--
-- QuickCheck tests for Megaparsec's lexer.
--
-- Copyright © 2015–2016 Megaparsec contributors
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are
-- met:
--
-- * Redistributions of source code must retain the above copyright notice,
--   this list of conditions and the following disclaimer.
--
-- * Redistributions in binary form must reproduce the above copyright
--   notice, this list of conditions and the following disclaimer in the
--   documentation and/or other materials provided with the distribution.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS “AS IS” AND ANY
-- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-- DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
-- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
-- OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
-- HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
-- STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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{-# LANGUAGE CPP              #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TupleSections    #-}
{-# LANGUAGE TypeFamilies     #-}

module Lexer (tests) where

import Control.Applicative (empty)
import Control.Monad (void)
import Data.Char
  ( readLitChar
  , showLitChar
  , isDigit
  , isAlphaNum
  , isSpace
  , toLower )
import Data.List (findIndices, isInfixOf, find)
import Data.Maybe
import Data.Scientific (fromFloatDigits)
import Numeric (showInt, showHex, showOct, showSigned)

import Test.Framework
import Test.Framework.Providers.HUnit (testCase)
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.HUnit (Assertion)
import Test.QuickCheck

import Text.Megaparsec.Error
import Text.Megaparsec.Lexer
import Text.Megaparsec.Pos
import Text.Megaparsec.Prim
import Text.Megaparsec.String
import qualified Text.Megaparsec.Char as C

import Util

#if !MIN_VERSION_base(4,8,0)
import Control.Applicative ((<$>), (<*), (<*>), (<$))
#endif

tests :: Test
tests = testGroup "Lexer"
  [ testProperty "space combinator"       prop_space
  , testProperty "symbol combinator"      prop_symbol
  , testProperty "symbol' combinator"     prop_symbol'
  , testCase     "skipBlockCommentNested" case_skipBlockCommentNested
  , testProperty "indentLevel"            prop_indentLevel
  , testProperty "incorrectIndent"        prop_incorrectIndent
  , testProperty "indentGuard combinator" prop_indentGuard
  , testProperty "nonIndented combinator" prop_nonIndented
  , testProperty "indentBlock combinator" prop_indentBlock
  , testProperty "indentBlock (many)"     prop_indentMany
  , testProperty "lineFold"               prop_lineFold
  , testProperty "charLiteral"            prop_charLiteral
  , testProperty "integer"                prop_integer
  , testProperty "decimal"                prop_decimal
  , testProperty "hexadecimal"            prop_hexadecimal
  , testProperty "octal"                  prop_octal
  , testProperty "float 0"                prop_float_0
  , testProperty "float 1"                prop_float_1
  , testProperty "number 0"               prop_number_0
  , testProperty "number 1"               prop_number_1
  , testProperty "number 2 (signed)"      prop_number_2
  , testProperty "signed"                 prop_signed ]

-- White space

mkWhiteSpace :: Gen String
mkWhiteSpace = concat <$> listOf whiteUnit
  where whiteUnit = oneof [whiteChars, whiteLine, whiteBlock]

mkSymbol :: Gen String
mkSymbol = (++) <$> symbolName <*> whiteChars

mkInterspace :: String -> Int -> Gen String
mkInterspace x n = oneof [si, mkIndent x n]
  where si = (++ x) <$> listOf (elements " \t")

mkIndent :: String -> Int -> Gen String
mkIndent x n = (++) <$> mkIndent' x n <*> eol
  where eol = frequency [(5, return "\n"), (1, listOf1 (return '\n'))]

mkIndent' :: String -> Int -> Gen String
mkIndent' x n = concat <$> sequence [spc, sym, tra]
  where spc = frequency [(5, vectorOf n itm), (1, listOf itm)]
        tra = listOf itm
        itm = elements " \t"
        sym = return x

whiteChars :: Gen String
whiteChars = listOf (elements "\t\n ")

