@file:OptIn(ExperimentalJsExport::class)

package nl.astraeus.vst.chip.midi

import kotlinx.browser.window
import org.khronos.webgl.Uint8Array
import org.w3c.dom.BroadcastChannel
import org.w3c.dom.MessageEvent
import kotlin.math.min

@JsExport
enum class MessageType {
  SYNC,
  MIDI
}

@JsExport
class SyncMessage(
  @JsName("timeOrigin")
  val timeOrigin: Double = window.performance.asDynamic().timeOrigin,
  @JsName("now")
  val now: Double = window.performance.now()
) {
  @JsName("type")
  val type: String = MessageType.SYNC.name
}

// time -> syncOrigin
// receive syn message
// syncOrigin = my timeOrigin - sync.timeOrigin
// - sync.timeOrigin = 50
// - my.timeOrigin = 100
// - syncOrigin = -50

// - sync.timeOrigin = 49
// - my.timeOrigin = 100
// - syncOrigin = update to -51

@JsExport
class MidiMessage(
  @JsName("data")
  val data: Uint8Array,
  @JsName("timestamp")
  val timestamp: dynamic = null,
  @JsName("timeOrigin")
  val timeOrigin: dynamic = window.performance.asDynamic().timeOrigin
) {
  @JsName("type")
  val type = MessageType.MIDI.name
}

object Sync {
  var syncOrigin = 0.0

  fun update(sync: SyncMessage) {
    syncOrigin = min(syncOrigin, window.performance.asDynamic().timeOrigin - sync.timeOrigin)
  }

  fun now(): Double = window.performance.now() + syncOrigin
}

object Broadcaster {
  val channels = mutableMapOf<Int, BroadcastChannel>()

  fun getChannel(channel: Int): BroadcastChannel = channels.getOrPut(channel) {
    println("Opening broadcast channel $channel")
    val bcChannel = BroadcastChannel("audio-worklet-$channel")

    bcChannel.onmessage = { event ->
      onMessage(channel, event)
    }

    bcChannel
  }

  private fun onMessage(channel: Int, event: MessageEvent) {
    val data: dynamic = event.data.asDynamic()

    console.log(
      "Received broadcast message on channel $channel",
      event
    )
    if (data.type == MessageType.SYNC.name) {
      val syncMessage = SyncMessage(
        data.timeOrigin,
        data.now
      )
      Sync.update(syncMessage)
    } else {
      console.log(
        "Received broadcast message on channel $channel",
        event,
        window.performance,
        window.performance.now() - event.timeStamp.toDouble()
      )
    }
  }

  fun send(channel: Int, message: Any) {
    console.log("Sending broadcast message on channel $channel:", message)
    getChannel(channel).postMessage(message)
  }

  fun sync() {
    for (channel in channels.values) {
      channel.postMessage(SyncMessage())
    }
  }

}