using System;
using System.Dynamic;
using System.Reflection;
using System.Runtime.CompilerServices;
using Newtonsoft.Json;

[assembly: InternalsVisibleTo("deployment.tests")]
namespace greyn.Deployment
{
    public static class Configurator<T> where T : new()
    {
        private const string confpath = "appsettings.json";
        private static FileSystemWatcher appsettingsWatcher = new FileSystemWatcher(".");

        public static event EventHandler Changed;
        public static event System.IO.ErrorEventHandler Error;

        private static T config;

        public static T Load() 
        {
            if (File.Exists(confpath))
            {
                /*
                 * if the configuration expects new values we write them in.
                 * if you left other junk for whatever reason, get rekt
                 */
                config = JsonConvert.DeserializeObject<T>(File.ReadAllText(confpath)) ?? new T();
            }
            else
            {
                config = new T();
            }
            File.WriteAllText(confpath, JsonConvert.SerializeObject(config, Formatting.Indented));
            



            appsettingsWatcher.Filter = confpath;

            appsettingsWatcher.NotifyFilter = NotifyFilters.LastWrite
                                 | NotifyFilters.Security
                                 | NotifyFilters.Size;

            appsettingsWatcher.Changed += internalOnChanged;
            appsettingsWatcher.Created += internalOnChanged;
            appsettingsWatcher.Deleted += internalOnChanged;
            appsettingsWatcher.Renamed += internalOnChanged;
            appsettingsWatcher.Error += Error;

            appsettingsWatcher.EnableRaisingEvents = true;

            return config;
        }

        internal static void internalOnChanged(object sender, FileSystemEventArgs e)
        {
            appsettingsWatcher.EnableRaisingEvents = false;

            Load();
            Changed(sender, new ConfigChangedEventArgs(){NewConfig = config});
        }

        //I would like to just pudate the values on our held reference, but we'd have to update each value by reflection.
        //2lazy.
        public class ConfigChangedEventArgs : EventArgs
        {
            public T NewConfig;
        }
    }
}