/*
 * Copyright 2020, gRPC Authors All rights reserved.
 *
 * 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.
 */
import NIOHPACK

public enum GRPCClientRequestPart<Request> {
  /// User provided metadata sent at the start of the request stream.
  case metadata(HPACKHeaders)

  /// A message to send to the server.
  case message(Request, MessageMetadata)

  /// The end the request stream.
  case end
}

public enum GRPCClientResponsePart<Response> {
  /// The metadata returned by the server at the start of the RPC.
  case metadata(HPACKHeaders)

  /// A response message from the server.
  case message(Response)

  /// The end of response stream sent by the server.
  case end(GRPCStatus, HPACKHeaders)
}

public enum GRPCServerRequestPart<Request> {
  /// Metadata received from the client at the start of the RPC.
  case metadata(HPACKHeaders)

  /// A request message sent by the client.
  case message(Request)

  /// The end the request stream.
  case end
}

public enum GRPCServerResponsePart<Response> {
  /// The metadata to send to the client at the start of the response stream.
  case metadata(HPACKHeaders)

  /// A response message sent by the server.
  case message(Response, MessageMetadata)

  /// The end of response stream sent by the server.
  case end(GRPCStatus, HPACKHeaders)
}

/// Metadata associated with a request or response message.
public struct MessageMetadata: Equatable, Sendable {
  /// Whether the message should be compressed. If compression has not been enabled on the RPC
  /// then this setting is ignored.
  public var compress: Bool

  /// Whether the underlying transported should be 'flushed' after writing this message. If a batch
  /// of messages is to be sent then flushing only after the last message may improve
  /// performance.
  public var flush: Bool

  public init(compress: Bool, flush: Bool) {
    self.compress = compress
    self.flush = flush
  }
}

extension GRPCClientResponsePart {
  @inlinable
  internal var isEnd: Bool {
    switch self {
    case .end:
      return true
    case .metadata, .message:
      return false
    }
  }
}

extension GRPCServerResponsePart {
  @inlinable
  internal var isEnd: Bool {
    switch self {
    case .end:
      return true
    case .metadata, .message:
      return false
    }
  }
}

extension GRPCClientRequestPart: Sendable where Request: Sendable {}
extension GRPCClientResponsePart: Sendable where Response: Sendable {}
extension GRPCServerRequestPart: Sendable where Request: Sendable {}
extension GRPCServerResponsePart: Sendable where Response: Sendable {}