XmlReadWrite

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;

namespace wpfInstructie
{
    class xmlReadWrite
    {
        private XmlDocument getDB(string xmlName)
        {
            XmlDocument doc = new XmlDocument();
            try
            {
                doc.Load(getXMLLocation(xmlName));
            }
            catch { doc = null; }
            if (doc == null)
            {
                doc = new XmlDocument();
                XmlDeclaration xmlDeclaration = doc.CreateXmlDeclaration("1.0", "UTF-8", null);
                XmlElement root = doc.CreateElement(string.Empty, xmlName, null);
                doc.AppendChild(root);
                doc.Save(getXMLLocation(xmlName));
            }

            return doc;
        }

        internal List<Comment> getAllComments()
        {
            List<Comment> comments = new List<Comment>();
            foreach (XmlNode node in getDB("Comment").DocumentElement.ChildNodes)
                comments.Add(new Comment(node.SelectSingleNode("Commenttext").InnerText, getUserByName(node.SelectSingleNode("Name").InnerText)));
            return comments;
        }

        private User getUserByName(string name)
        {
            foreach (XmlNode node in getDB("User").DocumentElement.ChildNodes)
                if (node.SelectSingleNode("Name").InnerText == name)
                        return new User(node.SelectSingleNode("Name").InnerText, node.SelectSingleNode("Pass").InnerText, node.SelectSingleNode("Email").InnerText);
            return null;
        }

        internal void saveNewComment(Comment comment)
        {
            XmlDocument doc = getDB("Comment");

            XmlNode newComment = doc.CreateNode(XmlNodeType.Element, "Comment", null);
            doc.DocumentElement.AppendChild(newComment);

            XmlNode commentText = doc.CreateNode(XmlNodeType.Element, "Commenttext", null);
            commentText.InnerText = comment.CommentText;
            newComment.AppendChild(commentText);

            XmlNode name = doc.CreateNode(XmlNodeType.Element, "Name", null);
            name.InnerText = comment.Poster.name.ToString();
            newComment.AppendChild(name);

            doc.Save(getXMLLocation("Comment"));
        }

        internal User searchForUser(string username, string password)
        {
            foreach (XmlNode node in getDB("User").DocumentElement.ChildNodes)
                if (node.SelectSingleNode("Name").InnerText == username)
                    if (node.SelectSingleNode("Pass").InnerText == password)
                        return new User(node.SelectSingleNode("Name").InnerText, node.SelectSingleNode("Pass").InnerText, node.SelectSingleNode("Email").InnerText);
            return null;
        }

        internal void saveNewUser(User user)
        {
            XmlDocument doc = getDB("User");

            if (checkForExistence(user.name, "Name", "User"))
                return;
            if (checkForExistence(user.email, "Email", "User"))
                return;

            XmlNode newUser = doc.CreateNode(XmlNodeType.Element, "User", null);
            doc.DocumentElement.AppendChild(newUser);

            XmlNode name = doc.CreateNode(XmlNodeType.Element, "Name", null);
            name.InnerText = user.name.ToString();
            newUser.AppendChild(name);

            XmlNode email = doc.CreateNode(XmlNodeType.Element, "Email", null);
            email.InnerText = user.email.ToString();
            newUser.AppendChild(email);

            XmlNode pass = doc.CreateNode(XmlNodeType.Element, "Pass", null);
            pass.InnerText = user.password.ToString();
            newUser.AppendChild(pass);

            doc.Save(getXMLLocation("User"));
        }
        /// <summary>
        ///
        /// </summary>
        /// <param name="value"></param>
        /// <param name="field"></param>
        /// <param name="xmldoc"></param>
        /// <returns></returns>
        private bool checkForExistence(string value, string field, string xmldoc)
        {
            foreach (XmlNode node in getDB(xmldoc).DocumentElement.ChildNodes)
            {
                if (value == node.SelectSingleNode(field).InnerText)
                    return true;
            }
            return false;
        }

        private string getXMLLocation(string xmlName)
        {
            switch (xmlName)
            {
                case "Comment":
                    return Environment.CurrentDirectory + @"/comment.xml";
                case "User":
                        return Environment.CurrentDirectory + @"/user.xml";
                default:
                    throw new MissingMemberException();
                    // return null;
            }
        }
    }
}