feat(wirepas): implement payload parsing

wirepas-5g-mesh-gateway/ScannableArray.ts

@@ -6,10 +6,29 @@ export class ScannableArray {
 		this.array = array
 	}
 
+	/**
+	 * Returns the current character and advances the pointer.
+	 */
 	getChar(): number {
-		const next = this.array.at(this.index++)
-		if (next === undefined) throw new Error(`Out of bounds!`)
-		return next
+		const current = this.peek()
+		this.next()
+		return current
+	}
+
+	/**
+	 * Returns the current character without advancing the pointer.
+	 */
+	peek(): number {
+		const current = this.array.at(this.index)
+		if (current === undefined) throw new Error(`Out of bounds!`)
+		return current
+	}
+
+	/**
+	 * Advance the counter
+	 */
+	next(): void {
+		this.index++
 	}
 
 	hasNext(): boolean {

wirepas-5g-mesh-gateway/decodePayload.spec.ts

@@ -3,27 +3,7 @@ import { decodePayload } from './decodePayload.js'
 import assert from 'node:assert/strict'
 
 void describe('decodePayload()', () => {
-	void it('should decode the payload', () => {
-		/*
-
-        For this payload (92 bytes), it is on TLV format: you have the information ID (1 byte), the data length (1 byte) and the data (n bytes).
-
-        For example, data 01 corresponds to the counter (4 bytes long, data is 42 c2 00 00 or 49730).
-
-        The relevant data starts with 0F for the temperature (here, it is this part: 0f 04 0a d7 c3 41, which gives a temperature of 24.48°C (it is a float32)).
-
-        Also, we send data starting with 01 but with a different length (3 bytes) which corresponds to a key press.
-        Example: 01 00 02 (because there is only one button).
-
-        You may see payloads starting with 03 (3 bytes): it is when LED status/color changes.
-        In this case, color is the following:
-            
-        Byte 1: ID (0x03)
-        Byte 2: Color. 0x00: red, 0x01: blue, 0x02: green
-        Byte 3: State. 0x00: off, 0x01: on.
-        We send this payload when requested (response to get LED status (starts with 0x82)) or when setting LED (message 0x81), as an acknowledgement (to confirm color/status has changed).
-            
-        */
+	void it('should decode a regular payload', () => {
 		const payload = Buffer.from(
 			[
 				// [0x01: COUNTER]         [0x04]   [size_t counter]
@@ -74,22 +54,25 @@ void describe('decodePayload()', () => {
 
 		const decoded = decodePayload(payload)
 
-		assert.deepEqual(decoded, [
-			{ counter: 49730 },
-			{
-				// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
-				temperature: 24.479999542236328,
-			},
-			{
-				// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
-				humidity: 17.695999145507812,
-			},
-			{
-				raw_pressure: 100325,
-			},
-			{
-				raw_gas: 81300,
-			},
-		])
+		assert.deepEqual(decoded, {
+			counter: 49730,
+			timestamp: 251355997789000,
+			// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
+			temperature: 24.479999542236328,
+			// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
+			humidity: 17.695999145507812,
+			raw_pressure: 100325,
+			raw_gas: 81300,
+		})
 	})
+
+	void it('should decode a button press', () =>
+		assert.deepEqual(decodePayload(Buffer.from('010002', 'hex')), {
+			button: 2,
+		}))
+
+	void it('should decode a LED state change', () =>
+		assert.deepEqual(decodePayload(Buffer.from('030101', 'hex')), {
+			led: { b: true },
+		}))
 })

wirepas-5g-mesh-gateway/decodePayload.ts

@@ -1,12 +1,19 @@
 import { ScannableArray } from './ScannableArray.js'
-export type Wirepas5GMeshNodePayload =
-	| { counter: number }
-	| { timestamp: number }
-	| { temperature: number }
-	| { button: number }
-	| { humidity: number }
-	| { raw_pressure: number }
-	| { raw_gas: number }
+export type Wirepas5GMeshNodePayload = {
+	counter?: number
+	// Uptime in nanoseconds
+	timestamp?: number // e.g. 251355997789000 / 1000 / 1000 / 1000 / 60 / 60 / 24 = 2.909 days
+	temperature?: number
+	button?: number
+	humidity?: number
+	raw_pressure?: number
+	raw_gas?: number
+	led?: {
+		r?: boolean
+		g?: boolean
+		b?: boolean
+	}
+}
 
 enum MessageType {
 	COUNTER = 0x01, //          [0x04]   [size_t counter]
@@ -31,12 +38,78 @@ enum MessageType {
 	GAS_RAW = 0x14, //          [0x04]   [float raw_gas]
 }
 
