using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading;
using System.Web;
using Umbraco.Core.Configuration;
using Umbraco.Core.IO;
using Umbraco.Core.Logging;
using Umbraco.Core.Models;
using Umbraco.Core.Models.EntityBase;
using Umbraco.Core.Models.Membership;
using Umbraco.Core.Persistence.Repositories;
using Umbraco.Core.Persistence.UnitOfWork;
using Umbraco.Core.Strings;
using umbraco.interfaces;

namespace Umbraco.Core.Services
{
    public class NotificationService : INotificationService
    {
        private readonly IDatabaseUnitOfWorkProvider _uowProvider;
        private readonly IUserService _userService;
        private readonly IContentService _contentService;
        private readonly ILogger _logger;

        public NotificationService(IDatabaseUnitOfWorkProvider provider, IUserService userService, IContentService contentService, ILogger logger)
        {
            if (provider == null) throw new ArgumentNullException("provider");
            if (userService == null) throw new ArgumentNullException("userService");
            if (contentService == null) throw new ArgumentNullException("contentService");
            if (logger == null) throw new ArgumentNullException("logger");
            _uowProvider = provider;
            _userService = userService;
            _contentService = contentService;
            _logger = logger;
        }

        /// <summary>
        /// Sends the notifications for the specified user regarding the specified node and action.
        /// </summary>
        /// <param name="entity"></param>
        /// <param name="operatingUser"></param>
        /// <param name="action"></param>
        /// <param name="actionName"></param>
        /// <param name="http"></param>
        /// <param name="createSubject"></param>
        /// <param name="createBody"></param>
        /// <remarks>
        /// Currently this will only work for Content entities!
        /// </remarks>
        public void SendNotifications(IUser operatingUser, IUmbracoEntity entity, string action, string actionName, HttpContextBase http,
            Func<IUser, string[], string> createSubject,
            Func<IUser, string[], string> createBody)
        {
            if ((entity is IContent) == false)
            {
                throw new NotSupportedException();
            }
            var content = (IContent) entity;
            //we'll lazily get these if we need to send notifications
            IEnumerable<IContent> allVersions = null;

            int totalUsers;
            var allUsers = _userService.GetAll(0, int.MaxValue, out totalUsers);
            foreach (var u in allUsers)
            {
                if (u.IsApproved == false) continue;
                var userNotifications = GetUserNotifications(u, content.Path).ToArray();
                var notificationForAction = userNotifications.FirstOrDefault(x => x.Action == action);
                if (notificationForAction != null)
                {
                    //lazy load versions if notifications are required
                    if (allVersions == null)
                    {
                        allVersions = _contentService.GetVersions(entity.Id);
                    }

                    try
                    {
                        SendNotification(
                            operatingUser, u, content,                            
                            allVersions, 
                            actionName, http, createSubject, createBody);


                        _logger.Debug<NotificationService>(string.Format("Notification type: {0} sent to {1} ({2})", action, u.Name, u.Email));
                    }
                    catch (Exception ex)
                    {
                        _logger.Error<NotificationService>("An error occurred sending notification", ex);
                    }
                }
            }
        }

        /// <summary>
        /// Gets the notifications for the user
        /// </summary>
        /// <param name="user"></param>
        /// <returns></returns>
        public IEnumerable<Notification> GetUserNotifications(IUser user)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            return repository.GetUserNotifications(user);
        }

        /// <summary>
        /// Gets the notifications for the user based on the specified node path
        /// </summary>
        /// <param name="user"></param>
        /// <param name="path"></param>
        /// <returns></returns>
        /// <remarks>
        /// Notifications are inherited from the parent so any child node will also have notifications assigned based on it's parent (ancestors)
        /// </remarks>
        public IEnumerable<Notification> GetUserNotifications(IUser user, string path)
        {
            var userNotifications = GetUserNotifications(user).ToArray();
            var pathParts = path.Split(new[] {','}, StringSplitOptions.RemoveEmptyEntries);
            var result = userNotifications.Where(r => pathParts.InvariantContains(r.EntityId.ToString(CultureInfo.InvariantCulture))).ToList();            
            return result;
        }

