xkeys.ts

import { EventEmitter } from 'events'
import {
	AnalogStates,
	ButtonEventMetadata,
	ButtonStates,
	Color,
	EventMetadata,
	JoystickValueEmit,
	XKeysEvents,
	XKeysInfo,
} from './api'
import { BackLightType, Product, PRODUCTS, XKEYS_VENDOR_ID } from './products'
import { literal } from './lib'
import { HIDDevice } from './genericHIDDevice'

export declare interface XKeys {
	on<U extends keyof XKeysEvents>(event: U, listener: XKeysEvents[U]): this
	emit<U extends keyof XKeysEvents>(event: U, ...args: Parameters<XKeysEvents[U]>): boolean
}

export class XKeys extends EventEmitter {
	private product: Product & { productId: number; interface: number }

	/** All button states */
	private _buttonStates: ButtonStates = new Map()
	/** Analogue states, such as jog-wheels, shuttle etc */
	private _analogStates: AnalogStates = {
		jog: [],
		joystick: [],
		shuttle: [],
		tbar: [],
		rotary: [],
		trackball: [],
	}

	private receivedVersionResolve?: () => void
	private receivedGenerateDataResolve?: () => void

	private _initialized = false
	private _firmwareVersion = 0 // is set after init()
	private _firmwareVersionIsSet = false
	private _unitId = 0 // is set after init()
	private _unitIdIsSet = false
	private _disconnected = false

	/** Vendor id for the X-keys panels */
	static get vendorId(): number {
		return XKEYS_VENDOR_ID
	}
	/**
	 * Takes a HID device as input. If the HID device is NOT an X-Keys returns null, otherwise some info about it.
	 */
	static filterDevice(deviceInfo: DeviceInfo): { product: Product; productId: number; interface: number } | null {
		if (deviceInfo.vendorId !== XKEYS_VENDOR_ID) return null

		for (const product of Object.values<Product>(PRODUCTS)) {
			for (const hidDevice of product.hidDevices) {
				if (
					hidDevice[0] === deviceInfo.productId &&
					(deviceInfo.interface === null || hidDevice[1] === deviceInfo.interface)
				) {
					return {
						product,
						productId: hidDevice[0],
						interface: hidDevice[1],
					} // Return & break out of the loops
				}
			}
		}
		return null
	}

	constructor(private device: HIDDevice, private deviceInfo: DeviceInfo, private _devicePath: string | undefined) {
		super()

		this.product = this._setupDevice(deviceInfo)
	}
	private _setupDevice(deviceInfo: DeviceInfo) {
		const found = XKeys.filterDevice(deviceInfo)
		if (!found)
			throw new Error(
				`Unknown/Unsupported X-keys: "${deviceInfo.product}" (productId: "${deviceInfo.productId}", interface: "${deviceInfo.interface}").\nPlease report this as an issue on the xkeys github page! (https://github.com/SuperFlyTV/xkeys)`
			)

		this.device.on('data', (data: Buffer) => {
			if (deviceInfo.productId === 210) {
				// Note: The RailDriver is an older device, which doesn't follow the rest of xkeys data structure.
				// To make it easy for us, we'll just remap the data to work for us.

				const rdData = new Uint8Array(32)
				rdData[0] = 0 // this sets the Unit ID to 0 always
				if (!this._firmwareVersionIsSet) {
					rdData[1] = 214 // Fake initial message to set _firmwareVersion
				} else if (!this._unitIdIsSet) {
					rdData[1] = 3 // Fake initial message to set _unitId
				} else {
					rdData[1] = 0 // no pg switch, byte is always 0
				}
				rdData[2] = data.readUInt8(7) // remap button bits
				rdData[3] = data.readUInt8(8) // remap button bits
				rdData[4] = data.readUInt8(9) // remap button bits
				rdData[5] = data.readUInt8(10) // remap button bits
				rdData[6] = data.readUInt8(11) // remap button bits
				rdData[7] = data.readUInt8(12) // remap button bits
				// Add Bailoff to button byte,
				if (data.readUInt8(4) >= 160) {
					// set bit 5 to 1

