import js from '@eslint/js';
import globals from 'globals';
import reactHooks from 'eslint-plugin-react-hooks';
import reactRefresh from 'eslint-plugin-react-refresh';

// Flat config scoped to the React client. The point is enforcement of the two
// rules that catch real React bugs — rules-of-hooks (conditional hooks) and
// exhaustive-deps (stale closures) — which nothing previously checked. Server
// code (CommonJS Node) is out of scope here; `npm run check:server` covers it.
export default [
  { ignores: ['dist/**', 'node_modules/**', 'coverage/**', 'client/**/*.test.*'] },
  {
    files: ['client/**/*.{js,jsx}'],
    languageOptions: {
      ecmaVersion: 2023,
      sourceType: 'module',
      globals: { ...globals.browser },
      parserOptions: { ecmaFeatures: { jsx: true } },
    },
    plugins: {
      'react-hooks': reactHooks,
      'react-refresh': reactRefresh,
    },
    rules: {
      ...js.configs.recommended.rules,
      // The two that matter most for correctness:
      'react-hooks/rules-of-hooks': 'error',
      'react-hooks/exhaustive-deps': 'warn',
      // HMR safety (Vite fast-refresh); allow non-component constant exports.
      'react-refresh/only-export-components': ['warn', { allowConstantExport: true }],
      // Keep the js-recommended noise as warnings so hook signal isn't drowned out.
      'no-unused-vars': ['warn', { varsIgnorePattern: '^[A-Z_]', argsIgnorePattern: '^_' }],
      'no-empty': ['warn', { allowEmptyCatch: true }],
    },
  },
];