{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Rank2Types #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-}
-- | Expression for 'Bool's.
module Language.LOL.Symantic.Expr.Bool where

import Data.Proxy (Proxy(..))
import Prelude hiding (and, not, or)

import Language.LOL.Symantic.AST
import Language.LOL.Symantic.Type
import Language.LOL.Symantic.Expr.Common
import Language.LOL.Symantic.Expr.Lambda
import Language.LOL.Symantic.Repr.Dup
import Language.LOL.Symantic.Trans.Common

-- * Class 'Sym_Bool'

-- | Symantic.
class Sym_Bool repr where
	bool ::      Bool -> repr Bool
	not  :: repr Bool -> repr Bool
	and  :: repr Bool -> repr Bool -> repr Bool
	or   :: repr Bool -> repr Bool -> repr Bool
	xor  :: repr Bool -> repr Bool -> repr Bool
	xor x y = (x `or` y) `and` not (x `and` y)
	
	default bool :: Trans t repr =>        Bool -> t repr Bool
	default not  :: Trans t repr => t repr Bool -> t repr Bool
	default and  :: Trans t repr => t repr Bool -> t repr Bool -> t repr Bool
	default or   :: Trans t repr => t repr Bool -> t repr Bool -> t repr Bool
	bool = trans_lift . bool
	not  = trans_map1 not
	and  = trans_map2 and
	or   = trans_map2 or

instance -- Sym_Bool Dup
 ( Sym_Bool r1
 , Sym_Bool r2
 ) => Sym_Bool (Dup r1 r2) where
	bool x = bool x `Dup` bool x
	not (x1 `Dup` x2)               = not x1    `Dup` not x2
	and (x1 `Dup` x2) (y1 `Dup` y2) = and x1 y1 `Dup` and x2 y2
	or  (x1 `Dup` x2) (y1 `Dup` y2) = or  x1 y1 `Dup` or  x2 y2
	xor (x1 `Dup` x2) (y1 `Dup` y2) = xor x1 y1 `Dup` xor x2 y2

-- * Type 'Expr_Bool'
-- | Expression.
data Expr_Bool (root:: *)
type instance Root_of_Expr (Expr_Bool root) = root
type instance Type_of_Expr (Expr_Bool root) = Type_Bool
type instance Sym_of_Expr (Expr_Bool root) repr = Sym_Bool repr
type instance Error_of_Expr ast (Expr_Bool root) = Error_Expr_Bool ast

instance -- Expr_from AST Expr_Bool
 ( Type_from AST (Type_Root_of_Expr root)
 , Expr_from AST root
 
 , Type_Root_Lift Type_Bool (Type_Root_of_Expr root)
 , Error_Type_Lift (Error_Type_Fun AST)
                   (Error_of_Type AST (Type_Root_of_Expr root))
 , Error_Expr_Lift (Error_Expr_Lambda (Error_of_Type AST (Type_Root_of_Expr root))
                                      (                   Type_Root_of_Expr root)
                                      AST)
                   (Error_of_Expr AST root)
 , Error_Expr_Lift (Error_Expr AST) (Error_of_Expr AST root)
 
 , Type_Unlift Type_Bool (Type_of_Expr root)
 
