Spotify.NET/SpotifyAPI/Local/SpotifyLocalAPI.cs

using System;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using System.Timers;
using SpotifyAPI.Local.Models;

namespace SpotifyAPI.Local
{
    public class SpotifyLocalAPI
    {
        [DllImport("user32.dll")]
        private static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, int dwExtraInfo);
        [DllImport("nircmd.dll")]
        private static extern bool DoNirCmd(String nirCmdStr);

        private bool _listenForEvents;
        public bool ListenForEvents
        {
            get
            {
                return _listenForEvents;
            }
            set
            {
                _listenForEvents = value;
                _eventTimer.Enabled = value;
            }
        }

        private ISynchronizeInvoke _synchronizingObject;
        public ISynchronizeInvoke SynchronizingObject
        {
            get
            {
                return _synchronizingObject;
            }
            set
            {
                _synchronizingObject = value;
                _eventTimer.SynchronizingObject = value;
            }
        }

        const byte VkMediaNextTrack = 0xb0;
        const byte VkMediaPrevTrack = 0xb1;
        const int KeyeventfExtendedkey = 0x1;
        const int KeyeventfKeyup = 0x2;

        readonly RemoteHandler _rh;
        private readonly Timer _eventTimer;
        private StatusResponse _eventStatusResponse;

        public delegate void TrackChangeEventHandler(TrackChangeEventArgs e);
        public delegate void PlayStateEventHandler(PlayStateEventArgs e);
        public delegate void VolumeChangeEventHandler(VolumeChangeEventArgs e);
        public delegate void TrackTimeChangeEventHandler(TrackTimeChangeEventArgs e);
        public event TrackChangeEventHandler OnTrackChange;
        public event PlayStateEventHandler OnPlayStateChange;
        public event VolumeChangeEventHandler OnVolumeChange;
        public event TrackTimeChangeEventHandler OnTrackTimeChange;

        public SpotifyLocalAPI()
        {
            _rh = new RemoteHandler();

            _eventTimer = new Timer
            {
                Interval = 50,
                AutoReset = false,
                Enabled = false
            };
            _eventTimer.Elapsed += ElapsedTick;
        }

        private void ElapsedTick(object sender, ElapsedEventArgs e)
        {
            if (_eventStatusResponse == null)
            {
                _eventStatusResponse = GetStatus();
                _eventTimer.Start();
                return;
            }
            StatusResponse newStatusResponse = GetStatus();
            if (newStatusResponse == null)
            {
                _eventTimer.Start();
                return;
            }
            if (!newStatusResponse.Running && newStatusResponse.Track == null)
            {
                _eventTimer.Start();
                return;
            }
            if (newStatusResponse.Track != null && _eventStatusResponse.Track != null)
            {
                if (newStatusResponse.Track.TrackResource?.Name != _eventStatusResponse.Track.TrackResource?.Name)
                {
                    OnTrackChange?.Invoke(new TrackChangeEventArgs()
                    {
                        OldTrack = _eventStatusResponse.Track,
                        NewTrack = newStatusResponse.Track
                    });
                }
            }
            if (newStatusResponse.Playing != _eventStatusResponse.Playing)
            {
                OnPlayStateChange?.Invoke(new PlayStateEventArgs()
                {
                    Playing = newStatusResponse.Playing
                });
            }
            if (newStatusResponse.Volume != _eventStatusResponse.Volume)
            {
                OnVolumeChange?.Invoke(new VolumeChangeEventArgs()
                {
                    OldVolume = _eventStatusResponse.Volume,
                    NewVolume = newStatusResponse.Volume
                });
            }
            if (newStatusResponse.PlayingPosition != _eventStatusResponse.PlayingPosition)
            {
                OnTrackTimeChange?.Invoke(new TrackTimeChangeEventArgs()
                {
                    TrackTime = newStatusResponse.PlayingPosition
                });
            }
            _eventStatusResponse = newStatusResponse;
            _eventTimer.Start();
        }

