-- -*- Mode: Haskell; -*-
--
-- QuickCheck tests for Megaparsec's primitive parser combinators.
--
-- Copyright © 2015 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
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--
-- 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
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{-# OPTIONS -fno-warn-orphans #-}

module Prim (tests) where

import Control.Applicative
#if MIN_VERSION_base(4,7,0)
import Data.Bool (bool)
#endif
import Data.Char (isLetter, toUpper)
import Data.Foldable (asum)
import Data.List (isPrefixOf)
import Data.Maybe (maybeToList, fromMaybe)

import Control.Monad.Reader
import Control.Monad.Trans.Identity
import qualified Control.Monad.State.Lazy    as L
import qualified Control.Monad.State.Strict  as S
import qualified Control.Monad.Writer.Lazy   as L
import qualified Control.Monad.Writer.Strict as S

import Test.Framework
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.QuickCheck hiding (label)

import Text.Megaparsec.Char
import Text.Megaparsec.Error (Message (..))
import Text.Megaparsec.Pos
import Text.Megaparsec.Prim
import Text.Megaparsec.String

import Pos ()
import Util
#if !MIN_VERSION_base(4,7,0)
bool :: a -> a -> Bool -> a
bool f _ False = f
bool _ t True  = t
#endif

tests :: Test
tests = testGroup "Primitive parser combinators"
        [ testProperty "ParsecT functor" prop_functor
        , testProperty "ParsecT applicative (<*>)" prop_applicative_0
        , testProperty "ParsecT applicative (*>)" prop_applicative_1
        , testProperty "ParsecT applicative (<*)" prop_applicative_2
        , testProperty "ParsecT alternative empty and (<|>)" prop_alternative_0
        , testProperty "ParsecT alternative (<|>)" prop_alternative_1
        , testProperty "ParsecT alternative (<|>) pos" prop_alternative_2
        , testProperty "ParsecT alternative (<|>) hints" prop_alternative_3
        , testProperty "ParsecT alternative many" prop_alternative_4
        , testProperty "ParsecT alternative some" prop_alternative_5
        , testProperty "ParsecT alternative optional" prop_alternative_6
        , testProperty "ParsecT monad return" prop_monad_0
        , testProperty "ParsecT monad (>>)" prop_monad_1
        , testProperty "ParsecT monad (>>=)" prop_monad_2
        , testProperty "ParsecT monad fail" prop_monad_3
        , testProperty "combinator unexpected" prop_unexpected
        , testProperty "combinator label" prop_label
        , testProperty "combinator hidden hints" prop_hidden_0
        , testProperty "combinator hidden error" prop_hidden_1
        , testProperty "combinator try" prop_try
        , testProperty "combinator lookAhead" prop_lookAhead_0
        , testProperty "combinator lookAhead hints" prop_lookAhead_1
        , testProperty "combinator lookAhead messages" prop_lookAhead_2
        , testProperty "combinator notFollowedBy" prop_notFollowedBy_0
        , testProperty "combinator notFollowedBy twice" prop_notFollowedBy_1
        , testProperty "combinator notFollowedBy eof" prop_notFollowedBy_2
        , testProperty "combinator token" prop_token
        , testProperty "combinator tokens" prop_tokens
        , testProperty "parser state position" prop_state_pos
        , testProperty "parser state input" prop_state_input
        , testProperty "parser state tab width" prop_state_tab
        , testProperty "parser state general" prop_state
        , testProperty "IdentityT try" prop_IdentityT_try
        , testProperty "IdentityT notFollowedBy" prop_IdentityT_notFollowedBy
        , testProperty "ReaderT try" prop_ReaderT_try
        , testProperty "ReaderT notFollowedBy" prop_ReaderT_notFollowedBy
        , testProperty "StateT alternative (<|>)" prop_StateT_alternative
        , testProperty "StateT lookAhead" prop_StateT_lookAhead
        , testProperty "StateT notFollowedBy" prop_StateT_notFollowedBy
        , testProperty "WriterT" prop_WriterT ]

instance Arbitrary (State String) where
  arbitrary = State <$> arbitrary <*> arbitrary <*> arbitrary

