ニコニコ動画の動画をダウンロードする

エコノミー症候群なんでlowならlow消えるまでdl待つとかやりたいがために作った。

WebClient.Downloadつ使いたかったけど。とりあえずこんなもんで。汎用性一切なし的な何か。

ポイントはhttp://flapi.nicovideo.jp/api/getflvとかhttp://ext.nicovideo.jp/api/getthumbinfoで情報が取れる。
ビデオのURLだけでなくて動画ページにアクセスしないといけない。
アクセスしたらすぐダウンロードしないといけない。

enum Mode {
	None,
	High,
	Low,
}

class ProgressionArgs : EventArgs {
	public long DownloadedSize { get; set; }
	public long VideoSize { get; set; }
	public string Title { get; set; }
	public Mode Mode { get; set; }

	public ProgressionArgs() {
	}
}

class Niconico {
	private static readonly Encoding _niconicoEncode = Encoding.UTF8;
	private readonly CookieContainer _cookie = new CookieContainer();

	public event EventHandler<ProgressionArgs> Progression;
	public event EventHandler<ProgressionArgs> Completed;

	public Niconico() {
	}

	string SecureStringToString( SecureString secureString ) {
		var pointer = IntPtr.Zero;

		try {
			var buffer = new char[secureString.Length];

			pointer = Marshal.SecureStringToCoTaskMemUnicode( secureString );
			Marshal.Copy( pointer, buffer, 0, buffer.Length );

			return new string( buffer );
		} finally {
			if ( pointer != IntPtr.Zero ) {
				Marshal.ZeroFreeCoTaskMemUnicode( pointer );
			}
		}
	}

	public void Login( string mail, SecureString password ) {
		var req = (HttpWebRequest)WebRequest.Create( "https://secure.nicovideo.jp/secure/login?site=niconico" );
		req.ContentType = "application/x-www-form-urlencoded";
		req.Method = "POST";
		req.CookieContainer = _cookie;

		var buff = _niconicoEncode.GetBytes( string.Format( "mail={0}&password={1}", mail, SecureStringToString( password ) ) );
		req.ContentLength = buff.Length;
		using ( var stream = req.GetRequestStream() ) {
			stream.Write( buff, 0, buff.Length );
		}

		req.GetResponse().Close();
		if ( _cookie.Count == 0 ) {
			throw new Exception( "ログインエラー" );
		}
	}

	public bool Recode( string url, string path ) {
		return Recode( url, path, false );
	}

	public bool Recode( string url, string path, bool allowedLowMode ) {
		var thumbInfo = GetThumbInfo( url );
		var videoInfo = GetFlv( url );
		var progression = new ProgressionArgs() { Title = thumbInfo["title"] };
		progression.Mode = GetMode( videoInfo["url"] );

		if ( !videoInfo.ContainsKey( "url" ) || ( progression.Mode == Mode.Low && !allowedLowMode ) ) {
			return false;
		}

		RequestPage( url );

		var req = (HttpWebRequest)WebRequest.Create( videoInfo["url"] );
		req.CookieContainer = _cookie;

		FillVideoSize( progression, thumbInfo );

		using ( var stream = req.GetResponse().GetResponseStream() ) {
			var fileName = thumbInfo["title"];
			Array.ForEach( Path.GetInvalidFileNameChars(), c => fileName = fileName.Replace( c.ToString(), "" ) );
			Path.GetInvalidFileNameChars().ForEach( c => fileName = fileName.Replace( c.ToString(), "" ) );

			var filePath = Path.Combine( path, fileName );

