stack-chan

import Serial from 'embedded:io/serial'
import config from 'mc/config'
import { PayloadBuffer } from 'payload-buffer'
import {
  angleToDynamixelPosition,
  dynamixelPositionToAngle,
  dynamixelStatusPayloadHasData,
  int16FromDynamixelPayload,
  int32FromDynamixelPayload,
  int32ToDynamixelBytes,
} from 'protocols/dynamixel-codec'
import { CommandTimeoutError } from 'servo-command-error'
import SingleWaitSlot from 'single-wait-slot'
import Timer from 'timer'

type Maybe<T> =
  | {
      success: true
      value: T
    }
  | {
      success: false
      reason?: string
    }

function el(h: number, l: number) {
  return ((h << 8) & 0xff00) + (l & 0xff)
}

let packetHandler: PacketHandler = null

const INSTRUCTION = {
  PING: 0x01,
  READ: 0x02,
  WRITE: 0x03,
  REG_WRITE: 0x04,
  ACTION: 0x05,
  FACTORY_RESET: 0x06,
  REBOOT: 0x08,
  STATUS: 0x55,
  SYNC_READ: 0x82,
  SYNC_WRITE: 0x83,
  BULK_READ: 0x92,
  BULK_WRITE: 0x93,
} as const
type Instruction = (typeof INSTRUCTION)[keyof typeof INSTRUCTION]

export const BAUDRATE = {
  BAUD_9600: 0x00,
  BAUD_57600: 0x01,
  BAUD_115200: 0x02,
  BAUD_1000000: 0x03,
  BAUD_2000000: 0x04,
} as const
type Baudrate = (typeof BAUDRATE)[keyof typeof BAUDRATE]

export const OPERATING_MODE = {
  CURRENT: 0x00,
  VELOCITY: 0x01,
  POSITION: 0x03,
  EXTENDED_POSITION: 0x04,
  CURRENT_BASED_POSITION: 0x05,
  PWM: 0x10,
} as const
type OperatingMode = (typeof OPERATING_MODE)[keyof typeof OPERATING_MODE]

const ADDRESS = {
  MODEL_NUMBER: 0,
  MODEL_INFORMATION: 2,
  VERSION_OF_FIRMWARE: 6,
  ID: 7,
  BAUDRATE: 8,
  RETURN_DELAY_TIME: 9,
  DRIVE_MODE: 10,
  OPERATING_MODE: 11,
  HOMING_OFFSET: 20,
  TORQUE_ENABLE: 64,
  LED: 65,
  GOAL_CURRENT: 102,
  GOAL_POSITION: 116,
  PROFILE_ACCELERATION: 108,
  PROFILE_VELOCITY: 112,
  PRESENT_CURRENT: 126,
  PRESENT_VELOCITY: 128,
  PRESENT_POSITION: 132,
} as const
type Address = (typeof ADDRESS)[keyof typeof ADDRESS]

const RX_STATE = {
  SEEK: 0,
  HEAD: 1,
  BODY: 2,
} as const
type RxState = (typeof RX_STATE)[keyof typeof RX_STATE]

function assertNeverRxState(state: never): never {
  throw new Error(`Unknown RX state: ${state}`)
}