+enum LED_COLOR {
+	RED = 0,
+	BLUE = 1,
+	GREEN = 2,
+}
+
+/*
+
+For this payload (92 bytes), it is on TLV format: you have the information ID (1 byte), the data length (1 byte) and the data (n bytes).
+
+For example, data 01 corresponds to the counter (4 bytes long, data is 42 c2 00 00 or 49730).
+
+The relevant data starts with 0F for the temperature (here, it is this part: 0f 04 0a d7 c3 41, which gives a temperature of 24.48°C (it is a float32)).
+
+## Button special case
+
+Also, we send data starting with 01 but with a different length (3 bytes) which corresponds to a key press.
+
+Example: 01 00 02 (because there is only one button).
+
+## LED special case
+
+You may see payloads starting with 03 (3 bytes): it is when LED status/color changes.
+In this case, color is the following:
+	
+Byte 1: ID (0x03)
+Byte 2: Color. 0x00: red, 0x01: blue, 0x02: green
+Byte 3: State. 0x00: off, 0x01: on.
+
+*/
 export const decodePayload = (
 	payload: Uint8Array,
-): Wirepas5GMeshNodePayload[] => {
-	const messages: Wirepas5GMeshNodePayload[] = []
+): Wirepas5GMeshNodePayload => {
 	const msg = new ScannableArray(payload)
 
+	let message: Wirepas5GMeshNodePayload = {}
+
+	// Button special case
+	if (payload.length === 3 && msg.peek() === 1) {
+		msg.next() // skip type
+		msg.next() // skip len
+		return { button: msg.peek() }
+	}
+
+	// LED special case
+	if (payload.length === 3 && msg.peek() === 3) {
+		msg.next() // skip type
+		const color = msg.getChar()
+		const state = msg.getChar()
+		switch (color) {
+			case LED_COLOR.BLUE:
+				return {
+					led: {
+						b: state === 1 ? true : false,
+					},
+				}
+			case LED_COLOR.GREEN:
+				return {
+					led: {
+						g: state === 1 ? true : false,
+					},
+				}
+			default:
+				return {
+					led: {
+						r: state === 1 ? true : false,
+					},
+				}
+		}
+	}
+
+	// Regular message
 	while (msg.hasNext()) {
 		const type = msg.getChar()
 		const len = msg.getChar()
@@ -46,11 +119,10 @@ export const decodePayload = (
 		switch (type) {
 			// Periodic message with a counter value
 			case MessageType.COUNTER:
-				messages.push({ counter: readUint(msg, len) })
+				message = { ...message, counter: readUint(msg, len) }
 				continue
 			case MessageType.TIMESTAMP:
-				// messages.push({ timestamp: readUint(msg, len) })
-				skip()
+				message = { ...message, timestamp: readUint(msg, len) }
 				continue
 			// Skip
 			case MessageType.IAQ:
@@ -70,16 +142,16 @@ export const decodePayload = (
 				skip()
 				continue
 			case MessageType.TEMPERATURE:
-				messages.push({ temperature: readFloat(msg, len) })
+				message = { ...message, temperature: readFloat(msg, len) }
 				continue
 			case MessageType.HUMIDITY:
-				messages.push({ humidity: readFloat(msg, len) })
+				message = { ...message, humidity: readFloat(msg, len) }
 				continue
 			case MessageType.PRESS_RAW:
-				messages.push({ raw_pressure: readFloat(msg, len) })
+				message = { ...message, raw_pressure: readFloat(msg, len) }
 				continue
 			case MessageType.GAS_RAW:
-				messages.push({ raw_gas: readFloat(msg, len) })
+				message = { ...message, raw_gas: readFloat(msg, len) }
 				continue
 			default:
 				console.error(`Unknown message type`, type)
@@ -88,7 +160,7 @@ export const decodePayload = (
 		}
 	}
 
-	return messages
+	return message
 }
 
 const readUint = (message: ScannableArray, numBytes: number): number => {