module TreeSitter where

import Diff
import Range
import Syntax
import Term
import Control.Comonad.Cofree
import qualified OrderedMap as Map
import Data.Set
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 :: Ptr TSLanguage
foreign import ccall "prototype/doubt-difftool/doubt-difftool-Bridging-Header.h ts_language_javascript" ts_language_javascript :: 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 _ = 24
  sizeOf _ = 24
  peek _ = error "Haskell code should never read TSNode values directly."
  poke _ _ = 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

keyedProductions :: Set String
keyedProductions = fromList [ "object" ]

fixedProductions :: Set String
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" ]

languageForType :: String -> Maybe (Ptr TSLanguage)
languageForType mediaType = 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
      annotation <- return . Info range $ singleton name
      return (name, annotation :< case children of
        [] -> Leaf $ substring range contents
        _ | member name keyedProductions -> Keyed . Map.fromList $ assignKey <$> children
        _ | member name fixedProductions -> Fixed $ fmap snd children
        _ | otherwise -> Indexed $ fmap snd children)
        where assignKey ("pair", node@(_ :< Fixed (key : _))) = (getSubstring key, node)
              assignKey (_, node) = (getSubstring node, node)
              getSubstring (Info range _ :< _) = substring range contents

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 }