chore: decode data in frontend

backend/src/Model/sparkplugb.ts

@@ -1,21 +1,98 @@
 import { Base64Message } from './Base64Message'
 import { Decoder } from './Decoder'
 import { get } from 'sparkplug-payload'
-var sparkplug = get("spBv1.0")
+var sparkplug = get('spBv1.0')
 
-export const SparkplugDecoder = {
-  decode(input: Buffer): Base64Message {
+export interface IDecoder<T = string> {
+  /**
+   * Can be used to
+   * @param topic
+   */
+  formats: T[]
+  canDecodeTopic?(topic: string): boolean
+  canDecodeData?(data: Base64Message): boolean
+  decode(input: Base64Message, format: T | string | undefined): Base64Message
+
+  /**
+   * If this is just an intermediate decoder, next-decoder can be defined
+   */
+  nextDecoder?: IDecoder
+}
+
+export const SparkplugDecoder: IDecoder = {
+  formats: ['Sparkplug'],
+  canDecodeTopic(topic: string) {
+    return !!topic.match(/spBv1\.0\/[^/]+\/(DDATA|NDATA|NCMD|DCMD|NBIRTH|DBIRTH|NDEATH|DDEATH\/[^/]+\/)/u)
+  },
+  decode(input: Base64Message): Base64Message {
     try {
-      const message = Base64Message.fromString(JSON.stringify(
-        // @ts-ignore
-        sparkplug.decodePayload(new Uint8Array(input)))
+      const message = Base64Message.fromString(
+        JSON.stringify(
+          // @ts-ignore
+          sparkplug.decodePayload(new Uint8Array(input.toBuffer()))
+        )
       )
       message.decoder = Decoder.SPARKPLUG
       return message
     } catch {
-      const message = Base64Message.fromString("Failed to decode sparkplugb payload")
+      const message = new Base64Message(undefined, 'Failed to decode sparkplugb payload')
       message.decoder = Decoder.NONE
       return message
     }
   },
 }
+
+export const StringDecoder: IDecoder = {
+  formats: ['string'],
+  decode(input: Base64Message): Base64Message {
+    return input
+  },
+}
+
+type BinaryFormats =
+  | 'int8'
+  | 'int16'
+  | 'int32'
+  | 'int64'
+  | 'uint8'
+  | 'uint16'
+  | 'uint32'
+  | 'uint64'
+  | 'float'
+  | 'double'
+
+/**
+ * Binary decode primitive binary data type and arrays of these
+ */
+export const BinaryDecoder: IDecoder<BinaryFormats> = {
+  formats: ['int8', 'int16', 'int32', 'int64', 'uint8', 'uint16', 'uint32', 'uint64', 'float', 'double'],
+  decode(input: Base64Message, format: BinaryFormats): Base64Message {
+    const decodingOption = {
+      int8: [Buffer.prototype.readInt8, 1],
+      int16: [Buffer.prototype.readInt16LE, 2],
+      int32: [Buffer.prototype.readInt32LE, 4],
+      int64: [Buffer.prototype.readBigInt64LE, 8],
+      uint8: [Buffer.prototype.readUint8, 1],
+      uint16: [Buffer.prototype.readUint16LE, 2],
+      uint32: [Buffer.prototype.readUint32LE, 4],
+      uint64: [Buffer.prototype.readBigUint64LE, 8],
+      float: [Buffer.prototype.readFloatLE, 4],
+      double: [Buffer.prototype.readDoubleLE, 8],
+    } as const
+
+    const [readNumber, bytesToRead] = decodingOption[format]
+
+    const buf = input.toBuffer()
+    let str: String[] = []
+    if (buf.length % bytesToRead !== 0) {
+      return new Base64Message(undefined, 'Data type does not align with message')
+    }
+    for (let index = 0; index < buf.length; index += bytesToRead) {
+      str.push((readNumber as any).apply(buf, [index]).toString())
+    }
+
+    return Base64Message.fromString(JSON.stringify(str.length === 1 ? str[0] : str))
+  },
+}
+
+export const decoders = [SparkplugDecoder, BinaryDecoder, StringDecoder] as const