{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveLift #-}
{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RankNTypes        #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE StrictData #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE UndecidableSuperClasses #-}
{-# LANGUAGE RecordWildCards #-}
{-|
Module      : Frames.Streamly.CSV
Description : CSV parsing/formatting tools for the Frames library, operating via streamly Streams.
Copyright   : (c) Adam Conner-Sax 2020
License     : BSD-3-Clause
Maintainer  : adam_conner_sax@yahoo.com
Stability   : experimental

This module can be used in-place of Frames.CSV in order to use streamly streams where Frames uses pipes.
This module adds some functionality for formatting in more flexible ways than the pipes version in Frames.
It allows us of Show instances, in addition to the ShowCSV class included in Frames.  And it allows one-off
specification of a format as well.  See the example for more details.

There is also support for parsing only a subset of columns of a file, which can save time and memory during
loading and parsing of text. See the readme or Frames.Streamly.TH for more details.
-}
module Frames.Streamly.CSV
    (
      -- * Parsing
      ParserOptions(..)
    , defaultParser
    , textToSeparator
    , separatorToText
    , useRowFilter
      -- * Strict version of ReadRec
    , StrictReadRec (..)
      -- * read from File to Stream of Recs
    , readTable
    , readTableOpt
    , readTableMaybe
    , readTableMaybeOpt
    , readTableEither
    , readTableEitherOpt
      -- * convert streaming Text to streaming Records
    , streamTable
    , streamTableOpt
    , streamTableMaybe
    , streamTableMaybeOpt
    , streamTableEither
    , streamTableEitherOpt
      -- * Produce (streaming) Text from Records
    , streamToCSV
    , streamCSV
    , streamToSV
    , streamSV
    , streamSV'
      -- *  write Records to Text File
    , writeLines
    , writeCSV
    , writeSV
    , writeStreamSV
    , writeCSV_Show
    , writeSV_Show
    , writeStreamSV_Show
      -- * Utilities
    , streamToList
    , foldableToStream
    , liftFieldFormatter
    , liftFieldFormatter1
    , formatTextAsIs
    , formatWithShow
    , formatWithShowCSV
    -- * TH Support
    , sTokenized
    , ColTypeInfo(..)
    , readColHeaders
    -- * debugging
      -- * Re-exports
    , Separator(..)
    , QuoteChar
    , QuotingMode(..)
    , defaultSep
    , defaultQuotingMode
    , FramesCSVException(..)
    , ParseColumnSelector
    , ColumnIdType
      -- * Parsing scan
    , Acc(..)
    , accToMaybe
    , parsingScanF
    , parseOne
    )
where

import qualified Frames.Streamly.Internal.CSV as ICSV
import Frames.Streamly.Internal.CSV (FramesCSVException(..), ParseColumnSelector, ColumnIdType)
import Frames.Streamly.Streaming.Class (StreamFunctions(..), StreamFunctionsIO(..))
import Frames.Streamly.Streaming.Common (Separator(..)
                                        , QuoteChar
                                        , QuotingMode(..)
                                        , defaultSep
                                        , defaultQuotingMode
                                        , textToSeparator
                                        , separatorToText)
--import qualified Frames.Streamly.Streaming.Common as Streaming
import qualified Frames.Streamly.ColumnTypeable as FSCT

import Prelude hiding(getCompose)

import           Control.Monad.Catch                     ( MonadThrow(..))

import Language.Haskell.TH.Syntax (Lift)
import qualified Data.Set as Set

import qualified Data.Strict.Either as Strict
import qualified Data.Strict.Maybe as Strict
import qualified Data.Text                              as T

import qualified Data.Vinyl                             as Vinyl
import qualified Data.Vinyl.Functor                     as Vinyl
import qualified Data.Vinyl.TypeLevel                   as Vinyl
import qualified Data.Vinyl.Class.Method                as Vinyl

import qualified Frames
import qualified Frames.ShowCSV                         as Frames
import qualified Data.Vinyl as V
import qualified Data.Vinyl.Functor as V (Compose(..), (:.))
import GHC.TypeLits (KnownSymbol, ErrorMessage (Text))

-- | Holds column separator, quote handling and column selection information.
-- NB: This is generated by the 'tableTypes` family of functions
-- in Frames.Streamly.TH. That value should be used if at all possible
-- since it carries the correct column selection info.
data ParserOptions = ParserOptions
  {
    columnSelector :: ICSV.ParseColumnSelector
  , columnSeparator :: Separator
  , quotingMode :: QuotingMode
  } deriving Lift

{-
-- | Pull out the parts of 'ParserOptions' required for tokenizing and
-- paste into Frames ParserOptions to pass to Frames tokenizer.
framesParserOptionsForTokenizing :: ParserOptions -> Frames.ParserOptions
framesParserOptionsForTokenizing (ParserOptions _ cs qm) = Frames.ParserOptions Nothing (Streaming.separatorToText cs) qm
{-# INLINE framesParserOptionsForTokenizing #-}
-}

