
        // Check primaryPage Validity - assign current Cluster to case details
        cc.validatePrimaryCluster();
        // Save the case cluster record, deleting a case cluster record
        csel[0].selected = false;
        System.assertNotEquals(csel[0].selected,true);
        pr = cc.saveClusters();
  // Test misc. actions
        pr = cc.cancel();
        pr = cc.createNew();
        pr = cc.editClusters();
        
        // Add a second cluster
        // Create a cluster
        Cluster__c theCLuster2 = new Cluster__c();
        theCluster2.Name = 'New Prod Cluster 2';
        theCluster2.account__c = a.Id;
        insert theCluster2;
        
        sc = new ApexPages.StandardController(theCase);
        cc = new extCaseClusters(sc);
        csel = cc.getClusterSelects();
        for (ClusterSelect cSelItem : cSel) {
         cSelItem.selected = true;
        }
        pr = cc.saveClusters();
        // Now do the primary cluster tests
        List<SelectOption> scs = cc.getCaseClustersSelect();
        cc.primaryCaseCluster =  theCluster2.Id;
        pr = cc.savePrimaryCluster();
        pr = cc.validateCaseAccount();
        
        // test the delete trigger for Case_Clusters
        delete theCluster2;
        
    }

}

<apex:page standardController="case" extensions="extCaseClusters" action="{!validateCaseAccount}">
<apex:sectionHeader title="Case {!Case.CaseNumber}" subtitle="Select the primary clusters for the case" description="Case Subject: {!Case.Subject}" />
 <apex:form id="theForm">
 <apex:pageBlock rendered="{!(!CaseHasValidCluster)}">
 <apex:pageBlockSection columns="4">   
 The case does not have an account assigned. Please assign an account before editing the related clusters.
   </apex:pageBlockSection>
 </apex:pageBlock>
 <apex:pageBlock rendered="{!CaseHasValidCluster}">
 <apex:pageBlockButtons >
     <apex:commandButton action="{!saveClusters}" value="Save" />
     <apex:commandButton action="{!cancel}" value="Cancel" />
     <apex:commandButton action="{!createNew}" value="Create New Cluster" />
   </apex:pageBlockButtons>
   <apex:pageBlockTable value="{!ClusterSelects}" var="s" id="list">
    <apex:column ><apex:facet name="header">Select</apex:facet><apex:inputCheckbox value="{!s.selected}" /></apex:column>
    <apex:column ><apex:facet name="header">Reference</apex:facet><apex:outputLink value="/{!s.cc.Id}">{!s.cc.Name}</apex:outputLink></apex:column>
    <apex:column ><apex:facet name="header">Location</apex:facet><apex:outputLink value="/{!s.cc.Id}">{!s.cc.Location__c}</apex:outputLink></apex:column>
    <apex:column ><apex:facet name="header">Release</apex:facet><apex:outputfield value="{!s.cc.Release__c}" /></apex:column>
    <apex:column ><apex:facet name="header">Leader Node</apex:facet><apex:outputLink value="/{!s.cc.Id}">{!s.cc.Leader_Node__c}</apex:outputLink></apex:column>
    <apex:column ><apex:facet name="header">Federation</apex:facet><apex:inputCheckbox disabled="true" value="{!s.cc.Federation__c}" /></apex:column>
    <apex:column ><apex:facet name="header">Primary Contact</apex:facet><apex:outputField value="{!s.cc.Primary_Contact__c}" /></apex:column>
   </apex:pageBlockTable>
   <apex:panelGrid columns="5">
    <apex:commandLink action="{!setCon.previous}">Previous</apex:commandlink>
     <apex:commandLink action="{!setCon.next}">Next</apex:commandlink>
   </apex:panelGrid>
 </apex:pageBlock>
  </apex:form>
</apex:page>

    public PageReference createNew(){
     Cluster__c theNewCluster = new Cluster__c();
     theNewCluster.Account__c = this.lCase.AccountId;
     return (new ApexPages.StandardController(theNewCluster)).edit();
    }