whiteLine :: Gen String
whiteLine = commentOut <$> arbitrary `suchThat` goodEnough
  where commentOut x = "//" ++ x ++ "\n"
        goodEnough x = '\n' `notElem` x

whiteBlock :: Gen String
whiteBlock = commentOut <$> arbitrary `suchThat` goodEnough
  where commentOut x = "/*" ++ x ++ "*/"
        goodEnough x = not $ "*/" `isInfixOf` x

symbolName :: Gen String
symbolName = listOf $ arbitrary `suchThat` isAlphaNum

sc :: Parser ()
sc = space (void $ C.oneOf " \t") empty empty

scn :: Parser ()
scn = space (void C.spaceChar) l b
  where l = skipLineComment "//"
        b = skipBlockComment "/*" "*/"

prop_space :: Property
prop_space = forAll mkWhiteSpace (checkParser p r)
  where p = scn
        r = Right ()

prop_symbol :: Maybe Char -> Property
prop_symbol t = forAll mkSymbol $ \s ->
  parseSymbol (symbol scn) id s t

prop_symbol' :: Maybe Char -> Property
prop_symbol' t = forAll mkSymbol $ \s ->
  parseSymbol (symbol' scn) (fmap toLower) s t

parseSymbol
  :: (String -> Parser String)
  -> (String -> String)
  -> String
  -> Maybe Char
  -> Property
parseSymbol p' f s' t = checkParser p r s
  where p = p' (f g)
        r | g == s || isSpace (last s) = Right g
          | otherwise = posErr (length s - 1) s [utok (last s), eeof]
        g = takeWhile (not . isSpace) s
        s = s' ++ maybeToList t

case_skipBlockCommentNested :: Assertion
case_skipBlockCommentNested = checkCase p r s
  where p = space (void C.spaceChar) empty
              (skipBlockCommentNested "/*" "*/") <* eof
        r = Right ()
        s = " /* foo bar /* baz */ quux */ "

-- Indentation

prop_indentLevel :: SourcePos -> Property
prop_indentLevel pos = p /=\ sourceColumn pos
  where p = setPosition pos >> indentLevel

prop_incorrectIndent :: Ordering -> Pos -> Pos -> Property
prop_incorrectIndent ord ref actual = checkParser p r s
  where p = incorrectIndent ord ref actual :: Parser ()
        r = posErr 0 s (ii ord ref actual)
        s = ""

prop_indentGuard :: NonNegative (Small Int) -> Property
prop_indentGuard n =
  forAll ((,,) <$> mki <*> mki <*> mki) $ \(l0,l1,l2) ->
    let r | col0 <= pos1 = posErr 0 s (ii GT pos1 col0)
          | col1 /= col0 = posErr (getIndent l1 + g 1) s (ii EQ col0 col1)
          | col2 <= col0 = posErr (getIndent l2 + g 2) s (ii GT col0 col2)
          | otherwise    = Right ()
        (col0, col1, col2) = (getCol l0, getCol l1, getCol l2)
        fragments = [l0,l1,l2]
        g x = sum (length <$> take x fragments)
        s = concat fragments
    in checkParser p r s
  where mki = mkIndent sbla (getSmall $ getNonNegative n)
        p  = ip GT pos1 >>=
          \x -> sp >> ip EQ x >> sp >> ip GT x >> sp >> scn
        ip = indentGuard scn
        sp = void (symbol sc sbla <* C.eol)

prop_nonIndented :: Property
prop_nonIndented = forAll (mkIndent sbla 0) $ \s ->
  let i = getIndent s
      r | i == 0    = Right sbla
        | otherwise = posErr i s (ii EQ pos1 (getCol s))
  in checkParser p r s
  where p = nonIndented scn (symbol scn sbla)

