module Main where

import Categorizable
import Diff
import Interpreter
import qualified Parser as P
import Syntax
import Range
import Split
import Term
import TreeSitter
import Unified
import Control.Comonad.Cofree
import qualified Data.Char as Char
import qualified Data.Map as Map
import qualified Data.ByteString.Char8 as B1
import qualified Data.ByteString.Lazy as B2
import Data.Set hiding (split)
import Options.Applicative
import System.FilePath

import Foreign.Ptr

data Output = Unified | Split

data Argument = Argument { output :: Output, 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"))
  <*> argument str (metavar "FILE a")
  <*> argument str (metavar "FILE b")

main :: IO ()
main = do
  arguments <- execParser opts
  let (sourceAPath, sourceBPath) = (sourceA arguments, sourceB arguments)
  aContents <- readFile sourceAPath
  bContents <- readFile sourceBPath
  (aTerm, bTerm) <- let parse = (parserForType . 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 output arguments of
      Unified -> do
        output <- unified diff aContents bContents
        B1.putStr output
      Split -> do
        output <- split diff aContents bContents
        B2.putStr output
    where
    opts = info (helper <*> arguments)
      (fullDesc <> progDesc "Diff some things" <> header "semantic-diff - diff semantically")

parserForType :: String -> P.Parser
parserForType mediaType = maybe P.lineByLineParser parseTreeSitterFile $ case mediaType of
    ".h" -> Just ts_language_c
    ".c" -> Just ts_language_c
    ".js" -> Just ts_language_javascript
    _ -> Nothing

replaceLeavesWithWordBranches :: String -> Term String Info -> Term String Info
replaceLeavesWithWordBranches source term@(Info range _ _ :< _) = replaceIn source range term
  where
    replaceIn source parentRange (info@(Info range lineRange categories) :< syntax) = info :< case syntax of
      Leaf _ | ranges <- rangesOfWordsFrom (start range) (substring range source), length (ranges) > 1 -> Indexed $ makeLeaf lineRange categories <$> ranges
      Indexed i -> Indexed $ replaceIn source parentRange <$> i
      Fixed f -> Fixed $ replaceIn source parentRange <$> f
      Keyed k -> Keyed $ replaceIn source parentRange <$> k
      _ -> syntax
    makeLeaf lineRange categories range = Info range lineRange categories :< Leaf (substring range source)

rangesOfWordsFrom :: Int -> String -> [Range]
rangesOfWordsFrom startIndex string = case break Char.isSpace string of
  ([], []) -> []
  ([], rest) -> rangesOfWordsAfterWhitespace startIndex rest
  (word, []) -> [ Range startIndex $ length word ]
  (word, rest) -> (Range startIndex $ length word) : rangesOfWordsAfterWhitespace (startIndex + length word) rest
  where
    rangesOfWordsAfterWhitespace startIndex string | (whitespace, rest) <- break (not . Char.isSpace) string = rangesOfWordsFrom (startIndex + length whitespace) rest