package {{invokerPackage}}

import java.io.File
import java.security.cert.X509Certificate
import javax.net.ssl._

import akka.actor.ActorSystem
import akka.io.IO
import akka.pattern.ask
import akka.util.Timeout
import org.joda.time.DateTime
import org.joda.time.format.ISODateTimeFormat
import org.json4s.JsonAST.JString
import org.json4s._
import org.json4s.jackson.JsonMethods._
import org.json4s.jackson.Serialization
import spray.can.Http
import spray.can.Http.HostConnectorSetup
import spray.client.pipelining
import spray.client.pipelining._
import spray.http.HttpEncodings._
import spray.http.HttpHeaders.{RawHeader, `Accept-Encoding`}
import spray.http.Uri.Query
import spray.http._
import spray.http.parser.HttpParser
import spray.httpx.encoding.{Deflate, Encoder, Gzip}
import spray.httpx.unmarshalling._
import spray.io.ClientSSLEngineProvider

import scala.concurrent.{ExecutionContext, Future}
import scala.reflect.ClassTag
import scala.util.control.NonFatal

object ApiInvoker {

  def apply()(implicit system: ActorSystem): ApiInvoker =
    apply(DefaultFormats + DateTimeSerializer)
  def apply(serializers: Traversable[Serializer[_]])(implicit system: ActorSystem): ApiInvoker =
    apply(DefaultFormats + DateTimeSerializer ++ serializers)
  def apply(formats: Formats)(implicit system: ActorSystem): ApiInvoker = new ApiInvoker(formats)

  case class CustomStatusCode(value: Int, reason: String = "Application-defined status code", isSuccess: Boolean = true)

  def addCustomStatusCode(code: CustomStatusCode): Unit = addCustomStatusCode(code.value, code.reason, code.isSuccess)

  def addCustomStatusCode(code: Int, reason: String = "Application defined code", isSuccess: Boolean = true) = {
    StatusCodes.getForKey(code) foreach { c =>
      StatusCodes.registerCustom(code, reason, reason, isSuccess, allowsEntity = true)
    }
  }

  /**
   * Allows request execution without calling apiInvoker.execute(request)
   * request.response can be used to get a future of the ApiResponse generated.
   * request.result can be used to get a future of the expected ApiResponse content. If content doesn't match, a
   *    Future will failed with a ClassCastException
   * @param request the apiRequest to be executed
   */
  implicit class ApiRequestImprovements[T](request: ApiRequest[T]) {

    def response(invoker: ApiInvoker)(implicit ec: ExecutionContext, system: ActorSystem): Future[ApiResponse[T]] =
      response(ec, system, invoker)

    def response(implicit ec: ExecutionContext, system: ActorSystem, invoker: ApiInvoker): Future[ApiResponse[T]] =
      invoker.execute(request)

    def result[U <: T](implicit c: ClassTag[U], ec: ExecutionContext, system: ActorSystem, invoker: ApiInvoker): Future[U] =
      invoker.execute(request).map(_.content).mapTo[U]

  }

  /**
   * Allows transformation from ApiMethod to spray HttpMethods
   * @param method the ApiMethod to be converted
   */
  implicit class ApiMethodExtensions(val method: ApiMethod) {
    def toSprayMethod: HttpMethod = HttpMethods.getForKey(method.value).getOrElse(HttpMethods.GET)
  }

  case object DateTimeSerializer extends CustomSerializer[DateTime](format => ( {
    case JString(s) =>
      ISODateTimeFormat.dateTimeParser().parseDateTime(s)
  }, {
    case d: DateTime =>
      JString(ISODateTimeFormat.dateTimeParser().print(d))
  }))
}

class ApiInvoker(formats: Formats)(implicit system: ActorSystem) extends UntrustedSslContext with CustomContentTypes {

  import io.swagger.client.core.ApiInvoker._
  import io.swagger.client.core.ParametersMap._

  implicit val ec = system.dispatcher
  implicit val jsonFormats = formats

  def settings = ApiSettings(system)

  import spray.http.MessagePredicate._

  val CompressionFilter = MessagePredicate({ _ => settings.compressionEnabled}) &&
    Encoder.DefaultFilter &&
    minEntitySize(settings.compressionSizeThreshold)