					rdData[7] = rdData[7] | 16
				}
				rdData[8] = data.readUInt8(0) // remap analog bytes
				rdData[9] = data.readUInt8(1) // remap analog bytes
				rdData[10] = data.readUInt8(2) // remap analog bytes
				rdData[11] = data.readUInt8(3) // remap analog bytes
				rdData[12] = data.readUInt8(5) // remap analog bytes
				rdData[13] = data.readUInt8(6) // remap analog bytes

				for (let i = 0; i < 15; i++) {
					data[i] = rdData[i]
				}
			}

			//------------------------
			if (data.readUInt8(1) === 214) {
				// this is a special report that does not correlate to the regular data report, it is created by sending getVersion()

				const firmVersion = data.readUInt8(10)
				// data.readUInt8(0) the unit ID is the first byte, index 0, used to tell between 2 identical X-keys, UID is set by user
				// data.readUInt16LE(11) // PID is also in this report as a double check.

				this._firmwareVersion = firmVersion || 1 // Firmware version
				this._firmwareVersionIsSet = true

				this.receivedVersionResolve?.()

				return // quit here because this data would be interpreted as button data and give bad results.
			}
			// TODO: Add other special reports here.
			// A standard data report will be sent when something physical happens on the keys, button press, or lever moved for example
			// other special reports may be sent in response to a request or some data input on the device.
			//
			if (data.readUInt8(1) > 3) return // Protect against all special data reports now and into the future.

			const newButtonStates: ButtonStates = new Map()
			const newAnalogStates: AnalogStates = {
				jog: [],
				joystick: [],
				shuttle: [],
				tbar: [],
				rotary: [],
				trackball: [],
			}

			// UID, unit id, is used to uniquely identify a certain panel, from factory it's set to 0, it can be set by a user with this.setUID()
			const UID = data.readUInt8(0) // the unit ID is the first byte, index 0, used to tell between 2 identical X-keys, UID is set by user
			// const PID = deviceInfo.productId // from USB hardware ID

			let timestamp: number | undefined = undefined
			if (this.product.timestampByte !== undefined) {
				timestamp = data.readUInt32BE(this.product.timestampByte) // Time stamp is 4 bytes, use UInt32BE
			}

			const dd = data.readUInt8(1)
			// The genData bit is set when the message is a reply to the Generate Data message
			const genData = dd & (1 << 1) ? true : false
			if (genData) {
				// Note, the generateData is used to get the full state

				this._unitId = UID
				this._unitIdIsSet = true

				this.receivedGenerateDataResolve?.()
			}

			// Note: first button data (bByte) is on byte index 2

			for (let x = 0; x < this.product.bBytes; x++) {
				for (let y = 0; y < this.product.bBits; y++) {
					const index = x * this.product.bBits + y + 1 // add 1 so PS is at index 0, more accurately displays the total button number, but confuses the index for other use, such as LED addressing.

					const d = data.readUInt8(2 + x)

					const bit = d & (1 << y) ? true : false

					newButtonStates.set(index, bit)
				}
			}
			if (this.product.hasPS) {
				// program switch/button is on byte index 1 , bit 1
				const d = data.readUInt8(1)
				const bit = d & (1 << 0) ? true : false // get first bit only
				newButtonStates.set(0, bit) // always keyIndex of PS to 0
			}
			this.product.hasExtraButtons?.forEach((exButton, index) => {
				//const d = data[jog.jogByte] // Jog
				//newAnalogStates.jog[index] = d < 128 ? d : d - 256

				const d = data.readUInt8(exButton.ebByte)
				const bit = d & (1 << exButton.ebBit) ? true : false
				const startIndex = this.product.bBytes * this.product.bBits + 1 // find the end of the button array

				newButtonStates.set(startIndex + index, bit) // start the extra buttons after that.
			})

