y18n

const y18n = require('y18n');

import y18n from 'y18n';

import y18n from "https://deno.land/x/y18n/deno.ts";

const __ = require('y18n')().__;
const __n = require('y18n')().__n;

// Simple string translation
console.log(__('Hello %s', 'world'));
// Output: "Hello world"

// Template literal support
const name = 'Alice';
console.log(__`Hello ${name}!`);
// Output: "Hello Alice!"

// Pluralization
console.log(__n('one item', '%d items', 2));
// Output: "2 items"

/**
 * Creates a y18n instance with the provided configuration
 * @param opts - Configuration options
 * @returns Object with translation methods and locale management
 */
function y18n(opts?: Y18NOpts): {
  __: (str: string, ...args: string[]) => string;
  __n: (singular: string, plural: string, count: number, ...args: string[]) => string;
  setLocale: (locale: string) => void;
  getLocale: () => string;
  updateLocale: (obj: Locale) => void;  
  locale: string;
};

interface Y18NOpts {
  /** The locale directory, defaults to './locales' */
  directory?: string;
  /** Should newly observed strings be updated in file, defaults to true */
  updateFiles?: boolean;
  /** What locale should be used, defaults to 'en' */
  locale?: string;
  /** Should fallback to language-only file be allowed, defaults to true */
  fallbackToLanguage?: boolean;
}

/**
 * Print a localized string, %s will be replaced with args
 * Can also be used as a tag for template literals
 * @param str - String to translate or template literal parts
 * @param args - Values to substitute for %s placeholders, optionally ending with callback function
 * @returns Translated string with substitutions
 */
__(str: string, ...args: (string | Function)[]): string;
__(parts: TemplateStringsArray, ...args: string[]): string;

const __ = y18n({ locale: 'en' }).__;

// Basic translation with parameters
console.log(__('Welcome %s!', 'Alice'));
// Output: "Welcome Alice!"

// Multiple parameters
console.log(__('User %s has %s points', 'Bob', '150'));
// Output: "User Bob has 150 points"

// Template literal usage
const user = 'Charlie';
const score = 200;
console.log(__`User ${user} has ${score} points`);
// Output: "User Charlie has 200 points"

// With callback (called after locale file updates)
__('New message', 'param', function(err) {
  if (err) console.error('Error updating locale file:', err);
  else console.log('Locale file updated successfully');
});

/**
 * Print a localized string with appropriate pluralization
 * If %d is provided in the string, count will replace this placeholder
 * @param singular - Singular form string
 * @param plural - Plural form string  
 * @param count - Number to determine singular/plural and optional %d substitution
 * @param args - Additional arguments for substitution, optionally ending with callback function
 * @returns Appropriate singular/plural string with substitutions
 */
__n(singular: string, plural: string, count: number, ...args: (string | Function)[]): string;

const __n = y18n({ locale: 'en' }).__n;

// Basic pluralization
console.log(__n('one item', '%d items', 1));
// Output: "one item"
console.log(__n('one item', '%d items', 5));
// Output: "5 items"

// With additional parameters
console.log(__n('one fish %s', '%d fishes %s', 2, 'swimming'));
// Output: "2 fishes swimming"

// With callback (called after locale file updates)
__n('one new item', '%d new items', 3, function(err) {
  if (err) console.error('Error updating locale file:', err);
  else console.log('Pluralization added to locale file');
});

/**
 * Set the current locale being used
 * @param locale - Locale string (e.g., 'en', 'fr', 'en_US')
 */
setLocale(locale: string): void;

/**
 * Get the current locale being used
 * @returns Current locale string
 */
getLocale(): string;

/**
 * Update the current locale with key-value pairs
 * @param obj - Object with translation key-value pairs
 */
updateLocale(obj: Locale): void;

const i18n = y18n({ locale: 'en' });

// Change locale
i18n.setLocale('fr');
console.log(i18n.getLocale()); // Output: "fr"

// Update translations
i18n.updateLocale({
  'Hello': 'Bonjour',
  'Goodbye': 'Au revoir'
});

console.log(i18n.__('Hello')); // Output: "Bonjour"

interface Locale {
  [key: string]: string;
}

interface Y18NOpts {
  directory?: string;
  updateFiles?: boolean;
  locale?: string;
  fallbackToLanguage?: boolean;
}

{
  "Hello %s": "Hello %s",
  "one item": {
    "one": "one item",
    "other": "%d items"
  }
}