besterd/source/handlers/response.d

module handlers.response;

import std.json : JSONValue, JSONException, parseJSON;
import std.conv : to;
import utils.debugging : debugPrint;
import std.string : cmp;
import std.stdio : writeln;
import connection.connection;
import base.types;
import std.socket : Socket,SocketOSException;
import connection.message;

/* The type of the command the message handler wants us to run */
private enum CommandType
{
	SEND_CLIENTS, SEND_SERVERS, SEND_HANDLER
}

public final class HandlerResponse
{
	/* The message-handler's response */
	private JSONValue messageResponse;

	/* The command to be executed */
	private CommandType commandType;

	this(JSONValue messageResponse)
	{
		/* Set the message-handler's response message */
		this.messageResponse = messageResponse;

		/* Attempt parsing the message and error checking it */
		parse(messageResponse);
	}

	private void parse(JSONValue handlerResponse)
	{
		/**
		 * Handles the response sent back to the server from the
		 * message handler.
		 */

		 /* Get the status */
		 ulong statusCode;

		 /* Error? */
		 bool error;
		
		/* TODO: Bounds checking, type checking */
		try
		{
			/* Get the header block */
			JSONValue headerBlock = handlerResponse["header"];
		
			/* Get the status */
			statusCode = to!(ulong)(headerBlock["status"].str());
			debugPrint("Status code: " ~ to!(string)(statusCode));
		
			/* If the status is 0, then it is all fine */
			if(statusCode == 0)
			{
				debugPrint("Status is fine, the handler ran correctly");
						
				/* The command block */
				JSONValue commandBlock = headerBlock["command"];
						
				/**
				 * Get the command that the message handler wants the
				 * server to run.
				 */
				string serverCommand = commandBlock["type"].str;
				debugPrint("Handler->Server command: \"" ~ serverCommand ~ "\"");
						
				/* Check the command to be run */
				if(cmp(serverCommand, "sendClients") == 0)
				{
					/* Set the command type to SEND_CLIENTS */
					commandType = CommandType.SEND_CLIENTS;

					/* TODO: Error check and do accesses JSON that would be done in `.execute` */
				}
				else if(cmp(serverCommand, "sendServers") == 0)
				{
					/* Set the command type to SEND_SERVERS */
					commandType = CommandType.SEND_SERVERS;

					/* TODO: Error check and do accesses JSON that would be done in `.execute` */
				}
				else if(cmp(serverCommand, "sendHandler") == 0)
				{
					/* Set the command type to SEND_HAANDLER */
					commandType = CommandType.SEND_HANDLER;

					/* TODO: Error check and do accesses JSON that would be done in `.execute` */
				}
				else
				{
					/* TODO: Error handling */
					debugPrint("The message handler is using an invalid command");
				}
			}
			else
			{
				/* If the message handler returned a response in error */
				debugPrint("Message handler returned an error code: " ~ to!(string)(statusCode));
				error = true;
			}
		}
		catch(JSONException exception)
		{
			debugPrint("<<< There was an error handling the response message >>>\n\n" ~ exception.toString());
			error = true;
		}

		/**
		 * If an error was envountered anyway down the processing of the
		 * message-handler then raise a `ResponseError` exception.
		 */
		if(error)
		{
			throw new ResponseError(messageResponse, statusCode);
		}
	}

	public void execute(BesterConnection originalRequester)
	{
		/* TODO: Implement me */

		/* If the command is SEND_CLIENTS */
		if(commandType == CommandType.SEND_CLIENTS)
		{
			/* Get the list of clients to send to */
			string[] clients;
			JSONValue[] clientList = messageResponse["header"]["command"]["data"].array();
			for(ulong i = 0; i < clientList.length; i++)
			{
				clients ~= clientList[i].str();
			}

			debugPrint("Users wanting to send to: " ~ to!(string)(clients));

			/* Find the users that are wanting to be sent to */
			BesterConnection[] connectionList = originalRequester.server.getClients(clients);
		//	debugPrint("Users matched online on server: " ~ to!(string)(connectionList));

			/* TODO: Implement me */

			/* TODO: Construct a payload for the receiving clients */
			JSONValue clientPayload;

			JSONValue headerBlock;
			//headerBlock["handlerName"] = 
			clientPayload["header"] = 2;

			/**
			 * Loop through each BesterConnection in connectionList and
			 * send the message-handler payload response message to each
			 * of them.
			 */
			for(ulong i = 0; i < connectionList.length; i++)
			{
				/* Get the conneciton */
				BesterConnection clientConnection = connectionList[i];

				try
				{
					/* Get the client's socket */
					Socket clientSocket = clientConnection.getSocket();
					//debugPrint("IsAlive?: " ~ to!(string)(clientSocket.isAlive()));
					
					/* Send the message to the client */
					debugPrint("Sending handler's response to client \"" ~ clientConnection.toString() ~ "\"...");
					
					sendMessage(clientSocket, clientPayload);
					debugPrint("Sending handler's response to client \"" ~ clientConnection.toString() ~ "\"... [sent]");
				}
				catch(SocketOSException exception)
				{
					/**
					 * If there was an error sending to the client, this can happen
					 * if the client has disconnected but hasn't yet been removed from
					 * the connections array and hence we try to send on a dead socket
					 * or get the remoteAddress on a dead socket, which causes a
					 * SocketOSException to be called.
					 */
					 debugPrint("Attempted interacting with dead socket");
				}
			}


			debugPrint("SEND_CLIENTS: Completed run");
		}
		else if (commandType == CommandType.SEND_SERVERS)
		{
			/* Get the list of servers to send to */
			string[] servers;
			JSONValue[] serverList = messageResponse["header"]["command"]["data"].array();
			for(ulong i = 0; i < serverList.length; i++)
			{
				servers ~= serverList[i].str();
			}
													
			/* TODO: Implement me */
			writeln("Servers wanting to send to ", servers);
		}
		else if (commandType == CommandType.SEND_HANDLER)
		{
			/* Name of the handler to send the message to */
			string handler = messageResponse["header"]["command"]["data"]["handler"].str();
			debugPrint("Handler to forward to: " ~ handler);

			/* TODO: Add me */
		}
	}

	override public string toString()
	{
		return messageResponse.toPrettyString();
	}
}

public final class ResponseError : BesterException
{

	/* */

	/* The status code that resulted in the response handling error */
	private ulong statusCode;

	this(JSONValue messageResponse, ulong statusCode)
	{
		/* TODO: Set message afterwards again */
		super("");
	}
}