import nextCoreWebVitals from 'eslint-config-next/core-web-vitals';
import prettier from 'eslint-config-prettier/flat';

const eslintConfig = [
  ...nextCoreWebVitals,
  prettier,
  {
    // Scope the typescript-eslint rule overrides to TS/TSX files. Without
    // the `files` filter, eslint flat-config attempts to apply these
    // rules to every walked file (including root-level JS / mjs / json
    // configs) and fails because the typescript-eslint plugin only
    // registers itself for TS/TSX. Surfaced 2026-05-14 when CI's
    // `pnpm lint` command ran across the whole repo root.
    files: ['**/*.ts', '**/*.tsx'],
    rules: {
      '@typescript-eslint/no-explicit-any': 'error',
      '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
      // React Compiler safety rules shipped with eslint-config-next@16 /
      // react-hooks@7. Triage status (2026-05-13 sweep):
      //   purity, set-state-in-render, immutability, refs,
      //   set-state-in-effect — promoted to error after the cleanup
      //   sweep (Wave 3 of the 2026-05-12 audit). All hits migrated to
      //   either useQuery, render-phase derivation, key-based remount,
      //   or a justified eslint-disable for canonical setState-on-
      //   subscription patterns. New regressions block CI.
      //   incompatible-library — informational only ("Compiler
      //   skipped this file because of a non-Compiler-safe import").
      //   No action needed; silenced to keep `pnpm lint` output
      //   actionable.
      'react-hooks/purity': 'error',
      'react-hooks/set-state-in-render': 'error',
      'react-hooks/immutability': 'error',
      'react-hooks/refs': 'error',
      'react-hooks/set-state-in-effect': 'error',
      'react-hooks/incompatible-library': 'off',
    },
  },
  {
    // User-facing copy in src/components and src/app should never use
    // em-dashes (—) in JSX text. The user reads em-dashes as a
    // tell-tale "AI-generated" marker; we prefer periods, commas, or
    // simple hyphens. Code comments / audit-log strings / templates
    // outside these directories are exempt.
    files: ['src/components/**/*.tsx', 'src/app/**/*.tsx'],
    rules: {
      'no-restricted-syntax': [
        // Bumped from warn → error after the 2026-05-21 sweep cleared
        // the existing 108 instances. New code reintroducing em-dashes
        // now fails the lint gate.
        'error',
        {
          selector: "JSXText[value=/\\u2014/]",
          message:
            'No em-dash in user-facing JSX text. Use period, comma, or hyphen instead.',
        },
      ],
    },
  },
  {
    // Tests assert response shape via expect() — narrowing every
    // `res.json()` to a structural type adds boilerplate without catching
    // bugs. Allow `any` casts at JSON boundaries in test files. Also
    // relax unused-vars to warn (destructured-but-unused helpers are
    // common in setup/teardown patterns).
    files: ['tests/**/*.ts', 'tests/**/*.tsx'],
    rules: {
      '@typescript-eslint/no-explicit-any': 'off',
      '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_' }],
    },
  },
  {
    ignores: [
      'client-portal/**',
      'next-env.d.ts',
      // Agent worktree artifacts — not part of the canonical tree.
      '.claude/**',
      // Build output + Next generated types
      '.next/**',
      'dist/**',
      // Other sub-projects with their own toolchains
      'website/**',
    ],
  },
];

export default eslintConfig;
