/*
 * Copyright 2018, 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 Foundation
import Dispatch
import SwiftProtobuf

public protocol ServerSessionBidirectionalStreaming: ServerSession { }

open class ServerSessionBidirectionalStreamingImpl<InputType: Message, OutputType: Message>: ServerSessionImpl, ServerSessionBidirectionalStreaming {
  public typealias ProviderBlock = (ServerSessionBidirectionalStreamingImpl) throws -> Void
  private var providerBlock: ProviderBlock
  
  public init(handler:Handler, providerBlock: @escaping ProviderBlock) {
    self.providerBlock = providerBlock
    super.init(handler:handler)
  }
  
  public func receive() throws -> InputType {
    let sem = DispatchSemaphore(value: 0)
    var requestMessage : InputType?
    try self.handler.receiveMessage() {(requestData) in
      if let requestData = requestData {
        do {
          requestMessage = try InputType(serializedData:requestData)
        } catch (let error) {
          print("error \(error)")
        }
      }
      sem.signal()
    }
    _ = sem.wait(timeout: DispatchTime.distantFuture)
    if let requestMessage = requestMessage {
      return requestMessage
    } else {
      throw ServerError.endOfStream
    }
  }
  
  public func send(_ response: OutputType, completion: ((Bool)->())?) throws {
    try handler.sendResponse(message:response.serializedData(), completion: completion)
  }
  
  public func close() throws {
    let sem = DispatchSemaphore(value: 0)
    try self.handler.sendStatus(statusCode:self.statusCode,
                                statusMessage:self.statusMessage,
                                trailingMetadata:self.trailingMetadata) { _ in sem.signal() }
    _ = sem.wait(timeout: DispatchTime.distantFuture)
  }
  
  public func run(queue:DispatchQueue) throws {
    try self.handler.sendMetadata(initialMetadata:initialMetadata) { _ in
      queue.async {
        do {
          try self.providerBlock(self)
        } catch (let error) {
          print("error \(error)")
        }
      }
    }
  }
}

/// Simple fake implementation of ServerSessionBidirectionalStreaming that returns a previously-defined set of results
/// and stores sent values for later verification.
open class ServerSessionBidirectionalStreamingTestStub<InputType: Message, OutputType: Message>: ServerSessionTestStub, ServerSessionBidirectionalStreaming {
  open var inputs: [InputType] = []
  open var outputs: [OutputType] = []
  
  open func receive() throws -> InputType {
    if let input = inputs.first {
      inputs.removeFirst()
      return input
    } else {
      throw ServerError.endOfStream
    }
  }
  
  open func send(_ response: OutputType, completion: ((Bool)->())?) throws {
    outputs.append(response)
  }
  
  open func close() throws { }
}