/*
 * Copyright (C) 2025 The Android Open Source Project
 *
 * 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.android.wm.shell.desktopmode

import android.os.IBinder
import android.view.Display.INVALID_DISPLAY
import android.view.SurfaceControl
import android.window.DesktopExperienceFlags
import android.window.TransitionInfo
import android.window.TransitionRequestInfo
import android.window.WindowContainerTransaction
import com.android.wm.shell.sysui.ShellInit
import com.android.wm.shell.transition.Transitions

/**
 * Handler to animate the transition from disconnecting a display.
 *
 * TODO: b/391652399 Consider moving this out of desktop package as it becomes less
 *   desktop-specific.
 */
class DisplayDisconnectTransitionHandler(val transitions: Transitions, shellInit: ShellInit) :
    Transitions.TransitionHandler {

    private val pendingTransitions = mutableSetOf<IBinder>()

    init {
        shellInit.addInitCallback({ onInit() }, this)
    }

    private fun onInit() {
        transitions.addHandler(this)
    }

    fun addPendingTransition(transition: IBinder) = pendingTransitions.add(transition)

    override fun startAnimation(
        transition: IBinder,
        info: TransitionInfo,
        startTransaction: SurfaceControl.Transaction,
        finishTransaction: SurfaceControl.Transaction,
        finishCallback: Transitions.TransitionFinishCallback,
    ): Boolean {
        if (!pendingTransitions.contains(transition)) return false
        // TODO: b/391652399 - Animate transitions
        startTransaction.apply()
        finishCallback.onTransitionFinished(null)
        pendingTransitions.remove(transition)
        return true
    }

    override fun handleRequest(
        transition: IBinder,
        request: TransitionRequestInfo,
    ): WindowContainerTransaction? {
        // Fallback method; if no other handler takes the transition, we still need to tell
        // this one to handle the animation later. Currently this is possible on a device
        // that supports multi-display but does not support desktop mode, as
        // DesktopTasksController will not handle the disconnect request.
        val displayChange = request.displayChange ?: return null
        if (
            DesktopExperienceFlags.ENABLE_DISPLAY_DISCONNECT_INTERACTION.isTrue &&
                displayChange.disconnectReparentDisplay != INVALID_DISPLAY
        ) {
            addPendingTransition(transition)
        }
        // Return null since another handler may want to make specific task changes.
        return null
    }
}