-- | A sensible default *only* for situations when all columns should be parsed.
defaultParser :: ParserOptions
defaultParser = ParserOptions (ICSV.ParseAll True) (CharSeparator ',') (RFC4180Quoting '\"')
{-# INLINEABLE defaultParser #-}

-- | Write a stream of Text to file at FilePath
writeLines :: StreamFunctionsIO s m => FilePath -> s (IOSafe s m) Text -> m ()
writeLines = sWriteTextLines
{-# INLINEABLE writeLines #-}

-- | Given a stream of @Records@, for which all fields satisfy the `ShowCSV` constraint,
-- produce a stream of `Text`, one item (line) per `Record` with the specified separator
-- between fields.
streamToSV
  :: forall rs m s.
     ( Frames.ColumnHeaders rs
     , Vinyl.RecordToList rs
     , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
     , StreamFunctions s m
     )
  => T.Text -- ^ column separator
  -> s m (Frames.Record rs) -- ^ stream of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamToSV = streamSVClass @Frames.ShowCSV Frames.showCSV
{-# INLINEABLE streamToSV #-}

-- | Given a stream of @Records@, for which all fields satisfy the `ShowCSV` constraint,
-- produce a stream of CSV `Text`, one item (line) per `Record`.
streamToCSV
  :: forall rs m s
     . ( Frames.ColumnHeaders rs
       , Vinyl.RecordToList rs
       , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
       , StreamFunctions s m
       )
  => s m (Frames.Record rs) -- ^ stream of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamToCSV = streamToSV ","
{-# INLINEABLE streamToCSV #-}

-- | Given a foldable of @Records@, for which all fields satisfy the `ShowCSV` constraint,
-- produce a stream of `Text`, one item (line) per `Record` with the specified separator
-- between fields.
streamSV
  :: forall f rs m s.
     ( Frames.ColumnHeaders rs
     , Foldable f
     , Vinyl.RecordToList rs
     , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
     , StreamFunctions s m
     )
  => T.Text -- ^ column separator
  -> f (Frames.Record rs) -- ^ foldable of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamSV sep = streamToSV sep . sFromFoldable
{-# INLINEABLE streamSV #-}

-- | Given a foldable of @Records@, for which all fields satisfy the `ShowCSV` constraint,
-- produce a stream of CSV `Text`, one item (line) per `Record`.
streamCSV
  :: forall f rs m s.
     ( Frames.ColumnHeaders rs
     , Foldable f
     , Vinyl.RecordToList rs
     , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
     , StreamFunctions s m
     )
  => f (Frames.Record rs)  -- ^ 'Foldable' of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamCSV = streamSV ","
{-# INLINEABLE streamCSV #-}

-- | Convert @Rec@s to lines of `Text` using a class (which must have an instance
-- for each type in the record) to covert each field to `Text`.
streamSVClass
  :: forall c rs s m .
      ( Vinyl.RecMapMethod c Vinyl.ElField rs
      , Vinyl.RecordToList rs
      , Frames.ColumnHeaders rs
      , StreamFunctions s m
     )
  => (forall a. c a => a -> T.Text) -- ^ @show@-like function for some constraint satisfied by all fields.
  -> T.Text -- ^ column separator
  -> s m (Frames.Record rs)  -- ^ stream of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamSVClass toTxt sep s =
  (T.intercalate sep . fmap T.pack $ Frames.columnHeaders (Proxy :: Proxy (Frames.Record rs)))
  `sCons`
  (sMap (svLineClass @c toTxt sep) s)
{-# INLINEABLE streamSVClass #-}

svLineClass :: forall c rs .
               ( Vinyl.RecMapMethod c Vinyl.ElField rs
               , Vinyl.RecordToList rs
               , Frames.ColumnHeaders rs
               )
  => (forall a. c a => a -> T.Text) -- ^ @show@-like function for some constraint satisfied by all fields.
  -> T.Text -- ^ column separator
  -> Frames.Record rs
  -> T.Text -- ^ stream of 'Text' rows
svLineClass toTxt sep = T.intercalate sep . Vinyl.recordToList . Vinyl.rmapMethod @c aux where
  aux :: (c (Vinyl.PayloadType Vinyl.ElField a))
      => Vinyl.ElField a
      -> Vinyl.Const T.Text a
  aux (Vinyl.Field x) = Vinyl.Const $ toTxt x
{-# INLINEABLE svLineClass #-}


