using System;
using System.Collections.Generic;
using System.IO;
using System.Net.Mail;
using System.Reflection;
using NVelocity;
using NVelocity.App;
using Spring.Objects.Factory;
using log4net;
using Spring.Template.Velocity;

namespace Sleis.Utility
{
    public class EmailUtility : IInitializingObject
    {
        private readonly ILog _log = LogManager.GetLogger(typeof(EmailUtility));

        public SmtpClient Smtp { get; set; }
        public System.Net.ICredentialsByHost Credentials { get; set; }
        public Dictionary<string, MailMessage> Messages { get; set; }
        public VelocityEngine VelocityEngine { get; set; }

        public void AfterPropertiesSet()
        {
            ArgumentValidationUtility.ThrowOnNull(Smtp, "Null Smtp");
            ArgumentValidationUtility.ThrowOnNull(Messages, "Null Messages");
            ArgumentValidationUtility.ThrowOnNull(VelocityEngine, "Null VelocityEngine");
            if (!Smtp.UseDefaultCredentials) Smtp.Credentials = Credentials;
        }

        public void SendObject(string to, string messageKey, object instance)
        {
            _log.DebugFormat("Send({0},{1},{2})", to, messageKey, instance);

            Dictionary<string, object> dict = new Dictionary<string, object>();
            dict.Add("item", instance);


            SendArgs(to, messageKey, dict, null);

        }
        public void SendArgs(string to, string messageKey, Dictionary<string, object> args)
        {
            SendArgs(to, messageKey, args, null);
        }
        public void SendArgs(string to, string messageKey, Dictionary<string, object> args, Attachment attachment)
        {
            _log.DebugFormat("Send({0},{1},{2})", to, messageKey, args);

            VelocityContext vcontext = new VelocityContext();
            
            if (args != null)
            {
                foreach (KeyValuePair<string, object> key in args)
                {
                    vcontext.Put(key.Key, key.Value);
                }
            }

            string message = null;
            string template = String.Format("{0}.vm", messageKey);

            using (StringWriter writer = new StringWriter())
            {
                VelocityEngine.MergeTemplate(template, "UTF-8", vcontext, writer);
                message = writer.ToString();                
            }

            Send(to, messageKey, message, attachment);

        }

        public void Send(string to, string messageKey, string body, Attachment attachment)
        {
            _log.DebugFormat("Send({0},{1},{2})", to, messageKey, body);

            if (String.IsNullOrEmpty(messageKey))
            {
                throw new ArgumentNullException("messageKey");
            }


            if (String.IsNullOrEmpty(to))
            {
                throw new ArgumentNullException("to");
            }

            if (String.IsNullOrEmpty(body))
            {
                throw new ArgumentNullException("body");
            }

            if (!Messages.ContainsKey(messageKey))
            {
                throw new ArgumentOutOfRangeException("Invalid messageKey: " + messageKey);
            }
            MailMessage msg = Messages[messageKey];
            try
            {

                
                msg.To.Clear();
                msg.To.Add(to);
                msg.Attachments.Clear(); //since we are using spring to manage email messages as static object, we need to make sure we clear out all attachments. That way each email is in a way "fresh"
                msg.Body = body;
                if (attachment != null)
                {
                    msg.Attachments.Add(attachment);
                }
                Smtp.Send(msg);

            }
            catch (Exception ex)
            {
                _log.Error("Error while sending message", ex);
                //TODO: Not sure if we want to swallow message or not. Originally we were swallowing, however, this created problem on FeedBack screen since it appeared message was sending successfully.  
                //Throwing exception now might cause problems if not properly catching for them in UI.
                throw new ApplicationException("Errow while sending message: " + ExceptionUtility.GetDeepExceptionMessageOnly(ex));
            }
            finally
            {
                //since we are using spring to manage email messages as static object, we need to make sure we clear out all attachments. That way each email is in a way "fresh"
                msg.Attachments.Clear();
            }
        }
    }
}