			Save( stream, filePath, progression );
		}
		return true;
	}

	private static void FillVideoSize( ProgressionArgs progression, Dictionary<string, string> thumbInfo ) {
		var size = thumbInfo["size_high"];
		if ( progression.Mode == Mode.Low ) {
			size = thumbInfo["size_low"];
		}

		progression.VideoSize = long.Parse( size );
	}

	void RequestPage( string url ) {
		var req = (HttpWebRequest)WebRequest.Create( url );
		req.CookieContainer = _cookie;
		req.GetResponse().Close();
		return;
	}

	private static Mode GetMode( string videoUrl ) {
		return videoUrl.ToLower().EndsWith( "low" ) ? Mode.Low : Mode.High;
	}

	private void Save( Stream stream, string filePath, ProgressionArgs videoInfo ) {
		long buffSize = Math.Min( videoInfo.VideoSize, 1024 * 1024 );

		byte[] buff = new byte[buffSize];
		var readSize = stream.Read( buff, 0, 3 );
		if ( buff[0] == 'F' && buff[1] == 'L' && buff[2] == 'V' ) {
			filePath += ".flv";
		} else {
			filePath += ".mp4";
		}
		var tempFilePath = Path.GetTempFileName();

		long totalReadSize = readSize;
		using ( var outStream = File.OpenWrite( tempFilePath ) ) {
			outStream.Write( buff, 0, 3 );
			while ( readSize != 0 ) {
				readSize = stream.Read( buff, 0, buff.Length );
				outStream.Write( buff, 0, readSize );

				totalReadSize += readSize;
				videoInfo.DownloadedSize = totalReadSize;

				OnProgression( videoInfo );
			}
		}

		if ( File.Exists( filePath ) ) {
			File.Delete( filePath );
		}
		File.Move( tempFilePath, filePath );
	}

	private Dictionary<string, string> GetThumbInfo( string url ) {
		var number = url.Split( '/' ).GetLastContents().Split( '?' )[0];
		var req = (HttpWebRequest)WebRequest.Create( "http://ext.nicovideo.jp/api/getthumbinfo/" + number );
		req.CookieContainer = _cookie;
		var resText = req.GetResponse().ReadToEnd( _niconicoEncode );

		var webData = new Dictionary<string, string>();
		var xml = new XmlDocument();
		xml.LoadXml( resText );

		webData.Add( "title", xml.GetElementsByTagName( "title" )[0].InnerText );
		webData.Add( "size_high", xml.GetElementsByTagName( "size_high" )[0].InnerText );
		webData.Add( "size_low", xml.GetElementsByTagName( "size_low" )[0].InnerText );

		return webData;
	}

	private Dictionary<string, string> GetFlv( string url ) {
		var number = url.Split( '/' ).GetLastContents().Split( '?' )[0];
		var req = (HttpWebRequest)WebRequest.Create( "http://flapi.nicovideo.jp/api/getflv/" + number );
		req.CookieContainer = _cookie;
		var resText = req.GetResponse().ReadToEnd( _niconicoEncode );
		return ConvertDic( resText );
	}

	static Dictionary<string, string> ConvertDic( string source ) {
		var webData = new Dictionary<string, string>();
		foreach ( var item in source.Split( '&' ) ) {
			var values = item.Split( '=' );
			webData.Add( values[0], Uri.UnescapeDataString( values[1] ) );
		}
		return webData;
	}

	protected void OnProgression( ProgressionArgs progressionArgs ) {
		if ( Progression != null ) {
			Progression( this, progressionArgs );
		}
	}

	protected void OnCompleted( ProgressionArgs progressionArgs ) {
		if ( Completed != null ) {
			Completed( this, progressionArgs );
		}
	}
}

static class Extentions {
	static public T GetLastContents<T>( this T[] array ) {
		return array[array.Length - 1];
	}

	static public void ForEach<T>( this T[] array, Action<T> action ) {
		Array.ForEach( array, action );
	}

	static public string ReadToEnd( this WebResponse response, Encoding encoding ) {
		using ( var reader = new StreamReader( response.GetResponseStream(), encoding ) ) {
			return reader.ReadToEnd();
		}
	}

	static public string ReadToEnd( this WebResponse response ) {
		using ( var reader = new StreamReader( response.GetResponseStream(), Encoding.UTF8 ) ) {
			return reader.ReadToEnd();
		}
	}
}

リテラルがどうこうとか昔言ってた気がするけど、ここまで小さいプログラムでこれほど大量のリテラルがあるとめんどうだし、可読性もあまり問題にならんとか思うけど。
constでわけるならそれだけじゃ意味があまりなくて、プロバイダとかで処理すら分けないとロジック＋リテラルって部分も多いわけで