prop_indentBlock :: Maybe (Positive (Small Int)) -> Property
prop_indentBlock mn'' = forAll mkBlock $ \(l0,l1,l2,l3,l4) ->
  let r | col1 <= col0 =
          posErr (getIndent l1 + g 1) s [utok (head sblb), eeof]
        | isJust mn && col1 /= ib' =
          posErr (getIndent l1 + g 1) s (ii EQ ib' col1)
        | col2 <= col1 =
          posErr (getIndent l2 + g 2) s (ii GT col1 col2)
        | col3 == col2 =
          posErr (getIndent l3 + g 3) s [utok (head sblb), etoks sblc]
        | col3 <= col0 =
          posErr (getIndent l3 + g 3) s [utok (head sblb), eeof]
        | col3 < col1 =
          posErr (getIndent l3 + g 3) s (ii EQ col1 col3)
        | col3 > col1 =
          posErr (getIndent l3 + g 3) s (ii EQ col2 col3)
        | col4 <= col3 =
          posErr (getIndent l4 + g 4) s (ii GT col3 col4)
        | otherwise = Right (sbla, [(sblb, [sblc]), (sblb, [sblc])])
      (col0, col1, col2, col3, col4) =
        (getCol l0, getCol l1, getCol l2, getCol l3, getCol l4)
      fragments = [l0,l1,l2,l3,l4]
      g x = sum (length <$> take x fragments)
      s = concat fragments
  in checkParser p r s
  where mkBlock = do
          l0 <- mkIndent sbla 0
          l1 <- mkIndent sblb ib
          l2 <- mkIndent sblc (ib + 2)
          l3 <- mkIndent sblb ib
          l4 <- mkIndent' sblc (ib + 2)
          return (l0,l1,l2,l3,l4)
        p = lvla
        lvla = indentBlock scn $ IndentMany mn      (l sbla) lvlb <$ b sbla
        lvlb = indentBlock scn $ IndentSome Nothing (l sblb) lvlc <$ b sblb
        lvlc = indentBlock scn $ IndentNone                  sblc <$ b sblc
        b    = symbol sc
        l x  = return . (x,)
        mn'  = getSmall . getPositive <$> mn''
        mn   = unsafePos . fromIntegral <$> mn'
        ib   = fromMaybe 2 mn'
        ib'  = unsafePos (fromIntegral ib)

prop_indentMany :: Property
prop_indentMany = forAll (mkIndent sbla 0) (checkParser p r)
  where r = Right (sbla, [])
        p = lvla
        lvla = indentBlock scn $ IndentMany Nothing (l sbla) lvlb <$ b sbla
        lvlb = b sblb
        b    = symbol sc
        l x  = return . (x,)

prop_lineFold :: Property
prop_lineFold = forAll mkFold $ \(l0,l1,l2) ->
  let r | end0 && col1 <= col0 =
          posErr (getIndent l1 + g 1) s (ii GT col0 col1)
        | end1 && col2 <= col0 =
          posErr (getIndent l2 + g 2) s (ii GT col0 col2)
        | otherwise = Right (sbla, sblb, sblc)
      (col0, col1, col2) = (getCol l0, getCol l1, getCol l2)
      (end0, end1)       = (getEnd l0, getEnd l1)
      fragments = [l0,l1,l2]
      g x = sum (length <$> take x fragments)
      s = concat fragments
  in checkParser p r s
  where
    mkFold = do
      l0 <- mkInterspace sbla 0
      l1 <- mkInterspace sblb 1
      l2 <- mkInterspace sblc 1
      return (l0,l1,l2)
    p = lineFold scn $ \sc' -> do
          a <- symbol sc' sbla
          b <- symbol sc' sblb
          c <- symbol scn sblc
          return (a, b, c)
    getEnd x = last x == '\n'

getIndent :: String -> Int
getIndent = length . takeWhile isSpace

getCol :: String -> Pos
getCol x = sourceColumn .
  updatePosString defaultTabWidth (initialPos "") $ take (getIndent x) x

sbla, sblb, sblc :: String
sbla = "aaa"
sblb = "bbb"
sblc = "ccc"

ii :: Ordering -> Pos -> Pos -> [EC]
ii ord ref actual = [cstm (DecIndentation ord ref actual)]

