module Ribosome.Nvim.Api.Generate where

import Data.Char (toUpper)
import qualified Data.Map.Strict as Map (fromList, lookup)
import Data.MessagePack (Object)
import Language.Haskell.TH
import Neovim.API.Parser (
  NeovimAPI(functions),
  NeovimFunction(NeovimFunction),
  NeovimType(NestedType, SimpleType, Void),
  customTypes,
  parseAPI,
  )

camelcase :: String -> String
camelcase =
  snd . foldr folder (False, "")
  where
    folder '_' (_, z) = (True, z)
    folder a (True, h : t) = (False, a : toUpper h : t)
    folder a (True, []) = (False, [a])
    folder a (False, z) = (False, a : z)

haskellTypes :: Map String TypeQ
haskellTypes =
  Map.fromList [
    ("Boolean", [t|Bool|]),
    ("Integer", [t|Int|]),
    ("Float", [t|Double|]),
    ("String", [t|Text|]),
    ("Array", [t|[Object]|]),
    ("Dictionary", [t|Map Text Object|]),
    ("void", [t|()|])
    ]

haskellType :: NeovimType -> Q Type
haskellType at =
  case at of
    Void -> [t|()|]
    NestedType t Nothing ->
      appT listT $ haskellType t
    NestedType t (Just n) ->
      foldl appT (tupleT n) . replicate n $ haskellType t
    SimpleType t ->
      fromMaybe (conT . mkName $ t) $ Map.lookup t haskellTypes

data FunctionData =
  FunctionData {
    apiName :: String,
    ccName :: Name,
    async :: Bool,
    names :: [Name],
    types :: [Type],
    returnType :: NeovimType
    }
  deriving (Eq, Show)

functionData :: NeovimFunction -> Q FunctionData
functionData (NeovimFunction name parameters _ async returnType) = do
  names <- traverse newName prefixedNames
  types <- traverse haskellType (fst <$> parameters)
  return (FunctionData name (mkName . camelcase $ name) async names types returnType)
  where
    prefix i n = "arg" <> show i <> "_" <> n
    prefixedNames = zipWith prefix [0 :: Int ..] (snd <$> parameters)

generateFromApi :: (FunctionData -> Q [Dec]) -> (Name -> Int64 -> DecsQ) -> Q [Dec]
generateFromApi handleFunction handleExtType = do
  api <- either (fail . show) return =<< runIO parseAPI
  funcs <- traverse functionData (functions api)
  funcDecs <- traverse handleFunction funcs
  tpeDecs <- traverse (uncurry handleExtType) $ first mkName <$> customTypes api
  return $ join (funcDecs <> tpeDecs)