{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE Rank2Types #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeOperators #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
module Expr.Maybe.Test where

import Test.Tasty
import Test.Tasty.HUnit

import qualified Control.Arrow as Arrow
import qualified Control.Monad as Monad
import Data.Proxy (Proxy(..))
import Data.Text (Text)
import Data.Type.Equality ((:~:)(Refl))
import Prelude hiding (maybe, not)

import Language.Symantic.Repr
import Language.Symantic.Expr
import Language.Symantic.Type

import AST.Test

-- * Expressions
e1 = maybe (bool True) (lam not) (just $ bool True)

-- * Tests
type Ex = Expr_Root
 (   Expr_Lambda
 .|. Expr_Maybe
 .|. Expr_Bool
 )
ex_from = root_expr_from (Proxy::Proxy Ex)

(==>) ast expected =
	testCase (show ast) $
	case ex_from ast of
	 Left err -> Left err @?= snd `Arrow.left` expected
	 Right (Exists_Type_and_Repr ty (Forall_Repr r)) ->
		case expected of
		 Left (_, err) -> Right ("…"::String) @?= Left err
		 Right (ty_expected::Type_Root_of_Expr Ex h, _::h, _::Text) ->
			(Monad.>>= (@?= (\(_::Proxy h, err) -> err) `Arrow.left` expected)) $
			case ty `eq_type` ty_expected of
			 Nothing -> Monad.return $ Left $
				error_expr (Proxy::Proxy Ex) $
				Error_Expr_Type_mismatch ast
				 (Exists_Type ty)
				 (Exists_Type ty_expected)
			 Just Refl -> do
				let h = host_from_expr r
				Monad.return $
					Right
					 ( ty
					 , h
					 , text_from_expr r
					 -- , (text_from_expr :: Repr_Text h -> Text) r
					 )

tests :: TestTree
tests = testGroup "Maybe"
 [ AST "just" [AST "bool" [AST "True" []]] ==> Right
	 ( type_maybe type_bool
	 , Just True
	 , "just True" )
 , AST "just"
	 [ AST "let"
		 [ AST "x" []
		 , AST "bool" [AST "True" []]
		 , AST "var" [AST "x" []]
		 ]
	 ] ==> Right
	 ( type_maybe type_bool
	 , Just True
	 , "just (let x0 = True in x0)" )
 , AST "maybe"
	 [ AST "bool" [AST "True" []]
	 , AST "\\"
		 [ AST "x" []
		 , AST "Bool" []
		 , AST "not" [AST "var" [AST "x" []]]
		 ]
	 , AST "nothing"
		 [ AST "Bool" []
		 ]
	 ] ==> Right
	 ( type_bool
	 , True
	 , "maybe True (\\x0 -> !x0) nothing" )
 , AST "maybe"
	 [ AST "bool" [AST "False" []]
	 , AST "\\"
		 [ AST "x" []
		 , AST "Bool" []
		 , AST "not" [AST "var" [AST "x" []]]
		 ]
	 , AST "just"
		 [ AST "bool" [AST "True" []]
		 ]
	 ] ==> Right
	 ( type_bool
	 , False
	 , "maybe False (\\x0 -> !x0) (just True)" )
 ]