			this.product.hasJog?.forEach((jog, index) => {
				const d = data[jog.jogByte] // Jog
				newAnalogStates.jog[index] = d < 128 ? d : d - 256
			})
			this.product.hasShuttle?.forEach((shuttle, index) => {
				const d = data[shuttle.shuttleByte] // Shuttle
				newAnalogStates.shuttle[index] = d < 128 ? d : d - 256
			})
			this.product.hasJoystick?.forEach((joystick, index) => {
				const x = data.readUInt8(joystick.joyXbyte) // Joystick X
				let y = data.readUInt8(joystick.joyYbyte) // Joystick Y
				const z = data.readUInt8(joystick.joyZbyte) // Joystick Z (twist of joystick)
				y = -y // "Up" on the joystick should be positive
				if (y === 0) y = 0 // To deal with negative signed zero

				newAnalogStates.joystick[index] = {
					x: x < 128 ? x : x - 256, // -127 to 127
					y: y < -128 ? y + 256 : y, // -127 to 127
					z: z, // joystick z is a continuous value that rolls over to 0 after 255
				}
			})
			this.product.hasTrackball?.forEach((trackball, index) => {
				const x = 256 * data.readUInt8(trackball.trackXbyte_H) + data.readUInt8(trackball.trackXbyte_L) // Trackball X //Delta X motion,  X ball motion = 256*DELTA_X_H + DELTA_X_L.
				const y = 256 * data.readUInt8(trackball.trackYbyte_H) + data.readUInt8(trackball.trackYbyte_L) // Trackball Y

				newAnalogStates.trackball[index] = {
					x: x < 32768 ? x : x - 65536, // -32768 to 32768// Trackball X //Delta X motion,  X ball motion = 256*DELTA_X_H + DELTA_X_L.
					y: y < 32768 ? y : y - 65536, // -32768 to 32768// Trackball Y
				}
			})
			this.product.hasTbar?.forEach((tBar, index) => {
				const d = data.readUInt8(tBar.tbarByte) // T-bar (calibrated)
				newAnalogStates.tbar[index] = d
			})
			this.product.hasRotary?.forEach((rotary, index) => {
				const d = data.readUInt8(rotary.rotaryByte)
				newAnalogStates.rotary[index] = d
			})

			// Disabled/nonexisting buttons: important as some "buttons" in the jog & shuttle devices are used for shuttle events in hardware.
			if (this.product.disableButtons) {
				this.product.disableButtons.forEach((keyIndex) => {
					newButtonStates.set(keyIndex, false)
				})
			}

			// Compare with previous button states:
			newButtonStates.forEach((buttonState: boolean, index: number) => {
				if ((this._buttonStates.get(index) || false) !== newButtonStates.get(index)) {
					const btnLocation = this._findBtnLocation(index)

					const metadata: ButtonEventMetadata = {
						row: btnLocation.row,
						col: btnLocation.col,
						timestamp: timestamp,
					}
					if (buttonState) {
						// Button is pressed
						this.emit('down', index, metadata)
					} else {
						this.emit('up', index, metadata)
					}
				}
			})
			const eventMetadata: EventMetadata = {
				timestamp: timestamp,
			}

			// Compare with previous analogue states:
			newAnalogStates.jog.forEach((newValue, index) => {
				const oldValue = this._analogStates.jog[index]
				// Special case for jog:
				// The jog emits the delta value followed by it being reset to 0
				// Ignore the 0, since that won't be useful
				if (newValue === 0) return
				if (newValue !== oldValue) this.emit('jog', index, newValue, eventMetadata)
			})
			newAnalogStates.shuttle.forEach((newValue, index) => {
				const oldValue = this._analogStates.shuttle[index]
				if (newValue !== oldValue) this.emit('shuttle', index, newValue, eventMetadata)
			})
			newAnalogStates.joystick.forEach((newValue, index) => {
				const oldValue = this._analogStates.joystick[index]
				if (!oldValue) {
					const emitValue: JoystickValueEmit = {
						...newValue,
						// Calculate deltaZ, since that is not trivial to do:
						deltaZ: 0,
					}
					this.emit('joystick', index, emitValue, eventMetadata)
				} else if (oldValue.x !== newValue.x || oldValue.y !== newValue.y || oldValue.z !== newValue.z) {
					const emitValue: JoystickValueEmit = {
						...newValue,
						// Calculate deltaZ, since that is not trivial to do:
						deltaZ: XKeys.calculateDelta(newValue.z, oldValue.z),
					}
					this.emit('joystick', index, emitValue, eventMetadata)
				}
			})
			newAnalogStates.tbar.forEach((newValue, index) => {
				const oldValue = this._analogStates.tbar[index]
				if (newValue !== oldValue) this.emit('tbar', index, newValue, eventMetadata)
			})
			newAnalogStates.rotary.forEach((newValue, index) => {
				const oldValue = this._analogStates.rotary[index]
				if (newValue !== oldValue) this.emit('rotary', index, newValue, eventMetadata)
			})
			newAnalogStates.trackball.forEach((newValue, index) => {
				// We only need to emit the value when not zero, since the trackball motion are relative values.
				if (newValue.x !== 0 || newValue.y !== 0) this.emit('trackball', index, newValue, eventMetadata)
			})

