const config = {
  // A list of paths to directories that Jest should use to search for files in
  // https://jestjs.io/docs/configuration#roots-arraystring
  roots: ['<rootDir>/app/'],

  // The test environment that will be used for testing, jsdom for browser environment
  // https://jestjs.io/docs/configuration#testenvironment-string
  testEnvironment: 'jsdom',

  // Jest transformations
  // https://jestjs.io/docs/configuration#transform-objectstring-pathtotransformer--pathtotransformer-object
  transform: {
    '^.+\\.tsx?$': 'ts-jest', // Transform TypeScript files using ts-jest
  },

  // A list of paths to modules that run some code to configure or set up the testing framework before each test file in the suite is executed
  // https://jestjs.io/docs/configuration#setupfilesafterenv-array
  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],

  // Code coverage config
  // https://jestjs.io/docs/configuration#collectcoveragefrom-array
  coverageDirectory: '<rootDir>/coverage/',
  collectCoverageFrom: ['<rootDir>/app/**/*.{ts,tsx}', '!**/node_modules/**', '!**/*.d.ts'],

  // Important: order matters, specific rules should be defined first
  // https://jestjs.io/fr/docs/configuration#modulenamemapper-objectstring-string--arraystring
  moduleNameMapper: {
    // Style imports have no meaning under Jest
    '\\.(css|scss|sass)$': '<rootDir>/app/__mocks__/styleMock.ts',

    // react-markdown is ESM-only and cannot be required by Jest's CommonJS runtime
    '^react-markdown$': '<rootDir>/app/__mocks__/reactMarkdown.tsx',

    // app/hmr.ts uses import.meta.hot, which TypeScript refuses to compile to the CommonJS
    // module ts-jest forces for Jest (TS1343); swap in the no-op mock instead
    '^app/hmr$': '<rootDir>/app/__mocks__/hmr.ts',

    // app/ absolute module alias
    'app/(.*)': '<rootDir>/app/$1',
  },

  testTimeout: 30000,
  clearMocks: true,
};

export default config;