{-# LANGUAGE BangPatterns, InstanceSigs, RankNTypes, ScopedTypeVariables, TypeFamilies #-}
-- | Continuation-passing parser for Parsing Expression Grammars that keeps track of the parsed prefix length
module Text.Grampa.PEG.Continued.Measured (Parser(..), Result(..), alt) where

import Control.Applicative (Applicative(..), Alternative(..), liftA2)
import Control.Monad (Monad(..), MonadPlus(..))

import Data.Char (isSpace)
import Data.Functor.Classes (Show1(..))
import Data.Functor.Compose (Compose(..))
import Data.List (nub)
import Data.Monoid (Monoid(mappend, mempty), (<>))
import Data.Monoid.Factorial(FactorialMonoid)
import Data.Monoid.Textual(TextualMonoid)
import Data.String (fromString)

import qualified Data.Monoid.Cancellative as Cancellative
import qualified Data.Monoid.Factorial as Factorial
import qualified Data.Monoid.Null as Null
import qualified Data.Monoid.Textual as Textual

import qualified Rank2

import qualified Text.Parser.Char
import Text.Parser.Char (CharParsing)
import Text.Parser.Combinators (Parsing(..))
import Text.Parser.LookAhead (LookAheadParsing(..))
import Text.Parser.Token (TokenParsing(someSpace))
import Text.Grampa.Class (MonoidParsing(..), MultiParsing(..), ParseResults, ParseFailure(..))
import Text.Grampa.Internal (FailureInfo(..))

data Result (g :: (* -> *) -> *) s v = Parsed{parsedPrefix :: !v,
                                              parsedSuffix :: !s}
                                     | NoParse FailureInfo

-- | Parser type for Parsing Expression Grammars that uses a continuation-passing algorithm and keeps track of the
-- parsed prefix length, fast for grammars in LL(1) class but with potentially exponential performance for longer
-- ambiguous prefixes.
newtype Parser (g :: (* -> *) -> *) s r =
   Parser{applyParser :: forall x. s -> (r -> Int -> s -> x) -> (FailureInfo -> x) -> x}

instance Show1 (Result g s) where
   liftShowsPrec showsPrecSub _showList prec Parsed{parsedPrefix= r} rest = "Parsed " ++ showsPrecSub prec r rest
   liftShowsPrec _showsPrec _showList _prec (NoParse f) rest = "NoParse " ++ shows f rest

instance Functor (Result g s) where
   fmap f (Parsed a rest) = Parsed (f a) rest
   fmap _ (NoParse failure) = NoParse failure
   
instance Functor (Parser g s) where
   fmap f (Parser p) = Parser (\input success-> p input (success . f))
   {-# INLINABLE fmap #-}

instance Applicative (Parser g s) where
   pure a = Parser (\input success _-> success a 0 input)
   (<*>) :: forall a b. Parser g s (a -> b) -> Parser g s a -> Parser g s b
   Parser p <*> Parser q = Parser r where
      r :: forall x. s -> (b -> Int -> s -> x) -> (FailureInfo -> x) -> x
      r rest success failure = p rest (\f len rest'-> q rest' (\a len'-> success (f a) $! len + len') failure) failure
   {-# INLINABLE (<*>) #-}

instance Factorial.FactorialMonoid s => Alternative (Parser g s) where
   empty = Parser (\rest _ failure-> failure $ FailureInfo 0 (fromIntegral $ Factorial.length rest) ["empty"])
   (<|>) = alt

-- | A named and unconstrained version of the '<|>' operator
alt :: forall g s a. Parser g s a -> Parser g s a -> Parser g s a
Parser p `alt` Parser q = Parser r where
   r :: forall x. s -> (a -> Int -> s -> x) -> (FailureInfo -> x) -> x
   r rest success failure = p rest success (\f1-> q rest success $ \f2 -> failure (f1 <> f2))

instance Monad (Parser g s) where
   return = pure
   (>>=) :: forall a b. Parser g s a -> (a -> Parser g s b) -> Parser g s b
   Parser p >>= f = Parser r where
      r :: forall x. s -> (b -> Int -> s -> x) -> (FailureInfo -> x) -> x
      r rest success failure = p rest 
                                 (\a len rest'-> applyParser (f a) rest' (\b len'-> success b $! len + len') failure)
                                 failure