			// Store the new states:
			this._buttonStates = newButtonStates
			this._analogStates = newAnalogStates
		})

		this.device.on('error', (err) => {
			if ((err + '').match(/could not read from/)) {
				// The device has been disconnected
				this._handleDeviceDisconnected().catch((error) => {
					this.emit('error', error)
				})
			} else {
				this.emit('error', err)
			}
		})

		return {
			...found.product,
			productId: found.productId,
			interface: found.interface,
		}
	}

	/** Initialize the device. This ensures that the essential information from the device about its state has been received. */
	public async init(): Promise<void> {
		const pReceivedVersion = new Promise<void>((resolve) => {
			this.receivedVersionResolve = resolve
		})
		const pReceivedGenerateData = new Promise<void>((resolve) => {
			this.receivedGenerateDataResolve = resolve
		})

		this._getVersion()
		this._generateData()

		await pReceivedVersion
		await pReceivedGenerateData

		this._initialized = true
	}
	/** Closes the device. Subsequent commands will raise errors. */
	public async close(): Promise<void> {
		await this._handleDeviceDisconnected()
	}

	/** Firmware version of the device */
	public get firmwareVersion(): number {
		return this._firmwareVersion
	}
	/** Unit id ("UID") of the device, is used to uniquely identify a certain panel, or panel type.
	 * From factory it's set to 0, but it can be changed using this.setUnitId()
	 */
	public get unitId(): number {
		return this._unitId
	}
	/** Various information about the device and its capabilities */
	public get info(): XKeysInfo {
		this.ensureInitialized()
		return literal<XKeysInfo>({
			name: this.product.name,

			vendorId: XKEYS_VENDOR_ID,
			productId: this.product.productId,
			interface: this.product.interface,

			unitId: this.unitId,
			firmwareVersion: this._firmwareVersion, // added this important to defend against older firmware bugs

			colCount: this.product.colCount,
			rowCount: this.product.rowCount,
			layout:
				this.product.layouts?.map((region) => {
					return literal<XKeysInfo['layout'][0]>({
						name: region[0],
						index: region[1],
						startRow: region[2],
						startCol: region[3],
						endRow: region[4],
						endCol: region[5],
					})
				}) || [],

			emitsTimestamp: this.product.timestampByte !== undefined,
			hasPS: this.product.hasPS,
			hasJoystick: this.product.hasJoystick?.length || 0,
			hasTrackball: this.product.hasTrackball?.length || 0,
			hasExtraButtons: this.product.hasExtraButtons?.length || 0,
			hasJog: this.product.hasJog?.length || 0,
			hasShuttle: this.product.hasShuttle?.length || 0,
			hasTbar: this.product.hasTbar?.length || 0,
			hasRotary: this.product.hasRotary?.length || 0,
			hasLCD: this.product.hasLCD || false,
			hasGPIO: this.product.hasGPIO || false,
			hasSerialData: this.product.hasSerialData || false,
			hasDMX: this.product.hasDMX || false,
		})
	}

	/**
	 * Returns an object with current Button states
	 */
	public getButtons(): ButtonStates {
		return new Map(this._buttonStates) // Make a copy
	}

