public with sharing class CCW_ContactPaginationController {
 
  //URL Passing Parameters. 
  String PageContractId = ApexPages.currentPage().getParameters().get('ContractId');     
  String PageAccountId  = ApexPages.currentPage().getParameters().get('AccountId');   
 
  public Asset   GetAccount{get;set;}
  public Asset   GetContract{get;set;} 
  public Asset   GetExpireDate{get;set;}
  public Asset   GetReseller{get;set;}
  public Asset   GetDistributor{get;set;}
  public String  IncumbentReseller{get;set;}
  public String  Education{get;set;}
  public Asset   GetOpportunity{get;set;}
  public Asset   GetNewOpportunity{get;set;}
  public String  ExpireTerms{get;set;}
  public boolean bundsprt{get;set;}
  public boolean Monthly_Quote {get;set;}
  
  //Our collection to class/wrapper objects wrapAsset
  public List<CCWRowItem> wrapAssetList {get; set;}
  public List<Asset> selectedAssets{get;set;} 
   /*
    *   item in context from the page
    */
    public String contextItem{get;set;}
    public String contextItem2{get;set;}
 
 
    /*
    *   set controller
    */
    private ApexPages.StandardSetController setCon;
    
    
    /*
    *   the contact ids selected by the user
    */
    private Set<Id> selectedContactIds;
    private Set<Id> selectedContactIds2= new set<Id>();
    
    
    /*
    *   constructor
    */
    public CCW_ContactPaginationController ()
    {
      GetAccount = new Asset();    //Get Account Id from Page 
      GetContract = new Asset();   //Get Contract Name from Page   
      GetExpireDate = new Asset();   // Date Picker   
      GetReseller = new Asset(); 
      GetDistributor = new Asset();  
      GetOpportunity = new Asset();   // Get Opportunity Id 
      GetNewOpportunity = new Asset();  // Get New Opportunity Name    
      fetch_data();        
     }
    
       
   public void fetch_data ()
   {
       
        //init variable
        this.selectedContactIds= new Set<Id>();
        //gather data set        
      Try 
       {  
       if ( GetAccount.AccountId == NULL && GetContract.Name == NULL )   
        {   
         if ( PageAccountId != NULL && PageContractId == NULL )
         {
          this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = :PageAccountId Order by Service_End_Date_Max__c Desc Limit 1000] );
         }
         else if ( PageAccountId == NULL && PageContractId != NULL )
         {
         Contract C;
         C = [SELECT Name FROM Contract WHERE Id = :PageContractId Limit 1]; 
         this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE last_contract_number__c = :C.Name Order by Service_End_Date_Max__c Desc Limit 1000] );
         }
         else 
         { 
         this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = '0013000000DULXG' Order by Service_End_Date_Max__c Desc Limit 1000] );                                            
         }
        }
      else if ( GetAccount.AccountId != NULL && GetContract.Name == NULL )   
        {
         this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = :GetAccount.AccountId Order by Service_End_Date_Max__c Desc Limit 1000] ); 
        } 
       else if ( GetAccount.AccountId == NULL && GetContract.Name != NULL )
        { 
        this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE last_contract_number__c  = :GetContract.Name Order by Service_End_Date_Max__c Desc Limit 1000] );
        } 
       else if ( GetAccount.AccountId != NULL && GetContract.Name != NULL ) 
        {
        this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = :GetAccount.AccountId and last_contract_number__c = :GetContract.Name  Order by Service_End_Date_Max__c Desc  Limit 1000] );
        } 
       else 
        { 
        this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = '0013000000DULXG' Order by Service_End_Date_Max__c Desc Limit 1000] );                                            
        }    
      }
      
      catch(Exception e) {  
       this.setCon = new ApexPages.StandardSetController( [SELECT Id, AccountId,Product2Id,SerialNumber,last_contract_number__c,Service_Start_Date_Min__c, Service_End_Date_Max__c,InstallDate,Bundle_Support__c FROM Asset WHERE AccountId = '0013000000DULXG' Order by Service_End_Date_Max__c Desc Limit 1000] );                                            
        }            
       
        if(this.setCon != null){                                        
        this.setCon.setpageNumber(1);
        this.setCon.setPageSize(25);
        }
   } 
   
       
    /*
    *   handle item selected
    */
    public void doSelectItem(){        
        this.selectedContactIds.add(this.contextItem);        
    }
    
    public void doSelectItem2(){        
        this.selectedContactIds2.add(this.contextItem2);        
    }
    