instance Factorial.FactorialMonoid s => MonadPlus (Parser g s) where
   mzero = empty
   mplus = (<|>)

instance Monoid x => Monoid (Parser g s x) where
   mempty = pure mempty
   mappend = liftA2 mappend

instance Factorial.FactorialMonoid s => Parsing (Parser g s) where
   try = id
   (<?>) = const
   eof = endOfInput
   unexpected msg = Parser (\t _ failure -> failure $ FailureInfo 0 (fromIntegral $ Factorial.length t) [msg])
   notFollowedBy (Parser p) = Parser q
      where q :: forall x. s -> (() -> Int -> s -> x) -> (FailureInfo -> x) -> x
            q input success failure = p input success' failure'
               where success' _ _ _ = failure (FailureInfo 1 (fromIntegral $ Factorial.length input) ["notFollowedBy"])
                     failure' _ = success () 0 input

instance Factorial.FactorialMonoid s => LookAheadParsing (Parser g s) where
   lookAhead :: forall a. Parser g s a -> Parser g s a
   lookAhead (Parser p) = Parser q
      where q :: forall x. s -> (a -> Int -> s -> x) -> (FailureInfo -> x) -> x
            q input success failure = p input success' failure'
               where success' a _ _ = success a 0 input
                     failure' f = failure f

instance (Show s, TextualMonoid s) => CharParsing (Parser g s) where
   satisfy = satisfyChar
   string s = Textual.toString (error "unexpected non-character") <$> string (fromString s)
   char = satisfyChar . (==)
   notChar = satisfyChar . (/=)
   anyChar = satisfyChar (const True)
   text t = (fromString . Textual.toString (error "unexpected non-character")) <$> string (Textual.fromText t)

instance (Show s, TextualMonoid s) => TokenParsing (Parser g s) where
   someSpace = () <$ takeCharsWhile1 isSpace