	/**
	 * Sets the indicator-LED on the device, usually a red and green LED at the top of many X-keys
	 * @param ledIndex the LED to set (1 = green (top), 2 = red (bottom))
	 * @param on boolean: on or off
	 * @param flashing boolean: flashing or not (if on)
	 * @returns undefined
	 */
	public setIndicatorLED(ledIndex: number, on: boolean, flashing?: boolean): void {
		this.ensureInitialized()
		//force to 6 or 7
		if (ledIndex === 1) ledIndex = 6
		else if (ledIndex === 2) ledIndex = 7

		this._write([0, 179, ledIndex, on ? (flashing ? 2 : 1) : 0])
	}
	/**
	 * Sets the backlight of a button
	 * @param keyIndex The button of which to set the backlight color
	 * @param color r,g,b or string (RGB, RRGGBB, #RRGGBB)
	 * @param bankIndex number: Which LED bank (top or bottom) to set the color of. (Only applicable to RGB-based panels. )
	 * @param flashing boolean: flashing or not (if on)
	 * @returns undefined
	 */
	public setBacklight(
		keyIndex: number,
		/** RGB, RRGGBB, #RRGGBB */
		color: Color | string | boolean | null,
		flashing?: boolean,
		bankIndex?: number
	): void {
		this.ensureInitialized()
		if (keyIndex === 0) return // PS-button has no backlight

		this._verifyButtonIndex(keyIndex)
		color = this._interpretColor(color, this.product.backLightType)

		const location = this._findBtnLocation(keyIndex)

		if (this.product.backLightType === BackLightType.REMAP_24) {
			// obsolete, Consider removing MHH
			const ledIndex = (location.col - 1) * 8 + location.row - 1
			// backlight LED type 5 is the RGB 24 buttons
			this._write([0, 181, ledIndex, color.g, color.r, color.b, flashing ? 1 : 0]) // Byte order is actually G,R,B,F)
		} else if (this.product.backLightType === BackLightType.RGBx2) {
			// backlight LED type 6, 2 banks of full RGB LEDs
			const ledIndex = keyIndex - 1 // 0 based linear numbering sort of...

			if (bankIndex !== undefined) {
				this._write([0, 165, ledIndex, bankIndex, color.r, color.g, color.b, flashing ? 1 : 0])
			} else {
				// There are  2 LEDs in under a key, 0 for top and 1 for bottom.
				this._write([0, 165, ledIndex, 0, color.r, color.g, color.b, flashing ? 1 : 0])
				this._write([0, 165, ledIndex, 1, color.r, color.g, color.b, flashing ? 1 : 0])
			}
		} else if (this.product.backLightType === BackLightType.STICK_BUTTONS) {
			// The stick buttons, that requires special mapping.

			let ledIndex = location.col - 1 // 0 based linear numbering sort of...
			if (ledIndex > 11) ledIndex = ledIndex + 4
			else if (ledIndex > 5) ledIndex = ledIndex + 2

			const on: boolean = color.r > 0 || color.g > 0 || color.b > 0
			this._write([0, 181, ledIndex, on ? (flashing ? 2 : 1) : 0, 1])
		} else if (this.product.backLightType === BackLightType.LINEAR) {
			// The 40 buttons, that requires special mapping.

			const ledIndexBlue = keyIndex - 1 // 0 based linear numbering sort of...
			const ledIndexRed = ledIndexBlue + this.product.backLight2offset

			this._write([0, 181, ledIndexBlue, color.b > 0 ? (flashing ? 2 : 1) : 0, 0])
			this._write([0, 181, ledIndexRed, color.r > 0 || color.g > 0 ? (flashing ? 2 : 1) : 0, 0])
		} else if (this.product.backLightType === BackLightType.LEGACY) {
			const ledIndexBlue = (location.col - 1) * 8 + location.row - 1
			const ledIndexRed = ledIndexBlue + (this.product.backLight2offset || 0)

			// Blue LED:
			this._write([0, 181, ledIndexBlue, color.b > 0 ? (flashing ? 2 : 1) : 0, 1])

