-- | Collect statistics.

module Agda.TypeChecking.Monad.Statistics
    ( MonadStatistics(..), tick, tickN, tickMax, getStatistics, modifyStatistics, printStatistics
    ) where

import Control.DeepSeq
import Control.Monad.Except
import Control.Monad.Reader
import Control.Monad.State
import Control.Monad.Writer
import Control.Monad.Trans.Maybe

import qualified Data.Map as Map
import qualified Text.PrettyPrint.Boxes as Boxes

import Agda.Syntax.Concrete.Name as C

import Agda.TypeChecking.Monad.Base
import Agda.TypeChecking.Monad.Debug

import Agda.Utils.Maybe
import Agda.Utils.Null
import Agda.Utils.Pretty
import Agda.Utils.String

class ReadTCState m => MonadStatistics m where
  modifyCounter :: String -> (Integer -> Integer) -> m ()

  default modifyCounter
    :: (MonadStatistics n, MonadTrans t, t n ~ m)
    =>  String -> (Integer -> Integer) -> m ()
  modifyCounter x = lift . modifyCounter x

instance MonadStatistics m => MonadStatistics (ExceptT e m)
instance MonadStatistics m => MonadStatistics (MaybeT m)
instance MonadStatistics m => MonadStatistics (ReaderT r m)
instance MonadStatistics m => MonadStatistics (StateT  s m)
instance (MonadStatistics m, Monoid w) => MonadStatistics (WriterT w m)

instance MonadStatistics TCM where
  modifyCounter x f = modifyStatistics $ force . update
    where
      -- We need to be strict in the map.
      -- Andreas, 2014-03-22:  Could we take Data.Map.Strict instead of this hack?
      -- Or force the map by looking up the very element we inserted?
      -- force m = Map.lookup x m `seq` m
      -- Or use insertLookupWithKey?
      -- update m = old `seq` m' where
      --   (old, m') = Map.insertLookupWithKey (\ _ new old -> f old) x dummy m
      -- Ulf, 2018-04-10: Neither of these approaches are strict enough in the
      -- map (nor are they less hacky). It's not enough to be strict in the
      -- values stored in the map, we also need to be strict in the *structure*
      -- of the map. A less hacky solution is to deepseq the map.
      force m = rnf m `seq` m
      update  = Map.insertWith (\ new old -> f old) x dummy
      dummy   = f 0

-- | Get the statistics.
getStatistics :: ReadTCState m => m Statistics
getStatistics = useR stStatistics

-- | Modify the statistics via given function.
modifyStatistics :: (Statistics -> Statistics) -> TCM ()
modifyStatistics f = stStatistics `modifyTCLens` f

-- | Increase specified counter by @1@.
tick :: MonadStatistics m => String -> m ()
tick x = tickN x 1

-- | Increase specified counter by @n@.
tickN :: MonadStatistics m => String -> Integer -> m ()
tickN s n = modifyCounter s (n +)

-- | Set the specified counter to the maximum of its current value and @n@.
tickMax :: MonadStatistics m => String -> Integer -> m ()
tickMax s n = modifyCounter s (max n)

-- | Print the given statistics.
printStatistics
  :: (MonadDebug m, MonadTCEnv m, HasOptions m)
  => Maybe C.TopLevelModuleName -> Statistics -> m ()
printStatistics mmname stats = do
  unlessNull (Map.toList stats) $ \ stats -> do
    let -- First column (left aligned) is accounts.
        col1 = Boxes.vcat Boxes.left  $ map (Boxes.text . fst) stats
        -- Second column (right aligned) is numbers.
        col2 = Boxes.vcat Boxes.right $ map (Boxes.text . showThousandSep . snd) stats
        table = Boxes.hsep 1 Boxes.left [col1, col2]
    reportSLn "" 1 $ caseMaybe mmname "Accumulated statistics" $ \ mname ->
      "Statistics for " ++ prettyShow mname
    reportSLn "" 1 $ Boxes.render table
