/*
 * Copyright 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.gen2.table.client;

import com.google.gwt.gen2.event.shared.*;
import com.google.gwt.gen2.table.event.client.*;

/**
 * A mutable version of the {@link TableModel} that supports inserting and
 * removing rows and setting cell data.
 *
 * @param <RowType> the data type of the row values
 */
public abstract class MutableTableModel<RowType> extends TableModel<RowType> implements HasRowInsertionHandlers,
                                                                                        HasRowRemovalHandlers,
                                                                                        HasRowValueChangeHandlers<RowType> {
    public HandlerRegistration addRowInsertionHandler( RowInsertionHandler handler ) {
        return addHandler( RowInsertionEvent.TYPE, handler );
    }

    public HandlerRegistration addRowRemovalHandler( RowRemovalHandler handler ) {
        return addHandler( RowRemovalEvent.TYPE, handler );
    }

    public HandlerRegistration addRowValueChangeHandler( RowValueChangeHandler<RowType> handler ) {
        return addHandler( RowValueChangeEvent.TYPE, handler );
    }

    /**
     * Insert a row and increment the row count by one.
     *
     * @param beforeRow the row index of the new row
     *                  TODO (jlabanca): should this require a row value?
     */
    public void insertRow( int beforeRow ) {
        if ( onRowInserted( beforeRow ) ) {
            // Fire listeners
            fireEvent( new RowInsertionEvent( beforeRow ) );

            // Increment the row count
            int numRows = getRowCount();
            if ( numRows != UNKNOWN_ROW_COUNT ) {
                setRowCount( numRows + 1 );
            }
        }
    }

    /**
     * Remove a row and decrement the row count by one.
     *
     * @param row the row index of the removed row
     */
    public void removeRow( int row ) {
        if ( onRowRemoved( row ) ) {
            // Fire listeners
            fireEvent( new RowRemovalEvent( row ) );

            // Decrement the row count
            int numRows = getRowCount();
            if ( numRows != UNKNOWN_ROW_COUNT ) {
                setRowCount( numRows - 1 );
            }
        }
    }

    /**
     * Set a new row value.
     *
     * @param row      the row index
     * @param rowValue the new row value at this row
     */
    public void setRowValue( int row, RowType rowValue ) {
        if ( onSetRowValue( row, rowValue ) ) {
            // Fire the listeners
            fireEvent( new RowValueChangeEvent<RowType>( row, rowValue ) );

            // Update the row count
            int numRows = getRowCount();
            if ( numRows != UNKNOWN_ROW_COUNT && row >= numRows ) {
                setRowCount( row + 1 );
            }
        }
    }

    /**
     * Event fired when a row is inserted. Returning true will increment the row
     * count by one.
     *
     * @param beforeRow the row index of the new row
     *
     * @return true if the action is successful
     */
    protected abstract boolean onRowInserted( int beforeRow );

    /**
     * Event fired when a row is removed. Returning true will decrement the row
     * count by one.
     *
     * @param row the row index of the removed row
     *
     * @return true if the action is successful
     */
    protected abstract boolean onRowRemoved( int row );

    /**
     * Event fired when the local data changes. Returning true will ensure that
     * the row count is at least as one greater than the row index.
     *
     * @param row      the row index
     * @param rowValue the new row value at this row
     *
     * @return true if the action is successful
     */
    protected abstract boolean onSetRowValue( int row, RowType rowValue );
}