pos1 :: Pos
pos1 = unsafePos 1

-- Character and string literals

prop_charLiteral :: String -> Bool -> Property
prop_charLiteral t i = checkParser charLiteral r s
  where b = listToMaybe $ readLitChar s
        (h, g) = fromJust b
        r | isNothing b = posErr 0 s $ elabel "literal character" :
            [ if null s then ueof else utok (head s) ]
          | null g      = Right h
          | otherwise   = posErr l s [utok (head g), eeof]
        l = length s - length g
        s = if null t || i then t else showLitChar (head t) (tail t)

-- Numbers

prop_integer :: NonNegative Integer -> Int -> Property
prop_integer n' i = checkParser integer r s
  where (r, s) = quasiCorrupted n' i showInt "integer"

prop_decimal :: NonNegative Integer -> Int -> Property
prop_decimal n' i = checkParser decimal r s
  where (r, s) = quasiCorrupted n' i showInt "decimal integer"

prop_hexadecimal :: NonNegative Integer -> Int -> Property
prop_hexadecimal n' i = checkParser hexadecimal r s
  where (r, s) = quasiCorrupted n' i showHex "hexadecimal integer"

prop_octal :: NonNegative Integer -> Int -> Property
prop_octal n' i = checkParser octal r s
  where (r, s) = quasiCorrupted n' i showOct "octal integer"

prop_float_0 :: NonNegative Double -> Property
prop_float_0 n' = checkParser float r s
  where n = getNonNegative n'
        r = Right n
        s = show n

prop_float_1 :: Maybe (NonNegative Integer) -> Property
prop_float_1 n' = checkParser float r s
  where r | isNothing n' = posErr 0 s [ueof, elabel "floating point number"]
          | otherwise    = posErr (length s) s
            [ueof, etok '.', etok 'E', etok 'e', elabel "digit"]
        s = maybe "" (show . getNonNegative) n'

prop_number_0 :: Either (NonNegative Integer) (NonNegative Double) -> Property
prop_number_0 n' = checkParser number r s
  where r = Right $ case n' of
              Left  x -> fromIntegral . getNonNegative $ x
              Right x -> fromFloatDigits . getNonNegative $ x
        s = either (show . getNonNegative) (show . getNonNegative) n'

prop_number_1 :: Property
prop_number_1 = checkParser number r s
  where r = posErr 0 s [ueof, elabel "number"]
        s = ""

prop_number_2 :: Either Integer Double -> Property
prop_number_2 n = checkParser p r s
  where p = signed (hidden C.space) number
        r = Right $ case n of
              Left  x -> fromIntegral x
              Right x -> fromFloatDigits x
        s = either show show n

prop_signed :: Integer -> Int -> Bool -> Property
prop_signed n i plus = checkParser p r s
  where p = signed (hidden C.space) integer
        r | i > length z = Right n
          | otherwise = posErr i s $ utok '?' :
            (if i <= 0 then [etok '+', etok '-'] else []) ++
            [elabel $ if isNothing . find isDigit $ take i s
                        then "integer"
                        else "rest of integer"] ++
            [eeof | i > head (findIndices isDigit s)]
        z = let bar = showSigned showInt 0 n ""
            in if n < 0 || plus then bar else '+' : bar
        s = if i <= length z then take i z ++ "?" ++ drop i z else z

quasiCorrupted
  :: NonNegative Integer
  -> Int
  -> (Integer -> String -> String)
  -> String
  -> (Either (ParseError Char Dec) Integer, String)
quasiCorrupted n' i shower l = (r, s)
  where n = getNonNegative n'
        r | i > length z = Right n
          | otherwise    = posErr i s $ utok '?' :
            [ eeof | i > 0 ] ++
            [if i <= 0 || null l
               then elabel l
               else elabel $ "rest of " ++ l]
        z = shower n ""
        s = if i <= length z then take i z ++ "?" ++ drop i z else z