modeling-app/src/lang/std/engineConnection.ts

import { PathToNode, Program, SourceRange } from 'lang/wasm'
import { VITE_KC_API_WS_MODELING_URL, VITE_KC_CONNECTION_TIMEOUT_MS } from 'env'
import { Models } from '@kittycad/lib'
import { exportSave } from 'lib/exportSave'
import { v4 as uuidv4 } from 'uuid'
import { getNodePathFromSourceRange } from 'lang/queryAst'
import { sceneInfra } from 'clientSideScene/sceneInfra'

let lastMessage = ''

interface CommandInfo {
  commandType: CommandTypes
  range: SourceRange
  pathToNode: PathToNode
  parentId?: string
}

type WebSocketResponse = Models['OkWebSocketResponseData_type']

interface ResultCommand extends CommandInfo {
  type: 'result'
  data: any
  raw: WebSocketResponse
  headVertexId?: string
}
interface FailedCommand extends CommandInfo {
  type: 'failed'
  errors: Models['FailureWebSocketResponse_type']['errors']
}
interface PendingCommand extends CommandInfo {
  type: 'pending'
  promise: Promise<any>
  resolve: (val: any) => void
}

export interface ArtifactMap {
  [key: string]: ResultCommand | PendingCommand | FailedCommand
}

interface NewTrackArgs {
  conn: EngineConnection
  mediaStream: MediaStream
}

// This looks funny, I know. This is needed because node and the browser
// disagree as to the type. In a browser it's a number, but in node it's a
// "Timeout".
type Timeout = ReturnType<typeof setTimeout>

type ClientMetrics = Models['ClientMetrics_type']

type Value<T, U> = U extends undefined
  ? { type: T; value: U }
  : U extends void
  ? { type: T }
  : { type: T; value: U }

type State<T, U> = Value<T, U>

export enum EngineConnectionStateType {
  Fresh = 'fresh',
  Connecting = 'connecting',
  ConnectionEstablished = 'connection-established',
  Disconnecting = 'disconnecting',
  Disconnected = 'disconnected',
}

export enum DisconnectingType {
  Error = 'error',
  Timeout = 'timeout',
  Quit = 'quit',
}

export interface ErrorType {
  // We may not necessary have an error to assign.
  error?: Error

  // We assign this in the state setter because we may have not failed at
  // a Connecting state, which we check for there.
  lastConnectingValue?: ConnectingValue
}

export type DisconnectingValue =
  | State<DisconnectingType.Error, ErrorType>
  | State<DisconnectingType.Timeout, void>
  | State<DisconnectingType.Quit, void>

// These are ordered by the expected sequence.
export enum ConnectingType {
  WebSocketConnecting = 'websocket-connecting',
  WebSocketEstablished = 'websocket-established',
  PeerConnectionCreated = 'peer-connection-created',
  ICEServersSet = 'ice-servers-set',
  SetLocalDescription = 'set-local-description',
  OfferedSdp = 'offered-sdp',
  ReceivedSdp = 'received-sdp',
  SetRemoteDescription = 'set-remote-description',
  WebRTCConnecting = 'webrtc-connecting',
  ICECandidateReceived = 'ice-candidate-received',
  TrackReceived = 'track-received',
  DataChannelRequested = 'data-channel-requested',
  DataChannelConnecting = 'data-channel-connecting',
  DataChannelEstablished = 'data-channel-established',
}

export enum ConnectingTypeGroup {
  WebSocket = 'WebSocket',
  ICE = 'ICE',
  WebRTC = 'WebRTC',
}

export const initialConnectingTypeGroupState: Record<
  ConnectingTypeGroup,
  [ConnectingType, boolean | undefined][]
> = {
  [ConnectingTypeGroup.WebSocket]: [
    [ConnectingType.WebSocketConnecting, undefined],
    [ConnectingType.WebSocketEstablished, undefined],
  ],
  [ConnectingTypeGroup.ICE]: [
    [ConnectingType.PeerConnectionCreated, undefined],
    [ConnectingType.ICEServersSet, undefined],
    [ConnectingType.SetLocalDescription, undefined],
    [ConnectingType.OfferedSdp, undefined],
    [ConnectingType.ReceivedSdp, undefined],
    [ConnectingType.SetRemoteDescription, undefined],
    [ConnectingType.WebRTCConnecting, undefined],
    [ConnectingType.ICECandidateReceived, undefined],
  ],
  [ConnectingTypeGroup.WebRTC]: [
    [ConnectingType.TrackReceived, undefined],
    [ConnectingType.DataChannelRequested, undefined],
    [ConnectingType.DataChannelConnecting, undefined],
    [ConnectingType.DataChannelEstablished, undefined],
  ],
}

export type ConnectingValue =
  | State<ConnectingType.WebSocketConnecting, void>
  | State<ConnectingType.WebSocketEstablished, void>
  | State<ConnectingType.PeerConnectionCreated, void>
  | State<ConnectingType.ICEServersSet, void>
  | State<ConnectingType.SetLocalDescription, void>
  | State<ConnectingType.OfferedSdp, void>
  | State<ConnectingType.ReceivedSdp, void>
  | State<ConnectingType.SetRemoteDescription, void>
  | State<ConnectingType.WebRTCConnecting, void>
  | State<ConnectingType.TrackReceived, void>
  | State<ConnectingType.ICECandidateReceived, void>
  | State<ConnectingType.DataChannelRequested, string>
  | State<ConnectingType.DataChannelConnecting, string>
  | State<ConnectingType.DataChannelEstablished, void>

export type EngineConnectionState =
  | State<EngineConnectionStateType.Fresh, void>
  | State<EngineConnectionStateType.Connecting, ConnectingValue>
  | State<EngineConnectionStateType.ConnectionEstablished, void>
  | State<EngineConnectionStateType.Disconnecting, DisconnectingValue>
  | State<EngineConnectionStateType.Disconnected, void>

