adding OHMA decoding

used on 737 MAX
airframesio · Aug 2, 2024 · b6e4ad8 · b6e4ad8
1 parent 3a077e1
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diff --git a/lib/plugins/Label_H1_OHMA.test.ts b/lib/plugins/Label_H1_OHMA.test.ts
@@ -0,0 +1,53 @@
+import { MessageDecoder } from '../MessageDecoder';
+import { Label_H1_OHMA } from './Label_H1_OHMA';
+
+test('matches Label H1 Preamble OHMA qualifiers', () => {
+  const decoder = new MessageDecoder();
+  const decoderPlugin = new Label_H1_OHMA(decoder);
+
+  expect(decoderPlugin.decode).toBeDefined();
+  expect(decoderPlugin.name).toBe('label-h1-ohma');
+  expect(decoderPlugin.qualifiers).toBeDefined();
+  expect(decoderPlugin.qualifiers()).toEqual({
+    labels: ['H1'],
+    preambles: ['OHMA'],
+  });
+});
+
+test('decodes Label H1 Preamble OHMA valid', () => {
+  const decoder = new MessageDecoder();
+  const decoderPlugin = new Label_H1_OHMA(decoder);
+
+  // https://app.airframes.io/messages/3126721669
+  const text = 'OHMAeJy1Ul2PojAU/SubPiuhlA/ljQHMkAElgDuTXTakqx2nCaAp1WQz8b/vFXTGEcw+LX26veece88p7+jARMO3NbKRpqhohCrWNHTDoH7P0arkrJbBOkd2jhaPkZOjUX6BeFSytqGpmj5WJ2NVyzC2ydTWiWJN9B8teE0lBRSIUS52Ja1ZA+VPqCXl5Xxf/WaiVZkTyzD0bsB2zcr2si1fS755kxfamu2okHvBHNDbCukCuMU+PSzSFk+F4Ada9vqLxLvSuxq9dELDtK56IdukEqZkvOpbVG0VXIJFYnYW2QFCuqzXFm5Jm+YcG2xLKyYFX32CB3V70XXQPzv2EX8R+Vn3BrxuJK1XH2HW9KxYyRgWv5gDJCSx72CnOH8dR1/RLhXl9+4f6MF1xRhgJPuSNUzeI1nE+hY5L7ZtO4/RmFjRQwj+4MNqCJf4pNhp/reosggXbhjEke8Fzrxwk2WQ+kUSZ8U/wgNi5kcxhpy9G2PENBVtqt+kcSZoQ4QJViyTDBO8YDYb4GBDwQTfUOIIx4mfpsvEH1xMhzHmfc7gbkTR1R7HcZ9m4eL53m5YmeAhTjA/jbrDMhULT08P3p0jOv4FG0dfvQ==';
+  const decodeResult = decoderPlugin.decode({ text: text });
+  console.log(JSON.stringify(decodeResult, null, 2));
+
+  expect(decodeResult.decoded).toBe(true);
+  expect(decodeResult.decoder.decodeLevel).toBe('full');
+  expect(decodeResult.decoder.name).toBe('label-h1-ohma');
+  expect(decodeResult.formatted.description).toBe('OHMA Message');
+  expect(decodeResult.message.text).toBe(text);
+  expect(decodeResult.raw.ohma).toBe('{\"version\":\"2.0\",\"message\":\"{\\\"clientId\\\":\\\"OHMA\\\",\\\"messageDate\\\":\\\"2024-08-02T11:39:43.784Z\\\",\\\"data\\\":{\\\"airplanes\\\":[{\\\"tailNumber\\\":\\\"N37554\\\",\\\"model\\\":\\\"\\\",\\\"flights\\\":[{\\\"departureAirportCode\\\":\\\"KBOS\\\",\\\"arrivalAirportCode\\\":\\\"KORD\\\",\\\"flightNumber\\\":\\\"UAL567\\\",\\\"flightLegStartTime\\\":\\\"2024-08-02T10:01:33.736Z\\\",\\\"events\\\":[{\\\"eventClassId\\\":\\\"parametric\\\",\\\"eventTime\\\":\\\"2024-08-02T11:39:43.784Z\\\",\\\"eventType\\\":\\\"OHMA_META\\\",\\\"instances\\\":[{\\\"name\\\":\\\"mtPartNumber\\\",\\\"values\\\":[\\\"\\\"]},{\\\"name\\\":\\\"mtCarlVersion\\\",\\\"values\\\":[\\\"4.5\\\"]},{\\\"name\\\":\\\"mtRulesetVersion\\\",\\\"values\\\":[\\\"737 MAX:::AHM-37MBL8-000010L:::1\\\"]}]},{\\\"eventClassId\\\":\\\"parametric\\\",\\\"eventTime\\\":\\\"2024-08-02T11:39:43.784Z\\\",\\\"eventType\\\":\\\"TM1_CLIPMEDIAN_CRUISE_RPT_A\\\",\\\"instances\\\":[{\\\"name\\\":\\\"TM1TEMP1_MED\\\",\\\"values\\\":[366.294]},{\\\"name\\\":\\\"TM1TEMP2_MED\\\",\\\"values\\\":[381.763]},{\\\"name\\\":\\\"TM1TEMPDIFF_MED\\\",\\\"values\\\":[15.131]},{\\\"name\\\":\\\"PM1PRESSURE1_MED\\\",\\\"values\\\":[34.766]},{\\\"name\\\":\\\"PM1PRESSURE2_MED\\\",\\\"values\\\":[33.406]},{\\\"name\\\":\\\"PACKFLOWDIFF_MED\\\",\\\"values\\\":[11.816]},{\\\"name\\\":\\\"PACKINPRESDIFF_MED\\\",\\\"values\\\":[6.719]}]}]}]}]}}\"}');