			// Red LED:
			this._write([0, 181, ledIndexRed, color.r > 0 || color.g > 0 ? (flashing ? 2 : 1) : 0, 1])
		} else if (this.product.backLightType === BackLightType.NONE) {
			// No backlight, do nothing
		}
	}
	/**
	 * Sets the backlight of all buttons
	 * @param color r,g,b or string (RGB, RRGGBB, #RRGGBB)
	 * @param bankIndex number: Which LED bank (top or bottom) to control.
	 */
	public setAllBacklights(color: Color | string | boolean | null, bankIndex?: number): void {
		this.ensureInitialized()
		color = this._interpretColor(color, this.product.backLightType)

		if (this.product.backLightType === BackLightType.RGBx2) {
			// backlight LED type 6 is the RGB devices

			if (bankIndex !== undefined) {
				this._write([0, 166, bankIndex, color.r, color.g, color.b])
			} else {
				// There are  2 LEDs in under a key, 0 for top and 1 for bottom.
				this._write([0, 166, 0, color.r, color.g, color.b])
				this._write([0, 166, 1, color.r, color.g, color.b])
			}
		} else {
			// Blue LEDs:
			this._write([0, 182, 0, color.b])
			// Red LEDs:
			this._write([0, 182, 1, color.r || color.g])
		}
	}
	/**
	 * On first call: Turn all backlights off
	 * On second call: Return all backlights to their previous states
	 */
	public toggleAllBacklights(): void {
		this.ensureInitialized()
		this._write([0, 184])
	}
	/**
	 * Sets the backlight intensity of the device
	 * @param blueIntensity 0-255
	 * @param redIntensity 0-255
	 */
	public setBacklightIntensity(blueIntensity: number, redIntensity?: number): void {
		this.ensureInitialized()
		if (redIntensity === undefined) redIntensity = blueIntensity

		blueIntensity = Math.max(Math.min(blueIntensity, 255), 0)
		redIntensity = Math.max(Math.min(redIntensity, 255), 0)

		if (
			this.product.backLightType === BackLightType.LEGACY ||
			this.product.backLightType === BackLightType.LINEAR
		) {
			this._write([0, 187, blueIntensity, redIntensity])
		} else {
			this._write([0, 187, blueIntensity])
		}
	}
	/**
	 * Save the current backlights. This will restore the backlights after a power cycle.
	 * Note: EEPROM command, don't call this function too often, or you'll kill the EEPROM!
	 * (An EEPROM only support a few thousands of write operations.)
	 */
	public saveBackLights(): void {
		this.ensureInitialized()
		this._write([0, 199, 1])
	}
	/**
	 * Sets the flash frequency of LEDs for the entire X-keys. Flashing will always be synchronized
	 * @param frequency 1-255, where 1 is fastest and 255 is the slowest. 255 is approximately 4 seconds between flashes.
	 * @returns undefined
	 */
	public setFrequency(frequency: number): void {
		this.ensureInitialized()
		if (!(frequency >= 1 && frequency <= 255)) {
			throw new Error(`Invalid frequency: ${frequency}`)
		}

		this._write([0, 180, frequency])
	}
	/**
	 * Sets the UID (unit Id) value in the X-keys hardware
	 * Note: EEPROM command, don't call this function too often, or you'll kill the EEPROM!
	 * (An EEPROM only supports a few thousands of write operations.)
	 * @param unitId Unit id ("UID"). Allowed values: 0-255. 0 is factory default
	 * @returns undefined
	 */
	public setUnitId(unitId: number): void {
		this.ensureInitialized()
		if (!(unitId >= 0 && unitId <= 255)) {
			throw new Error(`Invalid UID: ${unitId} (needs to be between 0 - 255)`)
		}

		this._write([0, 189, unitId])
		this._unitId = unitId
	}
	/**
	 * Reboots the device
	 * @returns undefined
	 */
	public rebootDevice(): void {
		this.ensureInitialized()
		this._write([0, 238])
	}
	/**
	 * Sets the 2x16 LCD display
	 * @param line  1 for top line, 2 for bottom line.
	 * @param displayChar // string to display, empty string to clear
	 * @param backlight  0 for off, 1 for on.
	 * @returns undefined
	 */
	public writeLcdDisplay(line: number, displayChar: string, backlight: boolean): void {
		this.ensureInitialized()
		if (!this.product.hasLCD) return // only used for LCD display devices.
		const byteValues = [0, 206, 0, 1, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32] // load the array with 206 op code and spaces

