Fix Node.js library path resolution for packaged Electron apps (#797)

Author: Andrey1994

nodejs_package/brainflow/board_shim.ts

@@ -12,6 +12,7 @@ import {
     LogLevels,
 } from './brainflow.types';
 import {BoardControllerCLikeFunctions as CLike, BoardControllerFunctions} from './functions.types';
+import {resolveLibPath} from './lib_path';
 
 export class BrainFlowInputParams
 {
@@ -60,7 +61,7 @@ class BoardControllerDLL extends BoardControllerFunctions
     private constructor()
     {
         super ();
-        this.libPath = `${__dirname}/../brainflow/lib`;
+        this.libPath = resolveLibPath();
         this.dllPath = this.getDLLPath();
         this.lib = this.getLib();
 
@@ -705,4 +706,4 @@ export class BoardShim
         }
         return JSON.parse(out[0].substring(0, len[0]));
     }
-}
+}

nodejs_package/brainflow/data_filter.ts

@@ -19,6 +19,7 @@ import {
 } from './brainflow.types';
 import {complex} from './complex';
 import {DataHandlerCLikeFunctions as CLike, DataHandlerFunctions} from './functions.types';
+import {resolveLibPath} from './lib_path';
 
 class DataHandlerDLL extends DataHandlerFunctions
 {
@@ -32,7 +33,7 @@ class DataHandlerDLL extends DataHandlerFunctions
     private constructor()
     {
         super ();
-        this.libPath = `${__dirname}/../brainflow/lib`;
+        this.libPath = resolveLibPath();
         this.dllPath = this.getDLLPath();
         this.lib = this.getLib();
 
@@ -606,4 +607,4 @@ export class DataFilter
         }
         return output[0];
     }
-}
+}

nodejs_package/brainflow/lib_path.ts

@@ -0,0 +1,28 @@
+import fs from 'fs';
+import path from 'path';
+
+const appAsarRegexp = new RegExp(`\\${path.sep}app\\.asar\\${path.sep}`, 'g');
+
+export function resolveLibPath(): string
+{
+    const defaultLibPath = path.resolve(__dirname, '..', 'brainflow', 'lib');
+    const electronProcess = process as NodeJS.Process & {resourcesPath?: string};
+    const searchRoots = [
+        __dirname,
+        __dirname.replace(appAsarRegexp, `${path.sep}app.asar.unpacked${path.sep}`),
+        typeof electronProcess.resourcesPath === 'string' ? electronProcess.resourcesPath : '',
+    ].filter(Boolean);
+
+    const libPathCandidates = [
+        defaultLibPath,
+        ...searchRoots.flatMap((root) => [
+            path.resolve(root, '..', 'brainflow', 'lib'),
+            path.resolve(root, '..', 'node_modules', 'brainflow', 'brainflow', 'lib'),
+            path.resolve(root, 'node_modules', 'brainflow', 'brainflow', 'lib'),
+            path.resolve(root, 'app.asar.unpacked', 'node_modules', 'brainflow', 'brainflow', 'lib'),
+        ]),
+    ];
+
+    const existingPath = libPathCandidates.find((candidate) => fs.existsSync(candidate));
+    return existingPath || defaultLibPath;
+}

nodejs_package/brainflow/ml_model.ts

@@ -11,6 +11,7 @@ import {
     LogLevels,
 } from './brainflow.types';
 import {MLModuleCLikeFunctions as CLike, MLModuleFunctions} from './functions.types';
+import {resolveLibPath} from './lib_path';
 
 export class BrainFlowModelParams
 {
@@ -52,7 +53,7 @@ class MLModuleDLL extends MLModuleFunctions
     private constructor()
     {
         super ();
-        this.libPath = `${__dirname}/../brainflow/lib`;
+        this.libPath = resolveLibPath();
         this.dllPath = this.getDLLPath();
         this.lib = this.getLib();