-- -*- Mode: Haskell; -*-
--
-- QuickCheck tests for Megaparsec's generic parser combinators.
--
-- Copyright © 2015 Megaparsec contributors
--
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module Combinator (tests) where

import Control.Applicative
import Data.List (intersperse)
import Data.Maybe (fromMaybe, maybeToList, isNothing, fromJust)

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

import Text.Megaparsec.Char
import Text.Megaparsec.Combinator

import Util

tests :: Test
tests = testGroup "Generic parser combinators"
        [ testProperty "combinator between"   prop_between
        , testProperty "combinator choice"    prop_choice
        , testProperty "combinator count"     prop_count
        , testProperty "combinator count'"    prop_count'
        , testProperty "combinator endBy"     prop_endBy
        , testProperty "combinator endBy1"    prop_endBy1
        , testProperty "combinator manyTill"  prop_manyTill
        , testProperty "combinator someTill"  prop_someTill
        , testProperty "combinator option"    prop_option
        , testProperty "combinator sepBy"     prop_sepBy
        , testProperty "combinator sepBy1"    prop_sepBy1
        , testProperty "combinator sepEndBy"  prop_sepEndBy
        , testProperty "combinator sepEndBy1" prop_sepEndBy1
        , testProperty "combinator skipMany"  prop_skipMany
        , testProperty "combinator skipSome"  prop_skipSome ]

prop_between :: String -> Char -> NonNegative Int -> String -> Property
prop_between pre c n' post = checkParser p r s
  where p = between (string pre) (string post) (many (char c))
        n = getNonNegative n'
        b = length $ takeWhile (== c) post
        r | b > 0 = posErr (length pre + n + b) s $ exStr post :
                    if length post == b
                    then [uneEof]
                    else [uneCh (post !! b), exCh c]
          | otherwise = Right z
        z = replicate n c
        s = pre ++ z ++ post

prop_choice :: NonEmptyList Char -> Char -> Property
prop_choice cs' s' = checkParser p r s
  where cs = getNonEmpty cs'
        p = choice $ char <$> cs
        r | s' `elem` cs = Right s'
          | otherwise    = posErr 0 s $ uneCh s' : (exCh <$> cs)
        s = [s']

prop_count :: Int -> NonNegative Int -> Property
prop_count n x' = checkParser p r s
  where x = getNonNegative x'
        p = count n (char 'x')
        r = simpleParse (count' n n (char 'x')) s
        s = replicate x 'x'

prop_count' :: Int -> Int -> NonNegative Int -> Property
prop_count' m n x' = checkParser p r s
  where x = getNonNegative x'
        p = count' m n (char 'x')
        r | n <= 0 || m > n  =
              if x == 0
              then Right ""
              else posErr 0 s [uneCh 'x', exEof]
          | m <= x && x <= n = Right s
          | x < m            = posErr x s [uneEof, exCh 'x']
          | otherwise        = posErr n s [uneCh 'x', exEof]
        s = replicate x 'x'

prop_endBy :: NonNegative Int -> Char -> Property
prop_endBy n' c = checkParser p r s
  where n = getNonNegative n'
        p = endBy (char 'a') (char '-')
        r | c == 'a' && n == 0 = posErr 1 s [uneEof, exCh '-']
          | c == 'a'           = posErr (g n) s [uneCh 'a', exCh '-']
          | c == '-' && n == 0 = posErr 0 s [uneCh '-', exCh 'a', exEof]
          | c /= '-'           = posErr (g n) s $ uneCh c :
                                 (if n > 0 then exCh '-' else exEof) :
                                 [exCh 'a' | n == 0]
          | otherwise = Right (replicate n 'a')
        s = intersperse '-' (replicate n 'a') ++ [c]