        /// <summary>
        /// Deletes notifications by entity
        /// </summary>
        /// <param name="entity"></param>
        public IEnumerable<Notification> GetEntityNotifications(IEntity entity)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            return repository.GetEntityNotifications(entity);
        }

        /// <summary>
        /// Deletes notifications by entity
        /// </summary>
        /// <param name="entity"></param>
        public void DeleteNotifications(IEntity entity)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            repository.DeleteNotifications(entity);
        }

        /// <summary>
        /// Deletes notifications by user
        /// </summary>
        /// <param name="user"></param>
        public void DeleteNotifications(IUser user)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            repository.DeleteNotifications(user);
        }

        /// <summary>
        /// Delete notifications by user and entity
        /// </summary>
        /// <param name="user"></param>
        /// <param name="entity"></param>
        public void DeleteNotifications(IUser user, IEntity entity)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            repository.DeleteNotifications(user, entity);
        }

        /// <summary>
        /// Creates a new notification
        /// </summary>
        /// <param name="user"></param>
        /// <param name="entity"></param>
        /// <param name="action">The action letter - note: this is a string for future compatibility</param>
        /// <returns></returns>
        public Notification CreateNotification(IUser user, IEntity entity, string action)
        {
            var uow = _uowProvider.GetUnitOfWork();
            var repository = new NotificationsRepository(uow);
            return repository.CreateNotification(user, entity, action);
        }

        #region private methods

        /// <summary>
        /// Sends the notification
        /// </summary>
        /// <param name="performingUser"></param>
        /// <param name="mailingUser"></param>
        /// <param name="content"></param>
        /// <param name="allVersions"></param>
        /// <param name="actionName">The action readable name - currently an action is just a single letter, this is the name associated with the letter </param>
        /// <param name="http"></param>
        /// <param name="createSubject">Callback to create the mail subject</param>
        /// <param name="createBody">Callback to create the mail body</param>
        private void SendNotification(IUser performingUser, IUser mailingUser, IContent content, IEnumerable<IContent> allVersions, string actionName, HttpContextBase http, 
            Func<IUser, string[], string> createSubject,
            Func<IUser, string[], string> createBody)
        {
            if (performingUser == null) throw new ArgumentNullException("performingUser");
            if (mailingUser == null) throw new ArgumentNullException("mailingUser");
            if (content == null) throw new ArgumentNullException("content");
            if (allVersions == null) throw new ArgumentNullException("allVersions");
            if (http == null) throw new ArgumentNullException("http");
            if (createSubject == null) throw new ArgumentNullException("createSubject");
            if (createBody == null) throw new ArgumentNullException("createBody");

            //Ensure they are sorted: http://issues.umbraco.org/issue/U4-5180
            var allVersionsAsArray = allVersions.OrderBy(x => x.UpdateDate).ToArray();

            int versionCount = (allVersionsAsArray.Length > 1) ? (allVersionsAsArray.Length - 2) : (allVersionsAsArray.Length - 1);
            var oldDoc = _contentService.GetByVersion(allVersionsAsArray[versionCount].Version);

            // build summary
            var summary = new StringBuilder();
            var props = content.Properties.ToArray();
            foreach (var p in props)
            {
                var newText = p.Value != null ? p.Value.ToString() : "";
                var oldText = newText;

                // check if something was changed and display the changes otherwise display the fields
                if (oldDoc.Properties.Contains(p.PropertyType.Alias))
                {
                    var oldProperty = oldDoc.Properties[p.PropertyType.Alias];
                    oldText = oldProperty.Value != null ? oldProperty.Value.ToString() : "";
                    
                    // replace html with char equivalent
                    ReplaceHtmlSymbols(ref oldText);
                    ReplaceHtmlSymbols(ref newText);
                }
                

