{-| Client functionality for the <http://wiki.ros.org/ROS/Master_API ROS Master API>
-}
module Ros.Graph.Master where
import Network.XmlRpc.Client
import Ros.Internal.RosTypes
import Ros.Service.ServiceTypes
import Network.XmlRpc.Internals (fromValue, toValue)
import Control.Monad.Except (ExceptT(..), runExceptT)
import System.IO.Error (catchIOError)

-- |Subscribe the caller to the specified topic. In addition to
-- receiving a list of current publishers, the subscriber will also
-- receive notifications of new publishers via the publisherUpdate
-- API. Takes the URI of the master, the caller_id, the topic name,
-- the topic type (must be a package-resource name, i.e. the .msg
-- name), and the API URI of the subscriber to register (used for new
-- publisher notifications). Returns a list of XML-RPC API URIs for
-- nodes currently publishing the specified topic.
registerSubscriber :: URI -> String -> TopicName -> TopicType -> String -> 
                      IO (Int, String, [String])
registerSubscriber = flip remote "registerSubscriber"

-- |Unregister the caller as a subscriber of the topic. Takes the URI
-- of the master, the caller_id, the topic name, and the API URI of
-- the subscriber to unregister. Returns zero if the caller was not
-- registered as a subscriber.
unregisterSubscriber :: URI -> String -> TopicName -> String -> 
                        IO (Int, String, Int)
unregisterSubscriber = flip remote "unregisterSubscriber"

-- |Register the caller as a publisher the topic. Takes the URI of the
-- master, the caller_id, the topic name, the topic type (must be a
-- package-resource name, i.e. the .msg name), and the API URI of the
-- publisher to register. Returns a list of the XML-RPC URIs of
-- current subscribers of the topic.
registerPublisher :: URI -> String -> TopicName -> TopicType -> String -> 
                     IO (Int, String, [String])
registerPublisher = flip remote "registerPublisher"

-- |Unregister the caller as a publisher of the topic. Takes the URI of
-- the master, caller_id, the topic name, and the API URI of the
-- publisher to unregister. Returns zero if the caller was not
-- registered as a publisher.
unregisterPublisher :: URI -> String -> TopicName -> String -> 
                       IO (Int, String, Int)
unregisterPublisher = flip remote "unregisterPublisher"

-- |@lookupService u s1 s2@ where @u@ is the URI of the ROS master, @s1@ is the ROS caller ID, and @s2@ is the ROS fully-qualified name of the service
--
-- In the result tuple @(code, statusMessage, serviceUrl)@, @code@ should be 1 upon a sucessful call. If @code@ is not 1 then @statusMessage@ may contain an error message. The host name and port of the service can be extracted from the @serviceUrl@
--
lookupService :: URI -> String -> ServiceName -> ExceptT ServiceResponseExcept IO (Int, String, String)
lookupService u s1 s2 = ExceptT . (flip catchIOError) handler $ do
  let res = call u "lookupService" (fmap toValue [s1, s2]) >>= fromValue
  err <- runExceptT res
  return $ case err of
    Left x -> Left $ MasterExcept $ "Could not look up service with master. Got message: " ++ x
    Right y -> Right y
  where
    handler x =  return . Left . MasterExcept $
                 "Could not look up service with master. Is the ROS master (roscore) running? Got exception: " ++ show x

-- | ROS API: registerService(caller_id, service, service_api, caller_api)
-- Register the caller as a provider of the specified service.
-- Parameters
-- caller_id (str)
-- ROS caller ID
-- service (str)
-- Fully-qualified name of service
-- service_api (str)
-- ROSRPC Service URI
-- caller_api (str)
-- XML-RPC URI of caller node
-- Returns (int, str, int)
-- (code, statusMessage, ignore)
registerService :: URI -> String -> ServiceName -> URI -> URI -> IO(Int, String, Int)
registerService = flip remote "registerService"


-- | ROS API: unregisterService(caller_id, service, service_api)
-- Unregister the caller as a provider of the specified service.
-- Parameters
-- caller_id (str)
-- ROS caller ID
-- service (str)
-- Fully-qualified name of service
-- service_api (str)
-- API URI of service to unregister. Unregistration will only occur if current registration matches.
-- Returns (int, str, int)
-- (code, statusMessage, numUnregistered).
-- Number of unregistrations (either 0 or 1). If this is zero it means that the caller was not registered as a service provider. The call still succeeds as the intended final state is reached.
unregisterService :: URI -> String -> ServiceName -> URI -> IO(Int, String, Int)
unregisterService = flip remote "unregisterService"