// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.GWT.client.widgets.datatables;

import org.litesoft.GWT.client.*;
import org.litesoft.bo.views.*;
import org.litesoft.core.util.*;

import com.google.gwt.gen2.table.client.TableModelHelper.*;

import java.util.*;

public class DeferredListTableModel<RowType extends IViewObject> extends ListTableModel<RowType> implements FetchRowsDataProviderCallBack<RowType>

{
    private VoDataProvider<RowType> mDataProvider;

    public DeferredListTableModel( VoDataProvider<RowType> pDataProvider ) {
        mDataProvider = pDataProvider;
    }

    @Override
    public void success( ImmutableArrayList<RowType> pRows ) {
        requestResponse( pRows );
    }

    @Override
    public void tooMany( long pCount ) {
        AlertManager.alert( this.getClass().getName(), "Too Many Rows", "" + pCount + " is Too Many Rows" );
        requestResponse( null );
    }

    @Override
    public void error( String pError ) {
        AlertManager.alert( this.getClass().getName(), "Error Fetching Data", pError + "\noccured when attempting to fetch the table data" );
        requestResponse( null );
    }

    protected void requestResponse( ArrayList<RowType> pList ) {
        if ( pList != null ) // Stupid Generics will not let me use a ?:
        {
            Collections.sort( mNewList = new ArrayList<RowType>( pList ) );
        } else {
            mNewList = Collections.emptyList();
        }
        updateTable();
    }

    protected void updateTable() {
        if ( (mNewList != null) && (mAsyncPending != null) ) {
            clear();
            addAll( mNewList );
            mNewList = null;
            updateRowCount();
            super.requestRows( mAsyncPending.getRequest(), mAsyncPending.getCallback() );
            mAsyncPending = null;
        }
    }

    private List<RowType> mNewList = null;
    private AsyncPending<RowType> mAsyncPending = null;

    @Override
    public void requestRows( Request pRequest, Callback<RowType> pCallback ) {
        mAsyncPending = new AsyncPending<RowType>( pRequest, pCallback );
        if ( mDataProvider != null ) {
            mDataProvider.requestAllRows( this );
        } else {
            updateTable();
        }
    }

    private static class AsyncPending<RowType> {
        private Request mRequest;
        private Callback<RowType> mCallback;

        private AsyncPending( Request pRequest, Callback<RowType> pCallback ) {
            mRequest = pRequest;
            mCallback = pCallback;
        }

        public Request getRequest() {
            return mRequest;
        }

        public Callback<RowType> getCallback() {
            return mCallback;
        }
    }
}