import { NativeEventEmitter, NativeModules } from "react-native";
import type {
  Calendar,
  Locale,
  NumberFormatSettings,
  TemperatureUnit,
} from "./types";

const { RNLocalize } = NativeModules;

if (__DEV__) {
  if (RNLocalize == null) {
    throw new Error(`react-native-localize: NativeModule.RNLocalize is null. To fix this issue try these steps:
• Run \`react-native link react-native-localize\` in the project root.
• Rebuild and re-run the app.
• If you are using CocoaPods on iOS, run \`pod install\` in the \`ios\` directory and then rebuild and re-run the app. You may also need to re-open Xcode to get the new pods.
• Check that the library was linked correctly when you used the link command by running through the manual installation instructions in the README.
• If you are getting this error while unit testing you need to mock the native module. Follow the guide in the README.
• If none of these fix the issue, please open an issue on the Github repository: https://github.com/zoontek/react-native-localize`);
  }
}

type LocalizationConstants = Readonly<{
  calendar: Calendar;
  country: string;
  currencies: string[];
  locales: Locale[];
  numberFormatSettings: NumberFormatSettings;
  temperatureUnit: TemperatureUnit;
  timeZone: string;
  uses24HourClock: boolean;
  usesMetricSystem: boolean;
  usesAutoDateAndTime?: boolean;
  usesAutoTimeZone?: boolean;
}>;

let constants: LocalizationConstants = RNLocalize.initialConstants;
const emitter = new NativeEventEmitter(RNLocalize);

export function getCalendar(): Calendar {
  return constants.calendar;
}
export function getCountry(): string {
  return constants.country;
}
export function getCurrencies(): string[] {
  return constants.currencies;
}
export function getLocales(): Locale[] {
  return constants.locales;
}
export function getNumberFormatSettings(): NumberFormatSettings {
  return constants.numberFormatSettings;
}
export function getTemperatureUnit(): TemperatureUnit {
  return constants.temperatureUnit;
}
export function getTimeZone(): string {
  return constants.timeZone;
}
export function uses24HourClock(): boolean {
  return constants.uses24HourClock;
}
export function usesMetricSystem(): boolean {
  return constants.usesMetricSystem;
}
export function usesAutoDateAndTime(): boolean | undefined {
  return constants.usesAutoDateAndTime;
}
export function usesAutoTimeZone(): boolean | undefined {
  return constants.usesAutoTimeZone;
}

export const handlers: Set<Function> = new Set();

emitter.addListener("localizationDidChange", (next: LocalizationConstants) => {
  if (JSON.stringify(next) !== JSON.stringify(constants)) {
    constants = next;
    handlers.forEach((handler) => handler());
  }
});