From 9adebc0b64a5caf83ad96f2a7a4ac15b587f72f9 Mon Sep 17 00:00:00 2001
From: Moreno Feltscher <moreno@smartive.ch>
Date: Fri, 6 Dec 2024 14:45:48 +0100
Subject: [PATCH] feat: add configuration for Next.js (#37)

---
 README.md                           |  3 +++
 package.json                        |  6 +++++-
 src/index.ts                        | 33 +++++++++++++++++++++++------
 src/typings/eslint-config-next.d.ts |  6 ++++++
 4 files changed, 40 insertions(+), 8 deletions(-)
 create mode 100644 src/typings/eslint-config-next.d.ts

diff --git a/README.md b/README.md
index 109ec13..3f603a9 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,9 @@ export default configs.typescript;
 
 // .. or React applications
 export default configs.react;
+
+// .. or Next.js applications
+export default configs.next;
 ```
 
 ### Legacy Config (`.eslintrc`)
diff --git a/package.json b/package.json
index ff4c5f6..0cd7f09 100644
--- a/package.json
+++ b/package.json
@@ -39,6 +39,7 @@
   },
   "homepage": "https://github.com/smartive/eslint-config#readme",
   "dependencies": {
+    "@eslint/eslintrc": "^3.2.0",
     "@typescript-eslint/eslint-plugin": "^8.15.0",
     "@typescript-eslint/parser": "^8.15.0",
     "eslint-config-prettier": "^9.1.0",
@@ -50,17 +51,20 @@
     "typescript-eslint": "^8.15.0"
   },
   "peerDependencies": {
-    "eslint": "^8.57.0 || ^9.0.0"
+    "eslint": "^8.57.0 || ^9.0.0",
+    "eslint-config-next": "^14.0.0 || ^15.0.0"
   },
   "devDependencies": {
     "@commitlint/cli": "^19.6.0",
     "@commitlint/config-conventional": "^19.6.0",
     "@eslint/js": "^9.15.0",
     "@smartive/prettier-config": "^3.0.0",
+    "@types/eslint__eslintrc": "^2.1.2",
     "@types/node": "^22.9.1",
     "cz-conventional-changelog": "^3.3.0",
     "esbuild": "0.24.0",
     "eslint": "^9.15.0",
+    "eslint-config-next": "^15.0.4",
     "husky": "^9.1.7",
     "prettier": "^3.3.3",
     "typescript": "^5.6.3"
diff --git a/src/index.ts b/src/index.ts
index 44cf7f9..985b551 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,4 @@
+import { FlatCompat } from '@eslint/eslintrc';
 import js from '@eslint/js';
 import type { Linter } from 'eslint';
 import { flatConfigs as eslintPluginImportConfigs } from 'eslint-plugin-import';
@@ -86,16 +87,34 @@ const flatConfigTypescript = tsEslint.config(
   },
 );
 
-const flatConfigReact = tsEslint.config(
-  flatConfigTypescript,
-  reactPlugin.configs.flat!.recommended as unknown as Linter.Config,
-  reactPlugin.configs.flat!['jsx-runtime'] as unknown as Linter.Config,
-  { rules: reactRules },
-);
+// This is just a workaround until Next.js decides to provide a flat config
+// the same way the rest of the world does..
+// Nid hässig, nur entüüscht.
+const flatConfigNext = () =>
+  new FlatCompat().extends('next').map((config) => {
+    const { plugins } = config;
+    if (plugins?.import) {
+      // ugly workaround to fix an issue when reusing the import plugin
+      // see https://github.com/eslint/eslintrc/issues/135
+      plugins.import = eslintPluginImportConfigs.errors.plugins!.import;
+    }
+
+    return config;
+  });
+
+const flatConfigReact = (includeNextConfig = false) =>
+  tsEslint.config(
+    flatConfigTypescript,
+    reactPlugin.configs.flat!.recommended as unknown as Linter.Config,
+    reactPlugin.configs.flat!['jsx-runtime'] as unknown as Linter.Config,
+    ...(includeNextConfig ? flatConfigNext() : []),
+    { rules: reactRules },
+  );
 
 export const configs = {
   typescript: flatConfigTypescript,
-  react: flatConfigReact,
+  react: flatConfigReact(),
+  next: flatConfigReact(true),
 };
 
 export const generateLegacyConfig = (react: boolean): Linter.LegacyConfig => ({
diff --git a/src/typings/eslint-config-next.d.ts b/src/typings/eslint-config-next.d.ts
new file mode 100644
index 0000000..c7185da
--- /dev/null
+++ b/src/typings/eslint-config-next.d.ts
@@ -0,0 +1,6 @@
+import type { Linter } from 'eslint';
+
+declare module 'eslint-config-next' {
+  const plugin: Linter.LegacyConfig;
+  export = plugin;
+}