eslint.config.ts

import { includeIgnoreFile } from '@eslint/compat';
import eslint from '@eslint/js';
import stylistic from '@stylistic/eslint-plugin';
import eslintPluginVitest from '@vitest/eslint-plugin';
import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
import eslintPluginUnicorn from 'eslint-plugin-unicorn';
import { dirname, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';
import tseslint from 'typescript-eslint';

const __filename = fileURLToPath(
  // @ts-expect-error: tsconfig needs to be configured to support 'import.meta'
  import.meta.url
);
const __dirname = dirname(__filename);
const gitignorePath = resolve(__dirname, '.gitignore');

const config: ReturnType<typeof tseslint.config> = tseslint.config(
  //#region global
  includeIgnoreFile(gitignorePath),
  {
    name: 'manual ignores',
    ignores: [
      'docs/.vitepress/config.mts',
      'docs/.vitepress/theme/index.ts',
      'templates',
      '.prettierrc.js',
    ],
  },
  {
    name: 'linter options',
    linterOptions: {
      reportUnusedDisableDirectives: 'error',
    },
  },
  //#endregion

  //#region eslint (js)
  eslint.configs.recommended,
  {
    name: 'eslint overrides',
    rules: {
      eqeqeq: ['error', 'always', { null: 'ignore' }],
      'logical-assignment-operators': 'error',
      'no-else-return': 'error',
      'prefer-exponentiation-operator': 'error',
      'prefer-template': 'error',
    },
  },
  //#endregion

  //#region typescript-eslint
  ...tseslint.configs.strictTypeChecked,
  {
    name: 'typescript-eslint overrides',
    languageOptions: {
      parserOptions: {
        // project: true,
        project: './tsconfig.lint.json',
        warnOnUnsupportedTypeScriptVersion: false,
      },
    },
    rules: {
      '@typescript-eslint/array-type': [
        'error',
        { default: 'array-simple', readonly: 'generic' },
      ],
      '@typescript-eslint/ban-ts-comment': [
        'error',
        {
          'ts-expect-error': 'allow-with-description',
          'ts-ignore': 'allow-with-description',
        },
      ],
      '@typescript-eslint/consistent-type-imports': [
        'error',
        {
          prefer: 'type-imports',
          disallowTypeAnnotations: false,
          fixStyle: 'separate-type-imports',
        },
      ],
      '@typescript-eslint/explicit-module-boundary-types': 'error',
      '@typescript-eslint/naming-convention': [
        'error',
        {
          format: ['PascalCase'],
          selector: ['class', 'interface', 'typeAlias'],
          leadingUnderscore: 'forbid',
          trailingUnderscore: 'forbid',
        },
        {
          format: ['UPPER_CASE', 'snake_case'],
          selector: ['enumMember'],
          leadingUnderscore: 'forbid',
          trailingUnderscore: 'forbid',
        },
        {
          format: ['PascalCase'],
          selector: ['typeParameter'],
          prefix: ['T'],
          leadingUnderscore: 'forbid',
          trailingUnderscore: 'forbid',
        },
      ],
      '@typescript-eslint/no-confusing-void-expression': [
        'error',
        {
          ignoreArrowShorthand: true,
        },
      ],
      '@typescript-eslint/no-inferrable-types': [
        'error',
        { ignoreParameters: true },
      ],
      '@typescript-eslint/no-non-null-assertion': 'warn',
      '@typescript-eslint/no-unnecessary-condition': 'off', // requires `strictNullChecks` to be enabled
      '@typescript-eslint/no-unsafe-assignment': 'off',
      '@typescript-eslint/no-unsafe-call': 'off',
      '@typescript-eslint/no-unsafe-member-access': 'off',
      '@typescript-eslint/prefer-regexp-exec': 'error',
      '@typescript-eslint/restrict-plus-operands': [
        'error',
        {
          allowAny: false,
          allowBoolean: false,
          allowNullish: false,
          allowNumberAndString: true,
          allowRegExp: false,
        },
      ],
      // TODO @Shinigami92 2024-02-29: Enable restrict-template-expressions later
      // '@typescript-eslint/restrict-template-expressions': [
      //   'error',
      //   { allowNumber: true, allowBoolean: true },
      // ],
      '@typescript-eslint/switch-exhaustiveness-check': [
        'error',
        { requireDefaultForNonUnion: true },
      ],
      '@typescript-eslint/unbound-method': 'off',

