module Main where

import Categorizable
import Diff
import Interpreter
import qualified Parsers as P
import Syntax
import Range
import Split
import Term
import Unified
import Source
import Control.Comonad.Cofree
import qualified Data.ByteString.Char8 as B1
import Options.Applicative
import System.Directory
import System.FilePath
import qualified Data.Text as T
import qualified Data.Text.Lazy.IO as TextIO
import qualified System.IO as IO

data Renderer = Unified | Split

data Argument = Argument { renderer :: Renderer, output :: Maybe FilePath, sourceA :: FilePath, sourceB :: FilePath }

arguments :: Parser Argument
arguments = Argument
  <$> (flag Split Unified (long "unified" <> help "output a unified diff")
  <|> flag' Split (long "split" <> help "output a split diff"))
  <*> (optional $ strOption (long "output" <> short 'o' <> help "output directory for split diffs, defaulting to stdout if unspecified"))
  <*> strArgument (metavar "FILE a")
  <*> strArgument (metavar "FILE b")

main :: IO ()
main = do
  arguments <- execParser opts
  let (sourceAPath, sourceBPath) = (sourceA arguments, sourceB arguments)
  aContents <- fromList <$> readFile sourceAPath
  bContents <- fromList <$> readFile sourceBPath
  (aTerm, bTerm) <- let parse = (P.parserForType . T.pack . takeExtension) sourceAPath in do
    aTerm <- parse aContents
    bTerm <- parse bContents
    return (replaceLeavesWithWordBranches aContents aTerm, replaceLeavesWithWordBranches bContents bTerm)
  let diff = interpret comparable aTerm bTerm in
    case renderer arguments of
      Unified -> do
        rendered <- unified diff aContents bContents
        B1.putStr rendered
      Split -> do
        rendered <- split diff aContents bContents
        case output arguments of
          Just path -> do
            isDir <- doesDirectoryExist path
            IO.withFile (if isDir then path </> (takeFileName sourceBPath -<.> ".html") else path) IO.WriteMode (write rendered)
          Nothing -> TextIO.putStr rendered
    where
    opts = info (helper <*> arguments)
      (fullDesc <> progDesc "Diff some things" <> header "semantic-diff - diff semantically")
    write rendered h = TextIO.hPutStr h rendered

replaceLeavesWithWordBranches :: Source Char -> Term T.Text Info -> Term T.Text Info
replaceLeavesWithWordBranches source = replaceIn source 0
  where
    replaceIn source startIndex (info@(Info range categories) :< syntax) | substring <- slice (offsetRange (negate startIndex) range) source = info :< case syntax of
      Leaf _ | ranges <- rangesAndWordsFrom (start range) (toList substring), length ranges > 1 -> Indexed $ makeLeaf categories <$> ranges
      Indexed i -> Indexed $ replaceIn substring (start range) <$> i
      Fixed f -> Fixed $ replaceIn substring (start range) <$> f
      Keyed k -> Keyed $ replaceIn substring (start range) <$> k
      _ -> syntax
    makeLeaf categories (range, substring) = Info range categories :< Leaf (T.pack substring)