/*
 * Copyright (C) 2016/2022 Litote
 *
 * 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 org.litote.kmongo.coroutine

import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.reactive.asFlow
import kotlinx.coroutines.reactive.collect
import org.reactivestreams.Publisher
import java.util.concurrent.ConcurrentLinkedQueue

/**
 * Gets coroutine version of [Publisher].
 */
val <T: Any> Publisher<T>.coroutine: CoroutinePublisher<T> get() = CoroutinePublisher(this)

/**
 * Provides a list of not null elements from the publisher.
 */
suspend fun <T> Publisher<T>.toList(): List<T> {
    val r = ConcurrentLinkedQueue<T>()
    collect { r.add(it) }
    return r.toList()
}


/**
 * Coroutine wrapper around [Publisher].
 */
open class CoroutinePublisher<T: Any>(open val publisher: Publisher<T>) {

    /**
     * Provides a list of not null elements from the publisher.
     */
    suspend fun toList(): List<T> = publisher.toList()

    /**
     * Provides a flow of not null elements from the publisher.
     */
    fun toFlow(): Flow<T> = publisher.asFlow()

    /**
     * iterates over all elements from the publisher
     */
    suspend fun consumeEach(action: suspend (T) -> kotlin.Unit) {
        publisher.collect { action(it) }
    }
}