// EngineConnection encapsulates the connection(s) to the Engine
// for the EngineCommandManager; namely, the underlying WebSocket
// and WebRTC connections.
class EngineConnection {
  websocket?: WebSocket
  pc?: RTCPeerConnection
  unreliableDataChannel?: RTCDataChannel
  mediaStream?: MediaStream

  private _state: EngineConnectionState = {
    type: EngineConnectionStateType.Fresh,
  }

  get state(): EngineConnectionState {
    return this._state
  }

  set state(next: EngineConnectionState) {
    console.log(`${JSON.stringify(this.state)} → ${JSON.stringify(next)}`)

    if (next.type === EngineConnectionStateType.Disconnecting) {
      console.trace()
      const sub = next.value
      if (sub.type === DisconnectingType.Error) {
        // Record the last step we failed at.
        // (Check the current state that we're about to override that
        // it was a Connecting state.)
        console.log(sub)
        if (this._state.type === EngineConnectionStateType.Connecting) {
          if (!sub.value) sub.value = {}
          sub.value.lastConnectingValue = this._state.value
        }

        console.error(sub.value)
      }
    }
    this._state = next
    this.onConnectionStateChange(this._state)
  }

  private failedConnTimeout: Timeout | null

  readonly url: string
  private readonly token?: string

  // For now, this is only used by the NetworkHealthIndicator.
  // We can eventually use it for more, but one step at a time.
  private onConnectionStateChange: (state: EngineConnectionState) => void

  // These are used for the EngineCommandManager and were created
  // before onConnectionStateChange existed.
  private onEngineConnectionOpen: (engineConnection: EngineConnection) => void
  private onConnectionStarted: (engineConnection: EngineConnection) => void
  private onClose: (engineConnection: EngineConnection) => void
  private onNewTrack: (track: NewTrackArgs) => void

  // TODO: actual type is ClientMetrics
  private webrtcStatsCollector?: () => Promise<ClientMetrics>

  constructor({
    url,
    token,
    onConnectionStateChange = () => {},
    onNewTrack = () => {},
    onEngineConnectionOpen = () => {},
    onConnectionStarted = () => {},
    onClose = () => {},
  }: {
    url: string
    token?: string
    onConnectionStateChange?: (state: EngineConnectionState) => void
    onEngineConnectionOpen?: (engineConnection: EngineConnection) => void
    onConnectionStarted?: (engineConnection: EngineConnection) => void
    onClose?: (engineConnection: EngineConnection) => void
    onNewTrack?: (track: NewTrackArgs) => void
  }) {
    this.url = url
    this.token = token
    this.failedConnTimeout = null
    this.onConnectionStateChange = onConnectionStateChange
    this.onEngineConnectionOpen = onEngineConnectionOpen
    this.onConnectionStarted = onConnectionStarted

    this.onClose = onClose
    this.onNewTrack = onNewTrack

    // TODO(paultag): This ought to be tweakable.
    const pingIntervalMs = 10000

    // Without an interval ping, our connection will timeout.
    let pingInterval = setInterval(() => {
      switch (this.state.type as EngineConnectionStateType) {
        case EngineConnectionStateType.ConnectionEstablished:
          this.send({ type: 'ping' })
          break
        case EngineConnectionStateType.Disconnecting:
        case EngineConnectionStateType.Disconnected:
          clearInterval(pingInterval)
          break
        default:
          break
      }
    }, pingIntervalMs)

    const connectionTimeoutMs = VITE_KC_CONNECTION_TIMEOUT_MS
    let connectRetryInterval = setInterval(() => {
      if (this.state.type !== EngineConnectionStateType.Disconnected) return

      // Only try reconnecting when completely disconnected.
      clearInterval(connectRetryInterval)
      console.log('Trying to reconnect')
      this.connect()
    }, connectionTimeoutMs)
  }

  isConnecting() {
    return this.state.type === EngineConnectionStateType.Connecting
  }

  isReady() {
    return this.state.type === EngineConnectionStateType.ConnectionEstablished
  }

  tearDown() {
    this.disconnectAll()
    this.state = {
      type: EngineConnectionStateType.Disconnecting,
      value: { type: DisconnectingType.Quit },
    }
  }

  // connect will attempt to connect to the Engine over a WebSocket, and
  // establish the WebRTC connections.
  //
  // This will attempt the full handshake, and retry if the connection
  // did not establish.
  connect() {
    if (this.isConnecting() || this.isReady()) {
      return
    }

    // Information on the connect transaction

    const createPeerConnection = () => {
      this.pc = new RTCPeerConnection()

      // Data channels MUST BE specified before SDP offers because requesting
      // them affects what our needs are!
      const DATACHANNEL_NAME_UMC = 'unreliable_modeling_cmds'
      this.pc.createDataChannel(DATACHANNEL_NAME_UMC)

      this.state = {
        type: EngineConnectionStateType.Connecting,
        value: {
          type: ConnectingType.DataChannelRequested,
          value: DATACHANNEL_NAME_UMC,
        },
      }

      this.pc.addEventListener('icecandidate', (event) => {
        if (event.candidate === null) {
          return
        }

        this.state = {
          type: EngineConnectionStateType.Connecting,
          value: {
            type: ConnectingType.ICECandidateReceived,
          },
        }

        // Request a candidate to use
        this.send({
          type: 'trickle_ice',
          candidate: event.candidate.toJSON(),
        })
      })

      this.pc.addEventListener('icecandidateerror', (_event: Event) => {
        const event = _event as RTCPeerConnectionIceErrorEvent
        console.warn(
          `ICE candidate returned an error: ${event.errorCode}: ${event.errorText} for ${event.url}`
        )
      })

