module Compiler.Lexer.Keywords where

import Common
import Compiler.Lexer.Whitespaces
import Control.Applicative
import Control.Monad
import Parser
import Test.Common

data Keyword
  = KwFor
  | KwEndFor
  | KwForEach
  | KwAs
  | KwEndForEach
  | KwBreak
  | KwWhile
  | KwEndWhile
  | KwLet
  | KwIf
  | KwEndFn
  | KwThen
  | KwElseIf
  | KwElse
  | KwEndIf
  | KwProc
  | KwLoop
  | KwEndLoop
  | KwEndProc
  | KwTo
  | KwReturn
  | KwAssignment
  | KwFn  -- We don't want to generate this in automatic tests because of the lookahead for (
  deriving (Show, Lift,Eq, Enum, Bounded)

instance HasParser Keyword where
  parser
    = parseFor KwForEach
    <|> parseFor KwEndForEach
    <|> parseFor KwFor
    <|> parseFor KwAs
    <|> parseFor KwEndFor
    <|> parseFor KwWhile
    <|> parseFor KwBreak
    <|> parseFor KwEndWhile
    <|> parseFor KwLet
    <|> parseFor KwIf
    <|> parseFor KwFn
    <|> parseFor KwEndFn
    <|> parseFor KwThen
    <|> parseFor KwElseIf
    <|> parseFor KwElse
    <|> parseFor KwEndIf
    <|> parseFor KwProc
    <|> parseFor KwLoop
    <|> parseFor KwEndLoop
    <|> parseFor KwEndProc
    <|> parseFor KwTo
    <|> parseFor KwReturn
    <|> parseFor KwAssignment
    where
      parseFor :: Keyword -> Parser Keyword
      parseFor kw = do
        pkw <- parseAndReturn (toSource kw) kw
        case pkw of
          KwAssignment -> pure pkw
          KwFn -> do
            lookAhead ((void $ do
              void $ many (parser @Whitespace)
              pText "(")) >>= \case
                Just _ -> pure pkw
                Nothing -> cantHandle
          KwEndFn -> pure pkw
          _ -> do
            lookAhead ((void $ parser @Whitespace) <|> eof) >>= \case
              Just _ -> pure pkw
              Nothing -> cantHandle

instance ToSource Keyword where
  toSource = \case
    KwFor        -> "for"
    KwEndFor     -> "endfor"
    KwForEach    -> "foreach"
    KwAs         -> "as"
    KwEndForEach -> "endforeach"
    KwBreak      -> "break"
    KwWhile      -> "while"
    KwEndWhile   -> "endwhile"
    KwLet        -> "let"
    KwIf         -> "if"
    KwFn         -> "fn"
    KwEndFn      -> "endfn"
    KwThen       -> "then"
    KwElseIf     -> "elseif"
    KwElse       -> "else"
    KwEndIf      -> "endif"
    KwProc       -> "proc"
    KwLoop       -> "loop"
    KwEndProc    -> "endproc"
    KwEndLoop    -> "endloop"
    KwTo         -> "to"
    KwReturn     -> "return"
    KwAssignment -> "="

instance HasGen Keyword where
  getGen = enum KwFor KwAssignment