refactor: split buildFromOxlintConfig into multiple files

src/build-from-oxlint-config.spec.ts

@@ -2,7 +2,7 @@ import { describe, expect, it } from 'vitest';
 import {
   buildFromOxlintConfig,
   buildFromOxlintConfigFile,
-} from './build-from-oxlint-config.js';
+} from './build-from-oxlint-config/index.js';
 import fs from 'node:fs';
 import { execSync } from 'node:child_process';
 import type { Linter } from 'eslint';

src/build-from-oxlint-config/categories.ts

@@ -0,0 +1,57 @@
+import { aliasPluginNames } from '../constants.js';
+import configByCategory from '../generated/configs-by-category.js';
+import {
+  OxlintConfig,
+  OxlintConfigCategories,
+  OxlintConfigPlugins,
+} from './types.js';
+import { isObject } from './utils.js';
+
+/**
+ * appends all rules which are enabled by a plugin and falls into a specific category
+ */
+export const handleCategoriesScope = (
+  plugins: OxlintConfigPlugins,
+  categories: OxlintConfigCategories,
+  rules: Record<string, 'off'>
+): void => {
+  for (const category in categories) {
+    const configName = `flat/${category}`;
+
+    // category is not enabled or not in found categories
+    if (categories[category] === 'off' || !(configName in configByCategory)) {
+      continue;
+    }
+
+    // @ts-expect-error -- come on TS, we are checking if the configName exists in the configByCategory
+    const possibleRules = configByCategory[configName].rules;
+
+    // iterate to each rule to check if the rule can be appended, because the plugin is activated
+    for (const rule of Object.keys(possibleRules)) {
+      for (const plugin of plugins) {
+        const pluginPrefix =
+          plugin in aliasPluginNames ? aliasPluginNames[plugin] : plugin;
+
+        // the rule has no prefix, so it is a eslint one
+        if (pluginPrefix === '' && !rule.includes('/')) {
+          rules[rule] = 'off';
+          // other rules with a prefix like @typescript-eslint/
+        } else if (rule.startsWith(`${pluginPrefix}/`)) {
+          rules[rule] = 'off';
+        }
+      }
+    }
+  }
+};
+
+/**
+ * tries to return the "categories" section from the config.
+ * it returns `undefined` when not found or invalid.
+ */
+export const readCategoriesFromConfig = (
+  config: OxlintConfig
+): OxlintConfigCategories | undefined => {
+  return 'categories' in config && isObject(config.categories)
+    ? (config.categories as OxlintConfigCategories)
+    : undefined;
+};