using System;
using System.Collections.Generic;
using System.IO;
using System.Xml;
using System.Web;
using NLog;

namespace dariog
{
    public class AppConfig
    {
        private static Logger logger = LogManager.GetCurrentClassLogger();
        private static AppConfig config = null;

        public static AppConfig Current
        {
            get
            {
                if(config == null)
                {
                    lock(typeof(AppConfig))
                    {
                        if(config == null)
                        {
                            config = new AppConfig();
                        }
                    }
                }
                return config;
            }
        }

        private Dictionary<string, string> items = null;
        private object locker = new object();

        private AppConfig()
        {
            this.LoadItems();
        }

        private void LoadItems()
        {
            items = new Dictionary<string, string>();
            string file = Path.Combine(HttpRuntime.AppDomainAppPath, "App_Data\\config\\application.xml");
            if (File.Exists(file))
            {
                XmlDocument xml = new XmlDocument();
                xml.Load(file);
                foreach (XmlNode node in xml.DocumentElement)
                {
                    if (node.NodeType != XmlNodeType.Comment)
                    {
                        XmlElement e = node as XmlElement;
                        items.Add(e.Name, e.InnerText);
                    }
                }

                string machine = System.Environment.MachineName.ToLower();
                file = Path.Combine(
                    HttpRuntime.AppDomainAppPath,
                    "App_Data\\config\\application.{0}.xml".FormatThis(machine));
                if (File.Exists(file))
                {
                    xml = new XmlDocument();
                    xml.Load(file);
                    foreach (XmlNode node in xml.DocumentElement)
                    {
                        if (node.NodeType != XmlNodeType.Comment)
                        {
                            XmlElement e = node as XmlElement;
                            if (items.ContainsKey(e.Name))
                            {
                                items[e.Name] = e.InnerText;
                            }
                            else
                            {
                                logger.Warn("Key exists in extended configuration file {0} but doesn't exists in base configuration file 'application.xml'.", file);
                            }
                        }
                    }
                }
            }
            else
            {
                logger.Error("File configuration {0} doesn't exists.", file);
            }
        }

        public T GetItem<T>(string key)
        {
            lock (locker)
            {
                if (!items.ContainsKey(key))
                {
                    throw new NotImplementedException(String.Format("The key '{0}' is not defined in application config file.", key));
                }
                return (T)Convert.ChangeType(items[key], typeof(T));
            }
        }

        public T GetItem<T>(string key, T defaultValue)
        {
            lock (locker)
            {
                if (items.ContainsKey(key))
                {
                    return (T)Convert.ChangeType(items[key], typeof(T));
                }
                return defaultValue;
            }
        }
    }
}