using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Text.Json;
using gehGassi.Core.Interfaces;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Caching.Distributed;
using Microsoft.Extensions.Options;

namespace gehGassi.Core.Services
{
    /// <summary>
    /// Schnittsellenbeschreibung für einen Service der die Validierung von E-Mail Adressen ermöglicht
    /// </summary>
    public class EmailValidationService : IEmailValidationService
    {
        private readonly IDistributedCache _memoryCache;
        private readonly IWebHostEnvironment _hostingEnvironment;
        private readonly IOptions<EmailValidationOptions> _emailValidationOptions;

        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        /// <param name="memoryCache">Instanz eines IDistributedCache</param>
        /// <param name="hostingEnvironment">Instanz eines IWebHostEnvironment</param>
        /// <param name="emailValidationOptions">Instanz eines EmailValidationOptions</param>
        public EmailValidationService(IDistributedCache memoryCache, IWebHostEnvironment hostingEnvironment, IOptions<EmailValidationOptions> emailValidationOptions)
        {
            _memoryCache = memoryCache;
            _hostingEnvironment = hostingEnvironment;
            _emailValidationOptions = emailValidationOptions;
            Init();
        }

        /// <summary>
        /// Initialisiert den Service
        /// </summary>
        private void Init()
        {
            var path = Path.Combine(_hostingEnvironment.WebRootPath, _emailValidationOptions.Value.File);
            if (File.Exists(path))
            {
                var fakeMailList = new List<string>();
                var allDomains = File.ReadAllLines(path, Encoding.Default);
                fakeMailList.AddRange(allDomains);
                //_memoryCache.Set("FakeMails", fakeMailList);
                _memoryCache.SetString("FakeMails", JsonSerializer.Serialize(fakeMailList));
            }
        }

        /// <summary>
        /// Gibt zurück ob es sich bei der E-Mail Adresse um eine Wegwerfadresse handelt
        /// </summary>
        /// <param name="emailAddress">E-Mail Adresse die geprüft werden soll</param>
        /// <returns>true wenn Wegwerf-Email, false sonst</returns>
        public bool IsDisposable(string emailAddress)
        {
            if (string.IsNullOrWhiteSpace(emailAddress))
                return false;

            var fakeMailList = new List<string>();
            var json = _memoryCache.GetString("FakeMails");
            if (string.IsNullOrWhiteSpace(json))
            {
                Init();
                fakeMailList = JsonSerializer.Deserialize<List<string>>(_memoryCache.GetString("FakeMails"));
            }
            else
            {
                fakeMailList = JsonSerializer.Deserialize<List<string>>(json);
            }

            if (fakeMailList != null && fakeMailList.Any())
            {
                var mailAddress = new MailAddress(emailAddress);
                return fakeMailList?.FirstOrDefault(c => c == mailAddress.Host.ToLower()) != null;
            }

            return false;
        }
    }

    /// <summary>
    /// Einstellungen für den Email-Valiiderungs-Service
    /// </summary>
    public class EmailValidationOptions
    {
        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        public EmailValidationOptions()
        {

        }

        /// <summary>
        /// Datei die verwendet werden soll
        /// </summary>
        public string File { get; set; }
    }
}