-- | Given a record of functions to map each field to Text,
-- transform a stream of records into a stream of lines of Text,
-- headers first, with headers/fields separated by the given separator.
streamSV'
  :: forall rs s m f.
     (Vinyl.RecordToList rs
     , Vinyl.RApply rs
     , Frames.ColumnHeaders rs
     , StreamFunctions s m
     )
  => Vinyl.Rec (Vinyl.Lift (->) f (Vinyl.Const T.Text)) rs -- ^ Vinyl record of formatting functions for the row-type.
  -> T.Text  -- ^ column separator
  -> s m (Frames.Rec f rs)  -- ^ stream of Records
  -> s m T.Text -- ^ stream of 'Text' rows
streamSV' toTextRec sep s =
 ( T.intercalate sep . fmap T.pack $ Frames.columnHeaders (Proxy :: Proxy (Frames.Record rs)))
  `sCons`
  (sMap (svLine toTextRec sep) s)
{-# INLINEABLE streamSV' #-}


svLine :: forall rs f.
          (Vinyl.RecordToList rs
          , Vinyl.RApply rs
          , Frames.ColumnHeaders rs
          )
       => Vinyl.Rec (Vinyl.Lift (->) f (Vinyl.Const T.Text)) rs -- ^ Vinyl record of formatting functions for the row-type.
       -> T.Text-- column separator
       -> Frames.Rec f rs
       -> T.Text
svLine toTextRec sep = T.intercalate sep . Vinyl.recordToList . Vinyl.rapply toTextRec
{-# INLINEABLE svLine #-}

-- | Convert a streamly stream into a (lazy) list
streamToList :: StreamFunctions s m => s m a -> m [a]
streamToList = sToList
{-# INLINE streamToList #-}

foldableToStream :: (Foldable f, StreamFunctions s m) => f a -> s m a
foldableToStream = sFromFoldable
{-# INLINE foldableToStream #-}

-- | lift a field formatting function into the right form to append to a Rec of formatters
liftFieldFormatter :: Vinyl.KnownField t
                   => (Vinyl.Snd t -> T.Text) -- ^ formatting function for the type in Field @t@
                   -> Vinyl.Lift (->) Vinyl.ElField (Vinyl.Const T.Text) t -- ^ formatting function in the form required to use in row-formatters.
liftFieldFormatter toTxt = Vinyl.Lift $ Vinyl.Const . toTxt . Vinyl.getField
{-# INLINEABLE liftFieldFormatter #-}

-- | lift a composed-field formatting function into the right form to append to a Rec of formatters
-- | Perhaps to format a parsed file with @Maybe@ or @Either@ composed with @ElField@
liftFieldFormatter1 :: (Functor f, Vinyl.KnownField t)
                    => (f (Vinyl.Snd t) -> T.Text) -- ^ formatting function for things like @Maybe a@
                    -> Vinyl.Lift (->) (f Vinyl.:. Vinyl.ElField) (Vinyl.Const T.Text) t
liftFieldFormatter1 toTxt = Vinyl.Lift $ Vinyl.Const . toTxt . fmap Vinyl.getField . Vinyl.getCompose
{-# INLINEABLE liftFieldFormatter1 #-}

-- | Format a @Text@ field as-is.
formatTextAsIs :: (Vinyl.KnownField t, Vinyl.Snd t ~ T.Text)
               => Vinyl.Lift (->) Vinyl.ElField (Vinyl.Const T.Text) t
formatTextAsIs = liftFieldFormatter id
{-# INLINE formatTextAsIs #-}

-- | Format a field using the @Show@ instance of the contained type
formatWithShow :: (Vinyl.KnownField t, Show (Vinyl.Snd t))
               => Vinyl.Lift (->) Vinyl.ElField (Vinyl.Const T.Text) t
formatWithShow = liftFieldFormatter $ T.pack . show
{-# INLINE formatWithShow #-}

-- | Format a field using the @Frames.ShowCSV@ instance of the contained type
formatWithShowCSV :: (Vinyl.KnownField t, Frames.ShowCSV (Vinyl.Snd t))
                  => Vinyl.Lift (->) Vinyl.ElField (Vinyl.Const T.Text) t
formatWithShowCSV = liftFieldFormatter Frames.showCSV
{-# INLINE formatWithShowCSV #-}

-- NB: Uses some internal modules from Streamly.  Will have to change when they become stable
-- | write a stream of @Records@ to a file, one line per @Record@.
-- Use the 'Frames.ShowCSV' class to format each field to @Text@
writeStreamSV
  ::  forall rs m s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
   , StreamFunctionsIO s m
   )
  => T.Text -- ^ column separator
  -> FilePath -- ^ path
  -> s (IOSafe s m) (Frames.Record rs) -- ^ stream of Records
  -> m ()
writeStreamSV sep fp = sWriteTextLines fp . streamToSV sep
{-# INLINEABLE writeStreamSV #-}

-- | write a foldable of @Records@ to a file, one line per @Record@.
-- Use the 'Frames.ShowCSV' class to format each field to @Text@
writeSV
  ::  forall rs m f s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
   , StreamFunctionsIO s m
   , Foldable f
   )
  => T.Text -- ^ column separator
  -> FilePath -- ^ file path
  -> f (Frames.Record rs) -- ^ Foldable of Records
  -> m ()
writeSV sep fp = writeStreamSV @_ @_ @s sep fp . sFromFoldable
{-# INLINEABLE writeSV #-}