class PacketHandler extends Serial {
  #callbacks: Map<number, (buffer: Uint8Array, length: number) => void>
  #rxBuffer: Uint8Array
  #payloadBuffer: PayloadBuffer
  #idx: number
  #state: RxState
  #count: number
  constructor(option) {
    const onReadable = function (this: PacketHandler, bytesReadable: number) {
      const rxBuf = this.#rxBuffer
      let bytes = bytesReadable
      while (bytes > 0) {
        // NOTE: We can safely read a number
        rxBuf[this.#idx++] = this.read() as number
        bytes -= 1
        switch (this.#state) {
          case RX_STATE.SEEK:
            if (this.#idx === 1 && rxBuf[0] !== 0xff) {
              this.#idx = 0
            }
            if (this.#idx === 2 && rxBuf[1] !== 0xff) {
              this.#idx = 0
            }
            if (this.#idx >= 3) {
              if (rxBuf[2] === 0xfd) {
                this.#state = RX_STATE.HEAD
              } else {
                // reset seek
                // trace('seeking failed. reset\n')
                this.#idx = 0
              }
            }
            break
          case RX_STATE.HEAD:
            if (this.#idx >= 7) {
              this.#count = (rxBuf[6] << 8) | rxBuf[5]
              this.#state = RX_STATE.BODY
              // trace(`length: ${this.#count}\n`)
            }
            break
          case RX_STATE.BODY:
            this.#count -= 1
            if (this.#count === 0) {
              const id = rxBuf[4]
              const command = rxBuf[7] as Instruction
              if (command === INSTRUCTION.WRITE || command === INSTRUCTION.READ) {
                // trace(`got echo.  ... ${rxBuf.subarray(0, this.#idx)} ignoring\n`)
              } else if (command === INSTRUCTION.STATUS) {
                // trace(`got response for ${id}. triggering callback ... ${rxBuf.subarray(0, this.#idx)} \n`)
                const payloadLength = this.#idx - 8
                const payloadView = this.#payloadBuffer.copyFrom(rxBuf, payloadLength, 7)
                const payload = new Uint8Array(payloadLength)
                payload.set(payloadView.subarray(0, payloadLength))
                this.#callbacks.get(id)?.(payload, payloadLength)
              } else {
                // trace(`something wrong for ${id}. ${rxBuf.subarray(0, this.#idx)} \n`)
                const payloadLength = this.#idx - 8
                const payloadView = this.#payloadBuffer.copyFrom(rxBuf, payloadLength, 7)
                const payload = new Uint8Array(payloadLength)
                payload.set(payloadView.subarray(0, payloadLength))
                this.#callbacks.get(id)?.(payload, payloadLength)
              }
              this.#idx = 0
              this.#state = RX_STATE.SEEK
            }
            break
          default:
            assertNeverRxState(this.#state)
        }
        // noop
      }
    }
    super({
      ...option,
      format: 'number',
      onReadable,
    })
    this.#callbacks = new Map<number, (buffer: Uint8Array, length: number) => void>()
    this.#rxBuffer = new Uint8Array(64)
    this.#payloadBuffer = new PayloadBuffer(32)
    this.#idx = 0
    this.#state = RX_STATE.SEEK
  }
  hasCallbackOf(id: number): boolean {
    return this.#callbacks.has(id)
  }
  registerCallback(id: number, callback: (buffer: Uint8Array, length: number) => void) {
    this.#callbacks.set(id, callback)
  }
  removeCallback(id: number) {
    this.#callbacks.delete(id)
  }
}

/**
 * calculates checksum
 * @param arr - packet array except checksum
 * @returns checksum number
 */
function checksum(arr: number[] | Uint8Array, start = 0, end = arr.length): number {
  let crc16 = 0
  for (let i = start; i < end; i++) {
    const n = arr[i]
    crc16 ^= n << 8
    for (let i = 0; i < 8; i++) {
      if (crc16 & 0x8000) {
        crc16 = (crc16 << 1) ^ 0x8005
      } else {
        crc16 = crc16 << 1
      }
    }
  }
  return crc16
}

type DynamixelSerialConfig = Partial<{
  receive: number
  transmit: number
  port: number
  baud: number
}>
type DynamixelConstructorParam = {
  id: number
  baudrate?: number
  commandTimeoutMs?: number
  serial?: DynamixelSerialConfig
}
type CommandCallback = (values: Uint8Array | undefined) => void
type ErrorCallback = (error: unknown) => void
type CompletionCallback = (error?: unknown) => void
type ValueCallback<T> = (value: T | undefined, error?: unknown) => void
type PendingCommand = {
  instruction: Instruction
  address: Address | undefined
  onResult: CommandCallback
  onError: ErrorCallback
  parameters: number[]
}
const COMMAND_BUSY_ERROR = 'command is already waiting for response'
const DEFAULT_COMMAND_TIMEOUT_MS = 200
// Give the half-duplex bus a short breather after a timeout before the next command
// so a late/echoed response cannot be misread as the reply to the following command.
const COMMAND_RECOVERY_DELAY_MS = 20

