using log4net;
using System;
using System.Web;
using System.Security.Cryptography;
using System.Web.Security;
using System.Xml;
using System.Net;
using System.Net.Cache;
using System.IO;

// Do-what-you-want license.
namespace BBB.Web
{
	public class BBBAPI
	{
		// This is the security salt that must match the value set in the BigBlueButton server
		string salt = "...";
	
		// This is the URL for the BigBlueButton server		
		string BigBlueButtonURL = "http://...";

        log4net.ILog logger = log4net.LogManager.GetLogger("bbb.web");		
		
		public BBBAPI ()
		{
		}
	
		
		//
		// Create a meeting with specific 
		//    - meetingID
		//    - welcome message
		//    - moderator password
		//    - viewer password
		//    - voiceBridge
		//    - logoutURL
		//
		public string createMeeting(string meetingID, string welcome, string moderatorPassword, string viewerPassword, int voiceBridge, string logoutURL) {
			string base_url_create = BigBlueButtonURL + "api/create?";
			string base_url_join = BigBlueButtonURL + "api/join?";
			
			string welcome_param = "";
			string checksum = "";
			
			string attendee_password_param = "&attendeePW=ap";
			string moderator_password_param = "&moderatorPW=mp";
			string voice_bridge_param = "";
			string logoutURL_param = "";
			
			if ( (welcome != null) && ! welcome.Equals("")) {
				welcome_param = "&welcome=" + urlEncode(welcome);
			}
			
			if ( (moderatorPassword != null) && ! moderatorPassword.Equals("")) {
				moderator_password_param = "&moderatorPW=" + urlEncode(moderatorPassword);
			} 
			
			if ( (viewerPassword != null) && ! viewerPassword.Equals("")) {
				attendee_password_param = "&attendeePW=" + urlEncode(viewerPassword);
			}
			
			if ( voiceBridge > 0 ) {
				voice_bridge_param = "&voiceBridge=" + urlEncode(voiceBridge + "");
			} else {
				// No voice bridge number passed, so we'll generate a random one for this meeting
				int n = 70000 + (new Random()).Next(9999);
				voice_bridge_param = "&voiceBridge=" + n;
			}	
		
			if ( (logoutURL != null) && ! logoutURL.Equals("")) {
				logoutURL_param = "&logoutURL=" + urlEncode(logoutURL);
			}
			
			//
			// Now create the URL
			//
		
			string create_parameters = "name=" + urlEncode(meetingID) + "&meetingID=" + urlEncode(meetingID)
			+ welcome_param + attendee_password_param + moderator_password_param + voice_bridge_param + logoutURL_param;
		
			XmlDocument doc = null;
		
			try {
				// Attempt to create a meeting using meetingID
				string xml = getURL(base_url_create + create_parameters + "&checksum=" + Checksum(create_parameters + salt) );
				doc = parseXml(xml);		
			} catch (Exception e) {
				logger.Debug(e.Message);
			}
		
			if (doc.GetElementsByTagName("returncode").Item(0).InnerText
					.Trim().Equals("SUCCESS")) {
		
				string meetingToken = "";
		
				if (doc.GetElementsByTagName("meetingToken").Item(0) != null) {
					return doc.GetElementsByTagName("meetingToken").Item(0)
							.InnerText.Trim();
				}
			}
			
			return "Error " + doc.GetElementsByTagName("messageKey").Item(0).InnerText.Trim() 
			+ ": " + doc.GetElementsByTagName("message").Item(0).InnerText.Trim();
		}		
		
		//
		// isMeetingRunning() -- check the BigBlueButton server to see if the meeting is running (i.e. there is someone in the meeting)
		//
		public String isMeetingRunning(string meetingToken, string meetingID) {
			string base_main = "meetingToken=" + meetingToken + "&meetingID=" + urlEncode(meetingID);
			string base_url = BigBlueButtonURL + "api/isMeetingRunning?";
			string checksum ="";
			
			try {
				checksum = FormsAuthentication.HashPasswordForStoringInConfigFile(base_main + salt, "sha1");
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
			}
			
			string xml = getURL(base_url + base_main + "&checksum=" + checksum);
	
