New lastWithTimeoutOrNull

package com.android.settingslib.spa.testutils

import kotlinx.coroutines.flow.Flow

import kotlinx.coroutines.flow.first

import kotlinx.coroutines.flow.firstOrNull

import kotlinx.coroutines.flow.toList

import kotlinx.coroutines.withTimeoutOrNull

/**

 * Collects the first element emitted by this flow within a given timeout.

 *

 * If the flow emits a value within the given timeout, this function returns that value. If the

 * timeout expires before the flow emits any values, this function returns null.

 *

 * This function is similar to [kotlinx.coroutines.flow.firstOrNull], but it adds a timeout to

 * prevent potentially infinite waiting.

 *

 * @param timeMillis The timeout in milliseconds. Defaults to 500 milliseconds.

 * @return The first element emitted by the flow within the timeout, or null if the timeout expires.

 */

suspend fun <T> Flow<T>.firstWithTimeoutOrNull(timeMillis: Long = 500): T? =

    withTimeoutOrNull(timeMillis) {

        first()

    }

    withTimeoutOrNull(timeMillis) { firstOrNull() }

/**

 * Collects elements from this flow for a given time and returns the last emitted element, or null

 * if the flow did not emit any elements.

 *

 * This function is useful when you need to retrieve the last value emitted by a flow within a

 * specific timeframe, but the flow might complete without emitting anything or might not emit a

 * value within the given timeout.

 *

 * @param timeMillis The timeout in milliseconds. Defaults to 500ms.

 * @return The last emitted element, or null if the flow did not emit any elements.

 */

suspend fun <T> Flow<T>.lastWithTimeoutOrNull(timeMillis: Long = 500): T? =

    toListWithTimeout(timeMillis).lastOrNull()

suspend fun <T> Flow<T>.toListWithTimeout(timeMillis: Long = 500): List<T> {

    val list = mutableListOf<T>()

    return withTimeoutOrNull(timeMillis) {

        toList(list)

    } ?: list

/**

 * Collects elements from this flow into a list with a timeout.

 *

 * This function attempts to collect all elements from the flow and store them in a list. If the

 * collection process takes longer than the specified timeout, the collection is canceled and the

 * function returns the elements collected up to that point.

 *

 * @param timeMillis The timeout duration in milliseconds. Defaults to 500 milliseconds.

 * @return A list containing the collected elements, or an empty list if the timeout was reached

 *   before any elements were collected.

 */

suspend fun <T> Flow<T>.toListWithTimeout(timeMillis: Long = 500): List<T> = buildList {

    withTimeoutOrNull(timeMillis) { toList(this@buildList) }

}