// Copyright 2012 Google Inc. All Rights Reserved.
//
// 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.collide.client.util;

import com.google.gwt.core.client.Scheduler;

/**
 * Executor of a cancellable scheduled command.
 */
public abstract class ScheduledCommandExecutor {

  private boolean scheduled;
  private boolean cancelled;

  private final Scheduler.ScheduledCommand scheduledCommand = new Scheduler.ScheduledCommand() {

    @Override
    public void execute() {
      scheduled = false;

      if (cancelled) {
        return;
      }

      ScheduledCommandExecutor.this.execute();
    }
  };

  protected abstract void execute();

  public void scheduleFinally() {
    cancelled = false;

    if (!scheduled) {
      scheduled = true;
      Scheduler.get().scheduleFinally(scheduledCommand);
    }
  }

  public void scheduleDeferred() {
    cancelled = false;

    if (!scheduled) {
      scheduled = true;
      Scheduler.get().scheduleDeferred(scheduledCommand);
    }
  }

  public void cancel() {
    cancelled = true;
  }
}