                // make sure to only highlight changes done using TinyMCE editor... other changes will be displayed using default summary
                // TODO: We should probably allow more than just tinymce??
                if ((p.PropertyType.PropertyEditorAlias == Constants.PropertyEditors.TinyMCEAlias) 
                    && string.CompareOrdinal(oldText, newText) != 0)
                {
                    summary.Append("<tr>");
                    summary.Append("<th style='text-align: left; vertical-align: top; width: 25%;'> Note: </th>");
                    summary.Append(
                        "<td style='text-align: left; vertical-align: top;'> <span style='background-color:red;'>Red for deleted characters</span>&nbsp;<span style='background-color:yellow;'>Yellow for inserted characters</span></td>");
                    summary.Append("</tr>");
                    summary.Append("<tr>");
                    summary.Append("<th style='text-align: left; vertical-align: top; width: 25%;'> New " +
                                   p.PropertyType.Name + "</th>");
                    summary.Append("<td style='text-align: left; vertical-align: top;'>" +
                                   ReplaceLinks(CompareText(oldText, newText, true, false, "<span style='background-color:yellow;'>", string.Empty), http.Request) +
                                   "</td>");
                    summary.Append("</tr>");
                    summary.Append("<tr>");
                    summary.Append("<th style='text-align: left; vertical-align: top; width: 25%;'> Old " +
                                   p.PropertyType.Name + "</th>");
                    summary.Append("<td style='text-align: left; vertical-align: top;'>" +
                                   ReplaceLinks(CompareText(newText, oldText, true, false, "<span style='background-color:red;'>", string.Empty), http.Request) +
                                   "</td>");
                    summary.Append("</tr>");
                }
                else
                {
                    summary.Append("<tr>");
                    summary.Append("<th style='text-align: left; vertical-align: top; width: 25%;'>" +
                                   p.PropertyType.Name + "</th>");
                    summary.Append("<td style='text-align: left; vertical-align: top;'>" + newText + "</td>");
                    summary.Append("</tr>");
                }
                summary.Append(
                    "<tr><td colspan=\"2\" style=\"border-bottom: 1px solid #CCC; font-size: 2px;\">&nbsp;</td></tr>");
            }

            string protocol = GlobalSettings.UseSSL ? "https" : "http";


            string[] subjectVars = {
                                       http.Request.ServerVariables["SERVER_NAME"] + ":" +
                                       http.Request.Url.Port +
                                       IOHelper.ResolveUrl(SystemDirectories.Umbraco), 
                                       actionName,
                                       content.Name
                                   };
            string[] bodyVars = {
                                    mailingUser.Name, 
                                    actionName, 
                                    content.Name, 
                                    performingUser.Name,
                                    http.Request.ServerVariables["SERVER_NAME"] + ":" + http.Request.Url.Port + IOHelper.ResolveUrl(SystemDirectories.Umbraco),
                                    content.Id.ToString(CultureInfo.InvariantCulture), summary.ToString(),
                                    string.Format("{2}://{0}/{1}",
                                                  http.Request.ServerVariables["SERVER_NAME"] + ":" + http.Request.Url.Port,
                                                  //TODO: RE-enable this so we can have a nice url
                                                  /*umbraco.library.NiceUrl(documentObject.Id))*/
                                                  content.Id + ".aspx",
                                                  protocol)
                                    
                                };

            // create the mail message 
            var mail = new MailMessage(UmbracoConfig.For.UmbracoSettings().Content.NotificationEmailAddress, mailingUser.Email);

            // populate the message
            mail.Subject = createSubject(mailingUser, subjectVars);
            if (UmbracoConfig.For.UmbracoSettings().Content.DisableHtmlEmail)
            {
                mail.IsBodyHtml = false;
                mail.Body = createBody(mailingUser, bodyVars);
            }
            else
            {
                mail.IsBodyHtml = true;
                mail.Body =
                    @"<html><head>
</head>
<body style='font-family: Trebuchet MS, arial, sans-serif; font-color: black;'>
" + createBody(mailingUser, bodyVars);
            }