			XmlDocument doc = null;
			try {
				doc = parseXml(xml);
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
			}
	
			if (doc.GetElementsByTagName("returncode").Item(0).InnerText.Trim().Equals("SUCCESS") ){
				return doc.GetElementsByTagName("running").Item(0).InnerText.Trim();
			}
			
			return  "false";
			
		}		

		//
		// getURLisMeetingRunning() -- return a URL that the client can use to poll for whether the given meeting is running
		//
		public string getURLisMeetingRunning(string meetingToken, string meetingID) {
			string base_main = "meetingToken=" + meetingToken + "&meetingID=" + urlEncode(meetingID);
			string base_url = BigBlueButtonURL + "api/isMeetingRunning?";
			string checksum = "";
			
			try {
				checksum = FormsAuthentication.HashPasswordForStoringInConfigFile(base_main + salt, "sha1");
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
			}
			
			return base_url + base_main + "&checksum=" + checksum;
		}		

		//
		// getJoinMeetingURL() -- get join meeting URL for both viewer and moderator
		//
		public string getJoinMeetingURL(string username, string meetingToken, string password) {
			string base_url_join = BigBlueButtonURL + "api/join?";
			string join_parameters = "meetingToken=" + meetingToken + "&fullName=" + urlEncode(username)
			+ "&password=" + urlEncode(password);
		
			return base_url_join + join_parameters + "&checksum=" + Checksum(join_parameters + salt);
		}
		
		// 
		// Create a meeting and return a URL to join it as moderator
		//
		public string getJoinURL(string username, string meetingID, string welcome) {
				string base_url_create = BigBlueButtonURL + "api/create?";
				string base_url_join = BigBlueButtonURL + "api/join?";
				
				string welcome_param = "";
				string checksum = "";
				
				int voiceBridge = 7000 + new Random().Next(9999);
				
				if ( (welcome != null) && ! welcome.Equals("")) {
					welcome_param = "&welcome=" + urlEncode(welcome);
				}
				
				//
				// When creating a meeting, the 'name' parameter is the name of the meeting (not to be confused with
				// the username).  For example, the name could be "Fred's meeting" and the meetingID could be "ID-1234312".
				//
				// While name and meetinID could be different, we'll keep them the same.  Why?  Because calling api/create? 
				// with a previously used meetingID will return same meetingToken (regardless if the meeting is running or not).
				//
				// This means the first person to call getJoinURL with meetingID="Demo Meeting" will actually create the
				// meeting.  Subsequent calls will return the same meetingToken and thus subsequent users will join the same
				// meeting.
				//
				// Note: We're hard-coding the password for moderator and attendee (viewer) for purposes of demo.
				//
		
				string create_parameters = "name=" + urlEncode(meetingID) + "&meetingID=" + urlEncode(meetingID)
				+ welcome_param + "&attendeePW=ap&moderatorPW=mp&voiceBridge="+voiceBridge;
		
				XmlDocument doc = null;
		
				try {
					// Attempt to create a meeting using meetingID
					string xml = getURL(base_url_create + create_parameters + "&checksum=" + Checksum(create_parameters + salt) );
					doc = parseXml(xml);		
				} catch (Exception e) {
					logger.Debug(e.Message);
				}
		
				if (doc.GetElementsByTagName("returncode").Item(0).InnerText.Trim().Equals("SUCCESS")) {
		
					string meetingToken = "";
		
					if (doc.GetElementsByTagName("meetingToken").Item(0) != null) {
						meetingToken = doc.GetElementsByTagName("meetingToken").Item(0).InnerText.Trim();
					}
		
					//
					// Now create a URL to join that meeting
					//
					string join_parameters = "meetingToken=" + meetingToken + "&fullName=" + urlEncode(username)
							+ "&password=mp";
		
					return base_url_join + join_parameters + "&checksum=" + Checksum(join_parameters + salt);
		
				}
				return doc.GetElementsByTagName("messageKey").Item(0).InnerText.Trim() 
				+ ": " + doc.GetElementsByTagName("message").Item(0).InnerText.Trim();
			}