-- | write a foldable of @Records@ to a file, one line per @Record@.
-- Use the 'Frames.ShowCSV' class to format each field to @Text@
writeCSV
  ::  forall rs m f s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Frames.ShowCSV Vinyl.ElField rs
   , StreamFunctionsIO s m
   , Foldable f
   )
  => FilePath -- ^ file path
  -> f (Frames.Record rs) -- ^ 'Foldable' of Records
  -> m ()
writeCSV = writeSV @_ @_ @_ @s ","
{-# INLINEABLE writeCSV #-}

-- NB: Uses some internal modules from Streamly.  Will have to change when they become stable

-- | write a stream of @Records@ to a file, one line per @Record@.
-- Use the 'Show' class to format each field to @Text@
writeStreamSV_Show
  ::  forall rs m s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Show Vinyl.ElField rs
   , StreamFunctionsIO s m
   )
  => T.Text -- ^ column separator
  -> FilePath -- ^ file path
  -> s (IOSafe s m) (Frames.Record rs) -- ^ stream of Records
  -> m ()
writeStreamSV_Show sep fp = sWriteTextLines fp . streamSVClass @Show (T.pack . show) sep
{-# INLINEABLE writeStreamSV_Show #-}

-- | write a foldable of @Records@ to a file, one line per @Record@.
-- Use the 'Show' class to format each field to @Text@
writeSV_Show
  ::  forall rs m f s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Show Vinyl.ElField rs
   , StreamFunctionsIO s m
   , Foldable f
   )
  => T.Text -- ^ column separator
  -> FilePath  -- ^ file path
  -> f (Frames.Record rs) -- ^ 'Foldable' of Records
  -> m ()
writeSV_Show sep fp = writeStreamSV_Show @_ @_ @s sep fp . sFromFoldable
{-# INLINEABLE writeSV_Show #-}

-- | write a foldable of @Records@ to a file, one line per @Record@.
-- Use the 'Show' class to format each field to @Text@
writeCSV_Show
  ::  forall rs m f s.
   ( Frames.ColumnHeaders rs
   , Vinyl.RecordToList rs
   , Vinyl.RecMapMethod Show Vinyl.ElField rs
   , StreamFunctionsIO s m
   , Foldable f
   )
  => FilePath -- ^ file path
  -> f (Frames.Record rs) -- ^ 'Foldable' of Records
  -> m ()
writeCSV_Show = writeSV_Show @_ @_ @_ @s ","
{-# INLINEABLE writeCSV_Show #-}

-- Thanks to Tim Pierson for the functions below!

-- | Stream a table from a file path, using the default options.
-- Results composed with the @Maybe@ functor. Unparsed fields are returned as @Nothing@.
-- NB:  If the inferred/given rs is different from the actual file row-type, things will go awry.
readTableMaybe
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctionsIO s m
    )
    => FilePath -- ^ file path
    -> s (IOSafe s m) (Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs) -- ^ stream of @Maybe :. ElField@ records after parsing.
readTableMaybe = readTableMaybeOpt @_ @s @m defaultParser
{-# INLINEABLE readTableMaybe #-}

-- | Stream a table from a file path.
-- Results composed with the @Maybe@ functor. Unparsed fields are returned as @Nothing@.
-- NB:  If the inferred/given rs is different from the actual file row-type, things will go awry.
readTableMaybeOpt
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctionsIO s m
    )
    => ParserOptions -- ^ parsing options
    -> FilePath -- ^ file path
    -> s (IOSafe s m) (Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs) -- ^ stream of @Maybe :. ElField@ records after parsing.
readTableMaybeOpt opts = sMap recEitherToMaybe . readTableEitherOpt @_ @s @m opts
{-# INLINEABLE readTableMaybeOpt #-}

-- | Stream a table from a file path.
-- Results composed with the @Either Text@ functor. Unparsed fields are returned as a @Left@
-- containing the string that failed to parse.
-- Uses default options.
-- NB:  If the inferred/given rs is different from the actual file row-type, things will go awry.
readTableEither
  :: forall rs s m.
     ( Vinyl.RMap rs
     , StrictReadRec rs
     , MonadThrow m
     , StreamFunctionsIO s m
     )
  => FilePath -- ^ file path
  -> s (IOSafe s m) (Vinyl.Rec (Either T.Text Vinyl.:. Vinyl.ElField) rs) -- ^ stream of @Either :. ElField@ records after parsing.
readTableEither = readTableEitherOpt @rs @s @m defaultParser
{-# INLINEABLE readTableEither #-}

-- | Stream a table from a file path.
-- Results composed with the @Either Text@ functor. Unparsed fields are returned as a @Left@
-- containing the string that failed to parse.
-- NB:  If the inferred/given rs is different from the actual file row-type, things will go awry.
readTableEitherOpt
  :: forall rs s m.
     ( Vinyl.RMap rs
     , StrictReadRec rs
     , StreamFunctionsIO s m
     )
  => ParserOptions -- ^ parsing options
  -> FilePath -- ^ file path
  -> s (IOSafe s m) (Vinyl.Rec (Either T.Text Vinyl.:. Vinyl.ElField) rs) -- ^ stream of @Either :. ElField@ records after parsing.
readTableEitherOpt opts = streamTableEitherOpt @rs @s @(IOSafe s m) opts . sTokenized @s @m (columnSeparator opts) (quotingMode opts)
{-# INLINEABLE readTableEitherOpt #-}

