fix: aligned Add File... behavior with IDE 1.x

 - code files will be copied to sketch folder root
 - other files go under the `data` folder in the sketch folder root

Closes #284

Signed-off-by: Akos Kitta <a.kitta@arduino.cc>

arduino-ide-extension/src/browser/contributions/add-file.ts

@@ -7,6 +7,7 @@ import {
   CommandRegistry,
   MenuModelRegistry,
   URI,
+  Sketch,
 } from './contribution';
 import { FileDialogService } from '@theia/filesystem/lib/browser';
 import { nls } from '@theia/core/lib/common';
@@ -46,9 +47,7 @@ export class AddFile extends SketchContribution {
     if (!toAddUri) {
       return;
     }
-    const sketchUri = new URI(sketch.uri);
-    const filename = toAddUri.path.base;
-    const targetUri = sketchUri.resolve('data').resolve(filename);
+    const { uri: targetUri, filename } = this.resolveTarget(sketch, toAddUri);
     const exists = await this.fileService.exists(targetUri);
     if (exists) {
       const { response } = await remote.dialog.showMessageBox({
@@ -80,6 +79,22 @@ export class AddFile extends SketchContribution {
       }
     );
   }
+
+  // https://github.com/arduino/arduino-ide/issues/284#issuecomment-1364533662
+  // File the file to add has one of the following extension, it goes to the sketch folder root: .ino, .h, .cpp, .c, .S
+  // Otherwise, the files goes to the `data` folder inside the sketch folder root.
+  private resolveTarget(
+    sketch: Sketch,
+    toAddUri: URI
+  ): { uri: URI; filename: string } {
+    const path = toAddUri.path;
+    const filename = path.base;
+    let root = new URI(sketch.uri);
+    if (!Sketch.Extensions.CODE_FILES.includes(path.ext)) {
+      root = root.resolve('data');
+    }
+    return { uri: root.resolve(filename), filename: filename };
+  }
 }
 
 export namespace AddFile {

arduino-ide-extension/src/common/protocol/sketches-service.ts

@@ -162,18 +162,9 @@ export namespace Sketch {
   }
   export namespace Extensions {
     export const MAIN = ['.ino', '.pde'];
-    export const SOURCE = ['.c', '.cpp', '.s'];
-    export const ADDITIONAL = [
-      '.h',
-      '.c',
-      '.hpp',
-      '.hh',
-      '.cpp',
-      '.S',
-      '.json',
-      '.md',
-      '.adoc',
-    ];
+    export const SOURCE = ['.c', '.cpp', '.S'];
+    export const CODE_FILES = [...MAIN, ...SOURCE, '.h', '.hh', '.hpp'];
+    export const ADDITIONAL = [...CODE_FILES, '.json', '.md', '.adoc'];
     export const ALL = Array.from(new Set([...MAIN, ...SOURCE, ...ADDITIONAL]));
   }
   export function isInSketch(uri: string | URI, sketch: Sketch): boolean {