'use strict';

/**
 * Module dependencies.
 */

var bytes = require('bytes');
var contentType = require('content-type');
var typeis = require('type-is');

/**
 * Module exports.
 */

module.exports = {
  getCharset,
  normalizeOptions,
};

/**
 * Get the charset of a request.
 *
 * @param {object} req
 * @api private
 */

function getCharset(req) {
  try {
    return (contentType.parse(req).parameters.charset || '').toLowerCase();
  } catch {
    return undefined;
  }
}

/**
 * Get the simple type checker.
 *
 * @param {string | string[]} type
 * @return {function}
 */

function typeChecker(type) {
  return function checkType(req) {
    return Boolean(typeis(req, type));
  };
}

/**
 * Normalizes the common options for all parsers.
 *
 * @param {object} options options to normalize
 * @param {string | string[] | function} defaultType default content type(s) or a function to determine it
 * @returns {object}
 */
function normalizeOptions(options, defaultType) {
  if (!defaultType) {
    // Parsers must define a default content type
    throw new TypeError('defaultType must be provided');
  }

  var inflate = options?.inflate !== false;
  var limit =
    typeof options?.limit !== 'number' ?
      bytes.parse(options?.limit || '100kb')
    : options?.limit;
  var type = options?.type || defaultType;
  var verify = options?.verify || false;

  if (verify !== false && typeof verify !== 'function') {
    throw new TypeError('option verify must be function');
  }

  // create the appropriate type checking function
  var shouldParse = typeof type !== 'function' ? typeChecker(type) : type;

  return {
    inflate,
    limit,
    verify,
    shouldParse,
  };
}