function reasonFromError(error: unknown): string {
  if (error && typeof error === 'object' && 'message' in error) {
    return String((error as { message: unknown }).message)
  }
  return String(error)
}

function maybeFailure<T>(error?: unknown): Maybe<T> {
  return {
    success: false,
    reason: error === undefined ? undefined : reasonFromError(error),
  }
}

class Dynamixel {
  static packetHandler: PacketHandler
  static setBaud(baud: number): void {
    // Dynamixel.packetHandler?.close()
    // Dynamixel.packetHandler = new PacketHandler({
    packetHandler?.close()
    packetHandler = new PacketHandler({
      receive: config.serial?.receive ?? 6,
      transmit: config.serial?.transmit ?? 7,
      baud: baud,
      port: 1,
    })
  }
  #id: number
  #onCommandRead: (buffer: Uint8Array, length: number) => void
  #txBuf: Uint8Array
  #waitSlot: SingleWaitSlot<Uint8Array>
  #commandQueue: PendingCommand[] = []
  #isWriting = false
  #commandTimeoutMs: number
  constructor({
    id,
    baudrate = 1_000_000,
    commandTimeoutMs = DEFAULT_COMMAND_TIMEOUT_MS,
    serial,
  }: DynamixelConstructorParam) {
    this.#id = id
    this.#commandTimeoutMs = commandTimeoutMs
    this.#waitSlot = new SingleWaitSlot<Uint8Array>(Timer.set, Timer.clear)
    this.#onCommandRead = (values, _length) => {
      this.#waitSlot.resolve(values)
    }
    this.#txBuf = new Uint8Array(64)
    if (packetHandler == null) {
      // Prefer the driver-specific serial config (e.g. the stackchan_rt subplatform's
      // driver.serial) so the Dynamixel bus pins are not silently inherited from the
      // top-level config.serial that targets the default SCServo bus.
      const receive = serial?.receive ?? config.serial?.receive ?? 6
      const transmit = serial?.transmit ?? config.serial?.transmit ?? 7
      const port = serial?.port ?? 1
      const baud = serial?.baud ?? baudrate
      trace(`[dynamixel] serial port=${port} tx=${transmit} rx=${receive} baud=${baud}\n`)
      packetHandler = new PacketHandler({
        receive,
        transmit,
        baud,
        port,
      })
    }
    if (packetHandler.hasCallbackOf(id)) {
      throw new Error('This id is already instantiated')
    }
    packetHandler.registerCallback(this.#id, this.#onCommandRead)
  }
  teardown(): void {
    packetHandler.removeCallback(this.#id)
  }
  get id(): number {
    return this.#id
  }

  #dispatchCommand(
    instruction: Instruction,
    address?: Address,
    onResult: CommandCallback = () => {},
    onError: ErrorCallback = () => {},
    ...parameters: number[]
  ): boolean {
    if (this.#isWriting || this.#waitSlot.isWaiting) {
      onError(new Error(COMMAND_BUSY_ERROR))
      return false
    }
    this.#isWriting = true
    this.#txBuf[0] = 0xff
    this.#txBuf[1] = 0xff
    this.#txBuf[2] = 0xfd
    this.#txBuf[3] = 0x00
    this.#txBuf[4] = this.#id

    this.#txBuf[7] = instruction // write or read
    let idx = 8
    if (address !== undefined && address !== null) {
      this.#txBuf[idx++] = address & 0xff
      this.#txBuf[idx++] = (address >> 8) & 0xff
    }

