/*
 * Copyright (C) 2023 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.systemui.util.kotlin

import com.android.systemui.lifecycle.repeatWhenAttached
import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.CoroutineStart
import kotlinx.coroutines.DisposableHandle
import kotlinx.coroutines.Job
import kotlinx.coroutines.awaitCancellation
import kotlinx.coroutines.launch

/**
 * Suspends to keep getting updates until cancellation. Once cancelled, mark this as eligible for
 * garbage collection.
 *
 * This utility is useful if you want to bind a [repeatWhenAttached] invocation to the lifetime of a
 * coroutine, such that cancelling the coroutine cleans up the handle. For example:
 * ```
 * myFlow.collectLatest { value ->
 *     val disposableHandle = myView.repeatWhenAttached { doStuff() }
 *     doSomethingWith(value)
 *     // un-bind when done
 *     disposableHandle.awaitCancellationThenDispose()
 * }
 * ```
 */
suspend fun DisposableHandle.awaitCancellationThenDispose() {
    try {
        awaitCancellation()
    } finally {
        dispose()
    }
}

/**
 * This will [launch], run [onLaunch] to get a [DisposableHandle], and finally
 * [awaitCancellationThenDispose][DisposableHandle.awaitCancellationThenDispose]. This can be used
 * to structure self-disposing code which attaches listeners, for example in ViewBinders:
 * ```
 * suspend fun bind(view: MyView, viewModel: MyViewModel) = coroutineScope {
 *     launchAndDispose {
 *         view.setOnClickListener { viewModel.handleClick() }
 *         DisposableHandle { view.setOnClickListener(null) }
 *     }
 * }
 * ```
 */
inline fun CoroutineScope.launchAndDispose(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    crossinline onLaunch: () -> DisposableHandle
): Job = launch(context, start) { onLaunch().awaitCancellationThenDispose() }