-- Functor instance

prop_functor :: Integer -> Integer -> Property
prop_functor n m =
  ((+ m) <$> return n) /=\ n + m .&&. ((* n) <$> return m) /=\ n * m

-- Applicative instance

prop_applicative_0 :: Integer -> Integer -> Property
prop_applicative_0 n m = ((+) <$> pure n <*> pure m) /=\ n + m

prop_applicative_1 :: Integer -> Integer -> Property
prop_applicative_1 n m = (pure n *> pure m) /=\ m

prop_applicative_2 :: Integer -> Integer -> Property
prop_applicative_2 n m = (pure n <* pure m) /=\ n

-- Alternative instance

prop_alternative_0 :: Integer -> Property
prop_alternative_0 n = (empty <|> return n) /=\ n

prop_alternative_1 :: String -> String -> Property
prop_alternative_1 s0 s1
  | s0 == s1 = checkParser p (Right s0) s1
  | null s0  = checkParser p (posErr 0 s1 [uneCh (head s1), exEof]) s1
  | s0 `isPrefixOf` s1 =
      checkParser p (posErr s0l s1 [uneCh (s1 !! s0l), exEof]) s1
  | otherwise = checkParser p (Right s0) s0 .&&. checkParser p (Right s1) s1
    where p   = try (string s0) <|> string s1
          s0l = length s0

prop_alternative_2 :: Char -> Char -> Char -> Bool -> Property
prop_alternative_2 a b c l = checkParser p r s
  where p = char a <|> (char b >> char a)
        r | l         = Right a
          | a == b    = posErr 1 s [uneCh c, exEof]
          | a == c    = Right a
          | otherwise = posErr 1 s [uneCh c, exCh a]
        s = if l then [a] else [b,c]

prop_alternative_3 :: Property
prop_alternative_3 = checkParser p r s
  where p  = asum [empty, try (string ">>>"), empty, return "foo"] <?> "bar"
        p' = bsum [empty, try (string ">>>"), empty, return "foo"] <?> "bar"
        bsum = foldl (<|>) empty
        r = simpleParse p' s
        s = ">>"

prop_alternative_4 :: NonNegative Int -> NonNegative Int
                   -> NonNegative Int -> Property
prop_alternative_4 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (++) <$> many (char 'a') <*> many (char 'b')
        r | null s = Right s
          | c > 0  = posErr (a + b) s $ [uneCh 'c', exCh 'b', exEof]
                     ++ [exCh 'a' | b == 0]
          | otherwise = Right s
        s = abcRow a b c

prop_alternative_5 :: NonNegative Int -> NonNegative Int
                   -> NonNegative Int -> Property
prop_alternative_5 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (++) <$> some (char 'a') <*> some (char 'b')
        r | null s = posErr 0 s [uneEof, exCh 'a']
          | a == 0 = posErr 0 s [uneCh (head s), exCh 'a']
          | b == 0 = posErr a s $ [exCh 'a', exCh 'b'] ++
                     if c > 0 then [uneCh 'c'] else [uneEof]
          | c > 0 = posErr (a + b) s [uneCh 'c', exCh 'b', exEof]
          | otherwise = Right s
        s = abcRow a b c

prop_alternative_6 :: Bool -> Bool -> Bool -> Property
prop_alternative_6 a b c = checkParser p r s
  where p = f <$> optional (char 'a') <*> optional (char 'b')
        f x y = maybe "" (:[]) x ++ maybe "" (:[]) y
        r | c = posErr ab s $ [uneCh 'c', exEof] ++
                [exCh 'a' | not a && not b] ++ [exCh 'b' | not b]
          | otherwise = Right s
        s = abcRow' a b c
        ab = fromEnum a + fromEnum b

-- Monad instance

prop_monad_0 :: Integer -> Property
prop_monad_0 n = checkParser (return n) (Right n) ""

prop_monad_1 :: Char -> Char -> Maybe Char -> Property
prop_monad_1 a b c = checkParser p r s
  where p = char a >> char b
        r = simpleParse (char a *> char b) s
        s = a : b : maybeToList c

prop_monad_2 :: Char -> Char -> Maybe Char -> Property
prop_monad_2 a b c = checkParser p r s
  where p = char a >>= \x -> char b >> return x
        r = simpleParse (char a <* char b) s
        s = a : b : maybeToList c

prop_monad_3 :: String -> Property
prop_monad_3 m = checkParser p r s
  where p = fail m :: Parser ()
        r | null m    = posErr 0 s []
          | otherwise = posErr 0 s [msg m]
        s = ""

