// internal storage for locale config files
import { Locale, LocaleData } from './locale.class';
import { baseConfig } from './locale.defaults';
import { hasOwnProp, isObject, isUndefined } from '../utils/type-checks';

const locales: { [key: string]: Locale } = {};
const localeFamilies: { [key: string]: Locale } = {};
let globalLocale: Locale;

function chooseLocale(name: string) {
  return locales[name];
}

// returns locale data
export function getLocale(key: string): Locale {
  if (!key) {
    return globalLocale;
  }

  return chooseLocale(key);
}

export function listLocales(): string[] {
  return Object.keys(locales);
}

export function mergeConfigs(
  parentConfig: LocaleData,
  childConfig: LocaleData
) {
  const res: { [key: string]: any } = Object.assign({}, parentConfig);

  for (const childProp in childConfig) {
    if (!hasOwnProp(childConfig, childProp)) {
      continue;
    }
    if (isObject(parentConfig[childProp]) && isObject(childConfig[childProp])) {
      res[childProp] = {};
      Object.assign(res[childProp], parentConfig[childProp]);
      Object.assign(res[childProp], childConfig[childProp]);
    } else if (childConfig[childProp] != null) {
      res[childProp] = childConfig[childProp];
    } else {
      delete res[childProp];
    }
  }
  for (const parentProp in parentConfig) {
    if (
      hasOwnProp(parentConfig, parentProp) &&
      !hasOwnProp(childConfig, parentProp) &&
      isObject(parentConfig[parentProp])
    ) {
      // make sure changes to properties don't modify parent config
      res[parentProp] = Object.assign({}, res[parentProp]);
    }
  }
  return res;
}

// This function will load locale and then set the global locale.  If
// no arguments are passed in, it will simply return the current global
// locale key.
export function getSetGlobalLocale(key: string, values?: LocaleData): string {
  let data: Locale;
  if (key) {
    data = isUndefined(values) ? getLocale(key) : defineLocale(key, values);

    if (data) {
      globalLocale = data;
    }
  }

  return globalLocale._abbr;
}

export function defineLocale(name: string, config?: LocaleData): Locale {
  if (config === null) {
    // useful for testing
    delete locales[name];
    return null;
  }

  config.abbr = name;

  locales[name] = new Locale(mergeConfigs(baseConfig, config));

  if (localeFamilies[name]) {
    localeFamilies[name].forEach(function(x: Locale) {
      defineLocale(x.name, x.config);
    });
  }

  // backwards compat for now: also set the locale
  // make sure we set the locale AFTER all child locales have been
  // created, so we won't end up with the child locale set.
  getSetGlobalLocale(name);

  return locales[name];
}