{-# LANGUAGE FlexibleContexts #-}
module Main where

import ALTO (Collection, collection, getWords)
import Control.Monad.Except.IOH (handle)
import Control.Monad.IO.Class (liftIO)
import Control.Monad.Reader (runReaderT)
import Control.Monad.State (MonadState(..), evalStateT)
import Control.Monad.Trans (lift)
import qualified Data.ByteString.Char8 as BS (readFile)
import qualified Data.ByteString.Lazy as Lazy (writeFile)
import Data.Id (Id(..))
import qualified Data.Map as Map (toList)
import Data.OrderedMap (mapi)
import PDF (Document, UnifiedLayers(..), parseDocument, render)
import PDF.Box (Box(..), at)
import PDF.Content.Operator (Instruction)
import PDF.Content.Text (Chunks(..))
import PDF.Layer (Layer)
import PDF.Object (Object)
import PDF.Pages (Contents(..), Pages(..), withFonts, withResources)
import System.Environment (getArgs)
import System.Exit (die)
import Text.Printf (printf)

synchronize :: Document -> Collection -> IO [(Id Object, Id Instruction, String)]
synchronize pdf alto =
  (r UnifiedLayers pdf >>= withFonts extractFromLayer) `handle` die
  where
    extractFromLayer layer =
      r Pages layer >>= fmap concat . mapM extractFromPage . Map.toList
    extractFromPage (pageNumber, page) = do
      altoWords <- liftIO $ getWords alto pageNumber
      withResources (flip evalStateT altoWords . extractWithResources) page
    extractWithResources page =
      r Contents page >>= fmap concat . sequence . mapi extractFromObject
    extractFromObject objectId content =
      lift (r Chunks content) >>= undefined

processFiles :: FilePath -> FilePath -> IO ()
processFiles inputFile altoDir = do
  pdf <- either die return . parseDocument =<< BS.readFile inputFile
  alto <- collection altoDir
  putStrLn "Object,Instruction,ALTO_ID"
  mapM_ (putStrLn . format) =<< synchronize pdf alto
  where
    format (objectId, instructionId, altoId) =
      printf "%d,%d,%s" (getId objectId) (getId instructionId) altoId

main :: IO ()
main = do
  args <- getArgs
  case args of
    [inputFile, altoDir] ->
      processFiles inputFile altoDir
    _ -> die "Syntax: pdfcleaner INPUT_PDF_FILE ALTO_DIR"