package kotlinx.coroutines.channels

import kotlinx.coroutines.*
import kotlinx.coroutines.selects.*

enum class TestChannelKind(
    val capacity: Int,
    private val description: String,
    val viaBroadcast: Boolean = false
) {
    RENDEZVOUS(0, "RendezvousChannel"),
    BUFFERED_1(1, "BufferedChannel(1)"),
    BUFFERED_2(2, "BufferedChannel(2)"),
    BUFFERED_10(10, "BufferedChannel(10)"),
    UNLIMITED(Channel.UNLIMITED, "UnlimitedChannel"),
    CONFLATED(Channel.CONFLATED, "ConflatedChannel"),
    BUFFERED_1_BROADCAST(1, "BufferedBroadcastChannel(1)", viaBroadcast = true),
    BUFFERED_10_BROADCAST(10, "BufferedBroadcastChannel(10)", viaBroadcast = true),
    CONFLATED_BROADCAST(Channel.CONFLATED, "ConflatedBroadcastChannel", viaBroadcast = true)
    ;

    fun <T> create(onUndeliveredElement: ((T) -> Unit)? = null): Channel<T> = when {
        viaBroadcast && onUndeliveredElement != null -> error("Broadcast channels to do not support onUndeliveredElement")
        viaBroadcast -> ChannelViaBroadcast(BroadcastChannel(capacity))
        else -> Channel(capacity, onUndeliveredElement = onUndeliveredElement)
    }

    val isConflated get() = capacity == Channel.CONFLATED
    override fun toString(): String = description
}

internal class ChannelViaBroadcast<E>(
    private val broadcast: BroadcastChannel<E>
): Channel<E>, SendChannel<E> by broadcast {
    val sub = broadcast.openSubscription()

    override val isClosedForReceive: Boolean get() = sub.isClosedForReceive
    override val isEmpty: Boolean get() = sub.isEmpty

    override suspend fun receive(): E = sub.receive()
    override suspend fun receiveCatching(): ChannelResult<E> = sub.receiveCatching()
    override fun iterator(): ChannelIterator<E> = sub.iterator()
    override fun tryReceive(): ChannelResult<E> = sub.tryReceive()

    override fun cancel(cause: CancellationException?) = broadcast.cancel(cause)

    // implementing hidden method anyway, so can cast to an internal class
    @Deprecated(level = DeprecationLevel.HIDDEN, message = "Since 1.2.0, binary compatibility with versions <= 1.1.x")
    override fun cancel(cause: Throwable?): Boolean = error("unsupported")

    override val onReceive: SelectClause1<E>
        get() = sub.onReceive
    override val onReceiveCatching: SelectClause1<ChannelResult<E>>
        get() = sub.onReceiveCatching
}