+  expect(decodeResult.formatted.items.length).toBe(1);
+  expect(decodeResult.formatted.items[0].type).toBe('ohma');
+  expect(decodeResult.formatted.items[0].code).toBe('OHMA');
+  expect(decodeResult.formatted.items[0].label).toBe('OHMA Downlink');
+  expect(decodeResult.formatted.items[0].value.length).toBe(2658)}); // instead of comparing to a giant json obj
+
+
+test('decodes Label H1 Preamble OHMA invalid', () => {
+  const decoder = new MessageDecoder();
+  const decoderPlugin = new Label_H1_OHMA(decoder);
+
+  const text = 'OHMA <Invalid text>';
+  const decodeResult = decoderPlugin.decode({ text: text });
+  console.log(JSON.stringify(decodeResult, null, 2));
+
+  expect(decodeResult.decoded).toBe(false);
+  expect(decodeResult.decoder.decodeLevel).toBe('none');
+  expect(decodeResult.decoder.name).toBe('label-h1-ohma');
+  expect(decodeResult.formatted.description).toBe('OHMA Message');
+  expect(decodeResult.message.text).toBe(text);
+  expect(decodeResult.remaining.text).toBe(text);
+});
diff --git a/lib/plugins/Label_H1_OHMA.ts b/lib/plugins/Label_H1_OHMA.ts
@@ -0,0 +1,59 @@
+import { DecoderPlugin } from '../DecoderPlugin';
+import { DecodeResult, Message, Options } from '../DecoderPluginInterface';
+
+import * as zlib  from "minizlib";
+
+export class Label_H1_OHMA extends DecoderPlugin {
+  name = 'label-h1-ohma';
+
+  qualifiers() { // eslint-disable-line class-methods-use-this
+    return {
+      labels: ["H1"],
+      preambles: ['OHMA'], //TODO - support data before #
+    };
+  }
+
+  decode(message: Message, options: Options = {}) : DecodeResult {
+    let decodeResult: any = this.defaultResult;
+    decodeResult.decoder.name = this.name;
+    decodeResult.formatted.description = 'OHMA Message';
+    decodeResult.message = message;
+    decodeResult.remaining.text = '';
+
+    const data = message.text.slice(4);
+
+    try {
+    const compressedBuffer = Buffer.from(data, 'base64');
+    const decompress = new zlib.Inflate({windowBits: 15});
+    decompress.write(compressedBuffer);
+    decompress.flush(zlib.constants.Z_SYNC_FLUSH);
+    const result = decompress.read();
+    const jsonText = result.toString();
+    const json = JSON.parse(jsonText);
+    const ohmaMsg = JSON.parse(json.message);
+
+    decodeResult.decoded = true;
+    decodeResult.decoder.decodeLevel = 'full';
+    decodeResult.raw.ohma = jsonText;
+    decodeResult.formatted.items.push({
+      type: 'ohma',
+      code: 'OHMA' ,
+      label: 'OHMA Downlink',
+      value: JSON.stringify(ohmaMsg, null, 2)
+    });
+    } catch {
+      // Unknown
+      if (options.debug) {
+        console.log(`Decoder: Unknown H1 OHMA message: ${message.text}`);
+      }
+      decodeResult.remaining.text += message.text;
+      decodeResult.decoded = false;
+      decodeResult.decoder.decodeLevel = 'none';
+    }
+
+	  return decodeResult;
+  }
+}
+
+export default {};
+