Resolve prettier against formatted file

src/PrettierEditProvider.ts

@@ -9,7 +9,8 @@ import {
     TextEdit
 } from 'vscode';
 
-const prettier = require('prettier');
+const path = require('path');
+const Module = require('module');
 
 interface PrettierConfig {
     printWidth: number,
@@ -20,8 +21,23 @@ interface PrettierConfig {
     bracketSpacing: boolean,
     parser: string
 }
+interface Prettier {
+    format: (string, PrettierConfig?) => string
+    readonly version: string
+}
+
+function requirePrettier(fspath: string): Prettier {
+    const fileModule = new Module(fspath);
+    fileModule.paths = Module._nodeModulePaths(path.join(fspath, '..'));
+    try {
+        return fileModule.require("prettier");
+    } catch (e) {
+        // No local prettier found
+    }
+    return require("prettier");
+}
 
-function format(text: string): string {
+function format(text: string, path: string): string {
     const config: PrettierConfig = workspace.getConfiguration('prettier') as any;
     /*
     handle deprecated parser option
@@ -30,6 +46,7 @@ function format(text: string): string {
     if (!parser) { // unset config
         parser = config.useFlowParser ? 'flow' : 'babylon';
     }
+    const prettier = requirePrettier(path);
     let transformed: string;
     try {
         return prettier.format(text, {
@@ -60,14 +77,20 @@ class PrettierEditProvider implements
         options: FormattingOptions,
         token: CancellationToken
     ): TextEdit[] {
-        return [TextEdit.replace(range, format(document.getText(range)))];
+        return [TextEdit.replace(
+            range,
+            format(document.getText(range), document.fileName)
+        )];
     }
     provideDocumentFormattingEdits(
         document: TextDocument,
         options: FormattingOptions,
         token: CancellationToken
     ): TextEdit[] {
-        return [TextEdit.replace(fullDocumentRange(document), format(document.getText()))];
+        return [TextEdit.replace(
+            fullDocumentRange(document),
+            format(document.getText(), document.fileName)
+        )];
     }
 }