/// <summary>
/// find the common parent locale, for example
/// en-us, en-gb, has the same parent locale: en.
/// and en-us, fr, has the no same parent locale.
/// </summary>
/// <param name="locale1">first locale.</param>
/// <param name="locale2">second locale.</param>
/// <returns>the most closest common ancestor local.</returns>
private static string FindCommonAncestorLocale(string locale1, string locale2)
{
var policy = new LanguagePolicy();
if (!policy.ContainsKey(locale1) || !policy.ContainsKey(locale2))
{
return(string.Empty);
}
var key1Policy = policy[locale1];
var key2Policy = policy[locale2];
foreach (var key1Language in key1Policy)
{
foreach (var key2Language in key2Policy)
{
if (key1Language == key2Language)
{
return(key1Language);
}
}
}
return(string.Empty);
}
/// <summary>
/// Get the fall back locale from the optional locales. for example
/// en-us, is a locale from English. But the option locales has [en, ''],
/// So,en would be picked.
/// </summary>
/// <param name="locale">current locale.</param>
/// <param name="optionalLocales">option locales.</param>
/// <returns>the final locale.</returns>
public static string FallbackLocale(string locale, IList <string> optionalLocales)
{
if (optionalLocales == null)
{
throw new ArgumentNullException(nameof(optionalLocales));
}
if (optionalLocales.Contains(locale))
{
return(locale);
}
var languagePolicy = new LanguagePolicy();
if (languagePolicy.ContainsKey(locale))
{
var fallbackLocals = languagePolicy[locale];
foreach (var fallbackLocal in fallbackLocals)
{
if (optionalLocales.Contains(fallbackLocal))
{
return(fallbackLocal);
}
}
}
else if (optionalLocales.Contains(string.Empty))
{
return(string.Empty);
}
throw new Exception($"there is no locale fallback for {locale}");
}