import { format, Locale } from 'date-fns';
import { enUS } from 'date-fns/locale/en-US';
import { es } from 'date-fns/locale/es';
import { el } from 'date-fns/locale/el';
import i18n from '../i18n';

/**
 * Maps i18next language codes to date-fns locale objects
 */
const localeMap: Record<string, Locale> = {
  en: enUS,
  es: es,
  el: el,
};

/**
 * Returns the date-fns locale object based on the current i18next language
 * Falls back to English if the current language is not supported
 */
export const getCurrentLocale = (): Locale => {
  const language = i18n.language || 'en';
  return localeMap[language] || enUS;
};

/**
 * Formats a date using the current locale from i18next
 * 
 * @param date - The date to format
 * @param formatStr - The format string (https://date-fns.org/v2.29.3/docs/format)
 * @returns The formatted date string
 */
export const formatLocalizedDate = (date: Date | number, formatStr: string): string => {
  return format(date, formatStr, {
    locale: getCurrentLocale(),
  });
};

/**
 * Gets the date format pattern from translation file
 * 
 * @param formatKey - The key for the format in the dateFormats object
 * @param fallback - Fallback format to use if translation is missing
 * @returns The format pattern string
 */
export const getDateFormatPattern = (formatKey: string, fallback: string): string => {
  const pattern = i18n.t(`dateFormats.${formatKey}`);
  // If the translation key doesn't exist, it will return the key itself
  return pattern === `dateFormats.${formatKey}` ? fallback : pattern;
};

/**
 * Formats a date in a long readable format based on the current locale
 * Example: "Monday, January 1, 2023" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted date string
 */
export const formatLongDate = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('long', 'EEEE, MMMM d, yyyy'));
};

/**
 * Formats a date in a short format based on the current locale
 * Example: "Jan 1, 2023" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted date string
 */
export const formatShortDate = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('short', 'MMM d, yyyy'));
};

/**
 * Formats a date to show only month and year based on the current locale
 * Example: "January 2023" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted date string
 */
export const formatMonthYear = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('monthYear', 'MMMM yyyy'));
};

/**
 * Formats a date to show only day and month based on the current locale
 * Example: "January 1" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted date string
 */
export const formatDayMonth = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('dayMonth', 'MMMM d'));
};

/**
 * Formats a date to show only time based on the current locale
 * Example: "3:30 PM" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted time string
 */
export const formatTime = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('time', 'h:mm a'));
};

/**
 * Formats a date to show date and time based on the current locale
 * Example: "Jan 1, 2023 3:30 PM" (in English)
 * 
 * @param date - The date to format
 * @returns The formatted date and time string
 */
export const formatDateTime = (date: Date | number): string => {
  return formatLocalizedDate(date, getDateFormatPattern('dateTime', 'MMM d, yyyy h:mm a'));
};