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/*
 * Copyright (C) 2014 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

import java.io.IOException
import java.util.concurrent.TimeUnit

/**
 * Observes, modifies, and potentially short-circuits requests going out and the corresponding
 * responses coming back in. Typically interceptors add, remove, or transform headers on the request
 * or response.
 *
 * Implementations of this interface throw [IOException] to signal connectivity failures. This
 * includes both natural exceptions such as unreachable servers, as well as synthetic exceptions
 * when responses are of an unexpected type or cannot be decoded.
 *
 * Other exception types cancel the current call:
 *
 *  * For synchronous calls made with [Call.execute], the exception is propagated to the caller.
 *
 *  * For asynchronous calls made with [Call.enqueue], an [IOException] is propagated to the caller
 *    indicating that the call was canceled. The interceptor's exception is delivered to the current
 *    thread's [uncaught exception handler][Thread.UncaughtExceptionHandler]. By default this
 *    crashes the application on Android and prints a stacktrace on the JVM. (Crash reporting
 *    libraries may customize this behavior.)
 *
 * A good way to signal a failure is with a synthetic HTTP response:
 *
 * ```
 *   @Throws(IOException::class)
 *   override fun intercept(chain: Interceptor.Chain): Response {
 *     if (myConfig.isInvalid()) {
 *       return Response.Builder()
 *           .request(chain.request())
 *           .protocol(Protocol.HTTP_1_1)
 *           .code(400)
 *           .message("client config invalid")
 *           .body("client config invalid".toResponseBody(null))
 *           .build()
 *     }
 *
 *     return chain.proceed(chain.request())
 *   }
 * ```
 */
fun interface Interceptor {
  @Throws(IOException::class)
  fun intercept(chain: Chain): Response

  companion object {
    /**
     * Constructs an interceptor for a lambda. This compact syntax is most useful for inline
     * interceptors.
     *
     * ```
     * val interceptor = Interceptor { chain: Interceptor.Chain ->
     *     chain.proceed(chain.request())
     * }
     * ```
     */
    inline operator fun invoke(crossinline block: (chain: Chain) -> Response): Interceptor =
      Interceptor { block(it) }
  }

  interface Chain {
    fun request(): Request

    @Throws(IOException::class)
    fun proceed(request: Request): Response

    /**
     * Returns the connection the request will be executed on. This is only available in the chains
     * of network interceptors; for application interceptors this is always null.
     */
    fun connection(): Connection?

    fun call(): Call

    fun connectTimeoutMillis(): Int

    fun withConnectTimeout(timeout: Int, unit: TimeUnit): Chain

    fun readTimeoutMillis(): Int

    fun withReadTimeout(timeout: Int, unit: TimeUnit): Chain

    fun writeTimeoutMillis(): Int

    fun withWriteTimeout(timeout: Int, unit: TimeUnit): Chain
  }
}