    if (instruction === INSTRUCTION.READ) {
      const numRead = parameters[0] ?? 1
      this.#txBuf[idx++] = numRead & 0xff
      this.#txBuf[idx++] = (numRead >> 8) & 0xff
    } else {
      for (const v of parameters) {
        this.#txBuf[idx++] = v
      }
    }

    const len = idx - 5 // instruction(1) + params(0~) + crc(2)
    this.#txBuf[5] = len & 0xff
    this.#txBuf[6] = (len >> 8) & 0xff

    const crc = checksum(this.#txBuf, 0, idx)
    this.#txBuf[idx++] = crc & 0xff
    this.#txBuf[idx++] = (crc >> 8) & 0xff
    /*
    trace('writing: ')
    for (const n of this.#txBuf.subarray(0, idx)) {
      trace(Number(n).toString(16).padStart(2, '0'))
      trace(' ')
    }
    trace('\n')
    */
    const originalFormat = packetHandler.format
    packetHandler.format = 'buffer'
    try {
      packetHandler.write(this.#txBuf.subarray(0, idx))
    } catch (error) {
      this.#isWriting = false
      onError(error)
      return false
    } finally {
      packetHandler.format = originalFormat
    }
    this.#isWriting = false
    const waiting = this.#waitSlot.wait(this.#commandTimeoutMs, onResult, () => {
      trace(
        `[dynamixel] timeout id=${this.#id} instruction=${instruction} address=${address} after ${this.#commandTimeoutMs}ms\n`,
      )
      onError(new CommandTimeoutError('dynamixel', this.#commandTimeoutMs))
    })
    if (!waiting) {
      onError(new Error(COMMAND_BUSY_ERROR))
      return false
    }
    return true
  }

  /**
   * Serializes commands per servo instance. Overlapping commands (e.g. the periodic
   * control loop racing an external setTorque) would otherwise collide on the shared
   * half-duplex bus and surface as busy/timeout errors, so every command is queued and
   * dispatched one at a time. Mirrors the SCServo driver's command queue.
   */
  #sendCommand(
    instruction: Instruction,
    address: Address | undefined,
    onResult: CommandCallback,
    onError: ErrorCallback,
    ...parameters: number[]
  ): boolean {
    this.#commandQueue.push({ instruction, address, onResult, onError, parameters })
    this.#drainCommandQueue()
    return true
  }

  #drainCommandQueue = (): void => {
    if (this.#isWriting || this.#waitSlot.isWaiting) {
      return
    }
    const pending = this.#commandQueue.shift()
    if (pending == null) {
      return
    }
    this.#dispatchCommand(
      pending.instruction,
      pending.address,
      (values) => {
        try {
          pending.onResult(values)
        } finally {
          Timer.set(this.#drainCommandQueue, 0)
        }
      },
      (error) => {
        try {
          pending.onError(error)
        } finally {
          // Timeouts get a short recovery delay so a late reply cannot bleed into the next command.
          Timer.set(this.#drainCommandQueue, error instanceof CommandTimeoutError ? COMMAND_RECOVERY_DELAY_MS : 0)
        }
      },
      ...pending.parameters,
    )
  }

  /**
   * resets values to factory default
   */
  factoryReset(callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.FACTORY_RESET,
      null,
      () => callback?.(),
      callback ?? (() => {}),
      0x01 /* reset values except id and baudrate*/,
    )
  }

  /**
   * reboots servo
   */
  reboot(callback?: CompletionCallback): void {
    this.#sendCommand(INSTRUCTION.REBOOT, undefined, () => callback?.(), callback ?? (() => {}))
  }

  /**
   * sets operating mode
   * @param mode - operating mode
   * @see https://emanual.robotis.com/docs/en/dxl/x/xl330-m288/#operating-mode
   */
  setOperatingMode(mode: OperatingMode, callback?: CompletionCallback): void {
    this.setTorque(false, (torqueError) => {
      if (torqueError != null) {
        callback?.(torqueError)
        return
      }
      this.#sendCommand(INSTRUCTION.WRITE, ADDRESS.OPERATING_MODE, () => callback?.(), callback ?? (() => {}), mode)
    })
  }

