Checkpoint

ui/src/services/APRSStream.ts

@@ -0,0 +1,117 @@
+import { BaseStream } from './Stream';
+
+export interface APRSMessage {
+  topic: string;
+  receivedAt: Date;
+  raw: string;
+  radioName?: string;
+}
+
+interface APRSJsonEnvelope {
+  raw?: string;
+  payload?: string;
+  payloadBase64?: string;
+  rawBase64?: string;
+  Raw?: string;
+  Payload?: string;
+  Time?: string;
+  time?: string;
+  timestamp?: string;
+}
+
+const fromBase64 = (value: string): string => {
+  return atob(value);
+};
+
+const pickString = (obj: Record<string, unknown>, keys: string[]): string | undefined => {
+  for (const key of keys) {
+    const value = obj[key];
+    if (typeof value === 'string' && value.trim().length > 0) {
+      return value;
+    }
+  }
+  return undefined;
+};
+
+export class APRSStream extends BaseStream {
+  constructor(autoConnect = false) {
+    super({}, autoConnect);
+  }
+
+  protected decodeMessage(topic: string, payload: Uint8Array): APRSMessage {
+    const text = new TextDecoder().decode(payload).trim();
+    const radioName = this.extractRadioNameFromTopic(topic);
+
+    if (!text.startsWith('{')) {
+      return {
+        topic,
+        receivedAt: new Date(),
+        raw: text,
+        radioName,
+      };
+    }
+
+    const envelope = JSON.parse(text) as APRSJsonEnvelope;
+    const record = envelope as unknown as Record<string, unknown>;
+
+    const raw = this.extractRawFrame(record);
+    const receivedAt = this.extractReceivedAt(record);
+
+    return {
+      topic,
+      receivedAt,
+      raw,
+      radioName,
+    };
+  }
+
+  private extractRawFrame(envelope: Record<string, unknown>): string {
+    const rawFrame = pickString(envelope, ['raw', 'payload']);
+    if (rawFrame && rawFrame.includes('>')) {
+      return rawFrame;
+    }
+
+    const maybeBase64 = pickString(envelope, ['Raw', 'payloadBase64', 'rawBase64', 'Payload']);
+    if (maybeBase64) {
+      const decoded = fromBase64(maybeBase64);
+      if (decoded.includes('>')) {
+        return decoded;
+      }
+    }
+
+    if (rawFrame) {
+      return rawFrame;
+    }
+
+    throw new Error('APRSStream: invalid payload envelope, no APRS frame found');
+  }
+
+  private extractReceivedAt(envelope: Record<string, unknown>): Date {
+    const timeValue = pickString(envelope, ['time', 'Time', 'timestamp']);
+    if (!timeValue) {
+      return new Date();
+    }
+
+    const parsed = new Date(timeValue);
+    if (Number.isNaN(parsed.getTime())) {
+      return new Date();
+    }
+
+    return parsed;
+  }
+
+  private extractRadioNameFromTopic(topic: string): string | undefined {
+    const parts = topic.split('/');
+    if (parts.length >= 3 && parts[0] === 'aprs' && parts[1] === 'packet') {
+      try {
+        return atob(parts[2]);
+      } catch (error) {
+        console.warn('Failed to decode radio name from topic:', topic, error);
+      }
+    }
+
+    return undefined;
+  }
+}
+
+export default APRSStream;