-- | Stream Table from a file path, dropping rows where any field fails to parse
-- | Use default options
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will go awry.
readTable
  :: forall rs s m.
     ( Vinyl.RMap rs
     , StrictReadRec rs
     , StreamFunctionsIO s m
     )
  => FilePath -- ^ file path
  -> s (IOSafe s m) (Frames.Record rs) -- ^ stream of Records
readTable = readTableOpt @rs @s @m defaultParser
{-# INLINEABLE readTable #-}

-- | Stream Table from a file path, dropping rows where any field fails to parse
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will go awry.
readTableOpt
  :: forall rs s m.
     ( Vinyl.RMap rs
     , StrictReadRec rs
     , StreamFunctionsIO s m
     )
  => ParserOptions  -- ^ parsing options
  -> FilePath -- ^ file path
  -> s (IOSafe s m) (Frames.Record rs)  -- ^ stream of Records
readTableOpt !opts !fp = streamTableOpt @rs @s @(IOSafe s m) opts $! sTokenized @s @m (columnSeparator opts) (quotingMode opts) fp
{-# INLINEABLE readTableOpt #-}

-- | Convert a stream of lines of `Text` to a table
-- Each field is returned in an @Either Text@ functor. @Right a@ for successful parses
-- and @Left Text@ when parsing fails, containing the text that failed to Parse.
--
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will go awry.
streamTableEither
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => s m [T.Text] -- ^ stream of 'Text' rows
    -> s m (Vinyl.Rec (Either T.Text Vinyl.:. Vinyl.ElField) rs) -- ^ stream of parsed @Either :. ElField@ rows
streamTableEither = streamTableEitherOpt defaultParser
{-# INLINEABLE streamTableEither #-}


data Acc b = AccInitial
           | AccResult  !(Maybe [Bool]) !(Strict.Maybe b)

accToMaybe :: Acc b -> Maybe b
accToMaybe AccInitial = Nothing
accToMaybe (AccResult _ smb) = case smb of
  Strict.Nothing -> Nothing
  Strict.Just x -> Just x
{-# INLINEABLE accToMaybe #-}

-- | Various parsing options have to handle the header line, if it exists,
-- differently.  This function pulls all that logic into one place.
-- We take the 'ParserOptions' and the stream of un-tokenized 'Text' lines
-- and do whatever is required, checking for various errors
-- (empty stream, missing headers, wrong number of columns when using positions for typing/naming)
-- along the way.
handleHeader :: forall m. (MonadThrow m)
             => ParserOptions
             -> [T.Text]
             -> m (Maybe [Bool], Bool)
handleHeader opts t = case columnSelector opts of
  ICSV.ParseAll True -> return (Nothing, True)
  ICSV.ParseAll False ->  return (Nothing, False)
  ICSV.ParseIgnoringHeader cs -> checkNumFirstRowCols t cs >> return (Just $ csToBool <$> cs, True)
  ICSV.ParseWithoutHeader cs -> checkNumFirstRowCols t cs >> return (Just $ csToBool <$> cs, False)
  ICSV.ParseUsingHeader hs -> (, True) . Just <$> boolsFromHeader hs t
  where
    csToBool x = x /= ICSV.Exclude

--    tokenizedFirstRow :: T.Text -> [Text]
--    tokenizedFirstRow x = Frames.tokenizeRow (framesParserOptionsForTokenizing opts) x

    boolsFromHeader :: [ICSV.HeaderText] ->  [T.Text] -> m [Bool]
    boolsFromHeader hs x = do
      let headersToInclude = Set.fromList hs
          includeHeader y = y `Set.member` headersToInclude
          fileHeaders = ICSV.HeaderText <$> x
          fileHeadersS = Set.fromList fileHeaders
          notPresentM y = if y `Set.member` fileHeadersS then Nothing else Just y
          missingIncluded = mapMaybe notPresentM hs
      unless (null missingIncluded) $ throwM $ ICSV.MissingHeadersException missingIncluded
      let bools = includeHeader <$> fileHeaders
      return bools

    checkNumFirstRowCols :: [T.Text] -> [ICSV.ColumnState] -> m ()
    checkNumFirstRowCols x cs = checkSameLength cs x

    checkSameLength :: [ICSV.ColumnState] -> [b] -> m ()
    checkSameLength givenCSs streamCols = do
      let nGiven = length givenCSs
          nStreamCols = length streamCols
          errMsg = "Number of given columns from type generation (" <> show nGiven
                   <> ") doesn't match the number of columns in the parsed file ("
                   <> show nStreamCols <> ")"
      when (nGiven /= nStreamCols) $ throwM $ ICSV.WrongNumberColumnsException errMsg
      return ()

parsingScanF :: MonadThrow m
             => ParserOptions
             -> (Maybe [Bool] -> [Text] -> Strict.Maybe b)
             -> (Acc b -> [Text] -> m (Acc b))
parsingScanF opts pF sta t = case sta of
  AccInitial -> do
    (rF, dropFirst) <- handleHeader opts t
    let res = if dropFirst then Strict.Nothing else pF rF t
    return $ AccResult rF res
  AccResult rF _ -> return $ AccResult rF $ pF rF t
{-# INLINEABLE parsingScanF #-}