      // https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/connectionstatechange_event
      // Event type: generic Event type...
      this.pc.addEventListener('connectionstatechange', (event: any) => {
        console.log('connectionstatechange: ' + event.target?.connectionState)
        switch (event.target?.connectionState) {
          // From what I understand, only after have we done the ICE song and
          // dance is it safest to connect the video tracks / stream
          case 'connected':
            // Let the browser attach to the video stream now
            this.onNewTrack({ conn: this, mediaStream: this.mediaStream! })
            break
          case 'failed':
            this.disconnectAll()
            this.state = {
              type: EngineConnectionStateType.Disconnecting,
              value: {
                type: DisconnectingType.Error,
                value: {
                  error: new Error(
                    'failed to negotiate ice connection; restarting'
                  ),
                },
              },
            }
            break
          default:
            break
        }
      })

      this.pc.addEventListener('track', (event) => {
        const mediaStream = event.streams[0]

        this.state = {
          type: EngineConnectionStateType.Connecting,
          value: {
            type: ConnectingType.TrackReceived,
          },
        }

        this.webrtcStatsCollector = (): Promise<ClientMetrics> => {
          return new Promise((resolve, reject) => {
            if (mediaStream.getVideoTracks().length !== 1) {
              reject(new Error('too many video tracks to report'))
              return
            }

            let videoTrack = mediaStream.getVideoTracks()[0]
            void this.pc?.getStats(videoTrack).then((videoTrackStats) => {
              let client_metrics: ClientMetrics = {
                rtc_frames_decoded: 0,
                rtc_frames_dropped: 0,
                rtc_frames_received: 0,
                rtc_frames_per_second: 0,
                rtc_freeze_count: 0,
                rtc_jitter_sec: 0.0,
                rtc_keyframes_decoded: 0,
                rtc_total_freezes_duration_sec: 0.0,
              }

              // TODO(paultag): Since we can technically have multiple WebRTC
              // video tracks (even if the Server doesn't at the moment), we
              // ought to send stats for every video track(?), and add the stream
              // ID into it.  This raises the cardinality of collected metrics
              // when/if we do, but for now, just report the one stream.

              videoTrackStats.forEach((videoTrackReport) => {
                if (videoTrackReport.type === 'inbound-rtp') {
                  client_metrics.rtc_frames_decoded =
                    videoTrackReport.framesDecoded || 0
                  client_metrics.rtc_frames_dropped =
                    videoTrackReport.framesDropped || 0
                  client_metrics.rtc_frames_received =
                    videoTrackReport.framesReceived || 0
                  client_metrics.rtc_frames_per_second =
                    videoTrackReport.framesPerSecond || 0
                  client_metrics.rtc_freeze_count =
                    videoTrackReport.freezeCount || 0
                  client_metrics.rtc_jitter_sec = videoTrackReport.jitter || 0.0
                  client_metrics.rtc_keyframes_decoded =
                    videoTrackReport.keyFramesDecoded || 0
                  client_metrics.rtc_total_freezes_duration_sec =
                    videoTrackReport.totalFreezesDuration || 0
                } else if (videoTrackReport.type === 'transport') {
                  // videoTrackReport.bytesReceived,
                  // videoTrackReport.bytesSent,
                }
              })
              resolve(client_metrics)
            })
          })
        }

        // The app is eager to use the MediaStream; as soon as onNewTrack is
        // called, the following sequence happens:
        // EngineConnection.onNewTrack -> StoreState.setMediaStream ->
        // Stream.tsx reacts to mediaStream change, setting a video element.
        // We wait until connectionstatechange changes to "connected"
        // to pass it to the rest of the application.

        this.mediaStream = mediaStream
      })

      this.pc.addEventListener('datachannel', (event) => {
        this.unreliableDataChannel = event.channel

        this.state = {
          type: EngineConnectionStateType.Connecting,
          value: {
            type: ConnectingType.DataChannelConnecting,
            value: event.channel.label,
          },
        }

        this.unreliableDataChannel.addEventListener('open', (event) => {
          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.DataChannelEstablished,
            },
          }

          // Everything is now connected.
          this.state = { type: EngineConnectionStateType.ConnectionEstablished }

          this.onEngineConnectionOpen(this)
        })

        this.unreliableDataChannel.addEventListener('close', (event) => {
          this.disconnectAll()
          this.finalizeIfAllConnectionsClosed()
        })

        this.unreliableDataChannel.addEventListener('error', (event) => {
          this.disconnectAll()

          this.state = {
            type: EngineConnectionStateType.Disconnecting,
            value: {
              type: DisconnectingType.Error,
              value: {
                error: new Error(event.toString()),
              },
            },
          }
        })
      })
    }

    this.state = {
      type: EngineConnectionStateType.Connecting,
      value: {
        type: ConnectingType.WebSocketConnecting,
      },
    }

    this.websocket = new WebSocket(this.url, [])
    this.websocket.binaryType = 'arraybuffer'

    this.websocket.addEventListener('open', (event) => {
      this.state = {
        type: EngineConnectionStateType.Connecting,
        value: {
          type: ConnectingType.WebSocketEstablished,
        },
      }

      // This is required for when KCMA is running stand-alone / within Tauri.
      // Otherwise when run in a browser, the token is sent implicitly via
      // the Cookie header.
      if (this.token) {
        this.send({ headers: { Authorization: `Bearer ${this.token}` } })
      }
    })

    this.websocket.addEventListener('close', (event) => {
      this.disconnectAll()
      this.finalizeIfAllConnectionsClosed()
    })

    this.websocket.addEventListener('error', (event) => {
      this.disconnectAll()

      this.state = {
        type: EngineConnectionStateType.Disconnecting,
        value: {
          type: DisconnectingType.Error,
          value: {
            error: new Error(event.toString()),
          },
        },
      }
    })

    this.websocket.addEventListener('message', (event) => {
      // In the EngineConnection, we're looking for messages to/from
      // the server that relate to the ICE handshake, or WebRTC
      // negotiation. There may be other messages (including ArrayBuffer
      // messages) that are intended for the GUI itself, so be careful
      // when assuming we're the only consumer or that all messages will
      // be carefully formatted here.