      // TODO @Shinigami92 2024-02-29: Remove these later
      '@typescript-eslint/consistent-type-exports': 'off',
      '@typescript-eslint/no-base-to-string': 'off',
      '@typescript-eslint/no-deprecated': 'off',
      '@typescript-eslint/no-floating-promises': 'off',
      '@typescript-eslint/no-unnecessary-type-parameters': 'off',
      '@typescript-eslint/no-unsafe-argument': 'off',
      '@typescript-eslint/no-unsafe-return': 'off',
      '@typescript-eslint/no-var-requires': 'off',
      '@typescript-eslint/restrict-template-expressions': 'off',
      '@typescript-eslint/unified-signatures': 'off',
    },
  },
  //#endregion

  //#region stylistic
  {
    name: 'stylistic overrides',
    plugins: {
      '@stylistic': stylistic,
    },
    rules: {
      '@stylistic/padding-line-between-statements': [
        'error',
        { blankLine: 'always', prev: 'block-like', next: '*' },
      ],
    },
  },
  //#endregion

  //#region unicorn
  eslintPluginUnicorn.configs['flat/recommended'],
  {
    name: 'unicorn overrides',
    rules: {
      'unicorn/filename-case': 'off',
      'unicorn/import-style': 'off', // subjective & doesn't do anything for us
      'unicorn/no-array-callback-reference': 'off', // reduces readability
      'unicorn/no-nested-ternary': 'off', // incompatible with prettier
      'unicorn/no-object-as-default-parameter': 'off', // https://github.com/sindresorhus/eslint-plugin-unicorn/issues/2199
      'unicorn/no-null': 'off', // incompatible with TypeScript
      'unicorn/no-zero-fractions': 'off', // deactivated to raise awareness of floating operations
      'unicorn/number-literal-case': 'off', // incompatible with prettier
      'unicorn/numeric-separators-style': 'off', // "magic numbers" may carry specific meaning
      'unicorn/prefer-string-slice': 'off', // string.substring is sometimes easier to use
      'unicorn/prefer-ternary': 'off', // ternaries aren't always better

      // TODO @Shinigami92 2024-04-27: Potentially enable later
      'unicorn/consistent-existence-index-check': 'off',
      'unicorn/consistent-function-scoping': 'off',
      'unicorn/no-process-exit': 'off',
      'unicorn/prefer-at': 'off',
      'unicorn/prefer-native-coercion-functions': 'off',
      'unicorn/prefer-string-raw': 'off',
      'unicorn/prefer-string-replace-all': 'off',
      'unicorn/prefer-structured-clone': 'off',
      'unicorn/prefer-top-level-await': 'off',
      'unicorn/prefer-type-error': 'off',
      'unicorn/prevent-abbreviations': 'off',
    },
  },
  //#endregion

  //#region prettier
  eslintPluginPrettierRecommended,
  //#endregion

  //#region overrides
  {
    name: 'test/**/*.ts overrides',
    files: ['test/**/*.spec.ts', 'test/**/*.spec.d.ts'],
    plugins: {
      vitest: eslintPluginVitest,
    },
    rules: {
      'deprecation/deprecation': 'off',

      '@typescript-eslint/restrict-template-expressions': [
        'error',
        {
          allowNumber: true,
          allowBoolean: true,
          allowAny: true,
        },
      ],

      ...eslintPluginVitest.configs.recommended.rules,

      'vitest/expect-expect': 'off',
      'vitest/no-alias-methods': 'error',
      'vitest/prefer-each': 'error',
      'vitest/prefer-to-have-length': 'error',
      'vitest/valid-expect': ['error', { maxArgs: 2 }],
    },
    settings: {
      vitest: {
        typecheck: true,
      },
    },
  },
  {
    name: 'test/migrations/*.js overrides',
    rules: {
      'no-undef': 'off',
      'unicorn/prefer-module': 'off',
      '@typescript-eslint/no-require-imports': 'off',
      '@typescript-eslint/no-throw-literal': 'off',
      'unicorn/no-array-reduce': 'off',
    },
  }
  //#endregion
);

export default config;