    
    /*
    *   handle item deselected
    */
    public void doDeselectItem(){        
        this.selectedContactIds.remove(this.contextItem);        
    }
    
    public void doDeselectItem2(){        
        this.selectedContactIds2.remove(this.contextItem2);        
    }
    
    
    /*
    *   return count of selected items
    */
    public Integer getSelectedCount(){
        
        return this.selectedContactIds.size();
        
    }
    
    
    /*
    *   advance to next page
    */
    public void doNext(){        
        if(this.setCon.getHasNext())
            this.setCon.next();
          }     
    
    
    /*
    *   advance to previous page
    */
    public void doPrevious(){        
        if(this.setCon.getHasPrevious())
            this.setCon.previous();          
    }
    
    //public List<CCWRowItem> rows = new List<CCWRowItem>();
    
    public List<CCWRowItem> rows {get; set;}
    /*
    *   return current page of groups
    */
    public List<CCWRowItem> getContacts(){        
       try  
        {
        rows = new List<CCWRowItem>();      
        
        for(sObject r : this.setCon.getRecords()){
            Asset c = (Asset)r;
            
            CCWRowItem row = new CCWRowItem(c);
            if(this.selectedContactIds.contains(c.Id)){
                row.IsSelected=true;
                if (this.selectedContactIds2.contains(c.Id)){
                    row.BundelSelected=true;
                    bundsprt=true;
                }
                else {
                    row.BundelSelected=false;
                    bundsprt=false;
                }

            }
            else {
                row.IsSelected=false;
            }
            rows.add(row);            
        }
                
        return rows;
        }
        catch(Exception e) { 
           return null;
             }
        
    }
  
 // Store Selected Records to Object/Table
 public void processSelected() {
    Integer currentPageNumber = setCon.getPageNumber();
    selectedAssets = new List<Asset>();
    list<Temp_Assets__c> TempAssetList = new list<Temp_Assets__c>();  
        
      
     setCon.setpageNumber(1);
     

while(true){
    List<Asset>  TempAssetLists = (List<Asset>)setCon.getRecords();
    for(Asset assetIns : TempAssetLists  ) {
          if(this.selectedContactIds.contains(assetIns.Id)){
             selectedAssets.add(assetIns);
             
             
           }
     }
 if(setCon.getHasNext()){
  setCon.next();
  }
  else{
  break;
  } 
   
}  
        /**********Added by Unnat*********************************/
        //below code should only execute if Expiry term has a value
        Date maxDate=Date.valueOf('2000-1-1');
        Date minDate;
        
        //Calculate the maximum Date off of the selected dates
      
        //finds the latest expiry date out of the selected assets
        for (Asset assets: selectedAssets) {
            if(assets.Service_End_Date_Max__c > maxDate) {
                maxDate=assets.Service_End_Date_Max__c;
            }
        }
        System.debug('== Latest Service end Date is:'+ maxDate);
        minDate = maxDate;
        for (Asset assets: selectedAssets) {
            if(minDate > assets.Service_End_Date_Max__c) {
                minDate=assets.Service_End_Date_Max__c;
            }
        }
        System.debug('== Least Service end Date is:'+ minDate);
        