  /**
   * sets baudrate
   * @param baudrate - baudrate(bps)
   */
  setBaudrate(baudrate: Baudrate, callback?: CompletionCallback): void {
    this.setTorque(false, (torqueError) => {
      if (torqueError != null) {
        callback?.(torqueError)
        return
      }
      this.#sendCommand(INSTRUCTION.WRITE, ADDRESS.BAUDRATE, () => callback?.(), callback ?? (() => {}), baudrate)
    })
  }

  /**
   * sets profile acceleration
   * @param accel - profile acceleration
   */
  setProfileAcceleration(accel: number, callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.WRITE,
      ADDRESS.PROFILE_ACCELERATION,
      () => callback?.(),
      callback ?? (() => {}),
      ...int32ToDynamixelBytes(accel),
    )
  }

  /**
   * sets profile velocity
   * Velocity [rpm] = Value * 0.229 [rpm]
   * @param velocity - goal velocity (ma)
   */
  setProfileVelocity(velocity: number, callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.WRITE,
      ADDRESS.PROFILE_VELOCITY,
      () => callback?.(),
      callback ?? (() => {}),
      ...int32ToDynamixelBytes(velocity),
    )
  }

  /**
   * sets goal current
   * @param position - goal current (ma)
   */
  setGoalCurrent(current: number, callback?: CompletionCallback): void {
    const a = current & 0xff
    const b = (current >> 8) & 0xff
    this.#sendCommand(INSTRUCTION.WRITE, ADDRESS.GOAL_CURRENT, () => callback?.(), callback ?? (() => {}), a, b)
  }

  /**
   * sets goal position
   * @param position - goal position (4096 per rotation)
   */
  setGoalPosition(position: number, callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.WRITE,
      ADDRESS.GOAL_POSITION,
      () => callback?.(),
      callback ?? (() => {}),
      ...int32ToDynamixelBytes(position),
    )
  }

  /**
   * sets goal angle
   * @param angle - angle in degree
   * @returns
   */
  setGoalAngle(angle: number, callback?: CompletionCallback): void {
    const position = angleToDynamixelPosition(angle)
    this.setGoalPosition(position, callback)
  }

  setLED(on: boolean, callback?: CompletionCallback): void {
    this.#sendCommand(INSTRUCTION.WRITE, ADDRESS.LED, () => callback?.(), callback ?? (() => {}), Number(on))
  }

  /**
   * sets offset angle
   * @param angle - offset angle
   */
  setOffsetAngle(angle: number, callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.WRITE,
      ADDRESS.HOMING_OFFSET,
      () => callback?.(),
      callback ?? (() => {}),
      ...int32ToDynamixelBytes(angleToDynamixelPosition(angle)),
    )
  }

  setId(id: number): void {
    this.#id = id
  }

  /**
   * changes id
   * @param enable - enable
   */
  flashId(id: number, callback?: CompletionCallback): void {
    if (packetHandler.hasCallbackOf(id)) {
      callback?.(new Error(`id(${id}) is already used\n`))
      return
    }
    this.setTorque(false, (torqueError) => {
      if (torqueError != null) {
        callback?.(torqueError)
        return
      }
      const oldId = this.#id
      if (
        !this.#sendCommand(
          INSTRUCTION.WRITE,
          ADDRESS.ID,
          () => {
            packetHandler.removeCallback(oldId)
            callback?.()
          },
          callback ?? (() => {}),
          id,
        )
      ) {
        return
      }
      this.#id = id
      packetHandler.registerCallback(this.#id, this.#onCommandRead)
    })
  }

  /**
   * sets torque
   * @param enable - enable
   */
  setTorque(enable: boolean, callback?: CompletionCallback): void {
    this.#sendCommand(
      INSTRUCTION.WRITE,
      ADDRESS.TORQUE_ENABLE,
      () => callback?.(),
      callback ?? (() => {}),
      Number(enable),
    )
  }

