Open Source Extensible Enterprise n-tier Application Framework with Multilayered Architecture

using System;
using SiberTek.Xenta.Data;
using SiberTek.Xenta.Data.Providers;
using SiberTek.Xenta.Entities;
using SiberTek.Xenta.Entities.Collections;
using SiberTek.Xenta.Enums;
using SiberTek.Xenta.Events;
using SiberTek.Xenta.Exceptions;
using SiberTek.Xenta.Utils;

namespace SiberTek.Xenta.Managers
{
    /// <summary>
    /// Contains methods to manage forum subscriptions
    /// </summary>
    public class ForumSubscriptionManager : IManager
    {
        #region Fields
        private static ForumSubscriptionManager _instance = null;
        private IForumSubscriptionDataProvider _dataProvider;
        private bool _initialized;
        #endregion

        #region Constructors
        private ForumSubscriptionManager()
        {
            _dataProvider = null;
            _initialized = false;
        }
        #endregion

        #region Events
        public event EntityEventHandler ForumSubscriptionCreated;
        public event EntityEventHandler ForumSubscriptionUpdated;
        public event EntityEventHandler ForumSubscriptionDeleted;
        #endregion

        #region Properties
        public static ForumSubscriptionManager Instance
        {
            get
            {
                if(_instance == null)
                {
                    _instance = new ForumSubscriptionManager();
                }
                return _instance;
            }
        }

        private IForumSubscriptionDataProvider DataProvider
        {
            get
            {
                return _dataProvider;
            }
        }
        #endregion

        #region Methods
        public void Initialize()
        {
            if(!_initialized)
            {
                _dataProvider = DataAccessManager.GetProviderInstance<IForumSubscriptionDataProvider>("ForumSubscriptionDataProvider");

                ForumProfileManager.Instance.ProfileDeleted += OnForumProfileDeleted;
                ForumManager.Instance.ForumDeleted += OnForumDeleted;
                ForumTopicManager.Instance.TopicDeleted += OnTopicDeleted;

                _initialized = true;
            }
        }

        public ForumSubscriptionInfo CreateForumSubscription(ForumSubscriptionType type, int forumEntityID, int userID)
        {
            if(UserManager.Instance.GetUser(userID) == null)
            {
                throw new XentaException("User does not exist", (int)CoreError.UserDoesNotExist);
            }

            switch(type)
            {
                case ForumSubscriptionType.Forum:
                    if(ForumManager.Instance.GetForum(forumEntityID) == null)
                    {
                        throw new XentaException("Forum does not exist", (int)ForumError.ForumDoesNotExist);
                    }
                    break;
                case ForumSubscriptionType.Topic:
                    if(ForumTopicManager.Instance.GetForumTopic(forumEntityID) == null)
                    {
                        throw new XentaException("Forum topic does not exist", (int)ForumError.TopicDoesNotExist);
                    }
                    break;
            }

            if(GetForumSubscriptionByForumEntityIDAndUserID(type, forumEntityID, userID) != null)
            {
                throw new XentaException("Forum subscription already exists", (int)ForumError.DuplicateSubscription);
            }

            ForumSubscriptionInfo subscription = null;
            int subscriptionID;

            if(DataProvider.InsertForumSubscription(type, forumEntityID, userID, DateTime.UtcNow, DateTime.UtcNow, out subscriptionID))
            {
                subscription = GetForumSubscription(subscriptionID);

                FireSubscriptionCreated(subscription);
            }

            return subscription;
        }

        public ForumSubscriptionInfo GetForumSubscription(int subscriptionID)
        {
            return DataMapper.Map(DataProvider.GetForumSubscription(subscriptionID));
        }

        public ForumSubscriptionInfo GetForumSubscriptionByForumEntityIDAndUserID(ForumSubscriptionType type, int forumEntityID, int userID)
        {
            return DataMapper.Map(DataProvider.GetForumSubscriptionByForumEntityIDAndUserID(type, forumEntityID, userID));
        }

        public ForumSubscriptionInfoCollection GetForumSubscriptionsByUserID(int userID)
        {
            return GetAllForumSubscriptions(null, null, userID, null, null);
        }

        public ForumSubscriptionInfoCollection GetForumSubscriptionsByForumEntityID(ForumSubscriptionType type, int forumEntityID)
        {
            return GetAllForumSubscriptions(type, forumEntityID, null, null, null);
        }

        public ForumSubscriptionInfoCollection GetAllForumSubscriptions(ForumSubscriptionType? type, int? forumEntityID, int? userID, DateTime? createdOnStart, DateTime? createdOnEnd)
        {
            int totalCount = 0;
            return GetAllForumSubscriptions(type, forumEntityID, userID, createdOnStart, createdOnEnd, 0, Int32.MaxValue, out totalCount);
        }