        /// <summary>
        /// Connects with Spotify. Needs to be called before all other SpotifyAPI functions
        /// </summary>
        /// <returns>Returns true, if it was successful, false if not</returns>
        public Boolean Connect()
        {
            return _rh.Init();
        }

        public StatusResponse GetStatus()
        {
            return _rh.GetNewStatus();
        }

        public void Mute()
        {
            if (File.Exists("nircmd.dll"))
                DoNirCmd("muteappvolume spotify.exe 1");
        }

        /// <summary>
        /// Unmutes Spotify (Requires nircmd.dll)
        /// </summary>
        public void UnMute()
        {
            if (File.Exists("nircmd.dll"))
                DoNirCmd("muteappvolume spotify.exe 0");
        }

        /// <summary>
        /// Pause function
        /// </summary>
        public void Pause()
        {
            _rh.SendPauseRequest();
        }

        /// <summary>
        /// Play function
        /// </summary>
        public void Play()
        {
            _rh.SendPlayRequest();
        }

        /// <summary>
        /// Simulates a KeyPress
        /// </summary>
        /// <param name="keyCode">The keycode for the represented Key</param>
        internal void PressKey(byte keyCode)
        {
            keybd_event(keyCode, 0x45, KeyeventfExtendedkey, 0);
            keybd_event(keyCode, 0x45, KeyeventfExtendedkey | KeyeventfKeyup, 0);
        }

        /// <summary>
        /// Plays a Spotify URI within an optional context.
        /// </summary>
        /// <param name="uri">The Spotify URI</param>
        /// <param name="context">The context in which to play the specified <paramref name="uri"/>. </param>
        /// <remarks>
        /// Contexts are basically a queue in spotify. a song can be played within a context, meaning that hitting next / previous would lead to another song. Contexts are leveraged by widgets as described in the "Multiple tracks player" section of the following documentation page: https://developer.spotify.com/technologies/widgets/spotify-play-button/
        /// </remarks>
        public void PlayURL(String uri, String context = "")
        {
            _rh.SendPlayRequest(uri, context);
        }

        /// <summary>
        /// Adds a Spotify URI to the Queue
        /// </summary>
        /// <param name="uri">The Spotify URI</param>
        [Obsolete("This method doesn't work with the current spotify version.")]
        public void AddToQueue(String uri)
        {
            _rh.SendQueueRequest(uri);
        }

        /// <summary>
        /// Skips the current song (Using keypress simulation)
        /// </summary>
        public void Skip()
        {
            PressKey(VkMediaNextTrack);
        }

        /// <summary>
        /// Emulates the "Previous" Key (Using keypress simulation)
        /// </summary>
        public void Previous()
        {
            PressKey(VkMediaPrevTrack);
        }

        /// <summary>
        /// Checks if Spotify is running
        /// </summary>
        /// <returns>True, if it's running, false if not</returns>
        public static Boolean IsSpotifyRunning()
        {
            return Process.GetProcessesByName("spotify").Length >= 1;
        }

        /// <summary>
        /// Checks if Spotify's WebHelper is running (Needed for API Calls)
        /// </summary>
        /// <returns>True, if it's running, false if not</returns>
        public static Boolean IsSpotifyWebHelperRunning()
        {
            return Process.GetProcessesByName("spotifywebhelper").Length >= 1;
        }

        /// <summary>
        /// Runs Spotify
        /// </summary>
        public static void RunSpotify()
        {
            if (!IsSpotifyRunning()) 
                Process.Start(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), @"spotify\spotify.exe"));
        }

        /// <summary>
        /// Runs Spotify's WebHelper
        /// </summary>
        public static void RunSpotifyWebHelper()
        {
            if (!IsSpotifyWebHelperRunning())
                Process.Start(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), @"spotify\data\spotifywebhelper.exe"));
        }
    }
}