--- * -*- outline-regexp:"--- \\*"; -*-
--- ** doc
-- In Emacs, use TAB on lines beginning with "-- *" to collapse/expand sections.
{-|

A reader for CSV (character-separated) data.
This also reads a rules file to help interpret the CSV data.

-}

--- ** language
{-# LANGUAGE FlexibleContexts     #-}
{-# LANGUAGE FlexibleInstances    #-}
{-# LANGUAGE OverloadedStrings    #-}
{-# LANGUAGE ScopedTypeVariables  #-}
{-# LANGUAGE TypeFamilies         #-}

--- ** exports
module Hledger.Read.CsvReader (
  -- * Reader
  reader,
  -- * Tests
  tests_CsvReader,
)
where

--- ** imports
import Prelude hiding (Applicative(..))
import Control.Monad.Except       (ExceptT(..), liftEither)
import Control.Monad.IO.Class     (MonadIO)
import System.IO                  (Handle)

import Hledger.Data
import Hledger.Utils
import Hledger.Read.Common (aliasesFromOpts, Reader(..), InputOpts(..), journalFinalise)
import Hledger.Read.RulesReader (readJournalFromCsv)

--- ** doctest setup
-- $setup
-- >>> :set -XOverloadedStrings

--- ** reader

reader :: MonadIO m => SepFormat -> Reader m
reader sep = Reader
  {rFormat     = Sep sep
  ,rExtensions = [show sep]
  ,rReadFn     = parse sep
  ,rParser     = const $ fail "sorry, CSV files can't be included yet"
    -- This unnecessarily shows the CSV file's first line in the error message,
    -- but gives a more useful message than just calling error'.
    -- XXX Note every call to error' in Hledger.Read.* is potentially a similar problem -
    -- the error message is good enough when the file was specified directly by the user,
    -- but not good if it was loaded by a possibly long chain of include directives.
  }

-- | Parse and post-process a "Journal" from a CSV(/SSV/TSV/*SV) data file, or give an error.
-- This currently ignores the provided input file handle, and reads from the data file itself,
-- inferring a corresponding rules file to help convert it.
-- This does not check balance assertions.
parse :: SepFormat -> InputOpts -> FilePath -> Handle -> ExceptT String IO Journal
parse sep iopts f h = do
  let mrulesfile = mrules_file_ iopts
  readJournalFromCsv (Right <$> mrulesfile) f h (Just sep)
  -- apply any command line account aliases. Can fail with a bad replacement pattern.
  >>= liftEither . journalApplyAliases (aliasesFromOpts iopts)
      -- journalFinalise assumes the journal's items are
      -- reversed, as produced by JournalReader's parser.
      -- But here they are already properly ordered. So we'd
      -- better preemptively reverse them once more. XXX inefficient
      . journalReverse
  >>= journalFinalise iopts{balancingopts_=(balancingopts_ iopts){ignore_assertions_=True}} f ""

--- ** tests

tests_CsvReader = testGroup "CsvReader" [
  ]