'use static'
/*
 * Copyright (c) 2026 Huawei Device Co., Ltd.
 * 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.
 */

/**
 * @file
 * @kit AbilityKit
 */

/**
 * The module is used to listen for state changes of the current application process. For ease of description, the term
 * "application process" will be referred to as "process" in the following sections.
 * You can call
 * [ApplicationContext.on('applicationStateChange')]{@link ./application/ApplicationContext:ApplicationContext.on(type:
 * 'applicationStateChange', callback: ApplicationStateChangeCallback)}
 *  and pass in a custom ApplicationStateChangeCallback to listen for foreground/background state changes of the current
 *  process. This allows you to perform certain actions based on the process state changes, for example, tracking the
 * duration of the process in the foreground and background, or clearing memory caches when the process moves to the
 * background.
 *
 * @syscap SystemCapability.Ability.AbilityRuntime.AbilityCore
 * @stagemodelonly
 * @crossplatform
 * @atomicservice
 * @since 23 static
 */
declare interface ApplicationStateChangeCallback {
  /**
   * Called when the current process switches from the background to the foreground. When this callback is triggered, 
   * it does not mean that the process is already fully in the foreground state, but rather that it is about to enter 
   * the foreground state. At this point, operations that depend on the foreground state (such as launching another 
   * UIAbility) cannot be performed.
   *
   * @syscap SystemCapability.Ability.AbilityRuntime.AbilityCore
   * @stagemodelonly
   * @crossplatform
   * @atomicservice
   * @since 23 static
   */
  onApplicationForeground(): void;

  /**
   * Called when the current process switches from the foreground to the background. When this callback is triggered, 
   * the process is fully in the background state, and you can perform operations suitable for the background state 
   * (for example, clearing memory caches).
   *
   * @syscap SystemCapability.Ability.AbilityRuntime.AbilityCore
   * @stagemodelonly
   * @crossplatform
   * @atomicservice
   * @since 23 static
   */
  onApplicationBackground(): void;
}

export default ApplicationStateChangeCallback;