-- TODO MonadReader instance of ParsecT

-- TODO MonadState instance of ParsecT

-- TODO MonadCont instance of ParsecT

-- TODO MonadError instance of ParsecT

-- Primitive combinators

prop_unexpected :: String -> Property
prop_unexpected m = conjoin [ checkParser p r s
                            , checkParser (runIdentityT p_IdentityT) r s
                            , checkParser (runReaderT p_ReaderT ()) r s
                            , checkParser (L.evalStateT p_lStateT ()) r s
                            , checkParser (S.evalStateT p_sStateT ()) r s
                            , checkParser (L.runWriterT p_lWriterT) r s
                            , checkParser (S.runWriterT p_sWriterT) r s ]
  where p           = unexpected m :: Parser ()
        p_IdentityT = unexpected m :: IdentityT Parser ()
        p_ReaderT   = unexpected m :: ReaderT () Parser ()
        p_lStateT   = unexpected m :: L.StateT () Parser ()
        p_sStateT   = unexpected m :: S.StateT () Parser ()
        p_lWriterT  = unexpected m :: L.WriterT [Integer] Parser ()
        p_sWriterT  = unexpected m :: S.WriterT [Integer] Parser ()
        r | null m    = posErr 0 s []
          | otherwise = posErr 0 s [uneSpec m]
        s = ""

prop_label :: NonNegative Int -> NonNegative Int
           -> NonNegative Int -> String -> Property
prop_label a' b' c' l = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (++) <$> many (char 'a') <*> (many (char 'b') <?> l)
        r | null s = Right s
          | c > 0 = posErr (a + b) s $ [uneCh 'c', exEof]
                    ++ [exCh 'a' | b == 0]
                    ++ [if b == 0 || null l
                        then exSpec l
                        else exSpec $ "rest of " ++ l]
          | otherwise = Right s
        s = abcRow a b c

prop_hidden_0 :: NonNegative Int -> NonNegative Int
              -> NonNegative Int -> Property
prop_hidden_0 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (++) <$> many (char 'a') <*> hidden (many (char 'b'))
        r | null s = Right s
          | c > 0  = posErr (a + b) s $ [uneCh 'c', exEof]
                     ++ [exCh 'a' | b == 0]
          | otherwise = Right s
        s = abcRow a b c

prop_hidden_1 :: String -> NonEmptyList Char -> String -> Property
prop_hidden_1 a c' s = checkParser p r s
  where c = getNonEmpty c'
        p = fromMaybe a <$> optional (hidden $ string c)
        r | null s = Right a
          | c == s = Right s
          | head c /= head s = posErr 0 s [uneCh (head s), exEof]
          | otherwise = simpleParse (string c) s

prop_try :: String -> String -> String -> Property
prop_try pre s1' s2' = checkParser p r s
  where s1 = pre ++ s1'
        s2 = pre ++ s2'
        p = try (string s1) <|> string s2
        r | s == s1 || s == s2 = Right s
          | otherwise = posErr 0 s $ bool [uneStr pre] [uneEof] (null s)
                        ++ [uneStr pre, exStr s1, exStr s2]
        s = pre

prop_lookAhead_0 :: Bool -> Bool -> Bool -> Property
prop_lookAhead_0 a b c = checkParser p r s
  where p = do
          l <- lookAhead (oneOf "ab" <?> "label")
          guard (l == h)
          char 'a'
        h = head s
        r | null s = posErr 0 s [uneEof, exSpec "label"]
          | s == "a" = Right 'a'
          | h == 'b' = posErr 0 s [uneCh 'b', exCh 'a']
          | h == 'c' = posErr 0 s [uneCh 'c', exSpec "label"]
          | otherwise  = posErr 1 s [uneCh (s !! 1), exEof]
        s = abcRow' a b c

