/*
 * Copyright 2024 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.compatui.letterbox

import com.android.wm.shell.compatui.letterbox.LetterboxControllerStrategy.LetterboxMode.MULTIPLE_SURFACES
import com.android.wm.shell.compatui.letterbox.LetterboxControllerStrategy.LetterboxMode.SINGLE_SURFACE
import com.android.wm.shell.compatui.letterbox.lifecycle.LetterboxLifecycleEvent
import com.android.wm.shell.dagger.WMSingleton
import javax.inject.Inject

/**
 * Encapsulate the logic related to the use of a single or multiple surfaces when implementing
 * letterbox in shell.
 */
@WMSingleton
class LetterboxControllerStrategy
@Inject
constructor(private val letterboxConfiguration: LetterboxConfiguration) {

    // Different letterbox implementation modes.
    enum class LetterboxMode {
        SINGLE_SURFACE,
        MULTIPLE_SURFACES,
    }

    @Volatile private var currentMode: LetterboxMode = SINGLE_SURFACE

    @Volatile private var supportsInputSurface: Boolean = false

    fun configureLetterboxMode(event: LetterboxLifecycleEvent) {
        // Decides whether to use a single surface or multiple surfaces for the letterbox.
        // The primary trade-off is memory usage versus rendering performance.
        //
        // The multi surfaces approach is only used when the activity is transparent. The single
        // surface approach is the default one because it is easier and less expensive to handle.
        // TODO(b/377875146): Improve heuristic for single/multiple surfaces
        currentMode =
            when {
                event.isBubble -> SINGLE_SURFACE
                event.isTranslucent -> MULTIPLE_SURFACES
                letterboxConfiguration.isLetterboxActivityCornersRounded() -> SINGLE_SURFACE
                else -> SINGLE_SURFACE
            }
        supportsInputSurface = event.supportsInput
    }

    /** @return The specific mode to use for implementing letterboxing for the given [request]. */
    fun getLetterboxImplementationMode(): LetterboxMode = currentMode

    /** Tells if the input surface should be created or not. This enabled reachability. */
    fun shouldSupportInputSurface(): Boolean = supportsInputSurface
}