import "R/R" as R

import "Simantics/DB"
import "http://www.simantics.org/R-1.0" as ROntology
import "http://www.simantics.org/Layer0-1.1" as L0

"""Creates a new session configuration to graph as a part of the parent resource. This function does
not link it to any other resources."""
createSessionConfiguration :: Resource -> R.SessionConfiguration -> <WriteGraph> Resource
createSessionConfiguration parent (R.SessionConfiguration host port username password) = do 
    r = newResource ()
    claim r L0.InstanceOf ROntology.SessionConfiguration
    claim r L0.PartOf parent
    sessionName = host + "-" + show port
    claimRelatedValue r L0.HasName sessionName
    claimRelatedValue r ROntology.SessionConfiguration.host host
    claimRelatedValue r ROntology.SessionConfiguration.port port
    claimRelatedValue r ROntology.SessionConfiguration.username username
    claimRelatedValue r ROntology.SessionConfiguration.password password
    r

"""Add an R script into the session configuration resource. The script is executed when a new session is opened with the createSession function."""
addScript :: Resource -> String -> <WriteGraph> Resource
addScript sessionConfiguration scriptText = do 
    r = newResource ()
    claim r L0.InstanceOf ROntology.Script
    claim sessionConfiguration ROntology.SessionConfiguration.hasScript r
    claimRelatedValue r ROntology.Script.text scriptText
    r

"""Read session configuration from the database."""
readSessionConfiguration :: Resource -> <ReadGraph> R.SessionConfiguration
readSessionConfiguration r = R.SessionConfiguration
    (relatedValue r ROntology.SessionConfiguration.host)
    (relatedValue r ROntology.SessionConfiguration.port)
    (relatedValue r ROntology.SessionConfiguration.username)
    (relatedValue r ROntology.SessionConfiguration.password)

"""Write an R session into the database."""
writeSession :: R.Session -> <WriteGraph> Resource
writeSession session = do 
    r = newResource ()
    claim r L0.InstanceOf ROntology.Session
    claimRelatedValue r L0.HasName $ R.sessionIdOf session
    r

"""Execute the scripts defined for a session configuration using the given session."""
executeScripts :: Resource -> R.Session -> <ReadGraph,Proc> ()
executeScripts configurationResource session = for (configurationResource # ROntology.SessionConfiguration.hasScript) $ \s -> do
    scriptText = relatedValue s ROntology.Script.text
    R.asyncExec session (R.evalR_ scriptText)

"""Read an R session from the database. If the session has been closed, a new session is opened with the
same configuration."""
readSession :: Resource -> <ReadGraph,Proc> R.Session
readSession r = let
    sessionId = relatedValue r L0.HasName
  in match R.sessionById sessionId with
      Just session -> session
      Nothing -> do
        configurationResource = singleObject r L0.PartOf
        session = R.getOrCreateSession (readSessionConfiguration $ configurationResource) sessionId
        executeScripts configurationResource session
        session
      
"""Create a session based on a given session configuration resource."""
createSession :: Resource -> <WriteGraph,Proc> Resource
createSession configurationResource = do
    session = R.createSession $ readSessionConfiguration configurationResource
    executeScripts configurationResource session
    sessionResource = writeSession session
    claim configurationResource L0.ConsistsOf sessionResource
    sessionResource

"""Delete a session resource and close the session that it represents."""
deleteSession :: Resource -> <WriteGraph,Proc> ()
deleteSession r = do
    session = readSession r
    R.closeSession session
    denyAllStatements r