prop_endBy1 :: NonNegative Int -> Char -> Property
prop_endBy1 n' c = checkParser p r s
  where n = getNonNegative n'
        p = endBy1 (char 'a') (char '-')
        r | c == 'a' && n == 0 = posErr 1 s [uneEof, exCh '-']
          | c == 'a'           = posErr (g n) s [uneCh 'a', exCh '-']
          | c == '-' && n == 0 = posErr 0 s [uneCh '-', exCh 'a']
          | c /= '-'           = posErr (g n) s $ uneCh c :
                                 [exCh '-' | n > 0] ++
                                 [exCh 'a' | n == 0]
          | otherwise = Right (replicate n 'a')
        s = intersperse '-' (replicate n 'a') ++ [c]

prop_manyTill :: NonNegative Int -> NonNegative Int
              -> NonNegative Int -> Property
prop_manyTill a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (,) <$> manyTill letterChar (char 'c') <*> many letterChar
        r | c == 0    = posErr (a + b) s [uneEof, exCh 'c', exSpec "letter"]
          | otherwise = let (pre, post) = break (== 'c') s
                        in Right (pre, drop 1 post)
        s = abcRow a b c

prop_someTill :: NonNegative Int -> NonNegative Int
              -> NonNegative Int -> Property
prop_someTill a' b' c' = checkParser p r s
  where [a,b,c] = getNonNegative <$> [a',b',c']
        p = (,) <$> someTill letterChar (char 'c') <*> many letterChar
        r | null s    = posErr 0 s [uneEof, exSpec "letter"]
          | c == 0    = posErr (a + b) s [uneEof, exCh 'c', exSpec "letter"]
          | s == "c"  = posErr 1 s [uneEof, exCh 'c', exSpec "letter"]
          | head s == 'c' = Right ("c", drop 2 s)
          | otherwise = let (pre, post) = break (== 'c') s
                        in Right (pre, drop 1 post)
        s = abcRow a b c

prop_option :: String -> String -> String -> Property
prop_option d a s = checkParser p r s
  where p = option d (string a)
        r = simpleParse (fromMaybe d <$> optional (string a)) s

prop_sepBy :: NonNegative Int -> Maybe Char -> Property
prop_sepBy n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepBy (char 'a') (char '-')
        r | isNothing c' = Right (replicate n 'a')
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a', exEof]
          | c == '-'  = posErr (length s) s [uneEof, exCh 'a']
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepBy1 :: NonNegative Int -> Maybe Char -> Property
prop_sepBy1 n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepBy1 (char 'a') (char '-')
        r | isNothing c' && n >= 1 = Right (replicate n 'a')
          | isNothing c' = posErr 0 s [uneEof, exCh 'a']
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a']
          | c == '-'  = posErr (length s) s [uneEof, exCh 'a']
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepEndBy :: NonNegative Int -> Maybe Char -> Property
prop_sepEndBy n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepEndBy (char 'a') (char '-')
        a = Right $ replicate n 'a'
        r | isNothing c' = a
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a', exEof]
          | c == '-'  = a
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_sepEndBy1 :: NonNegative Int -> Maybe Char -> Property
prop_sepEndBy1 n' c' = checkParser p r s
  where n = getNonNegative n'
        c = fromJust c'
        p = sepEndBy1 (char 'a') (char '-')
        a = Right $ replicate n 'a'
        r | isNothing c' && n >= 1 = a
          | isNothing c' = posErr 0 s [uneEof, exCh 'a']
          | c == 'a' && n == 0 = Right "a"
          | n == 0    = posErr 0 s [uneCh c, exCh 'a']
          | c == '-'  = a
          | otherwise = posErr (g n) s [uneCh c, exCh '-', exEof]
        s = intersperse '-' (replicate n 'a') ++ maybeToList c'

prop_skipMany :: Char -> NonNegative Int -> String -> Property
prop_skipMany c n' a = checkParser p r s
  where p = skipMany (char c) *> string a
        n = getNonNegative n'
        r = simpleParse (many (char c) >> string a) s
        s = replicate n c ++ a

prop_skipSome :: Char -> NonNegative Int -> String -> Property
prop_skipSome c n' a = checkParser p r s
  where p = skipSome (char c) *> string a
        n = getNonNegative n'
        r = simpleParse (some (char c) >> string a) s
        s = replicate n c ++ a

g :: Int -> Int
g x = x + if x > 0 then x - 1 else 0