      if (typeof event.data !== 'string') {
        return
      }

      const message: Models['WebSocketResponse_type'] = JSON.parse(event.data)

      if (!message.success) {
        const errorsString = message?.errors
          ?.map((error) => {
            return `  - ${error.error_code}: ${error.message}`
          })
          .join('\n')
        if (message.request_id) {
          const artifactThatFailed =
            engineCommandManager.artifactMap[message.request_id] ||
            engineCommandManager.lastArtifactMap[message.request_id]
          console.error(
            `Error in response to request ${message.request_id}:\n${errorsString}
failed cmd type was ${artifactThatFailed?.commandType}`
          )
          console.log(artifactThatFailed)
        } else {
          console.error(`Error from server:\n${errorsString}`)
        }
        return
      }

      let resp = message.resp

      // If there's no body to the response, we can bail here.
      // !resp.type is usually "pong" response for our "ping"
      if (!resp || !resp.type) {
        return
      }

      switch (resp.type) {
        case 'ice_server_info':
          let ice_servers = resp.data?.ice_servers

          // Now that we have some ICE servers it makes sense
          // to start initializing the RTCPeerConnection. RTCPeerConnection
          // will begin the ICE process.
          createPeerConnection()

          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.PeerConnectionCreated,
            },
          }

          // No ICE servers can be valid in a local dev. env.
          if (ice_servers?.length === 0) {
            console.warn('No ICE servers')
            this.pc?.setConfiguration({})
          } else {
            // When we set the Configuration, we want to always force
            // iceTransportPolicy to 'relay', since we know the topology
            // of the ICE/STUN/TUN server and the engine. We don't wish to
            // talk to the engine in any configuration /other/ than relay
            // from a infra POV.
            this.pc?.setConfiguration({
              iceServers: ice_servers,
              iceTransportPolicy: 'relay',
            })
          }

          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.ICEServersSet,
            },
          }

          // We have an ICE Servers set now. We just setConfiguration, so let's
          // start adding things we care about to the PeerConnection and let
          // ICE negotiation happen in the background. Everything from here
          // until the end of this function is setup of our end of the
          // PeerConnection and waiting for events to fire our callbacks.

          // Add a transceiver to our SDP offer
          this.pc?.addTransceiver('video', {
            direction: 'recvonly',
          })

          // Create a session description offer based on our local environment
          // that we will send to the remote end. The remote will send back
          // what it supports via sdp_answer.
          this.pc
            ?.createOffer()
            .then((offer: RTCSessionDescriptionInit) => {
              console.log(offer)
              this.state = {
                type: EngineConnectionStateType.Connecting,
                value: {
                  type: ConnectingType.SetLocalDescription,
                },
              }
              return this.pc?.setLocalDescription(offer).then(() => {
                this.send({
                  type: 'sdp_offer',
                  offer,
                })
                this.state = {
                  type: EngineConnectionStateType.Connecting,
                  value: {
                    type: ConnectingType.OfferedSdp,
                  },
                }
              })
            })
            .catch((error: Error) => {
              console.error(error)
              // The local description is invalid, so there's no point continuing.
              this.disconnectAll()
              this.state = {
                type: EngineConnectionStateType.Disconnecting,
                value: {
                  type: DisconnectingType.Error,
                  value: {
                    error,
                  },
                },
              }
            })
          break

        case 'sdp_answer':
          let answer = resp.data?.answer
          if (!answer || answer.type === 'unspecified') {
            return
          }

          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.ReceivedSdp,
            },
          }

          // As soon as this is set, RTCPeerConnection tries to
          // establish a connection.
          // @ts-ignore
          // Have to ignore because dom.ts doesn't have the right type
          void this.pc?.setRemoteDescription(answer)

          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.SetRemoteDescription,
            },
          }

          this.state = {
            type: EngineConnectionStateType.Connecting,
            value: {
              type: ConnectingType.WebRTCConnecting,
            },
          }
          break

        case 'trickle_ice':
          let candidate = resp.data?.candidate
          console.log('trickle_ice: using this candidate: ', candidate)
          void this.pc?.addIceCandidate(candidate as RTCIceCandidateInit)
          break

        case 'metrics_request':
          if (this.webrtcStatsCollector === undefined) {
            // TODO: Error message here?
            return
          }
          void this.webrtcStatsCollector().then((client_metrics) => {
            this.send({
              type: 'metrics_response',
              metrics: client_metrics,
            })
          })
          break
      }
    })

    const connectionTimeoutMs = VITE_KC_CONNECTION_TIMEOUT_MS
    if (this.failedConnTimeout) {
      clearTimeout(this.failedConnTimeout)
      this.failedConnTimeout = null
    }
    this.failedConnTimeout = setTimeout(() => {
      if (this.isReady()) {
        return
      }
      this.failedConnTimeout = null
      this.state = {
        type: EngineConnectionStateType.Disconnecting,
        value: {
          type: DisconnectingType.Timeout,
        },
      }
      this.disconnectAll()
      this.finalizeIfAllConnectionsClosed()
    }, connectionTimeoutMs)

    this.onConnectionStarted(this)
  }
  unreliableSend(message: object | string) {
    // TODO(paultag): Add in logic to determine the connection state and
    // take actions if needed?
    this.unreliableDataChannel?.send(
      typeof message === 'string' ? message : JSON.stringify(message)
    )
  }
  send(message: object | string) {
    // TODO(paultag): Add in logic to determine the connection state and
    // take actions if needed?
    this.websocket?.send(
      typeof message === 'string' ? message : JSON.stringify(message)
    )
  }
  disconnectAll() {
    this.websocket?.close()
    this.unreliableDataChannel?.close()
    this.pc?.close()

    this.webrtcStatsCollector = undefined
  }
  finalizeIfAllConnectionsClosed() {
    console.log(this.websocket, this.pc, this.unreliableDataChannel)
    const allClosed =
      this.websocket?.readyState === 3 &&
      this.pc?.connectionState === 'closed' &&
      this.unreliableDataChannel?.readyState === 'closed'
    if (allClosed) {
      this.state = { type: EngineConnectionStateType.Disconnected }
    }
  }
}

export type EngineCommand = Models['WebSocketRequest_type']
type ModelTypes = Models['OkModelingCmdResponse_type']['type']

