Add device connect mode

Author: microbit-grace

lib/index.ts

@@ -42,6 +42,7 @@ import {
 } from "./usb-radio-bridge.js";
 import {
   createWebUSBConnection,
+  DeviceConnectMode,
   MicrobitWebUSBConnection,
   MicrobitWebUSBConnectionOptions,
 } from "./usb.js";
@@ -58,6 +59,7 @@ export {
   createWebBluetoothConnection,
   createWebUSBConnection,
   DeviceConnectionEventMap,
+  DeviceConnectMode,
   DeviceError,
   FlashDataError,
   FlashEvent,

lib/usb.ts

@@ -37,11 +37,17 @@ export const isChromeOS105 = (): boolean => {
   return /CrOS/.test(userAgent) && /Chrome\/105\b/.test(userAgent);
 };
 
+export enum DeviceConnectMode {
+  TryInitialPair = "try initial pair",
+  TryInitialAndPrevPair = "try initial and prev pair",
+}
+
 export interface MicrobitWebUSBConnectionOptions {
   // We should copy this type when extracting a library, and make it optional.
   // Coupling for now to make it easy to evolve.
 
   logging: Logging;
+  deviceConnectMode: DeviceConnectMode;
 }
 
 export interface MicrobitWebUSBConnection
@@ -176,16 +182,21 @@ class MicrobitWebUSBConnectionImpl
   };
 
   private logging: Logging;
+  private deviceConnectMode: DeviceConnectMode;
 
   private addedListeners: Record<string, number> = {
     serialdata: 0,
   };
 
   constructor(
-    options: MicrobitWebUSBConnectionOptions = { logging: new NullLogging() },
+    options: MicrobitWebUSBConnectionOptions = {
+      logging: new NullLogging(),
+      deviceConnectMode: DeviceConnectMode.TryInitialPair,
+    },
   ) {
     super();
     this.logging = options.logging;
+    this.deviceConnectMode = options.deviceConnectMode;
   }
 
   private log(v: any) {
@@ -460,21 +471,49 @@ class MicrobitWebUSBConnectionImpl
   }
 
   private async connectInternal(): Promise<void> {
-    if (!this.connection) {
-      const device = await this.chooseDevice();
-      this.connection = new DAPWrapper(device, this.logging);
+    if (!this.connection && this.device) {
+      this.connection = new DAPWrapper(this.device, this.logging);
+      await withTimeout(this.connection.reconnectAsync(), 10_000);
+    } else if (!this.connection) {
+      if (this.deviceConnectMode === DeviceConnectMode.TryInitialAndPrevPair) {
+        await this.tryPrevConnectedDevices();
+      }
+      if (!this.connection) {
+        this.device = await this.chooseDevice();
+        this.connection = new DAPWrapper(this.device, this.logging);
+        await withTimeout(this.connection.reconnectAsync(), 10_000);
+      }
+    } else {
+      await withTimeout(this.connection.reconnectAsync(), 10_000);
     }
-    await withTimeout(this.connection.reconnectAsync(), 10_000);
     if (this.addedListeners.serialdata && !this.flashing) {
       this.startSerialInternal();
     }
     this.setStatus(ConnectionStatus.CONNECTED);
   }
 
-  private async chooseDevice(): Promise<USBDevice> {
-    if (this.device) {
-      return this.device;
+  // Drawn from https://github.com/microsoft/pxt/blob/ab97a2422879824c730f009b15d4bf446b0e8547/pxtlib/webusb.ts#L361
+  private async tryPrevConnectedDevices(): Promise<void> {
+    const prevPairedDevices = await this.tryGetDevicesAsync();
+    for (let i = 0; i < prevPairedDevices.length; ++i) {
+      const d = prevPairedDevices[i];
+      this.device = d;
+      this.log(`connect device: ${d.manufacturerName} ${d.productName}`);
+      this.log(`serial number: ${d.serialNumber}`);
+      try {
+        this.connection = new DAPWrapper(this.device, this.logging);
+        await withTimeout(this.connection.reconnectAsync(), 10_000);
+        // Success, stop trying.
+      } catch (e: any) {
+        // Clean slate and try next one.
+        this.device = undefined;
+        this.connection = undefined;
+        this.log(`connection attempt failed, ${e.message}`);
+      }
     }
+  }
+
+  private async chooseDevice(): Promise<USBDevice> {
     this.dispatchTypedEvent("beforerequestdevice", new BeforeRequestDevice());
     this.device = await navigator.usb.requestDevice({
       exclusionFilters: this.exclusionFilters,
@@ -484,6 +523,19 @@ class MicrobitWebUSBConnectionImpl
     return this.device;
   }
 
+  // Drawn from https://github.com/microsoft/pxt/blob/ab97a2422879824c730f009b15d4bf446b0e8547/pxtlib/webusb.ts#L530
+  private async tryGetDevicesAsync(): Promise<USBDevice[]> {
+    this.log("Getting web usb devices");
+    try {
+      const devs = await this.withEnrichedErrors(() =>
+        navigator.usb?.getDevices(),
+      );
+      return devs || [];
+    } catch (e: any) {
+      return [];
+    }
+  }
+
   protected eventActivated(type: string): void {
     switch (type as keyof SerialConnectionEventMap) {
       case "serialdata": {