Migrate to capacitor's BleClient

Quite a simplication as the service/characteristic lookups are deferred to
point of use and the interactions are internally queued.

I can't see how to filter with more than once namePrefix. That might require a
patch but can be deferred for now.

This works well via the demo for web.

It'll need flashing code integrating before it's useful for the app.

Reconnection logic feels like something that's going to conflict with flashing
(where disconnects happen as part of pairing) so we need to bottom that out as
part of the integration. But it's super-useful for typical use.

Author: microbit-matt-hillsdon

lib/accelerometer-service.ts

@@ -1,69 +1,27 @@
+import { BleClient } from "@capacitor-community/bluetooth-le";
 import { AccelerometerData, AccelerometerDataEvent } from "./accelerometer.js";
 import { Service } from "./bluetooth-device-wrapper.js";
-import { profile } from "./bluetooth-profile.js";
-import { BackgroundErrorEvent, DeviceError } from "./device.js";
 import {
-  CharacteristicDataTarget,
   TypedServiceEvent,
   TypedServiceEventDispatcher,
 } from "./service-events.js";
+import { profile } from "./bluetooth-profile.js";
 
 export class AccelerometerService implements Service {
+  static createService(
+    deviceId: string,
+    dispatchTypedEvent: TypedServiceEventDispatcher,
+  ): AccelerometerService {
+    return new AccelerometerService(deviceId, dispatchTypedEvent);
+  }
+
   constructor(
-    private accelerometerDataCharacteristic: BluetoothRemoteGATTCharacteristic,
-    private accelerometerPeriodCharacteristic: BluetoothRemoteGATTCharacteristic,
+    private deviceId: string,
     private dispatchTypedEvent: TypedServiceEventDispatcher,
-    private queueGattOperation: <R>(action: () => Promise<R>) => Promise<R>,
-  ) {
-    this.accelerometerDataCharacteristic.addEventListener(
-      "characteristicvaluechanged",
-      (event: Event) => {
-        const target = event.target as CharacteristicDataTarget;
-        const data = this.dataViewToData(target.value);
-        this.dispatchTypedEvent(
-          "accelerometerdatachanged",
-          new AccelerometerDataEvent(data),
-        );
-      },
-    );
-  }
+  ) {}
 
-  static async createService(
-    gattServer: BluetoothRemoteGATTServer,
-    dispatcher: TypedServiceEventDispatcher,
-    queueGattOperation: <R>(action: () => Promise<R>) => Promise<R>,
-    listenerInit: boolean,
-  ): Promise<AccelerometerService | undefined> {
-    let accelerometerService: BluetoothRemoteGATTService;
-    try {
-      accelerometerService = await gattServer.getPrimaryService(
-        profile.accelerometer.id,
-      );
-    } catch (err) {
-      if (listenerInit) {
-        dispatcher("backgrounderror", new BackgroundErrorEvent(err as string));
-        return;
-      } else {
-        throw new DeviceError({
-          code: "service-missing",
-          message: err as string,
-        });
-      }
-    }
-    const accelerometerDataCharacteristic =
-      await accelerometerService.getCharacteristic(
-        profile.accelerometer.characteristics.data.id,
-      );
-    const accelerometerPeriodCharacteristic =
-      await accelerometerService.getCharacteristic(
-        profile.accelerometer.characteristics.period.id,
-      );
-    return new AccelerometerService(
-      accelerometerDataCharacteristic,
-      accelerometerPeriodCharacteristic,
-      dispatcher,
-      queueGattOperation,
-    );
+  getRelevantEvents(): TypedServiceEvent[] {
+    return ["accelerometerdatachanged"];
   }
 
   private dataViewToData(dataView: DataView): AccelerometerData {
@@ -75,15 +33,19 @@ export class AccelerometerService implements Service {
   }
 
   async getData(): Promise<AccelerometerData> {
-    const dataView = await this.queueGattOperation(() =>
-      this.accelerometerDataCharacteristic.readValue(),
+    const dataView = await BleClient.read(
+      this.deviceId,
+      profile.accelerometer.id,
+      profile.accelerometer.characteristics.data.id,
     );
     return this.dataViewToData(dataView);
   }
 
   async getPeriod(): Promise<number> {
-    const dataView = await this.queueGattOperation(() =>
-      this.accelerometerPeriodCharacteristic.readValue(),
+    const dataView = await BleClient.read(
+      this.deviceId,
+      profile.accelerometer.id,
+      profile.accelerometer.characteristics.period.id,
     );
     return dataView.getUint16(0, true);
   }
@@ -99,23 +61,48 @@ export class AccelerometerService implements Service {
     // https://lancaster-university.github.io/microbit-docs/ble/profile/#about-the-accelerometer-service
     const dataView = new DataView(new ArrayBuffer(2));
     dataView.setUint16(0, value, true);
-    return this.queueGattOperation(() =>
-      this.accelerometerPeriodCharacteristic.writeValue(dataView),
+    await BleClient.write(
+      this.deviceId,
+      profile.accelerometer.id,
+      profile.accelerometer.characteristics.period.id,
+      dataView,
     );
   }
 
   async startNotifications(type: TypedServiceEvent): Promise<void> {
-    await this.characteristicForEvent(type)?.startNotifications();
+    const result = this.characteristicForEvent(type);
+    if (result) {
+      const { service, characteristic } = result;
+      BleClient.startNotifications(
+        this.deviceId,
+        service,
+        characteristic,
+        (value) => {
+          const data = this.dataViewToData(value);
+          this.dispatchTypedEvent(
+            "accelerometerdatachanged",
+            new AccelerometerDataEvent(data),
+          );
+        },
+      );
+    }
   }
 
   async stopNotifications(type: TypedServiceEvent): Promise<void> {
-    await this.characteristicForEvent(type)?.stopNotifications();
+    const result = this.characteristicForEvent(type);
+    if (result) {
+      const { service, characteristic } = result;
+      BleClient.stopNotifications(this.deviceId, service, characteristic);
+    }
   }
 
   private characteristicForEvent(type: TypedServiceEvent) {
     switch (type) {
       case "accelerometerdatachanged": {
-        return this.accelerometerDataCharacteristic;
+        return {
+          service: profile.accelerometer.id,
+          characteristic: profile.accelerometer.characteristics.data.id,
+        };
       }
       default: {
         return undefined;