prop_lookAhead_1 :: String -> Property
prop_lookAhead_1 s = checkParser p r s
  where p = lookAhead (some letterChar) >> fail "failed" :: Parser ()
        h = head s
        r | null s     = posErr 0 s [uneEof, exSpec "letter"]
          | isLetter h = posErr 0 s [msg "failed"]
          | otherwise  = posErr 0 s [uneCh h, exSpec "letter"]

prop_lookAhead_2 :: Bool -> Bool -> Bool -> Property
prop_lookAhead_2 a b c = checkParser p r s
  where p = lookAhead (some (char 'a')) >> char 'b'
        r | null s    = posErr 0 s [uneEof, exCh 'a']
          | a         = posErr 0 s [uneCh 'a', exCh 'b']
          | otherwise = posErr 0 s [uneCh (head s), exCh 'a']
        s = abcRow' a b c

prop_notFollowedBy_0 :: NonNegative Int -> NonNegative Int
                     -> NonNegative Int -> Property
prop_notFollowedBy_0 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = many (char 'a') <* notFollowedBy (char 'b') <* many (char 'c')
        r | b > 0 = posErr a s [uneCh 'b', exCh 'a']
          | otherwise = Right (replicate a 'a')
        s = abcRow a b c

prop_notFollowedBy_1 :: NonNegative Int -> NonNegative Int
                     -> NonNegative Int -> Property
prop_notFollowedBy_1 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = many (char 'a') <* f (char 'c') <* many (char 'c')
        f = notFollowedBy . notFollowedBy -- = 'lookAhead' in this case
        r | b == 0 && c > 0 = Right (replicate a 'a')
          | b > 0           = posErr a s [uneCh 'b', exCh 'a']
          | otherwise       = posErr a s [uneEof, exCh 'a']
        s = abcRow a b c

prop_notFollowedBy_2 :: NonNegative Int -> NonNegative Int
                     -> NonNegative Int -> Property
prop_notFollowedBy_2 a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = many (char 'a') <* notFollowedBy eof <* many anyChar
        r | b > 0 || c > 0 = Right (replicate a 'a')
          | otherwise      = posErr a s [uneEof, exCh 'a']
        s = abcRow a b c

-- We omit tests for 'eof' here because it's used virtually everywhere, it's
-- already thoroughly tested.

prop_token :: String -> Property
prop_token s = checkParser p r s
  where p = token updatePosChar testChar
        testChar x = if isLetter x
                     then Right x
                     else Left . pure . Unexpected . showToken $ x
        h = head s
        r | null s = posErr 0 s [uneEof]
          | isLetter h && length s == 1 = Right (head s)
          | isLetter h && length s > 1 = posErr 1 s [uneCh (s !! 1), exEof]
          | otherwise = posErr 0 s [uneCh h]

prop_tokens :: String -> String -> Property
prop_tokens a = checkString p a (==) (showToken a)
  where p = tokens updatePosString (==) a

-- Parser state combinators

prop_state_pos :: SourcePos -> Property
prop_state_pos pos = p /=\ pos
  where p = setPosition pos >> getPosition

prop_state_input :: String -> Property
prop_state_input s = p /=\ s
  where p = do
          st0    <- getInput
          guard (null st0)
          setInput s
          result <- string s
          st1    <- getInput
          guard (null st1)
          return result

prop_state_tab :: Int -> Property
prop_state_tab w = p /=\ w
  where p = setTabWidth w >> getTabWidth

prop_state :: State String -> State String -> Property
prop_state s1 s2 = runParser p "" "" === Right (f s2 s1)
  where f (State s1' pos w) (State s2' _ _) = State (max s1' s2' ) pos w
        p = do
          st <- getParserState
          guard (st == State "" (initialPos "") defaultTabWidth)
          setParserState s1
          updateParserState (f s2)
          getParserState

