module Main where

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

import Foreign
import Foreign.C
import Foreign.C.Types

data TSLanguage = TsLanguage deriving (Show, Eq)
foreign import ccall "prototype/doubt-difftool/doubt-difftool-Bridging-Header.h ts_language_c" ts_language_c :: IO (Ptr TSLanguage)
foreign import ccall "prototype/doubt-difftool/doubt-difftool-Bridging-Header.h ts_language_javascript" ts_language_javascript :: IO (Ptr TSLanguage)

data TSDocument = TsDocument deriving (Show, Eq)
foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_make" ts_document_make :: IO (Ptr TSDocument)
foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_set_language" ts_document_set_language :: Ptr TSDocument -> Ptr TSLanguage -> IO ()
foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_set_input_string" ts_document_set_input_string :: Ptr TSDocument -> CString -> IO ()
foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_parse" ts_document_parse :: Ptr TSDocument -> IO ()
foreign import ccall "prototype/External/tree-sitter/include/tree_sitter/runtime.h ts_document_free" ts_document_free :: Ptr TSDocument -> IO ()

data TSLength = TsLength { bytes :: CSize, chars :: CSize }
  deriving (Show, Eq)

data TSNode = TsNode { _data :: Ptr (), offset :: TSLength }
  deriving (Show, Eq)

instance Storable TSNode where
  alignment n = 24
  sizeOf n = 24
  peek p = error "Haskell code should never read TSNode values directly."
  poke p n = error "Haskell code should never write TSNode values directly."

foreign import ccall "app/bridge.h ts_document_root_node_p" ts_document_root_node_p :: Ptr TSDocument -> Ptr TSNode -> IO ()
foreign import ccall "app/bridge.h ts_node_p_name" ts_node_p_name :: Ptr TSNode -> Ptr TSDocument -> IO CString
foreign import ccall "app/bridge.h ts_node_p_named_child_count" ts_node_p_named_child_count :: Ptr TSNode -> IO CSize
foreign import ccall "app/bridge.h ts_node_p_named_child" ts_node_p_named_child :: Ptr TSNode -> CSize -> Ptr TSNode -> IO CSize
foreign import ccall "app/bridge.h ts_node_p_pos_chars" ts_node_p_pos_chars :: Ptr TSNode -> IO CSize
foreign import ccall "app/bridge.h ts_node_p_size_chars" ts_node_p_size_chars :: Ptr TSNode -> IO CSize
foreign import ccall "app/bridge.h ts_node_p_start_point" ts_node_p_start_point :: Ptr TSNode -> IO CSize
foreign import ccall "app/bridge.h ts_node_p_end_point" ts_node_p_end_point :: Ptr TSNode -> IO CSize

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
  output <- do
    let (sourceAPath, sourceBPath) = (sourceA arguments, sourceB arguments)
    aContents <- readFile sourceAPath
    bContents <- readFile sourceBPath
    language <- (parserForType . takeExtension) sourceAPath
    (aTerm, bTerm) <- case language of
      Just lang -> do aTerm <- parseTreeSitterFile lang aContents
                      bTerm <- parseTreeSitterFile lang bContents
                      return (aTerm, bTerm)
      Nothing -> error ("Unsupported language extension in path: " ++ sourceAPath)
    let diff = interpret comparable aTerm bTerm in
      case output arguments of
        Unified -> unified diff aContents bContents
        Split -> split diff aContents bContents
  ByteString.putStr output where
    opts = info (helper <*> arguments)
      (fullDesc <> progDesc "Diff some things" <> header "semantic-diff - diff semantically")

parserForType mediaType = sequence $ case mediaType of
    "h" -> Just ts_language_c
    "c" -> Just ts_language_c
    "js" -> Just ts_language_javascript
    _ -> Nothing

parseTreeSitterFile :: Ptr TSLanguage -> String -> IO (Term String Info)
parseTreeSitterFile language contents = do
  document <- ts_document_make
  ts_document_set_language document language
  withCString contents (\source -> do
    ts_document_set_input_string document source
    ts_document_parse document
    term <- documentToTerm document contents
    ts_document_free document
    return term)

documentToTerm :: Ptr TSDocument -> String -> IO (Term String Info)
documentToTerm document contents = alloca $ \root -> do
  ts_document_root_node_p document root
  snd <$> toTerm root where
    toTerm :: Ptr TSNode -> IO (String, Term String Info)
    toTerm node = do
      name <- ts_node_p_name node document
      name <- peekCString name
      children <- withNamedChildren node toTerm
      range <- range node
      lineRange <- getLineRange node
      annotation <- return . Info range lineRange $ singleton name
      return (name, annotation :< case children of
        [] -> Leaf $ substring range contents
        _ | member name keyedProductions -> Keyed $ Map.fromList children
        _ | member name fixedProductions -> Fixed $ fmap snd children
        _ | otherwise -> Indexed $ fmap snd children)

keyedProductions = fromList [ "object" ]
fixedProductions = fromList [ "pair", "rel_op", "math_op", "bool_op", "bitwise_op", "type_op", "math_assignment", "assignment", "subscript_access", "member_access", "new_expression", "function_call", "function", "ternary" ]

withNamedChildren :: Ptr TSNode -> (Ptr TSNode -> IO (String, a)) -> IO [(String, a)]
withNamedChildren node transformNode = do
  count <- ts_node_p_named_child_count node
  if count == 0
    then return []
    else mapM (alloca . getChild) [0..pred count] where
      getChild n out = do
        ts_node_p_named_child node n out
        transformNode out

range :: Ptr TSNode -> IO Range
range node = do
  pos <- ts_node_p_pos_chars node
  size <- ts_node_p_size_chars node
  let start = fromIntegral pos
      end = start + fromIntegral size
  return Range { start = start, end = end }

getLineRange :: Ptr TSNode -> IO Range
getLineRange node = do
  startLine <- ts_node_p_start_point node
  endLine <- ts_node_p_end_point node
  return Range { start = fromIntegral startLine, end = fromIntegral endLine }