-- | Convert a stream of lines of `Text` to records.
-- Each field is returned in an @Either Text@ functor. @Right a@ for successful parses
-- and @Left Text@ when parsing fails, containing the text that failed to Parse.
--
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will...go awry.
streamTableEitherOpt
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => ParserOptions -- ^ parsing options
    -> s m [T.Text] -- ^ stream of 'Text' rows
    -> s m (Vinyl.Rec ((Either T.Text) Vinyl.:. Vinyl.ElField) rs)  -- ^ stream of parsed @Either :. ElField@ rows
streamTableEitherOpt opts = sMapMaybe accToMaybe . sScanM (parsingScanF opts parseOne') (return AccInitial)
  where
    parseOne' :: Maybe [Bool] -> [Text] -> Strict.Maybe (Vinyl.Rec ((Either T.Text) Vinyl.:. Vinyl.ElField) rs)
    parseOne' rF = Strict.Just . recUnStrictEither . parse . useRowFilter rF
    parse = strictReadRec
{-# INLINEABLE streamTableEitherOpt #-}

-- | Convert a stream of lines of `Text` to a table.
--
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will..go awry.
streamTableMaybe
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => s m [T.Text] -- ^ stream of 'Text' rows
    -> s m (Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs) -- ^ stream of parsed @Maybe :. ElField@ rows
streamTableMaybe = streamTableMaybeOpt defaultParser
{-# INLINEABLE streamTableMaybe #-}

-- | Convert a stream of lines of Text to a table .
--
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will..go awry.
streamTableMaybeOpt
    :: forall rs s m.
    (Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => ParserOptions -- ^ parsing options
    -> s m [T.Text] -- ^ stream of 'Text' rows
    -> s m (Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs) -- ^ stream of parsed @Maybe :. ElField@ rows
streamTableMaybeOpt opts = sMap recEitherToMaybe . streamTableEitherOpt opts
{-# INLINEABLE streamTableMaybeOpt #-}

-- | Convert a stream of lines of 'Text' to a table,
-- dropping rows where any field fails to parse.
-- Use default options.
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will go awry.
streamTable
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => s m [T.Text] -- ^ stream of 'Text' rows
    -> s m (Frames.Record rs) -- ^ stream of Records
streamTable = streamTableOpt defaultParser
{-# INLINEABLE streamTable #-}

-- | Convert a stream of lines of 'Text' `Word8` to a table,
-- dropping rows where any field fails to parse.
-- NB:  If the inferred/given @rs@ is different from the actual file row-type, things will go awry.
streamTableOpt
    :: forall rs s m.
    ( Vinyl.RMap rs
    , StrictReadRec rs
    , MonadThrow m
    , StreamFunctions s m
    )
    => ParserOptions -- ^ parsing options
    -> s m [T.Text]  -- ^ stream of 'Text' rows
    -> s m (Frames.Record rs) -- ^ stream of Records
streamTableOpt opts = sMapMaybe accToMaybe . sScanM (parsingScanF opts parseOne) (return AccInitial)
{-# INLINEABLE streamTableOpt #-}

parseOne :: (V.RMap rs
            , StrictReadRec rs
            )
         => Maybe [Bool] -> [Text] -> Strict.Maybe (Frames.Record rs)
parseOne rF t = maybe Strict.Nothing Strict.Just $! Frames.recMaybe $! doParseStrict $! useRowFilter rF t
{-# INLINEABLE parseOne #-}

-- | Parse using StrictReadRec
doParseStrict :: (V.RMap rs, StrictReadRec rs) => [Text] -> V.Rec (Maybe V.:. V.ElField) rs
doParseStrict !x = recStrictEitherToMaybe $! strictReadRec x
{-# INLINEABLE doParseStrict #-}


recEitherToMaybe :: Vinyl.RMap rs => Vinyl.Rec (Either T.Text Vinyl.:. Vinyl.ElField) rs -> Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs
recEitherToMaybe = Vinyl.rmap (either (const (Vinyl.Compose Nothing)) (Vinyl.Compose . Just) . Vinyl.getCompose)
{-# INLINEABLE recEitherToMaybe #-}