type CommandTypes = Models['ModelingCmd_type']['type']

type UnreliableResponses = Extract<
  Models['OkModelingCmdResponse_type'],
  { type: 'highlight_set_entity' }
>
interface UnreliableSubscription<T extends UnreliableResponses['type']> {
  event: T
  callback: (data: Extract<UnreliableResponses, { type: T }>) => void
}

export interface Subscription<T extends ModelTypes> {
  event: T
  callback: (
    data: Extract<Models['OkModelingCmdResponse_type'], { type: T }>
  ) => void
}

export type CommandLog =
  | {
      type: 'send-modeling'
      data: EngineCommand
    }
  | {
      type: 'send-scene'
      data: EngineCommand
    }
  | {
      type: 'receive-reliable'
      data: WebSocketResponse
      id: string
      cmd_type?: string
    }
  | {
      type: 'execution-done'
      data: null
    }

export class EngineCommandManager {
  artifactMap: ArtifactMap = {}
  lastArtifactMap: ArtifactMap = {}
  sceneCommandArtifacts: ArtifactMap = {}
  private getAst: () => Program = () => ({ start: 0, end: 0, body: [] } as any)
  outSequence = 1
  inSequence = 1
  engineConnection?: EngineConnection
  defaultPlanes: { xy: string; yz: string; xz: string } = {
    xy: '',
    yz: '',
    xz: '',
  }
  _commandLogs: CommandLog[] = []
  _commandLogCallBack: (command: CommandLog[]) => void = () => {}
  // Folks should realize that wait for ready does not get called _everytime_
  // the connection resets and restarts, it only gets called the first time.
  // Be careful what you put here.
  private resolveReady = () => {}
  waitForReady: Promise<void> = new Promise((resolve) => {
    this.resolveReady = resolve
  })

  subscriptions: {
    [event: string]: {
      [localUnsubscribeId: string]: (a: any) => void
    }
  } = {} as any
  unreliableSubscriptions: {
    [event: string]: {
      [localUnsubscribeId: string]: (a: any) => void
    }
  } = {} as any

  callbacksEngineStateConnection: ((state: EngineConnectionState) => void)[] =
    []

  constructor() {
    this.engineConnection = undefined
    ;(async () => {
      // circular dependency needs one to be lazy loaded
      const { kclManager } = await import('lang/KclSingleton')
      this.getAst = () => kclManager.ast
    })()
  }

  start({
    setMediaStream,
    setIsStreamReady,
    width,
    height,
    executeCode,
    token,
  }: {
    setMediaStream: (stream: MediaStream) => void
    setIsStreamReady: (isStreamReady: boolean) => void
    width: number
    height: number
    executeCode: (code?: string, force?: boolean) => void
    token?: string
  }) {
    if (width === 0 || height === 0) {
      return
    }

    // If we already have an engine connection, just need to resize the stream.
    if (this.engineConnection) {
      this.handleResize({
        streamWidth: width,
        streamHeight: height,
      })
      return
    }

    const url = `${VITE_KC_API_WS_MODELING_URL}?video_res_width=${width}&video_res_height=${height}`
    this.engineConnection = new EngineConnection({
      url,
      token,
      onConnectionStateChange: (state: EngineConnectionState) => {
        for (let cb of this.callbacksEngineStateConnection) {
          cb(state)
        }
      },
      onEngineConnectionOpen: () => {
        // Make the axis gizmo.
        // We do this after the connection opened to avoid a race condition.
        // Connected opened is the last thing that happens when the stream
        // is ready.
        // We also do this here because we want to ensure we create the gizmo
        // and execute the code everytime the stream is restarted.
        const gizmoId = uuidv4()
        void this.sendSceneCommand({
          type: 'modeling_cmd_req',
          cmd_id: gizmoId,
          cmd: {
            type: 'make_axes_gizmo',
            clobber: false,
            // If true, axes gizmo will be placed in the corner of the screen.
            // If false, it will be placed at the origin of the scene.
            gizmo_mode: true,
          },
        })
        sceneInfra.camControls.onCameraChange()
        this.sendSceneCommand({
          // CameraControls subscribes to default_camera_get_settings response events
          // firing this at connection ensure the camera's are synced initially
          type: 'modeling_cmd_req',
          cmd_id: uuidv4(),
          cmd: {
            type: 'default_camera_get_settings',
          },
        })

        this.initPlanes().then(() => {
          this.resolveReady()
          setIsStreamReady(true)
          executeCode(undefined, true)
        })
      },
      onClose: () => {
        setIsStreamReady(false)
      },
      onConnectionStarted: (engineConnection) => {
        engineConnection?.pc?.addEventListener('datachannel', (event) => {
          let unreliableDataChannel = event.channel

          unreliableDataChannel.addEventListener('message', (event) => {
            const result: UnreliableResponses = JSON.parse(event.data)
            Object.values(
              this.unreliableSubscriptions[result.type] || {}
            ).forEach(
              // TODO: There is only one response that uses the unreliable channel atm,
              // highlight_set_entity, if there are more it's likely they will all have the same
              // sequence logic, but I'm not sure if we use a single global sequence or a sequence
              // per unreliable subscription.
              (callback) => {
                if (
                  result?.data?.sequence &&
                  result?.data.sequence > this.inSequence &&
                  result.type === 'highlight_set_entity'
                ) {
                  this.inSequence = result.data.sequence
                  callback(result)
                }
              }
            )
          })
        })