  settings.customCodes.foreach(addCustomStatusCode)

  private def addAuthentication(credentialsSeq: Seq[Credentials]): pipelining.RequestTransformer =
    request =>
      credentialsSeq.foldLeft(request) {
        case (req, BasicCredentials(login, password)) =>
          req ~> addCredentials(BasicHttpCredentials(login, password))
        case (req, ApiKeyCredentials(keyValue, keyName, ApiKeyLocations.HEADER)) =>
          req ~> addHeader(RawHeader(keyName, keyValue.value))
        case (req, _) => req
      }

  private def addHeaders(headers: Map[String, Any]): pipelining.RequestTransformer = { request =>

    val rawHeaders = for {
      (name, value) <- headers.asFormattedParams
      header = RawHeader(name, String.valueOf(value))
    } yield header

    request.withHeaders(rawHeaders.toList)
  }

  private def bodyPart(name: String, value: Any): BodyPart = {
    value match {
      case f: File =>
        BodyPart(f, name)
      case v: String =>
        BodyPart(HttpEntity(String.valueOf(v)))
      case NumericValue(v) =>
        BodyPart(HttpEntity(String.valueOf(v)))
      case m: ApiModel =>
        BodyPart(HttpEntity(Serialization.write(m)))
    }
  }

  private def formDataContent(request: ApiRequest[_]) = {
    val params = request.formParams.asFormattedParams
    if (params.isEmpty)
      None
    else
      Some(
        normalizedContentType(request.contentType).mediaType match {
          case MediaTypes.`multipart/form-data` =>
            MultipartFormData(params.map { case (name, value) => (name, bodyPart(name, value))})
          case MediaTypes.`application/x-www-form-urlencoded` =>
            FormData(params.mapValues(String.valueOf))
          case m: MediaType => // Default : application/x-www-form-urlencoded.
            FormData(params.mapValues(String.valueOf))
        }
      )
  }

  private def bodyContent(request: ApiRequest[_]): Option[Any] = {
    request.bodyParam.map(Extraction.decompose).map(compact)
  }

  private def createRequest(uri: Uri, request: ApiRequest[_]): HttpRequest = {

    val builder = new RequestBuilder(request.method.toSprayMethod)
    val httpRequest = request.method.toSprayMethod match {
      case HttpMethods.GET | HttpMethods.DELETE => builder.apply(uri)
      case HttpMethods.POST | HttpMethods.PUT =>
        formDataContent(request) orElse bodyContent(request) match {
          case Some(c: FormData) =>
            builder.apply(uri, c)
          case Some(c: MultipartFormData) =>
            builder.apply(uri, c)
          case Some(c: String) =>
            builder.apply(uri, HttpEntity(normalizedContentType(request.contentType), c))
          case _ =>
            builder.apply(uri, HttpEntity(normalizedContentType(request.contentType), " "))
        }
      case _ => builder.apply(uri)
    }

    httpRequest ~>
      addHeaders(request.headerParams) ~>
      addAuthentication(request.credentials) ~>
      encode(Gzip(CompressionFilter))
  }

  def makeQuery(r: ApiRequest[_]): Query = {
    r.credentials.foldLeft(r.queryParams) {
      case (params, ApiKeyCredentials(key, keyName, ApiKeyLocations.QUERY)) =>
        params + (keyName -> key.value)
      case (params, _) => params
    }.asFormattedParams
      .mapValues(String.valueOf)
      .foldRight[Query](Uri.Query.Empty) {
      case ((name, value), acc) => acc.+:(name, value)
    }
  }

  def makeUri(r: ApiRequest[_]): Uri = {
    val opPath = r.operationPath.replaceAll("\\{format\\}", "json")
    val opPathWithParams = r.pathParams.asFormattedParams
      .mapValues(String.valueOf)
      .foldLeft(opPath) {
      case (path, (name, value)) => path.replaceAll(s"\\{$name\\}", value)
    }
    val query = makeQuery(r)

