package ein.core.coroutine

import kotlinx.coroutines.*
import kotlin.browser.window
import kotlin.coroutines.CoroutineContext

@ExperimentalCoroutinesApi
@InternalCoroutinesApi
actual val eLooperDispatcher:CoroutineDispatcher = object:CoroutineDispatcher(), Delay {
    private val f:(Double)->Unit = ::loop
    private var blocks = mutableListOf<Runnable>()
    private var delay = mutableListOf<Pair<Double, CancellableContinuation<Unit>>>()
    private var invokes = mutableListOf<Pair<Double, Runnable>>()
    init{window.requestAnimationFrame(f)}
    fun loop(c:Double){
        val size = blocks.size
        if(size > 0) blocks.removeAt(size - 1).run()
        var i = delay.size
        while(i-- > 0){
            if(delay[i].first >= c){
                with(delay[i].second){resumeUndispatched(Unit)}
                delay.removeAt(i)
            }
        }
        i = invokes.size
        while(i-- > 0){
            if(invokes[i].first >= c){
                invokes[i].second.run()
                invokes.removeAt(i)
            }
        }
        window.requestAnimationFrame(f)
    }
    override fun dispatch(context:CoroutineContext, block:Runnable){
        blocks.add(block)
    }
    override fun scheduleResumeAfterDelay(timeMillis: Long, continuation:CancellableContinuation<Unit>) {
        delay.add(timeMillis.toDouble() + window.performance.now() to continuation)
    }
    override fun invokeOnTimeout(timeMillis: Long, block:Runnable):DisposableHandle {
        invokes.add(timeMillis.toDouble() + window.performance.now() to block)
        return object:DisposableHandle{override fun dispose(){}}
    }
}