//  Copyright (C) 2015, The Duplicati Team

//  http://www.duplicati.com, info@duplicati.com
//
//  This library is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as
//  published by the Free Software Foundation; either version 2.1 of the
//  License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful, but
//  WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Linq;
using System.Globalization;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Duplicati.Library.Localization.Short;

namespace Duplicati.Library.Localization
{
    /// <summary>
    /// Provides an entry point for localization, regardless of the underlying translation engine
    /// </summary>
    public static class LocalizationService
    {
        /// <summary>
        /// The cache of services
        /// </summary>
        private static Dictionary<CultureInfo, ILocalizationService> Services = new Dictionary<CultureInfo, ILocalizationService>();

        /// <summary>
        /// The key for accessing logical context
        /// </summary>
        internal const string LOGICAL_CONTEXT_KEY = "DUPLICATI_LOCALIZATION_CULTURE_CONTEXT";

        /// <summary>
        /// Regular expression to match a locale
        /// </summary>
        public static readonly Regex CI_MATCHER = new Regex(@"[A-z]{2}(-[A-z]{4})?(-[A-z]{2})?");

        /// <summary>
        /// Returns a temporary disposable localization context
        /// </summary>
        /// <returns>The context that must be disposed.</returns>
        /// <param name="ci">The locale to use.</param>
        public static IDisposable TemporaryContext(CultureInfo ci)
        {
            if (ci == null)
                return null;

            LC.setCulture(ci);
            return new LocalizationContext(ci);
        }

        /// <summary>
        /// A non-translating service
        /// </summary>
        private static ILocalizationService InvariantService = new MockLocalizationService();

        /// <summary>
        /// Gets a localization provider with the default language
        /// </summary>
        public static ILocalizationService Invariant { get { return Get(CultureInfo.InvariantCulture); } }

        /// <summary>
        /// Parses the culture string into a cultureinfo instance.
        /// </summary>
        /// <returns>The parsed culture.</returns>
        /// <param name="culture">The culture string.</param>
        /// <param name="returninvariant">Set to <c>true</c> to return the invariant culture if the string is not valid, otherwise null is returned.</param>
        public static CultureInfo ParseCulture(string culture, bool returninvariant = false)
        {
            var ci = returninvariant ? CultureInfo.InvariantCulture : null;

            if (CI_MATCHER.Match(culture).Success)
                try { ci = new CultureInfo(culture); }
                catch { }

            return ci;
        }

        /// <summary>
        /// Gets a localization provider with the current language
        /// </summary>
        public static ILocalizationService Current 
        { 
            get 
            {
                var lc = System.Runtime.Remoting.Messaging.CallContext.LogicalGetData(LOGICAL_CONTEXT_KEY) as string;
                if (!string.IsNullOrWhiteSpace(lc))
                    return Get(new CultureInfo(lc));
                return Get(CultureInfo.CurrentCulture); 
            } 
        }

        /// <summary>
        /// Gets a localization provider with the OS install language
        /// </summary>
        public static ILocalizationService Installed { get { return Get(CultureInfo.InstalledUICulture); } }

        /// <summary>
        /// Gets a localization provider with the specified language
        /// </summary>
        public static ILocalizationService Get(CultureInfo ci)
        {
            if (ci == CultureInfo.InvariantCulture)
                return InvariantService;

            ILocalizationService service;
            if (!Services.TryGetValue(ci, out service))
                service = Services[ci] = new PoLocalizationService(ci);

            return service;
        }

        /// <summary>
        /// Gets a list of all locales known by the CLR
        /// </summary>
        /// <value>All locales.</value>
        public static IEnumerable<string> AllLocales
        {
            get
            {
                return CultureInfo.GetCultures(CultureTypes.AllCultures).Select(x => x.Name).Where(x => !string.IsNullOrWhiteSpace(x)).Distinct().OrderBy(x => x);
            }
        }

        /// <summary>
        /// Gets all cultures with localization support
        /// </summary>
        public static IEnumerable<string> SupportedCultures
        {
            get { return PoLocalizationService.SupportedCultures; }
        }
    }
}