{-# LANGUAGE CPP               #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TupleSections     #-}

-- |
-- Copyright   : (c) 2020 Composewell Technologies
--
-- License     : BSD-3-Clause
-- Maintainer  : streamly@composewell.com
-- Stability   : experimental
-- Portability : GHC
--

module Streamly.Test.Unicode.Char (main) where

import Control.Monad (when)
import Data.Char (chr, isSpace, ord, toUpper)
import Data.List (intercalate, isPrefixOf)
import Data.Function ((&))
import Streamly.Internal.Unicode.Char
    ( NormalizationMode(NFC, NFD, NFKC, NFKD)
    , normalize
    )
import Streamly.Internal.Data.Stream (Stream)
import Text.Printf (printf)
import System.FilePath.Posix ((</>))

import qualified Streamly.Internal.Data.Stream as S
import qualified Streamly.Internal.Data.Fold as FL
import qualified System.Directory as Dir

chrToHex :: Char -> [Char]
chrToHex = map toUpper . printf "%.4x" . ord

strToHex :: [Char] -> String
strToHex = unwords . map chrToHex

type Text = Stream IO Char

toList = S.fold FL.toList

checkEqual :: String -> (Text -> Text) -> (Text, Text) -> IO Bool
checkEqual opName op (mc1, mc2) = do
    c1 <- toList mc1
    c2 <- toList mc2
    opc2 <- toList $ op mc2
    if c1 /= opc2 then do
        putStrLn $ opName ++ " "            ++ strToHex c2
                          ++ " = "          ++ strToHex opc2
                          ++ "; Expected: " ++ strToHex c1
        return False
    else return True

checkOp :: String -> NormalizationMode -> [(Text, Text)] -> IO Bool
checkOp name op pairs = do
    res <- mapM (checkEqual name (normalize op)) pairs
    return $ all (== True) res

checkNFC :: (Text, Text, Text, Text, Text) -> IO Bool
checkNFC (c1, c2, c3, c4, c5) =
    checkOp "toNFC" NFC $ map (c2, ) [c1, c2, c3] ++ map (c4, ) [c4, c5]

checkNFD :: (Text, Text, Text, Text, Text) -> IO Bool
checkNFD (c1, c2, c3, c4, c5) =
    checkOp "toNFD" NFD $ map (c3, ) [c1, c2, c3] ++ map (c5, ) [c4, c5]

checkNFKC :: (Text, Text, Text, Text, Text) -> IO Bool
checkNFKC (c1, c2, c3, c4, c5) =
    checkOp "toNFKC" NFKC $ map (c4,) [c1, c2, c3, c4, c5]

checkNFKD :: (Text, Text, Text, Text, Text) -> IO Bool
checkNFKD (c1, c2, c3, c4, c5) =
    checkOp "toNFKD" NFKD $ map (c5,) [c1, c2, c3, c4, c5]

splitOn predicate f = S.foldManyPost (FL.takeEndBy_ predicate f)

checkAllTestCases :: Int -> String -> IO ()
checkAllTestCases lineno line = do
    cs <- toList $ splitOn (== ';') FL.toList $ S.fromList line
    case cs of
        c1 : c2 : c3 : c4 : c5 : _ -> do
            let cps = map cpToText [c1, c2, c3, c4, c5]
            mapM_ (checkOneTestCase cps)
                  [checkNFD, checkNFKD, checkNFC, checkNFKC]
        _ -> error $ "Unrecognized line: " ++ line
    where
        cpToText xs = S.fromList $ map (chr . read . ("0x" ++)) (words xs)

        checkOneTestCase cps f = do
            res <- f (tuplify cps)
            when (not res) $ do
                strs <- mapM toList cps
                let codes = intercalate ";" $ map strToHex strs
                    txt = intercalate "; " strs
                putStrLn ("Failed at line: " ++ show lineno)
                putStrLn line
                putStrLn $ codes ++ "; # (" ++ txt
                error "Bailing out"

        tuplify [c1, c2, c3, c4, c5] = (c1, c2, c3, c4, c5)
        tuplify _ = error "tuplify bad arguments"

checkLine :: (Int, String) -> IO ()
checkLine (lineno, line) = do
    -- marker lines indicating a test block start with @
    if "@" `isPrefixOf` line
        then
            putStrLn line
        else
            checkAllTestCases lineno line

testNormalize :: FilePath -> IO ()
testNormalize file = do
    contents <- readFile file
    let ls = lines contents                        -- split into lines
         & map (dropWhile isSpace)                 -- trim leading spaces
         & zip [1..]                               -- add numbering
         & filter (not . null . snd)               -- remove blank lines
         & filter (not . ("#" `isPrefixOf`) . snd) -- remove comments
    checkAll ls
    where
        checkAll (x:xs) = checkLine x >> checkAll xs
        checkAll []     = return ()

filesDir :: String
filesDir = "test/Streamly/Test/Unicode"

main :: IO ()
main = do
    cdir <- Dir.getCurrentDirectory
    testNormalize $ cdir </> filesDir </> "ucd/NormalizationTest.txt"
    -- Additional test cases not in the unicode standard suite
    testNormalize $ cdir </> filesDir </> "extra/NormalizationTest.txt"