recStrictEitherToMaybe :: Vinyl.RMap rs => Vinyl.Rec (Strict.Either T.Text Vinyl.:. Vinyl.ElField) rs -> Vinyl.Rec (Maybe Vinyl.:. Vinyl.ElField) rs
recStrictEitherToMaybe = Vinyl.rmap (Strict.either (const (Vinyl.Compose Nothing)) (Vinyl.Compose . Just) . Vinyl.getCompose)
{-# INLINEABLE recStrictEitherToMaybe #-}

recUnStrictEither :: Vinyl.RMap rs => Vinyl.Rec (Strict.Either T.Text Vinyl.:. Vinyl.ElField) rs -> Vinyl.Rec (Either T.Text Vinyl.:. Vinyl.ElField) rs
recUnStrictEither = Vinyl.rmap (Vinyl.Compose . Strict.either Left Right . Vinyl.getCompose)
{-# INLINEABLE recUnStrictEither #-}
{-
-- | Convert a stream of Word8 to lines of `Text` by decoding as UTF8 and splitting on "\n"
word8ToTextLines :: (IsStream t, MonadIO m) => t m Word8 -> t m T.Text
word8ToTextLines =  Streamly.splitOnSuffix(=='\n') (toText <$> Streamly.Fold.toList)
                    . Streamly.Unicode.decodeUtf8
{-# INLINE word8ToTextLines #-}

word8ToTextLines2 :: (IsStream t, MonadIO m) => t m Word8 -> t m T.Text
word8ToTextLines2 =  Streamly.map (toText . Streamly.Array.toList)
                     . Streamly.Unicode.Array.lines
                     . Streamly.Unicode.decodeUtf8
{-# INLINE word8ToTextLines2 #-}
-}
-- | Parse list of text into @Rec (Either :. ElField)@ using strict @Either@
-- Don't make this INLINE!! GHC 8.10.7 goes on forever...
class StrictReadRec rs where
  strictReadRec :: [Text] -> V.Rec (Strict.Either Text V.:. V.ElField) rs

instance StrictReadRec '[] where
  strictReadRec _ = V.RNil
  {-# INLINEABLE strictReadRec #-}
-- Don't make this INLINE!! GHC 8.10.7 goes on forever.   INLINABLE seems okay

instance (FSCT.Parseable t, StrictReadRec ts, KnownSymbol s) => StrictReadRec (s Frames.:-> t ': ts) where
  -- This one is neccesary to avoid a warning about incomplete pattern matches. ??
  strictReadRec [] = V.Compose (Strict.Left mempty) V.:& strictReadRec []

  strictReadRec (!h : t) = maybe
                           (V.Compose (Strict.Left (T.copy h)))
                           (V.Compose . Strict.Right . V.Field)
                           (FSCT.parse' h)
                           V.:& strictReadRec t
  {-# INLINEABLE strictReadRec #-}
-- Don't make this INLINE!! GHC 8.10.7 goes on forever.

useRowFilter :: Maybe [Bool] -> [Text] -> [Text]
useRowFilter = maybe id f  where
  f bs xs = snd <$> filter fst (zip bs xs)
{-# INLINEABLE useRowFilter #-}

-- for TH inference
prefixInference :: forall a s m.(MonadThrow m
                                , Monad m
                                , StreamFunctions s m
                                , FSCT.ColumnTypeable a
                                )
                => FSCT.Parsers a
                -> (Text -> Bool)
                -> Maybe [Bool]
                -> s m [T.Text]
                -> m [a]
prefixInference parsers isMissing rF s = do
  sThrowIfEmpty s
  let inferCols = fmap (FSCT.inferType @a parsers isMissing) -- need type application here to know what col-type to infer
      step ts = zipWith (FSCT.updateWithParse parsers) ts . inferCols
      start = repeat FSCT.initialColType

  sFolder step start $ sMap (useRowFilter rF) s
{-# INLINEABLE prefixInference #-}

data ColTypeInfo a = ColTypeInfo { colTypeName :: ICSV.ColTypeName, orMissingWhen :: ICSV.OrMissingWhen, colBaseType :: a}

