Unregister device

Summary:
Add a new reducer to allow device unregistration. It works as follow:

If the device is disconnected, it will remove the device from the devices list.

If there are more devices, the first device will become selected. If there are running apps, the first app will be selected.

Reviewed By: antonk52

Differential Revision: D55795279

fbshipit-source-id: de90cddf386a9ad3fe0c955b3696c91036decc79

desktop/flipper-ui/src/reducers/connections.tsx

@@ -91,6 +91,10 @@ export type Action =
       type: 'REGISTER_DEVICE';
       payload: BaseDevice;
     }
+  | {
+      type: 'UNREGISTER_DEVICE';
+      payload: BaseDevice;
+    }
   | {
       type: 'SELECT_DEVICE';
       payload: BaseDevice;
@@ -259,6 +263,40 @@ export default (state: State = INITAL_STATE, action: Actions): State => {
       };
     }
 
+    case 'UNREGISTER_DEVICE': {
+      const {payload} = action;
+
+      const newDevices = state.devices.slice();
+      const existing = state.devices.findIndex(
+        (device) => device.serial === payload.serial,
+      );
+      if (existing !== -1) {
+        const d = newDevices[existing];
+        if (d.connected.get()) {
+          throw new Error(
+            `Cannot unregister, '${d.serial}' as is still connected`,
+          );
+        }
+        newDevices.splice(existing, 1);
+      }
+
+      let selectedNewDevice: BaseDevice | null = null;
+      let selectedNewAppId: null | string = null;
+      if (newDevices.length > 0) {
+        selectedNewDevice = newDevices[0];
+        selectedNewAppId =
+          getAllClients(state).find((c) => c.device === selectedNewDevice)
+            ?.id ?? null;
+      }
+
+      return {
+        ...state,
+        devices: newDevices,
+        selectedDevice: selectedNewDevice,
+        selectedAppId: selectedNewAppId,
+      };
+    }
+
     case 'SELECT_PLUGIN': {
       const {selectedPlugin, selectedAppId, deepLinkPayload} = action.payload;