-- IdentityT instance of MonadParsec

prop_IdentityT_try :: String -> String -> String -> Property
prop_IdentityT_try pre s1' s2' = checkParser (runIdentityT p) r s
  where s1 = pre ++ s1'
        s2 = pre ++ s2'
        p = try (string s1) <|> string s2
        r | s == s1 || s == s2 = Right s
          | otherwise = posErr 0 s $ bool [uneStr pre] [uneEof] (null s)
                        ++ [uneStr pre, exStr s1, exStr s2]
        s = pre

prop_IdentityT_notFollowedBy :: NonNegative Int -> NonNegative Int
                             -> NonNegative Int -> Property
prop_IdentityT_notFollowedBy a' b' c' = checkParser (runIdentityT p) r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = many (char 'a') <* notFollowedBy eof <* many anyChar
        r | b > 0 || c > 0 = Right (replicate a 'a')
          | otherwise      = posErr a s [uneEof, exCh 'a']
        s = abcRow a b c

-- ReaderT instance of MonadParsec

prop_ReaderT_try :: String -> String -> String -> Property
prop_ReaderT_try pre s1' s2' = checkParser (runReaderT p (s1', s2')) r s
  where s1 = pre ++ s1'
        s2 = pre ++ s2'
        getS1 = asks ((pre ++) . fst)
        getS2 = asks ((pre ++) . snd)
        p = try (string =<< getS1) <|> (string =<< getS2)
        r | s == s1 || s == s2 = Right s
          | otherwise = posErr 0 s $ bool [uneStr pre] [uneEof] (null s)
                        ++ [uneStr pre, exStr s1, exStr s2]
        s = pre

prop_ReaderT_notFollowedBy :: NonNegative Int -> NonNegative Int
                           -> NonNegative Int -> Property
prop_ReaderT_notFollowedBy a' b' c' = checkParser (runReaderT p 'a') r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = many (char =<< ask) <* notFollowedBy eof <* many anyChar
        r | b > 0 || c > 0 = Right (replicate a 'a')
          | otherwise      = posErr a s [uneEof, exCh 'a']
        s = abcRow a b c

-- StateT instance of MonadParsec

prop_StateT_alternative :: Integer -> Property
prop_StateT_alternative n = checkParser (L.evalStateT p 0) (Right n) "" .&&.
                            checkParser (S.evalStateT p' 0) (Right n) ""
  where p  = L.put n >> ((L.modify (* 2) >>
                          void (string "xxx")) <|> return ()) >> L.get
        p' = S.put n >> ((S.modify (* 2) >>
                          void (string "xxx")) <|> return ()) >> S.get

prop_StateT_lookAhead :: Integer -> Property
prop_StateT_lookAhead n = checkParser (L.evalStateT p 0) (Right n) "" .&&.
                          checkParser (S.evalStateT p' 0) (Right n) ""
  where p  = L.put n >> lookAhead (L.modify (* 2) >> eof) >> L.get
        p' = S.put n >> lookAhead (S.modify (* 2) >> eof) >> S.get

prop_StateT_notFollowedBy :: Integer -> Property
prop_StateT_notFollowedBy n = checkParser (L.runStateT p 0) r "abx" .&&.
                              checkParser (S.runStateT p' 0) r "abx"
  where p = do
          L.put n
          let notEof = notFollowedBy (L.modify (* 2) >> eof)
          some (try (anyChar <* notEof)) <* char 'x'
        p' = do
          S.put n
          let notEof = notFollowedBy (S.modify (* 2) >> eof)
          some (try (anyChar <* notEof)) <* char 'x'
        r = Right ("ab", n)

-- WriterT instance of MonadParsec

prop_WriterT :: String -> String -> Property
prop_WriterT pre post = checkParser (L.runWriterT p) r "abx" .&&.
                        checkParser (S.runWriterT p') r "abx"
  where logged_letter  = letterChar >>= \x -> L.tell [x] >> return x
        logged_letter' = letterChar >>= \x -> L.tell [x] >> return x
        logged_eof     = eof >> L.tell "EOF"
        logged_eof'    = eof >> L.tell "EOF"
        p = do
          L.tell pre
          cs <- L.censor (fmap toUpper) $
                  some (try (logged_letter <* notFollowedBy logged_eof))
          L.tell post
          void logged_letter
          return cs
        p' = do
          L.tell pre
          cs <- L.censor (fmap toUpper) $
                  some (try (logged_letter' <* notFollowedBy logged_eof'))
          L.tell post
          void logged_letter'
          return cs
        r = Right ("ab", pre ++ "AB" ++ post ++ "x")