		// change line number to 0 or 1 and set line # byte
		if (line < 2) line = 0
		if (line > 1) line = 1
		byteValues[2] = line
		// change backlight to 0 or 1 and set backlight byte
		let liteByte
		if (backlight) {
			liteByte = 1
		} else {
			liteByte = 0
		}
		byteValues[3] = liteByte // set the LCD backlight on or off.
		// loop through the string and load array with ascii byte values
		let i
		for (i = 0; i < displayChar.length; i++) {
			byteValues[i + 4] = displayChar.charCodeAt(i)
			if (i > 15) break // quit at 16 chars
		}

		this._write(byteValues)
	}

	/**
	 * Writes a Buffer of data bytes to the X-keys device
	 * Used to send custom messages to X-keys for testing and development, see documentation for valid messages
	 * @param buffer The buffer written to the device
	 * @returns undefined
	 */
	public writeData(message: HIDMessage): void {
		this._write(message)
	}

	/** (Internal function) Called when there has been detected that the device has been disconnected */
	public async _handleDeviceDisconnected(): Promise<void> {
		if (!this._disconnected) {
			this._disconnected = true
			await this.device.close()
			this.emit('disconnected')
		}
	}
	/** (Internal function) Called when there has been detected that a device has been reconnected */
	public async _handleDeviceReconnected(device: HIDDevice, deviceInfo: DeviceInfo): Promise<void> {
		if (this._disconnected) {
			this._disconnected = false

			// Re-vitalize:
			this.device = device
			this.product = this._setupDevice(deviceInfo)
			await this.init()

			this.emit('reconnected')
		}
	}
	public _getHIDDevice(): HIDDevice {
		return this.device
	}
	public _getDeviceInfo(): DeviceInfo {
		return this.deviceInfo
	}
	public get devicePath(): string | undefined {
		return this._devicePath
	}
	/** The unique id of the xkeys-panel. Note: This is only available if options.automaticUnitIdMode is set for the Watcher */
	public get uniqueId(): string {
		return `${this.info.productId}_${this.unitId}`
	}
	/**
	 * Writes a Buffer to the X-keys device
	 *
	 * @param buffer The buffer written to the device
	 * @returns undefined
	 */
	private _write(message: HIDMessage): void {
		if (this._disconnected) throw new Error('X-keys panel has been disconnected')
		message = this._padMessage(message)

		const intArray: number[] = []
		for (let index = 0; index < message.length; index++) {
			const value = message[index]
			intArray[index] = typeof value === 'string' ? parseInt(value, 10) : value
		}
		try {
			this.device.write(intArray)
		} catch (e) {
			this.emit('error', e)
		}
	}
	private _padMessage(message: HIDMessage): HIDMessage {
		const messageLength = 36
		while (message.length < messageLength) {
			message.push(0)
		}
		return message
	}