        // When the EngineConnection starts a connection, we want to register
        // callbacks into the WebSocket/PeerConnection.
        engineConnection.websocket?.addEventListener('message', (event) => {
          if (event.data instanceof ArrayBuffer) {
            // If the data is an ArrayBuffer, it's  the result of an export command,
            // because in all other cases we send JSON strings. But in the case of
            // export we send a binary blob.
            // Pass this to our export function.
            void exportSave(event.data)
          } else {
            const message: Models['WebSocketResponse_type'] = JSON.parse(
              event.data
            )
            if (
              message.success &&
              message.resp.type === 'modeling' &&
              message.request_id
            ) {
              this.handleModelingCommand(message.resp, message.request_id)
            } else if (
              !message.success &&
              message.request_id &&
              this.artifactMap[message.request_id]
            ) {
              this.handleFailedModelingCommand(message)
            }
          }
        })
      },
      onNewTrack: ({ mediaStream }) => {
        console.log('received track', mediaStream)

        mediaStream.getVideoTracks()[0].addEventListener('mute', () => {
          console.log('peer is not sending video to us')
          // this.engineConnection?.close()
          // this.engineConnection?.connect()
        })

        setMediaStream(mediaStream)
      },
    })

    this.engineConnection?.connect()
  }
  handleResize({
    streamWidth,
    streamHeight,
  }: {
    streamWidth: number
    streamHeight: number
  }) {
    if (!this.engineConnection?.isReady()) {
      return
    }

    const resizeCmd: EngineCommand = {
      type: 'modeling_cmd_req',
      cmd_id: uuidv4(),
      cmd: {
        type: 'reconfigure_stream',
        width: streamWidth,
        height: streamHeight,
        fps: 60,
      },
    }
    this.engineConnection?.send(resizeCmd)
  }
  handleModelingCommand(message: WebSocketResponse, id: string) {
    if (message.type !== 'modeling') {
      return
    }
    const modelingResponse = message.data.modeling_response
    const command = this.artifactMap[id]
    const sceneCommand = this.sceneCommandArtifacts[id]
    this.addCommandLog({
      type: 'receive-reliable',
      data: message,
      id,
      cmd_type: command?.commandType || this.lastArtifactMap[id]?.commandType,
    })
    Object.values(this.subscriptions[modelingResponse.type] || {}).forEach(
      (callback) => callback(modelingResponse)
    )

    if (command && command.type === 'pending') {
      const resolve = command.resolve
      const artifact = {
        type: 'result',
        range: command.range,
        pathToNode: command.pathToNode,
        commandType: command.commandType,
        parentId: command.parentId ? command.parentId : undefined,
        data: modelingResponse,
        raw: message,
      } as const
      this.artifactMap[id] = artifact
      if (
        command.commandType === 'entity_linear_pattern' ||
        command.commandType === 'entity_circular_pattern'
      ) {
        const entities = (modelingResponse as any)?.data?.entity_ids
        entities?.forEach((entity: string) => {
          this.artifactMap[entity] = artifact
        })
      }
      resolve({
        id,
        commandType: command.commandType,
        range: command.range,
        data: modelingResponse,
        raw: message,
      })
    } else if (sceneCommand && sceneCommand.type === 'pending') {
      const resolve = sceneCommand.resolve
      const artifact = {
        type: 'result',
        range: sceneCommand.range,
        pathToNode: sceneCommand.pathToNode,
        commandType: sceneCommand.commandType,
        parentId: sceneCommand.parentId ? sceneCommand.parentId : undefined,
        data: modelingResponse,
        raw: message,
      } as const
      this.sceneCommandArtifacts[id] = artifact
      resolve({
        id,
        commandType: sceneCommand.commandType,
        range: sceneCommand.range,
        data: modelingResponse,
      })
    } else if (command) {
      this.artifactMap[id] = {
        type: 'result',
        commandType: command?.commandType,
        range: command?.range,
        pathToNode: command?.pathToNode,
        data: modelingResponse,
        raw: message,
      }
    } else {
      this.sceneCommandArtifacts[id] = {
        type: 'result',
        commandType: sceneCommand?.commandType,
        range: sceneCommand?.range,
        pathToNode: sceneCommand?.pathToNode,
        data: modelingResponse,
        raw: message,
      }
    }
  }
  handleFailedModelingCommand({
    request_id,
    errors,
  }: Models['FailureWebSocketResponse_type']) {
    const id = request_id
    if (!id) return
    const command = this.artifactMap[id]
    if (command && command.type === 'pending') {
      const resolve = command.resolve
      this.artifactMap[id] = {
        type: 'failed',
        range: command.range,
        pathToNode: command.pathToNode,
        commandType: command.commandType,
        parentId: command.parentId ? command.parentId : undefined,
        errors,
      }
      resolve({
        id,
        commandType: command.commandType,
        range: command.range,
        errors,
      })
    } else {
      this.artifactMap[id] = {
        type: 'failed',
        range: command.range,
        pathToNode: command.pathToNode,
        commandType: command.commandType,
        parentId: command.parentId ? command.parentId : undefined,
        errors,
      }
    }
  }
  tearDown() {
    this.engineConnection?.tearDown()
  }
  startNewSession() {
    this.lastArtifactMap = this.artifactMap
    this.artifactMap = {}
  }
  subscribeTo<T extends ModelTypes>({
    event,
    callback,
  }: Subscription<T>): () => void {
    const localUnsubscribeId = uuidv4()
    const otherEventCallbacks = this.subscriptions[event]
    if (otherEventCallbacks) {
      otherEventCallbacks[localUnsubscribeId] = callback
    } else {
      this.subscriptions[event] = {
        [localUnsubscribeId]: callback,
      }
    }
    return () => this.unSubscribeTo(event, localUnsubscribeId)
  }
  private unSubscribeTo(event: ModelTypes, id: string) {
    delete this.subscriptions[event][id]
  }
  subscribeToUnreliable<T extends UnreliableResponses['type']>({
    event,
    callback,
  }: UnreliableSubscription<T>): () => void {
    const localUnsubscribeId = uuidv4()
    const otherEventCallbacks = this.unreliableSubscriptions[event]
    if (otherEventCallbacks) {
      otherEventCallbacks[localUnsubscribeId] = callback
    } else {
      this.unreliableSubscriptions[event] = {
        [localUnsubscribeId]: callback,
      }
    }
    return () => this.unSubscribeToUnreliable(event, localUnsubscribeId)
  }
  private unSubscribeToUnreliable(
    event: UnreliableResponses['type'],
    id: string
  ) {
    delete this.unreliableSubscriptions[event][id]
  }
  onConnectionStateChange(callback: (state: EngineConnectionState) => void) {
    this.callbacksEngineStateConnection.push(callback)
  }
  endSession() {
    // TODO: instead of sending a single command with `object_ids: Object.keys(this.artifactMap)`
    // we need to loop over them each individually because if the engine doesn't recognise a single
    // id the whole command fails.
    const artifactsToDelete: any = {}
    Object.entries(this.artifactMap).forEach(([id, artifact]) => {
      const artifactTypesToDelete: ArtifactMap[string]['commandType'][] = [
        // 'start_path' creates a new scene object for the path, which is why it needs to be deleted,
        // however all of the segments in the path are its children so there don't need to be deleted.
        // this fact is very opaque in the api and docs (as to what should can be deleted).
        // Using an array is the list is likely to grow.
        'start_path',
        'entity_linear_pattern',
        'entity_circular_pattern',
      ]
      if (artifactTypesToDelete.includes(artifact.commandType)) {
        artifactsToDelete[id] = artifact
      }
      if (artifact.commandType === 'import_files') {
        // TODO why is this handled differently from other artifacts, i.e. why does it not use the id from the
        // modeling command? We're having to do special clean up for this one special object.
        artifactsToDelete[(artifact as any)?.data?.data?.object_id] = artifact
      }
    })
    Object.keys(artifactsToDelete).forEach((id) => {
      const deleteCmd: EngineCommand = {
        type: 'modeling_cmd_req',
        cmd_id: uuidv4(),
        cmd: {
          type: 'remove_scene_objects',
          object_ids: [id],
        },
      }
      this.engineConnection?.send(deleteCmd)
    })
  }
  addCommandLog(message: CommandLog) {
    if (this._commandLogs.length > 500) {
      this._commandLogs.shift()
    }
    this._commandLogs.push(message)