        public ForumSubscriptionInfoCollection GetAllForumSubscriptions(ForumSubscriptionType? type, int? forumEntityID, int? userID, DateTime? createdOnStart, DateTime? createdOnEnd, int startIndex, int count, out int totalCount)
        {
            return DataMapper.Map(DataProvider.GetAllForumSubscriptions(type, forumEntityID, userID, createdOnStart, createdOnEnd, startIndex, count, out totalCount));
        }

        public ForumSubscriptionInfo UpdateForumSubscription(int subscriptionID, ForumSubscriptionType type, int forumEntityID, int userID)
        {
            if(UserManager.Instance.GetUser(userID) == null)
            {
                throw new XentaException("User does not exist", (int)CoreError.UserDoesNotExist);
            }

            switch(type)
            {
                case ForumSubscriptionType.Forum:
                    if(ForumManager.Instance.GetForum(forumEntityID) == null)
                    {
                        throw new XentaException("Forum does not exist", (int)ForumError.ForumDoesNotExist);
                    }
                    break;
                case ForumSubscriptionType.Topic:
                    if(ForumTopicManager.Instance.GetForumTopic(forumEntityID) == null)
                    {
                        throw new XentaException("Forum topic does not exist", (int)ForumError.TopicDoesNotExist);
                    }
                    break;
            }

            ForumSubscriptionInfo subscription = GetForumSubscription(subscriptionID);

            if(subscription == null)
            {
                throw new XentaException("Forum subscription does not exist", (int)ForumError.SubscriptionDoesNotExist);
            }
            if((subscription.ForumEntityID != forumEntityID || subscription.Type != type || subscription.UserID != userID) && GetForumSubscriptionByForumEntityIDAndUserID(type, forumEntityID, userID) != null)
            {
                throw new XentaException("Forum subscription already exists", (int)ForumError.DuplicateSubscription);
            }

            if(DataProvider.UpdateForumSubscription(subscriptionID, type, forumEntityID, userID, subscription.CreatedOn, DateTime.UtcNow))
            {
                subscription = GetForumSubscription(subscriptionID);

                FireSubscriptionUpdated(subscription);
            }

            return subscription;
        }

        public void DeleteForumSubscription(int subscriptionID)
        {
            ForumSubscriptionInfo subscription = GetForumSubscription(subscriptionID);

            if(subscription != null)
            {
                FireSubscriptionDeleted(subscription);
                DataProvider.DeleteForumSubscription(subscriptionID);
            }
        }
        #endregion

        #region Handlers
        private void OnForumProfileDeleted(object sender, EntityEventArgs e)
        {
            ForumProfileInfo profile = e.Entity as ForumProfileInfo;

            if(profile != null)
            {
                foreach(ForumSubscriptionInfo subscription in GetForumSubscriptionsByUserID(profile.UserID))
                {
                    DeleteForumSubscription(subscription.SubscriptionID);
                }
            }
        }

        private void OnForumDeleted(object sender, EntityEventArgs e)
        {
            ForumInfo forum = e.Entity as ForumInfo;

            if(forum != null)
            {
                foreach(ForumSubscriptionInfo subscription in GetForumSubscriptionsByForumEntityID(ForumSubscriptionType.Forum, forum.ForumID))
                {
                    DeleteForumSubscription(subscription.SubscriptionID);
                }
            }
        }

        private void OnTopicDeleted(object sender, EntityEventArgs e)
        {
            ForumTopicInfo topic = e.Entity as ForumTopicInfo;

            if(topic != null)
            {
                foreach(ForumSubscriptionInfo subscription in GetForumSubscriptionsByForumEntityID(ForumSubscriptionType.Topic, topic.TopicID))
                {
                    DeleteForumSubscription(subscription.SubscriptionID);
                }
            }
        }
        #endregion

        #region Utilties
        private void FireSubscriptionCreated(ForumSubscriptionInfo subscription)
        {
            if(ForumSubscriptionCreated != null)
            {
                ForumSubscriptionCreated(this, new EntityEventArgs(subscription));
            }
        }

        private void FireSubscriptionUpdated(ForumSubscriptionInfo subscription)
        {
            if(ForumSubscriptionUpdated != null)
            {
                ForumSubscriptionUpdated(this, new EntityEventArgs(subscription));
            }
        }

        private void FireSubscriptionDeleted(ForumSubscriptionInfo subscription)
        {
            if(ForumSubscriptionDeleted != null)
            {
                ForumSubscriptionDeleted(this, new EntityEventArgs(subscription));
            }
        }
        #endregion
    }
}