 , Root_of_Expr root ~ root
 
 , Implicit_HBool (Is_Last_Expr (Expr_Bool root) root)
 ) => Expr_from AST (Expr_Bool root) where
	expr_from _px_ex ctx ast k =
		case ast of
		 AST "bool" asts ->
			case asts of
			 [AST ast_bool []] ->
				case read_safe ast_bool of
				 Left err -> Left $ error_expr_lift $ Error_Expr_Read err ast
				 Right (i::Bool) ->
					k type_bool $ Forall_Repr_with_Context $
						const $ bool i
			 _ -> Left $ error_lambda_lift $
				Error_Expr_Fun_Wrong_number_of_arguments 3 ast
		 AST "not" asts -> unary_from  asts not
		 AST "and" asts -> binary_from asts and
		 AST "or"  asts -> binary_from asts or
		 AST "xor" asts -> binary_from asts xor
		 -- _ -> Left $ error_expr_lift $ Error_Expr_Unsupported_here ast
		 _ -> Left $
			case hbool :: HBool (Is_Last_Expr (Expr_Bool root) root) of
			 HTrue  -> error_expr_lift $ Error_Expr_Unsupported ast
			 HFalse -> error_expr_lift $ Error_Expr_Unsupported_here ast
		where
		unary_from asts
		 (op::forall repr. Sym_Bool repr
		    => repr Bool -> repr Bool) =
			case asts of
			 [ast_x] ->
				expr_from (Proxy::Proxy root) ctx ast_x $
				 \(ty_x::Type_Root_of_Expr root h_x) (Forall_Repr_with_Context x) ->
					case type_unlift $ unType_Root ty_x of
					 Just (Type_Bool::Type_Bool (Type_Root_of_Expr root) h_x) ->
						k ty_x $ Forall_Repr_with_Context (op . x)
					 _ -> Left $ error_lambda_lift $
						Error_Expr_Fun_Argument_mismatch
						 (Exists_Type type_bool)
						 (Exists_Type ty_x) ast
			 _ -> Left $ error_lambda_lift $
				Error_Expr_Fun_Wrong_number_of_arguments 1 ast
		binary_from asts
		 (op::forall repr. Sym_Bool repr
		    => repr Bool -> repr Bool -> repr Bool) =
			case asts of
			 [ast_x, ast_y] ->
				expr_from (Proxy::Proxy root) ctx ast_x $
				 \(ty_x::Type_Root_of_Expr root h_x) (Forall_Repr_with_Context x) ->
				expr_from (Proxy::Proxy root) ctx ast_y $
				 \(ty_y::Type_Root_of_Expr root h_y) (Forall_Repr_with_Context y) ->
					case type_unlift $ unType_Root ty_x of
					 Just (Type_Bool::Type_Bool (Type_Root_of_Expr root) h_x) ->
						case type_unlift $ unType_Root ty_y of
						 Just (Type_Bool::Type_Bool (Type_Root_of_Expr root) h_y) ->
							k ty_x $ Forall_Repr_with_Context $
							 \c -> x c `op` y c
						 Nothing -> Left $ error_lambda_lift $
							Error_Expr_Fun_Argument_mismatch
							 (Exists_Type type_bool)
							 (Exists_Type ty_y) ast
					 Nothing -> Left $ error_lambda_lift $
						Error_Expr_Fun_Argument_mismatch
						 (Exists_Type type_bool)
						 (Exists_Type ty_x) ast
			 _ -> Left $ error_lambda_lift $
				Error_Expr_Fun_Wrong_number_of_arguments 2 ast
		error_lambda_lift
		 :: Error_Expr_Lambda (Error_of_Type AST (Type_Root_of_Expr root)) (Type_Root_of_Expr root) AST
		 -> Error_of_Expr AST root
		error_lambda_lift = error_expr_lift

-- ** Type 'Expr_Lambda_Bool'
-- | Convenient alias.
type Expr_Lambda_Bool lam = Expr_Root (Expr_Cons (Expr_Lambda lam) Expr_Bool)

expr_lambda_bool_from
 :: forall lam ast.
 Expr_from ast (Expr_Lambda_Bool lam)
 => Proxy lam
 -> ast
 -> Either (Error_of_Expr ast (Expr_Lambda_Bool lam))
           (Exists_Type_and_Repr (Type_Root_of_Expr (Expr_Lambda_Bool lam))
                                 (Forall_Repr (Expr_Lambda_Bool lam)))
expr_lambda_bool_from _px_lam ast =
	expr_from
	 (Proxy::Proxy (Expr_Lambda_Bool lam))
	 Context_Empty ast $ \ty (Forall_Repr_with_Context repr) ->
		Right $ Exists_Type_and_Repr ty $
			Forall_Repr $ repr Context_Empty

-- * Type 'Error_Expr_Bool'
data Error_Expr_Bool ast
 =   Error_Expr_Bool
 deriving (Eq, Show)