nim-json-rpc/json_rpc/clients/websocketclient.nim

import
  std/[strtabs, tables, uri, strutils],
  pkg/[chronos, websock/websock, chronicles],
  websock/extensions/compression/deflate,
  stew/byteutils,
  ../client

export client

logScope:
  topics = "JSONRPC-WS-CLIENT"

type
  RpcWebSocketClient* = ref object of RpcClient
    transport*: WSSession
    uri*: Uri
    loop*: Future[void]

proc new*(T: type RpcWebSocketClient): T =
  T()

proc newRpcWebSocketClient*: RpcWebSocketClient =
  ## Creates a new client instance.
  RpcWebSocketClient.new()

method call*(self: RpcWebSocketClient, name: string,
             params: JsonNode): Future[Response] {.
    async, gcsafe, raises: [Defect, CatchableError].} =
  ## Remotely calls the specified RPC method.
  let id = self.getNextId()
  var value = $rpcCallNode(name, params, id) & "\r\n"
  if self.transport.isNil:
    raise newException(ValueError,
                    "Transport is not initialised (missing a call to connect?)")

  # completed by processMessage.
  var newFut = newFuture[Response]()
  # add to awaiting responses
  self.awaiting[id] = newFut

  await self.transport.send(value)
  return await newFut

proc processData(client: RpcWebSocketClient) {.async.} =
  var error: ref CatchableError
  let ws = client.transport
  try:
    while ws.readystate != ReadyState.Closed:
      var value = await ws.recv()

      if value.len == 0:
        # transmission ends
        break

      client.processMessage(string.fromBytes(value))
  except CatchableError as e:
    error = e

  await client.transport.close()
  client.transport = nil

  if client.awaiting.len != 0:
    if error.isNil:
      error = newException(IOError, "Transport was closed while waiting for response")
    for k, v in client.awaiting:
      v.fail(error)
    client.awaiting.clear()
  if not client.onDisconnect.isNil:
    client.onDisconnect()

proc connect*(client: RpcWebSocketClient, uri: string,
              compression: bool = false,
              flags: set[TLSFlags] = {
                NoVerifyHost, NoVerifyServerName}) {.async.} =

  var ext: seq[ExtFactory] = if compression:
                               @[deflateFactory()]
                             else:
                               @[]
  let uri = parseUri(uri)
  let secure = uri.scheme == "wss"
  let port = parseInt(uri.port)

  let ws = await WebSocket.connect(
    host = uri.hostname,
    port = Port(port),
    path = uri.path,
    secure=secure,
    flags=flags,
    factories=ext
  )
  client.transport = ws
  client.uri = uri

  client.loop = processData(client)

method close*(client: RpcWebSocketClient) {.async.} =
  await client.loop.cancelAndWait()
  if not client.transport.isNil:
    await client.transport.close()
    client.transport = nil