/*
 * 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.settings.network.telephony

import android.content.Context
import android.telephony.TelephonyCallback
import android.telephony.TelephonyManager
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.asExecutor
import kotlinx.coroutines.channels.ProducerScope
import kotlinx.coroutines.channels.awaitClose
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.callbackFlow
import kotlinx.coroutines.flow.conflate
import kotlinx.coroutines.flow.flowOn

/** Creates an instance of a cold Flow for Telephony callback of given [subId]. */
fun <T> Context.telephonyCallbackFlow(
    subId: Int,
    block: ProducerScope<T>.() -> TelephonyCallback,
): Flow<T> = telephonyManager(subId).telephonyCallbackFlow(block)

/** Creates an instance of a cold Flow for Telephony callback. */
fun <T> TelephonyManager.telephonyCallbackFlow(
    block: ProducerScope<T>.() -> TelephonyCallback,
): Flow<T> = callbackFlow {
    val callback = block()

    registerTelephonyCallback(Dispatchers.Default.asExecutor(), callback)

    awaitClose { unregisterTelephonyCallback(callback) }
}.conflate().flowOn(Dispatchers.Default)

fun Context.telephonyManager(subId: Int): TelephonyManager =
    getSystemService(TelephonyManager::class.java)!!
        .createForSubscriptionId(subId)