ReportUtils.hs

module Lattest.Util.ReportUtils
    ( writeResults
    , flushResults
    , initResultsFile
    , TestResult(..)
    ) where

import Data.Csv (ToRecord(..), record, toField, encode)
import Data.Maybe (fromMaybe)
import Data.Foldable (toList)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as BL
import qualified Data.Sequence as Seq
import Control.Monad (void)


data TestResult = TestResult
    { testNumber :: Int
    , verdict    :: String
    , trace      :: String
    }

defaultHeader :: (String, String, String)
defaultHeader = ("test_number", "verdict", "trace")

{-|
    Initialize a CSV file for test results with an optional header. If no header is
    provided, a default one will be used.
-}
initResultsFile :: FilePath -> Maybe (String, String, String) -> IO ()
initResultsFile csvPath mHeader =
    BS.writeFile csvPath (BL.toStrict (encode [fromMaybe defaultHeader mHeader]))

instance ToRecord TestResult where
    toRecord (TestResult n v t) = record [toField n, toField v, toField t]

{-| 
    Append a list of 'TestResult' rows to a CSV file, with optional buffering given by 'threshold'.
     - If 'threshold' is 0, results are written immediately.
     - If 'threshold' > 0, results are buffered until the buffer length reaches the threshold, at which
     point they are written to the file.
    Returns the updated (reverseBuffer, bufferLength) pair.
    Note: this function assumes the CSV file already exists.
-}
writeResults
    :: FilePath
    -> [TestResult]
    -> Seq.Seq TestResult
    -> Int
    -> IO (Seq.Seq TestResult)
writeResults csvPath newResults buf threshold = do
    let newBuf    = buf Seq.>< Seq.fromList newResults
        newBufLen = Seq.length newBuf
    if threshold == 0 || newBufLen >= threshold
        then do
            BS.appendFile csvPath (BL.toStrict (encode (toList newBuf)))
            return Seq.empty
        else
            return newBuf

{-| 
    Flush remaining 'TestResult' rows to a CSV file.
    Note: this function assumes the CSV file already exists.
-}
flushResults :: FilePath -> Seq.Seq TestResult -> IO ()
flushResults csvPath revBuf =
    void $ writeResults csvPath [] revBuf 0