<?php

namespace Friendica\Directory\Content;

/**
 * @author Hypolite Petovan <mrpetovan@gmail.com>
 */
class L10n
{
	/**
	 * @var string
	 */
	private $lang;

	/**
	 * @var array
	 */
	private $strings;

	/**
	 * @var string
	 */
	private $lang_path;

	public function __construct(string $language = 'en', string $lang_path = '')
	{
		$this->lang = $language;
		$this->lang_path = $lang_path;

		$this->loadTranslationTable();
	}

	/**
	 * Loads string translation table
	 *
	 * First addon strings are loaded, then globals
	 *
	 * Uses an App object shim since all the strings files refer to $a->strings
	 *
	 * @param string $lang language code to load
	 */
	private function loadTranslationTable(): void
	{
		if (file_exists($this->lang_path . '/' . $this->lang . '/strings.php')) {
			$this->strings = include $this->lang_path . '/' . $this->lang . '/strings.php';
		}
	}

	/**
	 * @brief Return the localized version of a singular/plural string with optional string interpolation
	 *
	 * This function takes two english strings as parameters, singular and plural, as
	 * well as a count. If a localized version exists for the current language, they
	 * are used instead. Discrimination between singular and plural is done using the
	 * localized function if any or the default one. Finally, a string interpolation
	 * is performed using the count as parameter.
	 *
	 * Usages:
	 * - L10n::tt('Like', 'Likes', $count)
	 * - L10n::tt("%s user deleted", "%s users deleted", count($users))
	 *
	 * @param string $singular
	 * @param string $plural
	 * @param int    $count
	 * @return string
	 */
	public function tt(string $singular, string $plural, int $count): string
	{
		if (!empty($this->strings[$singular])) {
			$t = $this->strings[$singular];
			if (is_array($t)) {
				$plural_function = 'string_plural_select_' . str_replace('-', '_', $this->lang);
				if (function_exists($plural_function)) {
					$i = $plural_function($count);
				} else {
					$i = $this->stringPluralSelectDefault($count);
				}

				// for some languages there is only a single array item
				if (!isset($t[$i])) {
					$s = $t[0];
				} else {
					$s = $t[$i];
				}
			} else {
				$s = $t;
			}
		} elseif ($this->stringPluralSelectDefault($count)) {
			$s = $plural;
		} else {
			$s = $singular;
		}

		$s = @sprintf($s, $count);

		return $s;
	}

	/**
	 * @brief Return the localized version of the provided string with optional string interpolation
	 *
	 * This function takes a english string as parameter, and if a localized version
	 * exists for the current language, substitutes it before performing an eventual
	 * string interpolation (sprintf) with additional optional arguments.
	 *
	 * Usages:
	 * - L10n::t('This is an example')
	 * - L10n::t('URL %s returned no result', $url)
	 * - L10n::t('Current version: %s, new version: %s', $current_version, $new_version)
	 *
	 * @param string $s
	 * @param array  $vars Variables to interpolate in the translation string
	 * @return string
	 */
	public function t($s, ...$vars): string
	{
		if (empty($s)) {
			return '';
		}

		if (!empty($this->strings[$s])) {
			$t = $this->strings[$s];
			$s = is_array($t) ? $t[0] : $t;
		}

		if (count($vars) > 0) {
			$s = sprintf($s, ...$vars);
		}

		return $s;
	}

	/**
	 * Provide a fallback which will not collide with a function defined in any language file
	 */
	private function stringPluralSelectDefault(int $n): bool
	{
		return $n != 1;
	}

}