		//
		// getJoinURLViewer() -- Get the URL to join a meeting as viewer
		//
		public string getJoinURLViewer(string username, string meetingToken) {			
			string base_url_join = BigBlueButtonURL + "api/join?";
			string join_parameters = "meetingToken=" + meetingToken + "&fullName=" + urlEncode(username)
			+ "&password=ap";
			
			return base_url_join + join_parameters + "&checksum=" + Checksum(join_parameters + salt);
		}
		
		//
		// checksum() -- create a hash based on the shared salt (located in bbb_api_conf.jsp)
		//
		public static string Checksum(string s) {
			string checksum = "";
			try {
				checksum = FormsAuthentication.HashPasswordForStoringInConfigFile(s, "SHA1");
				checksum = checksum.ToLower(); // BBB is case sensitive here.
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
			}
			return checksum;
		}	
		
		//
		// getURL() -- fetch a URL and return its contents as a string
		//
		public static string getURL(string url) {
			HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(url));
			request.CachePolicy = new HttpRequestCachePolicy(System.Net.Cache.HttpRequestCacheLevel.NoCacheNoStore);
			request.Method = "GET";
			
			HttpWebResponse response = (HttpWebResponse)request.GetResponse();
			if( response.StatusCode.Equals(HttpStatusCode.OK) ) {
				StreamReader input = new StreamReader(response.GetResponseStream());
				return input.ReadToEnd();
			}
			
			return "";
		}
				
		public string getMeetingInfoURL(string meetingID, string password) {
			string meetingParameters = "meetingID=" + urlEncode(meetingID) + "&password=" + password;
			return BigBlueButtonURL + "api/getMeetingInfo?" + meetingParameters + "&checksum=" + Checksum(meetingParameters + salt);
		}		

		public string getMeetingsURL() {
			string meetingParameters = "random=" + new Random().Next(9999);
			return BigBlueButtonURL + "api/getMeetings?" + meetingParameters + "&checksum=" + Checksum(meetingParameters + salt);
		}
		
		public string getMeetingInfo(string meetingID, string password) {
			try {
				HttpWebRequest hpCon = (HttpWebRequest)HttpWebRequest.Create(getMeetingInfoURL(meetingID, password));

				string data = (new StreamReader(hpCon.GetResponse().GetResponseStream())).ReadToEnd();
				return data;
			} catch (Exception e) {
				logger.Debug(e.Message);
				return "";
			}
		}		

		//
		// urlEncode() -- URL encode the string
		//
		public static string urlEncode(string s) {	
			try {
				return HttpUtility.UrlEncode(s);
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
			}
			return "";
		}			
		
		//
		// parseXml() -- return a DOM of the XML
		//
		public static XmlDocument parseXml(string xml) {
			XmlDocument doc = new XmlDocument();
			doc.LoadXml(xml);
			return doc;
		}			
		
		//
		// Calls getMeetings to obtain the list of meetings, then calls getMeetingInfo for each meeting
		// and concatenates the result.
		//
		public string getMeetings() {
			try {
				
				// Call the API and get the result
				HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(getMeetingsURL());
				string data = (new StreamReader(request.GetResponse().GetResponseStream())).ReadToEnd();
				XmlDocument doc = parseXml(data);
				
				// tags needed for parsing xml documents
				const string startTag = "<meetings>";
				const string endTag = "</meetings>";
				const string startResponse = "<response>";
				const string endResponse = "</response>";
				
				// if the request succeeded, then calculate the checksum of each meeting and insert it into the document
				XmlNodeList meetingsList = doc.GetElementsByTagName("meeting");
				
				string newXMldocument = startTag;
				foreach(XmlElement element in meetingsList) {
					string meetingID = element.GetElementsByTagName("meetingID")[0].InnerText;
					string password = element.GetElementsByTagName("moderatorPW")[0].InnerText;
					
					data = getMeetingInfoURL(meetingID, password);
					
					if( data.IndexOf("<response>") != -1) {
						int startIndex = data.IndexOf(startResponse) + startTag.Length;
						int endIndex = data.IndexOf(endResponse);
						
						newXMldocument += "<meeting>" + data.Substring(startIndex, endIndex) + "</meeting>";
					}
				}
				newXMldocument += endTag;
				
				return newXMldocument;
			} catch (Exception e) {
				log4net.LogManager.GetLogger("bbb.web").Debug(e.StackTrace);
				return null;
			}
		}		
	}
}