using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Xml;

using System.Globalization;

using LiteBlog.Common;



namespace LiteBlog.XmlLayer

{

    public class BlogData : IBlogData

    {

       



        public List<PostInfo> GetBlogItems()

        {

            List<PostInfo> posts = new List<PostInfo>();



            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }



            XmlNodeList blogList = blogDoc.SelectNodes("/Posts/Post");

            if (blogList == null)

                return posts;



            try

            {

                foreach (XmlNode blogNode in blogList)

                {

                    PostInfo post = new PostInfo();

                    post.Title = blogNode.Attributes["Title"].Value;

                    if (blogNode.Attributes["Author"] != null)

                        post.Author = blogNode.Attributes["Author"].Value;

                    post.FileID  = blogNode.Attributes["FileID"].Value;

                    post.CatID = blogNode.Attributes["CatID"].Value;

                    

                    try

                    {

                        post.Time = DateTime.ParseExact(blogNode.Attributes["Time"].Value, DataContext.DateTimeFormat, CultureInfo.InvariantCulture);

                    }

                    catch (Exception ex)

                    {

                        string msg = String.Format(DATE_FORMAT_ERROR, post.FileID );

                        Logger.Log(msg, ex);

                        post.Time = DateTime.MinValue;

                    }

                    post.MonthID = blogNode.Attributes["MonthID"].Value;

                    posts.Add(post);

                }

            }

            catch (Exception ex)

            {

                Logger.Log(XML_FORMAT_ERROR, ex);

                throw new ApplicationException(XML_FORMAT_ERROR, ex);

            }

           



            return posts;

        }



        public void Create(PostInfo postInfo)

        {

            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, postInfo.FileID));

            if (postNode != null)

            {

                Logger.Log(DUP_POST_ERROR);

                throw new ApplicationException(DUP_POST_ERROR);

            }



            XmlElement postElem = blogDoc.CreateElement("Post");

            XmlAttribute titleAttr = blogDoc.CreateAttribute("Title");

            titleAttr.Value = postInfo.Title;

            XmlAttribute urlAttr = blogDoc.CreateAttribute("FileID");

            urlAttr.Value = postInfo.FileID;

            XmlAttribute authAttr = blogDoc.CreateAttribute("Author");

            authAttr.Value = postInfo.Author;

            XmlAttribute catAttr = blogDoc.CreateAttribute("CatID");

            catAttr.Value = postInfo.CatID;

            XmlAttribute monthAttr = blogDoc.CreateAttribute("MonthID");

            monthAttr.Value = postInfo.MonthID;

            XmlAttribute timeAttr = blogDoc.CreateAttribute("Time");

            timeAttr.Value = postInfo.Time.ToString(DataContext.DateTimeFormat, CultureInfo.InvariantCulture);

            postElem.Attributes.Append(titleAttr);

            postElem.Attributes.Append(urlAttr);

            postElem.Attributes.Append(authAttr);

            postElem.Attributes.Append(catAttr);

            postElem.Attributes.Append(monthAttr);

            postElem.Attributes.Append(timeAttr);



            

            try

            {



                XmlNode blogNode = blogDoc.SelectSingleNode("/Posts");

                bool lastNode = true;

                if (blogNode.ChildNodes.Count > 0)

                {

                    foreach (XmlNode postNode2 in blogNode.ChildNodes)

                    {



                        DateTime refDate;

                        try

                        {

                            refDate = DateTime.ParseExact(postNode2.Attributes["Time"].Value, DataContext.DateTimeFormat, CultureInfo.InvariantCulture);

                        }

                        catch (Exception ex)

                        {

                            string msg = String.Format(DATE_FORMAT_ERROR, postNode2.Attributes["FileID"].Value);

                            Logger.Log(msg, ex);

                            refDate = DateTime.MaxValue;

                        }



                        

                        if (postInfo.Time > refDate)

                        {

                            blogNode.InsertBefore(postElem, postNode2);

