using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading.Tasks;
using gehGassi.Core.Interfaces;
using gehGassi.Web.Helper;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;

namespace gehGassi.Web.Services
{
    /// <summary>
    /// Service der die Verwaltung von verfügbaren Sprachen realisiert
    /// </summary>
    public class LanguageService : ILanguageService
    {
        private readonly List<Language> _languages;
        private readonly IOptions<LocalizationOptions> _localizeOptions;
        private readonly IHttpContextAccessor _httpContextAccessor;

        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        /// <param name="localizeOptions">Instanz eines LocalizationOptions</param>
        /// <param name="httpContextAccessor">Instanz eines IHttpContextAccessor</param>
        public LanguageService(IOptions<LocalizationOptions> localizeOptions, IHttpContextAccessor httpContextAccessor)
        {
            _languages = new List<Language>();
            _localizeOptions = localizeOptions;
            _httpContextAccessor = httpContextAccessor;
        }

        /// <summary>
        /// Gibt eine Sprache anhand des ISO2-Codes zurück
        /// </summary>
        /// <param name="iso2"></param>
        /// <returns>Sprache oder null, wenn keine gefunden</returns>
        public Language Get(string iso2)
        {
            return GetAll().FirstOrDefault(c => c.Iso2.ToLowerInvariant() == iso2.ToLowerInvariant());
        }

        /// <summary>
        /// Gibt die Standard-Sprache des Systems zurück
        /// </summary>
        /// <returns>Standard-Sprache</returns>
        public Language GetDefault()
        {
            var defaultLang = GetAll().FirstOrDefault(c => c.IsDefault) ?? GetAll().First();
            return defaultLang;
        }

        /// <summary>
        /// Gibt die Auflistung aller Sprachen des Systems zurück
        /// </summary>
        /// <returns>Liste von Sprachen</returns>
        public List<Language> GetAll()
        {
            if (_languages.Count == 0)
            {
                var definedCodes = new List<string>();

                if (!string.IsNullOrWhiteSpace(_localizeOptions.Value.Languages))
                    definedCodes = _localizeOptions.Value.Languages.Split(",").ToList();

                foreach (var definedCode in definedCodes)
                {
                    var culture = CultureInfo.GetCultures(CultureTypes.AllCultures).FirstOrDefault(c => string.Equals(c.TwoLetterISOLanguageName, definedCode, StringComparison.InvariantCultureIgnoreCase));
                    if (culture != null)
                    {
                        var language = new Language
                        {
                            Iso2 = culture.TwoLetterISOLanguageName,
                            IsDefault = false,
                            Name = culture.NativeName,
                            NameEnglish = culture.EnglishName
                        };
                        if (string.Equals(definedCode, _localizeOptions.Value.DefaultCulture, StringComparison.InvariantCultureIgnoreCase))
                            language.IsDefault = true;
                        if (_languages.FirstOrDefault(c => c.Iso2 == language.Iso2) == null)
                            _languages.Add(language);
                    }
                }
            }

            return _languages;
        }

        /// <summary>
        /// Gibt die Auflistung aller Sprachen des Systems zurück als ISO2 Liste
        /// </summary>
        /// <returns>Liste von Sprachen</returns>
        public List<string> GetAllIso2()
        {
            var languages = GetAll();
            return languages.Select(c => c.Iso2).ToList();
        }

        /// <summary>
        /// Gibt eine gefilterte Liste von Sprachen zurück. Sucht nur im Namen
        /// </summary>
        /// <param name="filter">Filterbegriff der in bestimmten Feldern gesucht wird</param>
        /// <returns>List betroffener Kunden</returns>
        public List<Language> Search(string filter)
        {
            var languages = GetAll();
            return languages.Where(c => c.Name.Contains(filter) || c.NameEnglish.Contains(filter)).ToList();
        }
    }
}