	private _verifyButtonIndex(keyIndex: number): void {
		if (!(keyIndex >= 0 && keyIndex < 8 * this.product.bBytes + 1)) {
			throw new Error(`Invalid keyIndex: ${keyIndex}`)
		}
	}
	private _findBtnLocation(keyIndex: number): { row: number; col: number } {
		let location: { row: number; col: number } = { row: 0, col: 0 }
		// derive the Row and Column from the button index for many products
		if (keyIndex !== 0) {
			// program switch is always on index 0 and always R:0, C:0 unless remapped by btnLocation array
			location.row = keyIndex - this.product.bBits * (Math.ceil(keyIndex / this.product.bBits) - 1)
			location.col = Math.ceil(keyIndex / this.product.bBits)
		}
		// if the product has a btnLocation array, then look up the Row and Column
		if (this.product.btnLocation !== undefined) {
			location = {
				row: this.product.btnLocation[keyIndex][0],
				col: this.product.btnLocation[keyIndex][1],
			}
		}
		return location
	}
	/**
	 * Generate data: forces the unit to send a data report with current states. Important to get the Unit ID.
	 * @param none
	 * @returns undefined //an input report will be generated by the X-keys with bit 2 of PS set. This is useful in determining the initial state of the device before any data has changed.
	 */
	private _generateData(): void {
		this._write([0, 177])
	}
	/**
	 * Gets the firmware version and UID : forces the unit to send a special data report with firmware version and Unit ID.
	 * @param none
	 * @returns undefined //an input report will be generated by the X-keys with byte 2 set to 214. This has the firmware version and UID.
	 */
	private _getVersion(): void {
		this._write([0, 214])
	}
	/** Makes best effort to interpret a color */
	private _interpretColor(color: Color | string | boolean | null, _backLightType: BackLightType): Color {
		if (typeof color === 'boolean' || color === null) {
			// todo: Should we use _backLightType in some way to determine different default colors?
			if (color) return { r: 0, g: 0, b: 255 }
			else return { r: 0, g: 0, b: 0 }
		} else if (typeof color === 'string') {
			// Note: Handle a few "worded" colors, these colors are tweaked to look nice with the X-keys LEDs:
			if (color === 'red') color = 'ff0000'
			else if (color === 'blue') color = '0000ff'
			else if (color === 'violet') color = '600096'
			else if (color === 'aquamarine') color = '00ff45'
			else if (color === 'turquoise') color = '00ff81'
			else if (color === 'purple') color = '960096'
			else if (color === 'redblue') color = 'ff00ff'
			else if (color === 'pink') color = 'ff0828'
			else if (color === 'orange') color = 'ff1400'
			else if (color === 'yellow') color = 'ff8000'
			else if (color === 'green') color = '00ff00'
			else if (color === 'black') color = '000000'
			else if (color === 'white') color = 'ffffff'
			else if (color === 'on') color = 'ffffff'
			else if (color === 'off') color = '000000'

			let m
			if ((m = color.match(/([0-9a-fA-F]{2})([0-9a-fA-F]{2})([0-9a-fA-F]{2})/))) {
				// 'RRGGBB'
				return {
					r: parseInt(m[1], 16),
					g: parseInt(m[2], 16),
					b: parseInt(m[3], 16),
				}
			} else if ((m = color.match(/([0-9a-fA-F]{1})([0-9a-fA-F]{1})([0-9a-fA-F]{1})/))) {
				// 'RGB'
				return {
					r: parseInt(m[1] + m[1], 16),
					g: parseInt(m[2] + m[2], 16),
					b: parseInt(m[3] + m[3], 16),
				}
			} else if ((m = color.match(/([0-9]{1,3}),([0-9]{1,3}),([0-9]{1,3})/))) {
				// '255,127,0' // comma separated integers
				return {
					r: parseInt(m[1], 10),
					g: parseInt(m[2], 10),
					b: parseInt(m[3], 10),
				}
			} else {
				// Fallback:
				this.emit('error', new Error(`Unable to interpret color "${color}"`))
				return {
					r: 127,
					g: 127,
					b: 127,
				}
			}
		} else {
			return color
		}
	}
	/** Check that the .init() function has run, throw otherwise */
	private ensureInitialized() {
		if (!this._initialized) throw new Error('XKeys.init() must be run first!')
	}
	/** Calculate delta value */
	static calculateDelta(newValue: number, oldValue: number, overflow = 256): number {
		let delta = newValue - oldValue
		if (delta < -overflow * 0.5) delta += overflow // Deal with when the new value overflows
		if (delta > overflow * 0.5) delta -= overflow // Deal with when the new value underflows
		return delta
	}
}
type HIDMessage = (string | number)[]
interface DeviceInfo {
	/** Name of the panel */
	product: string | undefined
	vendorId: number
	productId: number
	interface: number | null // null means "anything goes", used when interface isn't available
}