eslint.config.mjs

// @ts-check

import eslintReact from "@eslint-react/eslint-plugin";
import eslintJs from "@eslint/js";
import compat from "eslint-plugin-compat";
import escompat from "eslint-plugin-escompat";
import hooks from "eslint-plugin-react-hooks";
import globals from "globals";
import { readFileSync } from "node:fs";
import tseslint from "typescript-eslint";

// Read "target" from tsconfig.json. require("./tsconfig.json") and
// JSON.parse(tsconfig) won't work because it contains comments.
const tsconfig = readFileSync(import.meta.dirname + "/tsconfig.json", "utf8");
const tstarget = tsconfig.match(/"target": "es(\d\d\d\d)"/)[1];

export default tseslint.config(
  eslintJs.configs.recommended,
  tseslint.configs.strictTypeChecked,
  tseslint.configs.stylisticTypeChecked,
  compat.configs["flat/recommended"],
  escompat.configs["flat/recommended"],
  escompat.configs["flat/typescript-" + tstarget],
  eslintReact.configs["recommended-type-checked"],
  {
    // https://github.com/facebook/react/issues/28313
    plugins: { "react-hooks": hooks },
    rules: hooks.configs.recommended.rules,
  },
  {
    languageOptions: {
      parserOptions: {
        projectService: true,
        tsconfigRootDir: import.meta.dirname,
      },
    },
  },
  {
    rules: {
      // Good rules.
      "curly": ["warn", "multi-line"],

      // Nice to have. Not too valuable, but not too bothersome. We can remove
      // them if they cause trouble later.
      "@eslint-react/naming-convention/component-name": "warn",
      "@eslint-react/naming-convention/use-state": "warn",
      "@eslint-react/no-children-prop": "warn",
      "@eslint-react/no-missing-component-display-name": "warn",
      "@eslint-react/no-unused-class-component-members": "warn",
      "@eslint-react/hooks-extra/no-unnecessary-use-callback": "warn",
      "@eslint-react/hooks-extra/no-unnecessary-use-memo": "warn",
      "@typescript-eslint/default-param-last": "warn",
      "@typescript-eslint/no-dupe-class-members": "warn",
      "@typescript-eslint/no-import-type-side-effects": "warn",
      "@typescript-eslint/no-invalid-this": "warn",
      "@typescript-eslint/no-loop-func": "warn",
      "@typescript-eslint/no-redeclare": "warn",
      "@typescript-eslint/no-unused-expressions": "warn",
      "@typescript-eslint/require-array-sort-compare": "warn",
      "accessor-pairs": "warn",
      "block-scoped-var": "warn",
      "consistent-return": "warn",
      "default-case-last": "warn",
      "default-case": "warn",
      "eqeqeq": "off", // TODO: Maybe enable later; maybe { "null": "ignore" }
      "grouped-accessor-pairs": "warn",
      "lines-between-class-members": "warn",
      "logical-assignment-operators": "warn",
      "new-cap": "warn",
      "no-await-in-loop": "warn",
      "no-bitwise": "warn",
      "no-caller": "warn",
      "no-constant-binary-expression": "warn",
      "no-eval": "warn",
      "no-extend-native": "warn",
      "no-extra-bind": "warn",
      "no-extra-label": "warn",
      "no-label-var": "warn",
      "no-lone-blocks": "warn",
      "no-multi-str": "warn",
      "no-new-func": "warn",
      "no-new-object": "warn",
      "no-new-wrappers": "warn",
      "no-octal-escape": "warn",
      "no-param-reassign": ["warn", { "props": true }],
      "no-promise-executor-return": "warn",
      "no-return-assign": "warn",
      "no-self-compare": "warn",
      "no-sequences": ["warn", { "allowInParentheses": false }],
      "no-template-curly-in-string": "warn",
      "no-underscore-dangle": "warn",
      "no-unmodified-loop-condition": "warn",
      "no-unneeded-ternary": ["warn", { "defaultAssignment": false }],
      "no-unreachable-loop": "warn",
      "no-useless-call": "warn",
      "no-useless-computed-key": "warn",
      "no-useless-concat": "warn",
      "no-useless-rename": "warn",
      "no-useless-return": "warn",
      "no-void": "warn",
      "operator-assignment": "warn",
      "prefer-arrow-callback": "warn",
      "prefer-numeric-literals": "warn",
      "prefer-object-spread": "warn",
      "prefer-promise-reject-errors": "warn",
      "symbol-description": "warn",
      "yoda": "warn",

      "no-restricted-syntax": [
        "error",
        {
          "selector":
            "MemberExpression[object.name='Date'][property.name='now']",
          "message": "Remember to use getMsecNow() instead of Date.now()",
        },
        {
          "selector": "NewExpression[callee.name='Date'][arguments.length=0]",
          "message": "Remember to use getDateNow() instead of new Date()",
        },
      ],

      // I slightly dislike the changes proposed by this rule. For now let's
      // at least disable it for function parameters.
      "@typescript-eslint/no-inferrable-types": [
        "error",
        { "ignoreParameters": true },
      ],

      // Too annoying with default options.
      "@typescript-eslint/no-confusing-void-expression": [
        "error",
        { "ignoreArrowShorthand": true },
      ],

      // Too annoying with default options. The docs warn that you should use
      // toFixed() or toPrecision() with floats, but Votr only uses integers.
      "@typescript-eslint/restrict-template-expressions": [
        "error",
        { "allowNumber": true },
      ],

      // TODO: Maybe enable later.
      "@eslint-react/no-use-context": "off",
      "@typescript-eslint/no-deprecated": "off",
      "@typescript-eslint/prefer-regexp-exec": "off",

      // Many false positives and almost no true positives.
      "@typescript-eslint/prefer-nullish-coalescing": "off",

      // What a pointless rule. Both postfix `!` and `eslint-disable-line` are
      // assertions that mean "trust me, I know what I'm doing". Why lock one
      // of them behind the other?
      "@typescript-eslint/no-non-null-assertion": "off",

      // Good idea per se, but Votr often has a good reason to do it.
      "@eslint-react/no-array-index-key": "off",

      // I don't think "no-shadow" is useful enough to enable permanently, but
      // you can occasionally try it with:
      //   ./x pnpm eslint . --rule '{"@typescript-eslint/no-shadow":"warn"}'
    },
  },
  {
    files: ["eslint.config.mjs", "webpack.config.js"],
    extends: [
      tseslint.configs.disableTypeChecked,
      eslintReact.configs["disable-type-checked"],
    ],
    rules: { "@typescript-eslint/no-require-imports": "off" },
    languageOptions: { globals: globals.node },
  },
  {
    ignores: [
      "**/*.tmp*",
      "**/*env*/",
      "**/docs/_build",
      "**/static",
      "**/var",
    ],
  },
);