          
        //Validations 
        if ((selectedAssets.size() < 1 ) || (expireTerms == '0' && GetExpireDate.Expire_Date__c== null )|| (expireTerms != '0' && GetExpireDate.Expire_Date__c!= null ) || (GetDistributor.Primary_Distributor__c == null ) || (GetReseller.Primary_Reseller__c == null ) || (GetOpportunity.Opportunity__c==null && GetNewOpportunity.New_Opportunity__c== null ) || (GetOpportunity.Opportunity__c!=null && GetNewOpportunity.New_Opportunity__c!= null )|| (GetExpireDate.Expire_Date__c < maxDate )) {
        //Validates that atleast one of the assets is selected from the install base
        if(selectedAssets.size() < 1 ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Please select atleast one Asset to renew from the Install Base.'));
        }
        //Validates that atleast one of the Expiry Dates needs to have a value
        if(expireTerms == '0' && GetExpireDate.Expire_Date__c== null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Please enter the Expiry Term or Expiry Date for the selected Assets.'));
        }
        //Valation that only of the Expirty Dates can have a value
        else if(expireTerms != '0' && GetExpireDate.Expire_Date__c!= null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'You can enter a value either in Expiry Date or Expiry Term, but not in both.'));
        }
        //Validation that the Distributor Name is required
        if(GetDistributor.Primary_Distributor__c == null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Please enter a value in Distributor'));
        }
        //Validation that Reseller Name is required
        if(GetReseller.Primary_Reseller__c == null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Please enter a value in Reseller'));
        } 
        //Validation that atleast one Opportunity needs to have a value
        if(GetOpportunity.Opportunity__c==null && GetNewOpportunity.New_Opportunity__c== null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Please enter a value in either of the Opportunity'));
        }
        //Validation that only one of the Opportunities can have a value
        else if(GetOpportunity.Opportunity__c!=null && GetNewOpportunity.New_Opportunity__c!= null ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'You can enter a value either in Opportunity or New Opportunity, but not in both.'));
        }
        //Validation that will check if the Expiry Date has value less than the selected Asset Service End Date
        if(GetExpireDate.Expire_Date__c < maxDate ){
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Expiry Date that you entered is lower than Service End Date of the Asset'));
        }
        }
        else {
        //below code should only execute if Expiry term has a value
        //Date maxDate=Date.valueOf('2000-1-1');
        //Calculate the maximum Date off of the selected dates
        
        if (ExpireTerms !=null) {
        System.debug('== Expire Terms has a value');
            //finds the latest expiry date out of the selected assets
           /***************************moved this upwards*********************************** 
           for (Asset assets: selectedAssets) {
                if(assets.Service_End_Date_Max__c > maxDate) {
                    maxDate=assets.Service_End_Date_Max__c;
                }
            }
            System.debug('== Latest Service end Date is:'+ maxDate);
            
            //Validation that will check if the Expiry Date has value less than the selected Asset Service End Date
            if(GetExpireDate.Expire_Date__c < maxDate ){
                ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Expiry Date that you entered is lower than Service End Date of the Asset'));
            }
            *********************************************************************************/
            //There will be another condition to add the expiry term to the latest expiry date
            //String a='1 Year';
            System.debug('== ExpireTerms is: '+ ExpireTerms);
            if (ExpireTerms=='1') {
                System.debug('== First if condition');
                maxDate=maxDate.addYears(1);
            }
            else if (ExpireTerms == '3') {
            System.debug('== Second if condition');
                maxDate=maxDate.addYears(3);
            }
            else if (ExpireTerms == '5') {
            System.debug('== third if condition');
                maxDate=maxDate.addYears(5);
            }
            else {
                maxDate= GetExpireDate.Expire_Date__c; 
            }
        }
        else {
        System.debug('== Else condition');
            maxDate= GetExpireDate.Expire_Date__c;   
        } 
        System.debug('== Max Date is: ' + maxDate);
        Integer totalDays = minDate.daysBetween(maxDate); 
        System.debug('== Total days difference is: '+ totalDays);
        /****************Completed by Unnat*****************************/
        
        //checks if the Monthly Quote is going to be more than 36 months and Monthly Quote Checkbox is selected
        /*if (totalDays > 1080 && Monthly_Quote == true ) {
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.Error,'Since the Renewals in Months is more than 3 years, please uncheck the Monthly Quote checkbox'));
        }
        else {*/        
            System.debug('=- after the if condition');           
            Account ResellerAct; 
            Account DistributorAct;  
            Opportunity Oppt;           
                                
            for(Asset Act : selectedAssets)
            {               
                Temp_Assets__c TempAsset = new Temp_Assets__c();
                TempAsset.Name = 'Sudhir';
                TempAsset.AccountId__c = Act.AccountId;
                TempAsset.Product__c = Act.Product2Id;
                //Added by Unnat
                TempAsset.Product_lookup__c= Act.Product2Id;
                TempAsset.Asset_Id__c = Act.Id;
                TempAsset.Serial_Number__c = Act.SerialNumber;
                TempAsset.Last_Contract_Number__c = Act.last_contract_number__c; 
                TempAsset.Service_Start_Date__c = Act.Service_Start_Date_Min__c;
                
                //TempAsset.Service_End_Date__c = Act.Service_End_Date_Max__c;
                /***************Added by Unnat********************************************/
                TempAsset.Opp_Close_Date__c = minDate;
                TempAsset.Monthly_Quote__c = Monthly_Quote;
                System.debug('=- Monthly Quote is: ' + monthly_Quote);
                
                if (Act.Service_End_Date_Max__c != null) {
                    TempAsset.Service_End_Date__c = Act.Service_End_Date_Max__c;
                }
                else {
                    TempAsset.Service_End_Date__c = Act.InstallDate;
                }
                