-- | Extract column names and inferred types from a CSV file.
readColHeaders :: forall a b s m.
                  (Show (ICSV.ColumnIdType b)
                  , Monad m
                  , MonadThrow m
                  , StreamFunctions s m
                  , FSCT.ColumnTypeable a
                  )
               => FSCT.Parsers a
               -> ICSV.RowGenColumnSelector b-- headerOverride
               -> s m [Text]
               -> m ([ColTypeInfo a], ICSV.ParseColumnSelector)
readColHeaders parsers rgColHandler s =  do
  let csToBool =  (/= ICSV.Exclude)
  (firstRow, mTail) <- sUncons s >>= maybe (throwM ICSV.EmptyStreamException) return
  -- headerRow :: [(ICSV.ColTypeName , ICSV.OrMissingWhen)]
  -- pch :: ICSV.ParseColumnSelector
  -- rF :: Maybe [Bool]
  (headerRow, pch, rF, inferS) <- case rgColHandler of
    ICSV.GenUsingHeader f mrF -> do
      let allHeaders = ICSV.HeaderText <$> firstRow -- (draw >>= maybe err return)
      checkColumnIds mrF allHeaders
      let allColStates = f <$> allHeaders
          allBools = csToBool <$> allColStates
          includedInfo = ICSV.includedColTypeInfo allColStates
          parseColHeader = ICSV.colStatesAndHeadersToParseColHandler allColStates allHeaders
      return (includedInfo, parseColHeader, Just allBools, mTail)
    ICSV.GenIgnoringHeader f mrF -> do
      let allHeaders = firstRow -- <- draw >>= maybe err return
          allIndexes = [0..(length allHeaders - 1)]
      checkColumnIds mrF allIndexes
      let allColStates = f  <$> allIndexes
          allBools = csToBool <$> allColStates
          includedInfo = ICSV.includedColTypeInfo allColStates
          parseColHeader = ICSV.ParseIgnoringHeader allColStates
      return (includedInfo, parseColHeader, Just allBools, mTail)
    ICSV.GenWithoutHeader f mrF -> do
      let sampleRow = firstRow -- <- peek >>= maybe err return
          allIndexes = [0..(length sampleRow - 1)]
      checkColumnIds mrF allIndexes
      let allColStates =  f <$> allIndexes
          allBools = csToBool <$> allColStates
          includedInfo = ICSV.includedColTypeInfo allColStates
          parseColHeader = ICSV.ParseWithoutHeader allColStates
      return (includedInfo, parseColHeader, Just allBools, s)
  let isMissing t = T.null t || t == "NA"
      assembleCTI :: (ICSV.ColTypeName, ICSV.OrMissingWhen) -> a -> ColTypeInfo a
      assembleCTI (a, b) c = ColTypeInfo a b c
  colTypes <- prefixInference @a @s parsers isMissing rF inferS
  unless (length headerRow == length colTypes) $ errNumColumns headerRow colTypes
  return (zipWith assembleCTI headerRow colTypes, pch)
  where errNumColumns hs cts =
          throwM
          $ ICSV.BadHeaderException
          $ (unlines
          [ ""
          , "Error parsing CSV: "
          , "  Number of columns in header differs from number of columns"
          , "  found in the remaining file. This may be due to newlines"
          , "  being present within the data itself (not just separating"
          , "  rows). If support for embedded newlines is required, "
          , "  consider using the Frames-dsv package in conjunction with"
          , "  Frames to make use of a different CSV parser."])
          <> "\nHeaders: " <> show hs <> "\nNumber ColTypes: " <> show (length cts)
        checkColumnIds :: ICSV.MissingRequiredIdsF b -> [ICSV.ColumnIdType b] -> m ()
        checkColumnIds mrF fileIds = do
          let missing = mrF fileIds
          unless (null missing)
            $ throwM
            $ ICSV.BadHeaderException
            $ "Required columnIds (headers or positions) are missing from file being parsed.  Missing=" <> show missing
          return ()
{-# INLINEABLE readColHeaders #-}
{-
streamWord8 :: (Streamly.IsStream t, Streamly.MonadAsync m, MonadCatch m) => FilePath -> t m Word8
streamWord8 =  Streamly.File.toBytes
{-# INLINE streamWord8 #-}

streamTextLines :: (Streamly.IsStream t, Streamly.MonadAsync m, MonadCatch m) => FilePath -> t m Text
streamTextLines = word8ToTextLines2 . streamWord8
{-# INLINE streamTextLines #-}
-}
{-
streamTokenized' :: forall s m.StreamFunctionsIO s m => FilePath -> Frames.Separator -> s (IOSafe s m) [Text]
streamTokenized' fp sep =  sMap (fmap T.copy . Frames.tokenizeRow popts) $ sReadTextLines @s @m fp where
  popts = Frames.defaultParser { Frames.columnSeparator = sep }
{-# INLINE streamTokenized' #-}

streamTokenized :: forall s m.StreamFunctionsIO s m => FilePath -> s (IOSafe s m) [Text]
streamTokenized =  sMap (fmap T.copy . Frames.tokenizeRow Frames.defaultParser) . sReadTextLines @s @m
{-# INLINE streamTokenized #-}

streamParsed :: forall rs s m.(V.RMap rs, StrictReadRec rs, StreamFunctionsIO s m)
             => FilePath
             -> s (IOSafe s m) (V.Rec (Strict.Either Text V.:. V.ElField) rs)
streamParsed = sMap (strictReadRec . Frames.tokenizeRow Frames.defaultParser) . sReadTextLines @s @m
{-# INLINE streamParsed #-}

streamParsedMaybe :: forall rs s m.(V.RMap rs, StrictReadRec rs, StreamFunctionsIO s m)
                  => FilePath -> s (IOSafe s m) (V.Rec (Maybe V.:. V.ElField) rs)
streamParsedMaybe =  sMap (recStrictEitherToMaybe . strictReadRec . Frames.tokenizeRow Frames.defaultParser) . sReadTextLines @s @m
{-# INLINE streamParsedMaybe #-}
-}