package com.softwaremill.sttp.asynchttpclient.scalaz

import java.nio.ByteBuffer

import com.softwaremill.sttp.asynchttpclient.AsyncHttpClientBackend
import com.softwaremill.sttp.{FollowRedirectsBackend, MonadAsyncError, SttpBackend, SttpBackendOptions}
import io.netty.buffer.ByteBuf
import org.asynchttpclient.{AsyncHttpClient, AsyncHttpClientConfig, DefaultAsyncHttpClient}
import org.reactivestreams.Publisher

import scalaz.concurrent.Task
import scalaz.{-\/, \/-}

class AsyncHttpClientScalazBackend private (asyncHttpClient: AsyncHttpClient, closeClient: Boolean)
    extends AsyncHttpClientBackend[Task, Nothing](asyncHttpClient, TaskMonad, closeClient) {

  override protected def streamBodyToPublisher(s: Nothing): Publisher[ByteBuf] =
    s // nothing is everything

  override protected def publisherToStreamBody(p: Publisher[ByteBuffer]): Nothing =
    throw new IllegalStateException("This backend does not support streaming")

  override protected def publisherToString(p: Publisher[ByteBuffer]): Task[String] =
    throw new IllegalStateException("This backend does not support streaming")
}

object AsyncHttpClientScalazBackend {
  private def apply(asyncHttpClient: AsyncHttpClient, closeClient: Boolean): SttpBackend[Task, Nothing] =
    new FollowRedirectsBackend[Task, Nothing](new AsyncHttpClientScalazBackend(asyncHttpClient, closeClient))

  def apply(options: SttpBackendOptions = SttpBackendOptions.Default): SttpBackend[Task, Nothing] =
    AsyncHttpClientScalazBackend(AsyncHttpClientBackend.defaultClient(options), closeClient = true)

  def usingConfig(cfg: AsyncHttpClientConfig): SttpBackend[Task, Nothing] =
    AsyncHttpClientScalazBackend(new DefaultAsyncHttpClient(cfg), closeClient = true)

  def usingClient(client: AsyncHttpClient): SttpBackend[Task, Nothing] =
    AsyncHttpClientScalazBackend(client, closeClient = false)
}

private[scalaz] object TaskMonad extends MonadAsyncError[Task] {
  override def unit[T](t: T): Task[T] = Task.point(t)

  override def map[T, T2](fa: Task[T])(f: (T) => T2): Task[T2] = fa.map(f)

  override def flatMap[T, T2](fa: Task[T])(f: (T) => Task[T2]): Task[T2] =
    fa.flatMap(f)

  override def async[T](register: ((Either[Throwable, T]) => Unit) => Unit): Task[T] =
    Task.async { cb =>
      register {
        case Left(t)  => cb(-\/(t))
        case Right(t) => cb(\/-(t))
      }
    }

  override def error[T](t: Throwable): Task[T] = Task.fail(t)

  override protected def handleWrappedError[T](rt: Task[T])(h: PartialFunction[Throwable, Task[T]]): Task[T] =
    rt.handleWith(h)
}