  /**
   * reads model number
   * @returns Model number
   */
  readModelNumber(callback: ValueCallback<number>): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.MODEL_NUMBER,
      (values) => {
        if (values == null || values.length < 4) {
          callback(undefined, new Error('failed to read model number'))
          return
        }
        if (values[1] !== 0) {
          callback(undefined, new Error(`servo returned error code: ${values[1]} while reading model number`))
          return
        }
        // payload layout: [instruction/status, status_code, low, high]
        callback(el(values[3], values[2]))
      },
      (error) => callback(undefined, error),
      2,
    )
  }

  /**
   * reads firmware version
   * @returns Firmware version
   */
  readFirmwareVersion(callback: (result: Maybe<{ version: number }>) => void): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.VERSION_OF_FIRMWARE,
      (values) => {
        if (values != null && values.length >= 3 && values[1] === 0) {
          callback({
            success: true,
            value: {
              version: values[2],
            },
          })
          return
        }
        callback({
          success: false,
          reason: 'failed to read firmware version',
        })
      },
      (error) => callback(maybeFailure(error)),
      1,
    )
  }

  /**
   * reads offset angle
   * @returns offset angle
   */
  readOffsetAngle(callback: ValueCallback<number>): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.HOMING_OFFSET,
      (values) => {
        if (values == null || values.length < 2) {
          callback(undefined, new Error('failed to read offset angle'))
          return
        }
        if (values[1] !== 0) {
          callback(undefined, new Error(`servo returned error code: ${values[1]} while reading offset angle`))
          return
        }
        if (!dynamixelStatusPayloadHasData(values, 4)) {
          callback(undefined, new Error('failed to read offset angle'))
          return
        }
        callback(dynamixelPositionToAngle(int32FromDynamixelPayload(values)))
      },
      (error) => callback(undefined, error),
      4,
    )
  }

  /**
   * reads present current value (ma)
   * @returns current value
   */
  readPresentCurrent(callback: (result: Maybe<{ current: number }>) => void): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.PRESENT_CURRENT,
      (values) => {
        if (values != null && values.length >= 2 && values[1] !== 0) {
          callback({
            success: false,
            reason: `servo returned error code: ${values[1]}`,
          })
          return
        }
        if (dynamixelStatusPayloadHasData(values, 2)) {
          callback({
            success: true,
            value: {
              current: int16FromDynamixelPayload(values),
            },
          })
          return
        }
        callback({
          success: false,
        })
      },
      (error) => callback(maybeFailure(error)),
      2,
    )
  }

  /**
   * reads present velocity [rpm]
   * Velocity [rpm] = Value * 0.229 [rpm]
   * @returns velocity value
   */
  readPresentVelocity(callback: (result: Maybe<number>) => void): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.PRESENT_VELOCITY,
      (values) => {
        if (values != null && values.length >= 2 && values[1] !== 0) {
          callback({
            success: false,
            reason: `servo returned error code: ${values[1]}`,
          })
          return
        }
        if (dynamixelStatusPayloadHasData(values, 4)) {
          callback({
            success: true,
            value: int32FromDynamixelPayload(values),
          })
          return
        }
        callback({
          success: false,
        })
      },
      (error) => callback(maybeFailure(error)),
      4,
    )
  }

  /**
   * reads present position (4096 per rotation)
   * @returns position value
   */
  readPresentPosition(callback: (result: Maybe<number>) => void): void {
    this.#sendCommand(
      INSTRUCTION.READ,
      ADDRESS.PRESENT_POSITION,
      (values) => {
        if (values != null && values.length >= 2 && values[1] !== 0) {
          callback({
            success: false,
            reason: `servo returned error code: ${values[1]}`,
          })
          return
        }
        if (dynamixelStatusPayloadHasData(values, 4)) {
          callback({
            success: true,
            value: int32FromDynamixelPayload(values),
          })
          return
        }
        callback({
          success: false,
        })
      },
      (error) => callback(maybeFailure(error)),
      4,
    )
  }
}

export default Dynamixel