    this._commandLogCallBack([...this._commandLogs])
  }
  clearCommandLogs() {
    this._commandLogs = []
    this._commandLogCallBack(this._commandLogs)
  }
  registerCommandLogCallback(callback: (command: CommandLog[]) => void) {
    this._commandLogCallBack = callback
  }
  sendSceneCommand(
    command: EngineCommand,
    forceWebsocket = false
  ): Promise<any> {
    if (this.engineConnection === undefined) {
      return Promise.resolve()
    }

    if (!this.engineConnection?.isReady()) {
      return Promise.resolve()
    }

    if (
      !(
        command.type === 'modeling_cmd_req' &&
        (command.cmd.type === 'highlight_set_entity' ||
          command.cmd.type === 'mouse_move' ||
          command.cmd.type === 'camera_drag_move' ||
          command.cmd.type === 'default_camera_look_at' ||
          command.cmd.type === ('default_camera_perspective_settings' as any))
      )
    ) {
      // highlight_set_entity, mouse_move and camera_drag_move are sent over the unreliable channel and are too noisy
      this.addCommandLog({
        type: 'send-scene',
        data: command,
      })
    }

    if (
      command.type === 'modeling_cmd_req' &&
      command.cmd.type !== lastMessage
    ) {
      console.log('sending command', command.cmd.type)
      lastMessage = command.cmd.type
    }
    if (command.type === 'modeling_cmd_batch_req') {
      this.engineConnection?.send(command)
      // TODO - handlePendingCommands does not handle batch commands
      // return this.handlePendingCommand(command.requests[0].cmd_id, command.cmd)
      return Promise.resolve()
    }
    if (command.type !== 'modeling_cmd_req') return Promise.resolve()
    const cmd = command.cmd
    if (
      (cmd.type === 'camera_drag_move' ||
        cmd.type === 'handle_mouse_drag_move' ||
        cmd.type === 'default_camera_look_at' ||
        cmd.type === ('default_camera_perspective_settings' as any)) &&
      this.engineConnection?.unreliableDataChannel &&
      !forceWebsocket
    ) {
      ;(cmd as any).sequence = this.outSequence
      this.outSequence++
      this.engineConnection?.unreliableSend(command)
      return Promise.resolve()
    } else if (
      cmd.type === 'highlight_set_entity' &&
      this.engineConnection?.unreliableDataChannel
    ) {
      cmd.sequence = this.outSequence
      this.outSequence++
      this.engineConnection?.unreliableSend(command)
      return Promise.resolve()
    } else if (
      cmd.type === 'mouse_move' &&
      this.engineConnection.unreliableDataChannel
    ) {
      cmd.sequence = this.outSequence
      this.outSequence++
      this.engineConnection?.unreliableSend(command)
      return Promise.resolve()
    }
    if (
      command.cmd.type === 'default_camera_look_at' ||
      command.cmd.type === ('default_camera_perspective_settings' as any)
    ) {
      ;(cmd as any).sequence = this.outSequence++
    }
    // since it's not mouse drag or highlighting send over TCP and keep track of the command
    this.engineConnection?.send(command)
    return this.handlePendingSceneCommand(command.cmd_id, command.cmd)
  }
  sendModelingCommand({
    id,
    range,
    command,
    ast,
  }: {
    id: string
    range: SourceRange
    command: EngineCommand | string
    ast: Program
  }): Promise<any> {
    if (this.engineConnection === undefined) {
      return Promise.resolve()
    }