    Uri(r.basePath + opPathWithParams).withQuery(query)
  }

  def execute[T](r: ApiRequest[T]): Future[ApiResponse[T]] = {
    try {
      implicit val timeout: Timeout = settings.connectionTimeout

      val uri = makeUri(r)

      val connector = HostConnectorSetup(
        uri.authority.host.toString,
        uri.effectivePort,
        sslEncryption = "https".equals(uri.scheme),
        defaultHeaders = settings.defaultHeaders ++ List(`Accept-Encoding`(gzip, deflate)))

      val request = createRequest(uri, r)

      for {
        Http.HostConnectorInfo(hostConnector, _) <- IO(Http) ? connector
        response <- hostConnector.ask(request).mapTo[HttpResponse]
      } yield {
        response ~> decode(Deflate) ~> decode(Gzip) ~> unmarshallApiResponse(r)
      }
    }
    catch {
      case NonFatal(x) => Future.failed(x)
    }
  }

  def unmarshallApiResponse[T](request: ApiRequest[T])(response: HttpResponse): ApiResponse[T] = {
    request.responseForCode(response.status.intValue) match {
      case Some( (manifest: Manifest[T], state: ResponseState) ) =>
        entityUnmarshaller(manifest)(response.entity) match {
          case Right(value) ⇒
            state match {
              case ResponseState.Success =>
                ApiResponse(response.status.intValue, value, response.headers.map(header => (header.name, header.value)).toMap)
              case ResponseState.Error =>
                throw new ApiError(response.status.intValue, "Error response received",
                  Some(value),
                  headers = response.headers.map(header => (header.name, header.value)).toMap)
            }

          case Left(MalformedContent(error, Some(cause))) ⇒
            throw new ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString), cause)

          case Left(MalformedContent(error, None)) ⇒
            throw new ApiError(response.status.intValue, s"Unable to unmarshall content to [$manifest]", Some(response.entity.toString))

          case Left(ContentExpected) ⇒
            throw new ApiError(response.status.intValue, s"Unable to unmarshall empty response to [$manifest]", Some(response.entity.toString))
        }

      case _ => throw new ApiError(response.status.intValue, "Unexpected response code", Some(response.entity.toString))
    }
  }

  def entityUnmarshaller[T](implicit mf: Manifest[T]): Unmarshaller[T] =
    Unmarshaller[T](MediaTypes.`application/json`) {
      case x: HttpEntity.NonEmpty ⇒
        parse(x.asString(defaultCharset = HttpCharsets.`UTF-8`))
          .noNulls
          .camelizeKeys
          .extract[T]
    }

}

sealed trait CustomContentTypes {

  def normalizedContentType(original: String): ContentType =
    MediaTypes.forExtension(original) map (ContentType(_)) getOrElse parseContentType(original)

  def parseContentType(contentType: String): ContentType = {
    val contentTypeAsRawHeader = HttpHeaders.RawHeader("Content-Type", contentType)
    val parsedContentTypeHeader = HttpParser.parseHeader(contentTypeAsRawHeader)
    (parsedContentTypeHeader: @unchecked) match {
      case Right(ct: HttpHeaders.`Content-Type`) =>
        ct.contentType
      case Left(error: ErrorInfo) =>
        throw new IllegalArgumentException(
          s"Error converting '$contentType' to a ContentType header: '${error.summary}'")
    }
  }
}

sealed trait UntrustedSslContext {
  this: ApiInvoker =>

  implicit lazy val trustfulSslContext: SSLContext = {
    settings.alwaysTrustCertificates match {
      case false =>
        SSLContext.getDefault

      case true =>
        class IgnoreX509TrustManager extends X509TrustManager {
          def checkClientTrusted(chain: Array[X509Certificate], authType: String): Unit = {}

          def checkServerTrusted(chain: Array[X509Certificate], authType: String): Unit = {}

          def getAcceptedIssuers = null
        }

        val context = SSLContext.getInstance("TLS")
        context.init(null, Array(new IgnoreX509TrustManager), null)
        context
    }
  }

  implicit val clientSSLEngineProvider =
    ClientSSLEngineProvider {
      _ =>
        val engine = trustfulSslContext.createSSLEngine()
        engine.setUseClientMode(true)
        engine
    }
}
