using System.Text.Json;
using gehGassiApp.Core.Interfaces;
using gehGassiApp.Domain.Common;
using Microsoft.Extensions.Caching.Memory;

namespace gehGassiApp.Core.Services
{
    /// <summary>
    /// Service der den Umgang mit Ländern vereinfacht
    /// </summary>
    public class CountryService : ICountryService
    {
        private readonly IMemoryCache _memoryCache;

        public CountryService()
        {
            _memoryCache = new MemoryCache(new MemoryCacheOptions(){});
        }

        /// <summary>
        /// Initialisieren der Länder-Daten
        /// </summary>
        /// <returns>Task</returns>
        private async Task InitAsync()
        {
            //Englisch
            await using var streamEn = await FileSystem.OpenAppPackageFileAsync("countries/en/world.json");
            using var readerEn = new StreamReader(streamEn);
            var jsonEn = await readerEn.ReadToEndAsync();
            _memoryCache.Set("Countries_EN", jsonEn);

            //Deutsch
            await using var streamDe = await FileSystem.OpenAppPackageFileAsync("countries/de/world.json");
            using var readerDe = new StreamReader(streamDe);
            var jsonDe = await readerDe.ReadToEndAsync();
            _memoryCache.Set("Countries_DE", jsonDe);

            //Bundesländer
            await using var streamStates = await FileSystem.OpenAppPackageFileAsync("countries/subdivisions.json");
            using var readerStates = new StreamReader(streamStates);
            var jsonStates = await readerStates.ReadToEndAsync();
            _memoryCache.Set("States", jsonStates);
        }

        /// <summary>
        /// Gibt eine Liste aller Länder zurück
        /// </summary>
        /// <returns>Liste</returns>
        public async Task<List<Country>> GetCountriesAsync()
        {
            var dummy = _memoryCache.Get<string>("Countries_EN");
            if (string.IsNullOrWhiteSpace(dummy))
                await InitAsync();

            var countriesJson = _memoryCache.Get<string>("Countries_" + Thread.CurrentThread.CurrentCulture.TwoLetterISOLanguageName.ToUpper());
            if (string.IsNullOrWhiteSpace(countriesJson))
                countriesJson = _memoryCache.Get<string>("Countries_EN");

            var countries = JsonSerializer.Deserialize<List<Country>>(countriesJson);
            countries.ForEach(c => c.Iso2 = c.Iso2.ToUpper());
            return (countries ?? throw new InvalidOperationException()).OrderBy(c => c.Name).ToList();
        }

        /// <summary>
        /// Gibt ein Land anhand des Codes zurück
        /// </summary>
        /// <param name="countryCode">ISO2</param>
        /// <returns>Land oder null, wenn nicht gefunden</returns>
        public async Task<Country> GetCountryAsync(string countryCode)
        {
            var country = (await GetCountriesAsync()).FirstOrDefault(c => String.Equals(c.Iso2, countryCode, StringComparison.CurrentCultureIgnoreCase));
            return country;
        }

        /// <summary>
        /// Gibt eine Liste von Bundesländern zurück
        /// </summary>
        /// <returns>Liste von Bundesländern</returns>
        public async Task<List<State>> GetStatesAsync()
        {
            var statesJson = _memoryCache.Get<string>("States");
            if (string.IsNullOrWhiteSpace(statesJson))
            {
                await InitAsync();
                statesJson = _memoryCache.Get<string>("States");
            }

            var states = JsonSerializer.Deserialize<List<State>>(statesJson);
            return states;
        }

        /// <summary>
        /// Gibt eine Liste von Bundesländern / Staaten eines Landes zurück
        /// </summary>
        /// <param name="countryCode">ISO2 des Landes</param>
        /// <returns>Liste von Bundesländern</returns>
        public async Task<List<State>> GetStatesAsync(string countryCode)
        {
            if (string.IsNullOrWhiteSpace(countryCode))
                countryCode = "";

            var statesJson = _memoryCache.Get<string>("States");
            if (string.IsNullOrWhiteSpace(statesJson))
            {
                await InitAsync();
                statesJson = _memoryCache.Get<string>("States");
            }

            var states = JsonSerializer.Deserialize<List<State>>(statesJson);
            return states != null ? states.Where(c => c.Iso2 == countryCode.ToUpper()).OrderBy(c => c.Name).ToList() : new List<State>();
        }