    if (!this.engineConnection?.isReady()) {
      return Promise.resolve()
    }
    if (typeof command !== 'string') {
      this.addCommandLog({
        type: 'send-modeling',
        data: command,
      })
    } else {
      this.addCommandLog({
        type: 'send-modeling',
        data: JSON.parse(command),
      })
    }
    this.engineConnection?.send(command)
    if (typeof command !== 'string' && command.type === 'modeling_cmd_req') {
      return this.handlePendingCommand(id, command?.cmd, ast, range)
    } else if (typeof command === 'string') {
      const parseCommand: EngineCommand = JSON.parse(command)
      if (parseCommand.type === 'modeling_cmd_req')
        return this.handlePendingCommand(id, parseCommand?.cmd, ast, range)
    }
    throw Error('shouldnt reach here')
  }
  handlePendingSceneCommand(
    id: string,
    command: Models['ModelingCmd_type'],
    ast?: Program,
    range?: SourceRange
  ) {
    let resolve: (val: any) => void = () => {}
    const promise = new Promise((_resolve, reject) => {
      resolve = _resolve
    })
    const getParentId = (): string | undefined => {
      if (command.type === 'extend_path') {
        return command.path
      }
      // TODO handle other commands that have a parent
    }
    const pathToNode = ast
      ? getNodePathFromSourceRange(ast, range || [0, 0])
      : []
    this.sceneCommandArtifacts[id] = {
      range: range || [0, 0],
      pathToNode,
      type: 'pending',
      commandType: command.type,
      parentId: getParentId(),
      promise,
      resolve,
    }
    return promise
  }
  handlePendingCommand(
    id: string,
    command: Models['ModelingCmd_type'],
    ast?: Program,
    range?: SourceRange
  ) {
    let resolve: (val: any) => void = () => {}
    const promise = new Promise((_resolve, reject) => {
      resolve = _resolve
    })
    const getParentId = (): string | undefined => {
      if (command.type === 'extend_path') {
        return command.path
      }
      // TODO handle other commands that have a parent
    }
    const pathToNode = ast
      ? getNodePathFromSourceRange(ast, range || [0, 0])
      : []
    this.artifactMap[id] = {
      range: range || [0, 0],
      pathToNode,
      type: 'pending',
      commandType: command.type,
      parentId: getParentId(),
      promise,
      resolve,
    }
    return promise
  }
  sendModelingCommandFromWasm(
    id: string,
    rangeStr: string,
    commandStr: string
  ): Promise<any> {
    if (this.engineConnection === undefined) {
      return Promise.resolve()
    }
    if (!this.engineConnection?.isReady()) {
      return Promise.resolve()
    }
    if (id === undefined) {
      throw new Error('id is undefined')
    }
    if (rangeStr === undefined) {
      throw new Error('rangeStr is undefined')
    }
    if (commandStr === undefined) {
      throw new Error('commandStr is undefined')
    }
    const range: SourceRange = JSON.parse(rangeStr)

    // We only care about the modeling command response.
    return this.sendModelingCommand({
      id,
      range,
      command: commandStr,
      ast: this.getAst(),
    }).then(({ raw }) => JSON.stringify(raw))
  }
  commandResult(id: string): Promise<any> {
    const command = this.artifactMap[id]
    if (!command) {
      throw new Error('No command found')
    }
    if (command.type === 'result') {
      return command.data
    } else if (command.type === 'failed') {
      return Promise.resolve(command.errors)
    }
    return command.promise
  }
  async waitForAllCommands(): Promise<{
    artifactMap: ArtifactMap
  }> {
    const pendingCommands = Object.values(this.artifactMap).filter(
      ({ type }) => type === 'pending'
    ) as PendingCommand[]
    const proms = pendingCommands.map(({ promise }) => promise)
    await Promise.all(proms)

    return {
      artifactMap: this.artifactMap,
    }
  }
  private async initPlanes() {
    const [xy, yz, xz] = [
      await this.createPlane({
        x_axis: { x: 1, y: 0, z: 0 },
        y_axis: { x: 0, y: 1, z: 0 },
        color: { r: 0.7, g: 0.28, b: 0.28, a: 0.4 },
      }),
      await this.createPlane({
        x_axis: { x: 0, y: 1, z: 0 },
        y_axis: { x: 0, y: 0, z: 1 },
        color: { r: 0.28, g: 0.7, b: 0.28, a: 0.4 },
      }),
      await this.createPlane({
        x_axis: { x: 1, y: 0, z: 0 },
        y_axis: { x: 0, y: 0, z: 1 },
        color: { r: 0.28, g: 0.28, b: 0.7, a: 0.4 },
      }),
    ]
    this.defaultPlanes = { xy, yz, xz }

    this.subscribeTo({
      event: 'select_with_point',
      callback: ({ data }) => {
        if (!data?.entity_id) return
        if (
          ![
            this.defaultPlanes.xy,
            this.defaultPlanes.yz,
            this.defaultPlanes.xz,
          ].includes(data.entity_id)
        )
          return
        this.onPlaneSelectCallback(data.entity_id)
      },
    })
  }
  planesInitialized(): boolean {
    return (
      this.defaultPlanes.xy !== '' &&
      this.defaultPlanes.yz !== '' &&
      this.defaultPlanes.xz !== ''
    )
  }

  onPlaneSelectCallback = (id: string) => {}
  onPlaneSelected(callback: (id: string) => void) {
    this.onPlaneSelectCallback = callback
  }

  async setPlaneHidden(id: string, hidden: boolean): Promise<string> {
    return await this.sendSceneCommand({
      type: 'modeling_cmd_req',
      cmd_id: uuidv4(),
      cmd: {
        type: 'object_visible',
        object_id: id,
        hidden: hidden,
      },
    })
  }

  private async createPlane({
    x_axis,
    y_axis,
    color,
  }: {
    x_axis: Models['Point3d_type']
    y_axis: Models['Point3d_type']
    color: Models['Color_type']
  }): Promise<string> {
    const planeId = uuidv4()
    await this.sendSceneCommand({
      type: 'modeling_cmd_req',
      cmd: {
        type: 'make_plane',
        size: 100,
        origin: { x: 0, y: 0, z: 0 },
        x_axis,
        y_axis,
        clobber: false,
        hide: true,
      },
      cmd_id: planeId,
    })
    await this.sendSceneCommand({
      type: 'modeling_cmd_req',
      cmd: {
        type: 'plane_set_color',
        plane_id: planeId,
        color,
      },
      cmd_id: uuidv4(),
    })
    await this.setPlaneHidden(planeId, true)
    return planeId
  }
}

export const engineCommandManager = new EngineCommandManager()