import js from '@eslint/js';
import tseslint from 'typescript-eslint';
import sonarjs from 'eslint-plugin-sonarjs';
import globals from 'globals';

// Named `.mjs` because this package is CommonJS — `eslint.config.js` would be
// parsed as CJS and the imports above would fail.
//
// Policy: every preset is downgraded to advisory, and the rules that actually
// fail the build are listed once at the bottom. That way the CI gate is
// readable in one place rather than inferred from four presets' defaults.
// The reasoning behind the split, and the measurements it rests on, are in
// docs/superpowers/specs/2026-08-19-eslint-design.md.

/**
 * Rewrites a preset's enabled rules to `warn`, preserving each rule's options.
 * Rules the preset explicitly turned off stay off — a preset that disables a
 * rule means it, and flipping those to `warn` turns the whole of SonarJS's
 * opt-in catalogue (file headers, naming conventions) into daily noise.
 */
const advisory = (config) => ({
  ...config,
  rules: Object.fromEntries(
    Object.entries(config.rules ?? {}).map(([rule, level]) => {
      const severity = Array.isArray(level) ? level[0] : level;
      if (severity === 'off' || severity === 0) return [rule, level];
      return [rule, Array.isArray(level) ? ['warn', ...level.slice(1)] : 'warn'];
    })
  ),
});

export default tseslint.config(
  { ignores: ['dist/**', 'coverage/**', 'eslint.config.mjs'] },

  ...[js.configs.recommended, ...tseslint.configs.recommended, sonarjs.configs.recommended].map(
    advisory
  ),

  {
    // `tests/` is deliberately out of scope for now: tsconfig.json only includes
    // `src`, so type-aware linting has no program for the test files, and
    // widening it is a separate change with its own violation count.
    files: ['src/**/*.ts'],
    languageOptions: {
      globals: globals.node,
      parserOptions: {
        projectService: true,
        tsconfigRootDir: import.meta.dirname,
      },
    },
    rules: {
      // The two rules this repo has actually been bitten by. #59 is the whole
      // argument: an async handler whose rejection nothing forwards produces no
      // response at all, and the request hangs rather than failing visibly.
      '@typescript-eslint/no-floating-promises': 'error',
      '@typescript-eslint/no-misused-promises': [
        'error',
        { checksVoidReturn: { attributes: false } },
      ],
    },
  }
);