instance MonoidParsing (Parser g) where
   endOfInput = Parser p
      where p rest success failure
               | Null.null rest = success () 0 rest
               | otherwise = failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["endOfInput"])
   getInput = Parser p
      where p rest success _ = success rest len mempty
               where !len = Factorial.length rest
   anyToken = Parser p
      where p rest success failure =
               case Factorial.splitPrimePrefix rest
               of Just (first, suffix) -> success first 1 suffix
                  _ -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["anyToken"])
   satisfy :: forall s. FactorialMonoid s => (s -> Bool) -> Parser g s s
   satisfy predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure =
               case Factorial.splitPrimePrefix rest
               of Just (first, suffix) | predicate first -> success first 1 suffix
                  _ -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["satisfy"])
   satisfyChar :: forall s. TextualMonoid s => (Char -> Bool) -> Parser g s Char
   satisfyChar predicate = Parser p
      where p :: forall x. s -> (Char -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure =
               case Textual.splitCharacterPrefix rest
               of Just (first, suffix) | predicate first -> success first 1 suffix
                  _ -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["satisfyChar"])
   satisfyCharInput :: forall s. TextualMonoid s => (Char -> Bool) -> Parser g s s
   satisfyCharInput predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure =
               case Textual.splitCharacterPrefix rest
               of Just (first, suffix) | predicate first -> success (Factorial.primePrefix rest) 1 suffix
                  _ -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["satisfyChar"])
   notSatisfy :: forall s. FactorialMonoid s => (s -> Bool) -> Parser g s ()
   notSatisfy predicate = Parser p
      where p :: forall x. s -> (() -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure =
               case Factorial.splitPrimePrefix rest
               of Just (first, _)
                     | predicate first -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["notSatisfy"])
                  _ -> success () 0 rest
   notSatisfyChar :: forall s. TextualMonoid s => (Char -> Bool) -> Parser g s ()
   notSatisfyChar predicate = Parser p
      where p :: forall x. s -> (() -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure =
               case Textual.characterPrefix rest
               of Just first | predicate first
                               -> failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["notSatisfyChar"])
                  _ -> success () 0 rest
   scan :: forall t s. FactorialMonoid t => s -> (s -> t -> Maybe s) -> Parser g t t
   scan s0 f = Parser (p s0)
      where p :: forall x. s -> t -> (t -> Int -> t -> x) -> (FailureInfo -> x) -> x
            p s rest success _ = success prefix len suffix
               where (prefix, suffix, _) = Factorial.spanMaybe' s f rest
                     !len = Factorial.length prefix
   scanChars :: forall t s. TextualMonoid t => s -> (s -> Char -> Maybe s) -> Parser g t t
   scanChars s0 f = Parser (p s0)
      where p :: forall x. s -> t -> (t -> Int -> t -> x) -> (FailureInfo -> x) -> x
            p s rest success _ = success prefix len suffix
               where (prefix, suffix, _) = Textual.spanMaybe_' s f rest
                     !len = Factorial.length prefix
   takeWhile :: forall s. FactorialMonoid s => (s -> Bool) -> Parser g s s
   takeWhile predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success _ 
               | (prefix, suffix) <- Factorial.span predicate rest, 
                 !len <- Factorial.length prefix = success prefix len suffix
   takeWhile1 :: forall s. FactorialMonoid s => (s -> Bool) -> Parser g s s
   takeWhile1 predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure
               | (prefix, suffix) <- Factorial.span predicate rest, 
                 !len <- Factorial.length prefix =
                    if len == 0
                    then failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["takeWhile1"])
                    else success prefix len suffix
   takeCharsWhile :: forall s. TextualMonoid s => (Char -> Bool) -> Parser g s s
   takeCharsWhile predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success _ 
               | (prefix, suffix) <- Textual.span_ False predicate rest, 
                 !len <- Factorial.length prefix = success prefix len suffix
   takeCharsWhile1 :: forall s. TextualMonoid s => (Char -> Bool) -> Parser g s s
   takeCharsWhile1 predicate = Parser p
      where p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
            p rest success failure
               | Null.null prefix = failure (FailureInfo 1 (fromIntegral $ Factorial.length rest) ["takeCharsWhile1"])
               | otherwise = success prefix len suffix
               where (prefix, suffix) = Textual.span_ False predicate rest
                     !len = Factorial.length prefix
   string :: forall s. (Cancellative.LeftReductiveMonoid s, FactorialMonoid s, Show s) => s -> Parser g s s
   string s = Parser p where
      p :: forall x. s -> (s -> Int -> s -> x) -> (FailureInfo -> x) -> x
      p s' success failure
         | Just suffix <- Cancellative.stripPrefix s s', !len <- Factorial.length s = success s len suffix
         | otherwise = failure (FailureInfo 1 (fromIntegral $ Factorial.length s') ["string " ++ show s])
   whiteSpace = () <$ takeCharsWhile isSpace
   concatMany :: forall s a. Monoid a => Parser g s a -> Parser g s a
   concatMany (Parser p) = Parser q
      where q :: forall x. s -> (a -> Int -> s -> x) -> (FailureInfo -> x) -> x
            q rest success _ = p rest success' failure
               where success' prefix !len suffix = 
                        q suffix (\prefix' !len'-> success (prefix <> prefix') (len + len')) 
                          (const $ success prefix len suffix)
                     failure _ = success mempty 0 rest
   {-# INLINABLE string #-}

-- | Continuation-passing PEG parser that keeps track of the parsed prefix length
--
-- @
-- 'parseComplete' :: ("Rank2".'Rank2.Functor' g, 'FactorialMonoid' s) =>
--                  g (Continued.'Parser' g s) -> s -> g 'ParseResults'
-- @
instance MultiParsing Parser where
   type ResultFunctor Parser = ParseResults
   -- | Returns an input prefix parse paired with the remaining input suffix.
   parsePrefix g input = Rank2.fmap (Compose . (\p-> applyParser p input (\a _ rest-> Right (rest, a)) 
                                                                 (Left . fromFailure input))) g
   parseComplete g input = Rank2.fmap (\p-> applyParser p input (const . const . Right) (Left . fromFailure input))
                                      (Rank2.fmap (<* endOfInput) g)

fromFailure :: FactorialMonoid s => s -> FailureInfo -> ParseFailure
fromFailure s (FailureInfo _ pos msgs) = ParseFailure (Factorial.length s - fromIntegral pos + 1) (nub msgs)