            // nh, issue 30724. Due to hardcoded http strings in resource files, we need to check for https replacements here
            // adding the server name to make sure we don't replace external links
            if (GlobalSettings.UseSSL && string.IsNullOrEmpty(mail.Body) == false)
            {
                string serverName = http.Request.ServerVariables["SERVER_NAME"];
                mail.Body = mail.Body.Replace(
                    string.Format("http://{0}", serverName),
                    string.Format("https://{0}", serverName));
            }


            // send it  asynchronously, we don't want to got up all of the request time to send emails!
            ThreadPool.QueueUserWorkItem(state =>
                {
                    try
                    {
                        using (mail)
                        {
                            using (var sender = new SmtpClient())
                            {
                                sender.Send(mail);
                            }    
                        }
                        
                    }
                    catch (Exception ex)
                    {
                        _logger.Error<NotificationService>("An error occurred sending notification", ex);
                    }
                });
        }

        private static string ReplaceLinks(string text, HttpRequestBase request)
        {
            string domain = GlobalSettings.UseSSL ? "https://" : "http://";
            domain += request.ServerVariables["SERVER_NAME"] + ":" + request.Url.Port + "/";
            text = text.Replace("href=\"/", "href=\"" + domain);
            text = text.Replace("src=\"/", "src=\"" + domain);
            return text;
        }

        /// <summary>
        /// Replaces the HTML symbols with the character equivalent.
        /// </summary>
        /// <param name="oldString">The old string.</param>
        private static void ReplaceHtmlSymbols(ref string oldString)
        {
            oldString = oldString.Replace("&nbsp;", " ");
            oldString = oldString.Replace("&rsquo;", "'");
            oldString = oldString.Replace("&amp;", "&");
            oldString = oldString.Replace("&ldquo;", "“");
            oldString = oldString.Replace("&rdquo;", "”");
            oldString = oldString.Replace("&quot;", "\"");
        }

        /// <summary>
        /// Compares the text.
        /// </summary>
        /// <param name="oldText">The old text.</param>
        /// <param name="newText">The new text.</param>
        /// <param name="displayInsertedText">if set to <c>true</c> [display inserted text].</param>
        /// <param name="displayDeletedText">if set to <c>true</c> [display deleted text].</param>
        /// <param name="insertedStyle">The inserted style.</param>
        /// <param name="deletedStyle">The deleted style.</param>
        /// <returns></returns>
        private static string CompareText(string oldText, string newText, bool displayInsertedText,
                                          bool displayDeletedText, string insertedStyle, string deletedStyle)
        {
            var sb = new StringBuilder();
            var diffs = Diff.DiffText1(oldText, newText);

            int pos = 0;
            for (int n = 0; n < diffs.Length; n++)
            {
                Diff.Item it = diffs[n];

                // write unchanged chars
                while ((pos < it.StartB) && (pos < newText.Length))
                {
                    sb.Append(newText[pos]);
                    pos++;
                } // while

                // write deleted chars
                if (displayDeletedText && it.DeletedA > 0)
                {
                    sb.Append(deletedStyle);
                    for (int m = 0; m < it.DeletedA; m++)
                    {
                        sb.Append(oldText[it.StartA + m]);
                    } // for
                    sb.Append("</span>");
                }

                // write inserted chars
                if (displayInsertedText && pos < it.StartB + it.InsertedB)
                {
                    sb.Append(insertedStyle);
                    while (pos < it.StartB + it.InsertedB)
                    {
                        sb.Append(newText[pos]);
                        pos++;
                    } // while
                    sb.Append("</span>");
                } // if                
            } // while

            // write rest of unchanged chars
            while (pos < newText.Length)
            {
                sb.Append(newText[pos]);
                pos++;
            } // while

            return sb.ToString();
        }

        #endregion
    }
}