                TempAsset.Install_Date__c = Act.InstallDate;  
                System.debug ('==== Reseller id is: '+ GetReseller.Primary_Reseller__c);
                TempAsset.Reseller__c = GetReseller.Primary_Reseller__c;
                TempAsset.Distributor__c = GetDistributor.Primary_Distributor__c;
                
                /****************Commented by Unnat****************************************************************************
                
                If (GetReseller.AccountId <> NULL) 
                {      
                ResellerAct = [ SELECT Id FROM Account WHERE ID = :GetReseller.Primary_Reseller__c Limit 1];
                TempAsset.Reseller__c = ResellerAct.Id;      
                 System.debug ('==== Reseller id 2 is: '+ ResellerAct.Id);        
                }
               
                If (GetDistributor.AccountId <> NULL )
                {
                DistributorAct = [ SELECT Id FROM Account WHERE ID = :GetDistributor.Primary_Distributor__c Limit 1];
                TempAsset.Distributor__c = DistributorAct.Id;
                }
                
                ****************Completed by Unnat *****************************************************************************/
                If ( GetOpportunity.Opportunity__c <> NULL )
                {
                Oppt = [SELECT Id FROM Opportunity WHERE ID = :GetOpportunity.Opportunity__c Limit 1];
                TempAsset.Existing_Opportunity__c = Oppt.Id;
                }                
                TempAsset.Incumbent_Reseller__c = IncumbentReseller;
                TempAsset.Education__c = Education; 
                //TempAsset.Expiry_Date__c = GetExpireDate.Expire_Date__c;
                TempAsset.Expiry_Date__c= maxDate;
                
                TempAsset.New_Opportunity__c = GetNewOpportunity.New_Opportunity__c;
                TempAsset.Expiry_Term__c = ExpireTerms;
                
                /* Insert Bundel Checkbox Value */                
                if (this.selectedContactIds2.contains(Act.Id)){
                    bundsprt=true;
                }
                else {
                    bundsprt=false;
                }
                
                
                TempAsset.Bundle_Support__c = bundsprt; 
                System.debug('== Bundle Value is: ' + bundsprt);
                
                             //Add the selected Assets to the List
                TempAssetList.add(TempAsset);
            }
                
            Insert TempAssetList;                            
            Redirect();
            
       // } //end of if Condition for check of days more than 3 years
       }
        setCon.setpageNumber(currentPageNumber);
        
    }
    
public pagereference Redirect()
   {

     PageReference pageref = new PageReference('/006m0000002MqNf');   //instead of hardcoded id you can mention opp id by using query
     pageref.setRedirect(true); 
     return pageref;
    }
      
    
    /*
    *   return whether previous page exists
    */
    public Boolean getHasPrevious(){       
       try  
        {
        return this.setCon.getHasPrevious();         
        }
        catch(Exception e) { 
           return false;
             }
    }
    
    
    /*
    *   return whether next page exists
    */
    public Boolean getHasNext(){       
    try  
        {
        return this.setCon.getHasNext();
        }
      catch(Exception e) { 
           return false;
             }
    }

    
    /*
    *   return page number
    */
    public Integer getPageNumber(){   
    try  
        {     
        return this.setCon.getPageNumber();        
    }
    catch(Exception e) { 
           return 1;
             }
    }

    
    /*
    *    return total pages
    */
    Public Integer getTotalPages(){
    Decimal totalSize;
    Decimal pageSize;
    Decimal pages;
    try  
        { 
          totalSize = this.setCon.getResultSize();
          pageSize = this.setCon.getPageSize();      
          pages = totalSize/pageSize;
          return (Integer)pages.round(System.RoundingMode.CEILING);      
        }
         catch(Exception e) { 
           return 1;
             }
    }

 
    
    /*
    *   helper class that represents a row
    */
    public with sharing class CCWRowItem{
        
        public Asset tContact{get;set;}
        public Boolean IsSelected{get;set;}
        public Boolean BundelSelected{get;set;}
         
        public CCWRowItem(Asset c){
            this.tContact=c;            
            this.IsSelected=false;
            this.BundelSelected=false;
        }
        
    } 
  
       
     
    
}

Thanks
Sudhir