module Handler.Graph where

import Import

import Handler.Tables
import Handler.Shared
import Data.Maybe
import Data.List ((!!))
import Database.Persist.Sql

getChallengeGraphDataR :: Text -> Handler Value
getChallengeGraphDataR challengeName = submissionsToJSON (\_ -> True) challengeName

submissionsToJSON :: ((Entity Submission) -> Bool) -> Text -> Handler Value
submissionsToJSON condition challengeName = do
  (Entity challengeId _) <- runDB $ getBy404 $ UniqueName challengeName

  (_, entries) <- getLeaderboardEntriesByCriterion challengeId condition (\(TableEntry (Entity submissionId _) _ _ _ _ _) -> submissionId)

  let naturalRange = getNaturalRange entries
  let submissionIds = map leaderboardBestSubmissionId entries

  forks <- runDB $ selectList [ForkSource <-. submissionIds, ForkTarget <-. submissionIds] []

  return $ object [ "nodes" .= (Data.Maybe.catMaybes $ map (auxSubmissionToNode naturalRange) $ zip [0..] entries),
                    "edges" .= map forkToEdge forks ]

getNaturalRange :: [LeaderboardEntry] -> Double
getNaturalRange entries = 2.0 * (interQuantile $ Data.Maybe.catMaybes $ map (evaluationScore . leaderboardEvaluation) entries)

auxSubmissionToNode :: Double -> (Int, LeaderboardEntry) -> Maybe Value
auxSubmissionToNode naturalRange (n, entry) = case evaluationScore $ leaderboardEvaluation entry of
  Just score ->  Just $ object [
    "id" .= (nodeId $ leaderboardBestSubmissionId entry),
    "x"  .= (stampToX $ submissionStamp $ leaderboardBestSubmission entry),
    "y"  .= (- ((score / naturalRange) * 100.0)),
    "size" .= (2 :: Int),
    "label" .= submissionDescription (leaderboardBestSubmission entry) ]
  Nothing -> Nothing

forkToEdge :: Entity Fork -> Value
forkToEdge (Entity forkId fork) = object [
  "source" .= nodeId (forkSource fork),
  "target" .= nodeId (forkTarget fork),
  "id"     .= edgeId forkId,
  "type"   .= ["arrow" :: String]
  ]

nodeId :: Key Submission -> String
nodeId = ("n" ++) . show . fromSqlKey

edgeId :: Key Fork -> String
edgeId = ("e" ++) . show . fromSqlKey

stampToX :: UTCTime -> Integer
stampToX = toModifiedJulianDay . utctDay

-- taken from Math.Statistics

interQuantile :: (Fractional b, Ord b) => [b] -> b
interQuantile [] = 10.0
interQuantile xs = (q' - q)
    where q = quantile 0.25 xs
          q' = quantile 0.75 xs

quantile :: (Fractional b, Ord b) => Double -> [b] -> b
quantile q = quantileAsc q . sort

quantileAsc :: (Fractional b, Ord b) => Double -> [b] -> b
quantileAsc _ [] = error "x"
quantileAsc q xs
    | q < 0 || q > 1 = error "quantile out of range"
    | otherwise = xs !! (quantIndex (length xs) q)
    where quantIndex :: Int -> Double -> Int
          quantIndex len q = case round $ q * (fromIntegral len - 1) of
                               idx | idx < 0    -> error "Quantile index too small"
                                   | idx >= len -> error "Quantile index too large"
                                   | otherwise  -> idx