                            lastNode = false;

                            break;

                        }

                    }



                }



                if (lastNode)

                    blogNode.AppendChild(postElem);



                blogDoc.Save(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(XML_FORMAT_ERROR, ex);

                throw new ApplicationException(XML_FORMAT_ERROR, ex);

            }

        }



        public void Update(string fileID, string title, string catID)

        {

            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, fileID));

            if (postNode == null)

            {

                string msg = String.Format(NO_POST_ERROR, fileID);

                Logger.Log(msg);

                throw new ApplicationException(msg);

            }



            postNode.Attributes["Title"].Value = title;

            postNode.Attributes["CatID"].Value = catID;



            blogDoc.Save(_path);

                

        }



        /// <summary>

        /// If author is deleted or edited

        /// </summary>

        public void ChangeAuthor(string fileID, string author)

        {

            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, fileID));

            if (postNode == null)

            {

                string msg = String.Format(NO_POST_ERROR, fileID);

                Logger.Log(msg);

                throw new ApplicationException(msg);

            }



            XmlAttribute authAttr = postNode.Attributes["Author"];

            if (authAttr == null)

            {

                authAttr = blogDoc.CreateAttribute("Author");

                XmlAttribute catAttr = postNode.Attributes["CatID"];

                postNode.Attributes.InsertBefore(authAttr, catAttr);

            }

               

            authAttr.Value = author;



            blogDoc.Save(_path);



        }



        /// <summary>

        /// If category is deleted or edited

        /// </summary>

        public void ChangeCategory(string fileID, string oldCatID, string newCatID)

        {

            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, fileID));

            if (postNode == null)

            {

                string msg = String.Format(NO_POST_ERROR, fileID);

                Logger.Log(msg);

                throw new ApplicationException(msg);

            }



           

            string[] catIDs = postNode.Attributes["CatID"].Value.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);

            string newCatIDs = "";

            foreach (string catID in catIDs)

            {

                if (catID == oldCatID)

                {

                    if (newCatID != "")

                        newCatIDs += newCatID + ",";

                }

                else

                {

                    newCatIDs += catID + ",";

                }

            }



            if (newCatIDs.Length > 0)

                if (newCatIDs[newCatIDs.Length - 1] == ',')

                    newCatIDs = newCatIDs.Substring(0, newCatIDs.Length - 1);

            



            postNode.Attributes["CatID"].Value = newCatIDs;



            blogDoc.Save(_path);



        }





        public void Delete(string fileID)

        {

            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, fileID));

            if (postNode == null)

            {

                string msg = String.Format(NO_POST_ERROR, fileID);

                Logger.Log(msg);

                throw new ApplicationException(msg);

            }



            blogDoc.DocumentElement.RemoveChild(postNode);

            blogDoc.Save(_path);





        }



        internal bool PostExists(string fileID)

        {



            XmlDocument blogDoc = new XmlDocument();



            try

            {

                blogDoc.Load(_path);

            }

            catch (Exception ex)

            {

                Logger.Log(NO_FILE_ERROR, ex);

                throw new ApplicationException(NO_FILE_ERROR, ex);

            }





            string xpath = "/Posts/Post[@FileID='{0}']";

            XmlNode postNode = blogDoc.SelectSingleNode(String.Format(xpath, fileID));

            return ((postNode == null) ? false : true);

        }



         internal static string Path

        {

            get { return DataContext.Path + "Blog.xml"; }

        }



        public BlogData()

        {

            _path = DataContext.Path + "Blog.xml";

        }



        private string _path;

        private const string NO_FILE_ERROR = "Blog meta file could not be found";

        private const string XML_FORMAT_ERROR = "Blog meta file is not in the right format";

        private const string DUP_POST_ERROR = "A duplicate post was found in the blog meta file";

        private const string DATE_FORMAT_ERROR = "Time field for {0} is not in the right format";

        private const string NO_POST_ERROR = "Post = {0} could not be found";

       

    }

}