RealEventSource.kt

/*
 * Copyright (C) 2018 Square, Inc.
 *
 * 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 okhttp3.sse.internal

import java.io.IOException
import okhttp3.Call
import okhttp3.Callback
import okhttp3.Request
import okhttp3.Response
import okhttp3.ResponseBody
import okhttp3.internal.stripBody
import okhttp3.sse.EventSource
import okhttp3.sse.EventSourceListener

internal class RealEventSource private constructor(
  private val call: Call?,
  private val request: Request,
  private val listener: EventSourceListener,
) : EventSource,
  ServerSentEventReader.Callback,
  Callback {
  constructor(call: Call, listener: EventSourceListener) : this(call, call.request(), listener)

  constructor(response: Response, listener: EventSourceListener) : this(null, response.request, listener)

  @Volatile private var canceled = false

  override fun onResponse(
    call: Call,
    response: Response,
  ) {
    processResponse(response)
  }

  internal fun processResponse(response: Response) {
    response.use {
      if (!response.isSuccessful) {
        listener.onFailure(this, null, response)
        return
      }

      val body = response.body

      if (!body.isEventStream()) {
        listener.onFailure(
          this,
          IllegalStateException("Invalid content-type: ${body.contentType()}"),
          response,
        )
        return
      }

      // This is a long-lived response. Cancel full-call timeouts.
      call?.timeout()?.cancel()

      // Replace the body with a stripped one so the callbacks can't see real data.
      val response = response.stripBody()

      val reader = ServerSentEventReader(body.source(), this)
      try {
        if (!canceled) {
          listener.onOpen(this, response)
          while (!canceled && reader.processNextEvent()) {
          }
        }
      } catch (e: Exception) {
        val exception =
          when {
            canceled -> IOException("canceled", e)
            else -> e
          }
        listener.onFailure(this, exception, response)
        return
      }
      if (canceled) {
        listener.onFailure(this, IOException("canceled"), response)
      } else {
        listener.onClosed(this)
      }
    }
  }

  private fun ResponseBody.isEventStream(): Boolean {
    val contentType = contentType() ?: return false
    return contentType.type == "text" && contentType.subtype == "event-stream"
  }

  override fun onFailure(
    call: Call,
    e: IOException,
  ) {
    listener.onFailure(this, e, null)
  }

  override fun request(): Request = request

  override fun cancel() {
    canceled = true
    call?.cancel()
  }

  override fun onEvent(
    id: String?,
    type: String?,
    data: String,
  ) {
    listener.onEvent(this, id, type, data)
  }

  override fun onRetryChange(timeMs: Long) {
    // Ignored. We do not auto-retry.
  }
}