        /// <summary>
        /// Gibt ein Bundesland / Staat eines Landes zurück
        /// </summary>
        /// <param name="countryCode">ISO2 des Landes</param>
        /// <param name="stateCode">Code des Bundeslandes</param>
        /// <returns>Bundesland oder null, wenn nicht gefunden</returns>
        public async Task<State> GetStateAsync(string countryCode, string stateCode)
        {
            var states = await GetStatesAsync(countryCode);
            return states.FirstOrDefault(c => c.Code == stateCode);
        }

        /// <summary>
        /// Gibt ein Bundesland / Staat eines Landes zurück
        /// </summary>
        /// <param name="countryCode">ISO2 des Landes</param>
        /// <param name="stateName">Name des Bundeslandes</param>
        /// <returns>Bundesland oder null, wenn nicht gefunden</returns>
        public async Task<State> GetStateByNameAsync(string countryCode, string stateName)
        {
            var states = await GetStatesAsync(countryCode);
            return states.FirstOrDefault(c => c.Name.ToLowerInvariant() == stateName.ToLowerInvariant());
        }

        /// <summary>
        /// Gibt eine Liste der Ländercodes zurück die zu einem Filter passen
        /// </summary>
        /// <param name="filter">Filter</param>
        /// <param name="operatorValue">Operator der angewendet werden soll</param>
        /// <returns>Liste gefundener Ländercodes</returns>
        public async Task<List<string>> FindCountryCodesAsync(string filter, string operatorValue)
        {
            var countries = await GetCountriesAsync();

            if (operatorValue == "equals")
                return (from country in countries where country.Name.ToLower().Equals(filter.ToLower()) select country.Iso2).ToList();
            if (operatorValue == "notequals")
                return (from country in countries where country.Name.ToLower().Equals(filter.ToLower()) == false select country.Iso2).ToList();
            if (operatorValue == "startswith")
                return (from country in countries where country.Name.ToLower().StartsWith(filter.ToLower()) select country.Iso2).ToList();
            if (operatorValue == "endswith")
                return (from country in countries where country.Name.ToLower().EndsWith(filter.ToLower()) select country.Iso2).ToList();
            if (operatorValue == "contains")
                return (from country in countries where country.Name.ToLower().Contains(filter.ToLower()) select country.Iso2).ToList();

            return new List<string>();
        }

        /// <summary>
        /// Gibt eine Liste der Bundesland-Codes zurück die zu einem Filter passen
        /// </summary>
        /// <param name="filter">Filter</param>
        /// <param name="operatorValue">Operator der angewendet werden soll</param>
        /// <returns>Liste gefundener Bundeslandcodes</returns>
        public async Task<List<string>> FindStateCodesAsync(string filter, string operatorValue)
        {
            var states = await GetStatesAsync();

            if (operatorValue == "equals")
                return (from state in states where state.Name.ToLower().Equals(filter.ToLower()) select state.Code).ToList();
            if (operatorValue == "notequals")
                return (from state in states where state.Name.ToLower().Equals(filter.ToLower()) == false select state.Code).ToList();
            if (operatorValue == "startswith")
                return (from state in states where state.Name.ToLower().StartsWith(filter.ToLower()) select state.Code).ToList();
            if (operatorValue == "endswith")
                return (from state in states where state.Name.ToLower().EndsWith(filter.ToLower()) select state.Code).ToList();
            if (operatorValue == "contains")
                return (from state in states where state.Name.ToLower().Contains(filter.ToLower()) select state.Code).ToList();

            return new List<string>();
        }

        /// <summary>
        /// Gibt eine Liste aller Länder zurück die in der Nationalitätenliste enthalten sind
        /// </summary>
        /// <returns>Liste</returns>
        public async Task<List<Country>> GetNationalitiesAsync()
        {
            var currentLanguage = "EN";
            if(Thread.CurrentThread.CurrentCulture.TwoLetterISOLanguageName.ToLower() == "de")
                currentLanguage = "DE";

            await using var stream = await FileSystem.OpenAppPackageFileAsync($"countries/{currentLanguage.ToLower()}/nationalities.json");
            using var reader = new StreamReader(stream);
            var json = await reader.ReadToEndAsync();

            var countries = JsonSerializer.Deserialize<List<Country>>(json);
            countries.ForEach(c => c.Iso2 = c.Iso2.ToUpper());
            return (countries ?? throw new InvalidOperationException()).OrderBy(c => c.Name).ToList();
        }
    }
}