using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Mail;
using System.Threading.Tasks;
using xCommons.Extensions;
using xExceptions.Constants;
using xMessageService.Interfaces;
using xMessageService.Models;

namespace xMessageService.Providers {
    public partial class XMailService : IXMailService {
        private SmtpClient smtpClient;
        private readonly string defaultProvider;
        private readonly IDictionary<string, XMailConfiguration> configurations;

        public XMailService (
            string defaultProvider,
            IDictionary<string, XMailConfiguration> configurations
        ) {
            this.defaultProvider = defaultProvider;
            this.configurations = configurations;

            //
            // Get instance of SMTP Client ...
            PrepareSmtpClient ();
        }

        public Task SendMailAsync (
            XMessage message,
            string provider = null
        ) {
            //
            // Run Send Mail Asynchronous ...
            return Task.Run (() => {
                SendMail (message, provider);
            });
        }

        #region Private ...
        /// <summary>
        /// Validate and Retrieve Provider Configuration for Service
        /// </summary>
        /// <param name="provider"></param>
        /// <returns></returns>
        private XMailConfiguration GetConfiguration (string provider = null) {
            //
            if (provider.IsNullOrEmpty ()) {
                provider = defaultProvider;
            }

            //
            if (!configurations.Keys.Contains (provider)) {
                XException.MessageServiceInitialFailed.Throw ();
            }

            //
            return configurations[provider];
        }

        /// <summary>
        /// Prepare SMTP Client by Using Specified/Default Provider
        /// </summary>
        /// <param name="provider"></param>
        private void PrepareSmtpClient (string provider = null) {
            //
            var config = GetConfiguration (provider);
            if (config.IsNull()) {
                return;
            }

            //
            smtpClient = new SmtpClient () {
                Host = config.Host,
                Port = config.Port,
                EnableSsl = config.EnableSsl,
                UseDefaultCredentials = false,
                Credentials = new NetworkCredential (
                config.Username,
                config.Password)
            };
        }

        /// <summary>
        /// Prepare Mail Message With Specified/Default Provider
        /// </summary>
        /// <param name="message"></param>
        /// <param name="provider"></param>
        /// <returns></returns>
        private MailMessage PrepareMailMessage (
            XMessage message,
            string provider = null
        ) {
            //
            if (message == null ||
                message.Message.IsNullOrEmpty () ||
                message.Recievers.Count == 0) {
                XException.InvalidMessage.Throw ();
            }

            //
            var config = GetConfiguration (provider);
            var mailMessage = new MailMessage () {
                From = new MailAddress (config.Username),
                Subject = config.Title,
                Body = message.Message
            };

            //
            foreach (var reciever in message.Recievers) {
                mailMessage.To.Add (reciever);
            }

            //
            return mailMessage;
        }

        /// <summary>
        /// Send Mail Using Specified/Default Provider
        /// </summary>
        /// <param name="message"></param>
        /// <param name="provider"></param>
        private void SendMail (
            XMessage message,
            string provider = null
        ) {
            //
            if (smtpClient.IsNull()) {
                //
                Console.WriteLine ($"SMTP Error: MessageServiceInitialFailed ...");
                XException.MessageServiceInitialFailed.Throw ();
            }

            //
            var mailMessage = PrepareMailMessage (message, provider);

            //
            try {
                smtpClient.Send (mailMessage);
            } catch (Exception ex) {
                //
                Console.WriteLine ($"SMTP Error: {ex.Message}");
                XException.MessageServiceInitialFailed.Throw ();
            }
        }
        #endregion        
    }
}