/// <summary>
/// Use this method to send multimedia files. On success, the sent Message is returned.
/// </summary>
/// <param name="chat_id">Unique identifier for the message recipient — User or GroupChat id.</param>
/// <param name="file_path">File to send. You can upload a new file using multipart/form-data.</param>
/// <param name="type">Type of file to send.</param>
/// <param name="reply_markup">Additional interface options. A JSON-serialized object for a custom reply keyboard, instructions to hide keyboard or to force a reply from the user.</param>
/// <param name="caption">Photo caption (only use with Type.Photo).</param>
/// <param name="reply_to_message_id">If the message is a reply, ID of the original message.</param>
/// <returns></returns>
public Message SendMultimedia(int chat_id, string file_path, MultimediaType type, ReplyKeyboardHide reply_markup, string caption = null, int reply_to_message_id = -1)
{
string url = BaseUrl + "send" + type.ToString();
byte[] file = null;
using (var content = new MultipartFormDataContent("-------BotAPIDotNET"))
{
content.Add(new StringContent(string.Format("{0}", chat_id)), "chat_id");
var fileStream = File.Open(file_path, FileMode.Open, FileAccess.Read);
content.Add(new StreamContent(fileStream), type.ToString().ToLower(), file_path.Replace("\\", "/").Split('/').LastOrDefault());
if (!string.IsNullOrEmpty(caption) && type == MultimediaType.Photo)
content.Add(new StringContent(caption), "caption");
if (reply_to_message_id != -1)
content.Add(new StringContent(string.Format("{0}", reply_to_message_id)), "reply_to_message_id");
if (reply_markup != null)
content.Add(new StringContent(JsonConvert.SerializeObject(reply_markup, Formatting.None)), "reply_markup");
Stream multipart = content.ReadAsStreamAsync().Result;
file = new byte[multipart.Length];
multipart.Seek(0, SeekOrigin.Begin);
multipart.Read(file, 0, (int)multipart.Length);
}
var request = (HttpWebRequest)WebRequest.Create(url);
request.ContentType = "multipart/form-data; boundary=\"-------BotAPIDotNET\"";
request.Method = "POST";
using (Stream writer = request.GetRequestStream())
{
writer.Write(file, 0, file.Length);
}
var response = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
return ParseResponseMessage(responseString);
}