Wallpaper Changer

settings.json

{
  "TTW_Max": 120,
  "TTW_Min": 10,
  "PicturesFolder": "<<Pictures Directory>>",
}

Wallpaperchanger.cs

using Microsoft.Win32;
using Newtonsoft.Json.Linq;
using System;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Threading;

namespace Wallpaperchanger
{
    class WallpaperSetter
    {
        const int SetDeskWallpaper = 20;
        const int UpdateIniFile = 0x01;
        const int SendWinIniChange = 0x02;
        int TTW_MIN;
        int TTW_MAX;
        Random random;
        string filelocation;
        String currentfile = "";

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int SystemParametersInfo(int uAction, int uParam, string lpvParam, int fuWinIni);

        public WallpaperSetter()
        {
            random = new Random();
            getJSONSettings();
        }


        public void SetWallpaper(String file)
        {
            if (File.Exists(file))
            {
                //set new Wallpaper
                RegistryKey key = Registry.CurrentUser.OpenSubKey(@"Control Panel\Desktop", true);
                SystemParametersInfo(SetDeskWallpaper, 0, file, UpdateIniFile | SendWinIniChange);
            }
        }

        public void startTask()
        {
            while (true)
            {
                wait(); //waits before a new wallpaper is set
                getJSONSettings(); //sets the new json settings
                SetWallpaper(getRandomFile()); //sets the new wallpaper
            }
        }

        public String getRandomFile()
        {
            if (Directory.Exists(filelocation)) //check if filelocation exists
            {
                String[] files = Directory.GetFileSystemEntries(filelocation,"*.jpg"); //get all files from the location
                String selectedFile = files[random.Next(0, files.Length)]; //gets a random file from the location
                if(currentfile.Equals(selectedFile) && files.Length > 1) //checks if the currently selected file is the same as the random
                {
                    return getRandomFile(); //calls the Method again to get a new random file
                }
                currentfile = selectedFile; //sets the current file to the newly selected one
                return selectedFile; //returns the file
            }else
            {
                return "";
            }
        }

        public int getRandomWaitTime()
        {
            return random.Next(TTW_MIN, TTW_MAX); //gets a random time based on the settings in the settings file
        }

        private void wait()
        {
            Thread.Sleep(1000 * 60 * getRandomWaitTime()); //waits a random time
        }

        private void getJSONSettings()
        {
            String currentDirectory = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location); //gets the path of the current directory
            String jsonpath = currentDirectory + "\\settings.json"; //gets the path to the settingsfile

            if (File.Exists(jsonpath)) //checks if the settings file exists
            {
                JObject settingsjson = JObject.Parse(File.ReadAllText(@"" + jsonpath)); //gets the jsonobject from the settingsfile
                TTW_MIN = settingsjson.GetValue("TTW_Min").Value<int>(); //sets the waittime minimum
                TTW_MAX = settingsjson.GetValue("TTW_Max").Value<int>(); //sets the waittime maximum
                filelocation = Path.Combine(currentDirectory, settingsjson.GetValue("PicturesFolder").Value<String>()); //gets the path to the picturesFolder
            }
        }
    }
}