/**
 * @fileoverview The schema to validate language options
 * @author Nicholas C. Zakas
 */

'use strict';

//-----------------------------------------------------------------------------
// Data
//-----------------------------------------------------------------------------

const globalVariablesValues = new Set([
  true,
  'true',
  'writable',
  'writeable',
  false,
  'false',
  'readonly',
  'readable',
  null,
  'off',
]);

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Check if a value is a non-null object.
 * @param {any} value The value to check.
 * @returns {boolean} `true` if the value is a non-null object.
 */
function isNonNullObject(value) {
  return typeof value === 'object' && value !== null;
}

/**
 * Check if a value is a non-null non-array object.
 * @param {any} value The value to check.
 * @returns {boolean} `true` if the value is a non-null non-array object.
 */
function isNonArrayObject(value) {
  return isNonNullObject(value) && !Array.isArray(value);
}

/**
 * Check if a value is undefined.
 * @param {any} value The value to check.
 * @returns {boolean} `true` if the value is undefined.
 */
function isUndefined(value) {
  return typeof value === 'undefined';
}

//-----------------------------------------------------------------------------
// Schemas
//-----------------------------------------------------------------------------

/**
 * Validates the ecmaVersion property.
 * @param {string|number} ecmaVersion The value to check.
 * @returns {void}
 * @throws {TypeError} If the value is invalid.
 */
function validateEcmaVersion(ecmaVersion) {
  if (isUndefined(ecmaVersion)) {
    throw new TypeError(
      'Key "ecmaVersion": Expected an "ecmaVersion" property.'
    );
  }

  if (typeof ecmaVersion !== 'number' && ecmaVersion !== 'latest') {
    throw new TypeError('Key "ecmaVersion": Expected a number or "latest".');
  }
}

/**
 * Validates the sourceType property.
 * @param {string} sourceType The value to check.
 * @returns {void}
 * @throws {TypeError} If the value is invalid.
 */
function validateSourceType(sourceType) {
  if (
    typeof sourceType !== 'string' ||
    !/^(?:script|module|commonjs)$/u.test(sourceType)
  ) {
    throw new TypeError(
      'Key "sourceType": Expected "script", "module", or "commonjs".'
    );
  }
}

/**
 * Validates the globals property.
 * @param {Object} globals The value to check.
 * @returns {void}
 * @throws {TypeError} If the value is invalid.
 */
function validateGlobals(globals) {
  if (!isNonArrayObject(globals)) {
    throw new TypeError('Key "globals": Expected an object.');
  }

  for (const key of Object.keys(globals)) {
    // avoid hairy edge case
    if (key === '__proto__') {
      continue;
    }

    if (key !== key.trim()) {
      throw new TypeError(
        `Key "globals": Global "${key}" has leading or trailing whitespace.`
      );
    }

    if (!globalVariablesValues.has(globals[key])) {
      throw new TypeError(
        `Key "globals": Key "${key}": Expected "readonly", "writable", or "off".`
      );
    }
  }
}

/**
 * Validates the parser property.
 * @param {Object} parser The value to check.
 * @returns {void}
 * @throws {TypeError} If the value is invalid.
 */
function validateParser(parser) {
  if (
    !parser ||
    typeof parser !== 'object' ||
    (typeof parser.parse !== 'function' &&
      typeof parser.parseForESLint !== 'function')
  ) {
    throw new TypeError(
      'Key "parser": Expected object with parse() or parseForESLint() method.'
    );
  }
}

/**
 * Validates the language options.
 * @param {Object} languageOptions The language options to validate.
 * @returns {void}
 * @throws {TypeError} If the language options are invalid.
 */
function validateLanguageOptions(languageOptions) {
  if (!isNonArrayObject(languageOptions)) {
    throw new TypeError('Expected an object.');
  }

  const {
    ecmaVersion,
    sourceType,
    globals,
    parser,
    parserOptions,
    ...otherOptions
  } = languageOptions;

  if ('ecmaVersion' in languageOptions) {
    validateEcmaVersion(ecmaVersion);
  }

  if ('sourceType' in languageOptions) {
    validateSourceType(sourceType);
  }

  if ('globals' in languageOptions) {
    validateGlobals(globals);
  }

  if ('parser' in languageOptions) {
    validateParser(parser);
  }

  if ('parserOptions' in languageOptions) {
    if (!isNonArrayObject(parserOptions)) {
      throw new TypeError('Key "parserOptions": Expected an object.');
    }
  }

  const otherOptionKeys = Object.keys(otherOptions);

  if (otherOptionKeys.length > 0) {
    throw new TypeError(`Unexpected key "${otherOptionKeys[0]}" found.`);
  }
}

module.exports = { validateLanguageOptions };