module Pas2C where

import PascalParser

import Text.PrettyPrint.HughesPJ

import Data.Maybe

pascal2C :: PascalUnit -> Doc

pascal2C (Unit unitName interface implementation init fin) = implementation2C implementation

implementation2C :: Implementation -> Doc

implementation2C (Implementation uses tvars) = typesAndVars2C tvars

typesAndVars2C :: TypesAndVars -> Doc

typesAndVars2C (TypesAndVars ts) = vcat $ map tvar2C ts

tvar2C :: TypeVarDeclaration -> Doc

tvar2C (FunctionDeclaration (Identifier name) (Identifier returnType) Nothing) = 

    text $ maybeVoid returnType ++ " " ++ name ++ "();"

tvar2C (FunctionDeclaration (Identifier name) (Identifier returnType) (Just phrase)) = 

    text (maybeVoid returnType ++ " " ++ name ++ "()") 

    $$

    phrase2C phrase

tvar2C _ = empty

phrase2C :: Phrase -> Doc

phrase2C (Phrases p) = braces . nest 4 . vcat . map phrase2C $ p

phrase2C (ProcCall (Identifier name) params) = text name <> parens (hsep . punctuate (char ',') . map expr2C $ params) <> semi

phrase2C (IfThenElse (expr) phrase1 mphrase2) = text "if" <> parens (expr2C expr) $$ (braces . nest 4 . phrase2C) phrase1 $+$ elsePart

    where

    elsePart | isNothing mphrase2 = empty

             | otherwise = text "else" $$ (braces . nest 4 . phrase2C) (fromJust mphrase2)

phrase2C (Assignment (Identifier name) expr) = text name <> text " = " <> expr2C expr <> semi

phrase2C (WhileCycle expr phrase) = text "while" <> parens (expr2C expr) $$ nest 4 (phrase2C phrase)

phrase2C (SwitchCase expr cases mphrase) = text "switch" <> parens (expr2C expr) <> text "of" $$ (nest 4 . vcat . map case2C) cases

    where

    case2C :: (Expression, Phrase) -> Doc

    case2C (e, p) = text "case" <+> parens (expr2C e) <> char ':' <> nest 4 (phrase2C p $$ text "break;")

{-

        | RepeatCycle Expression Phrase

        | ForCycle

        | SwitchCase Expression [(Expression, Phrase)] (Maybe Phrase)

        | Assignment Identifier Expression

        -}

phrase2C _ = empty

expr2C :: Expression -> Doc

expr2C (Expression s) = text s

expr2C (FunCall (Identifier name) params) = text name <> parens (hsep . punctuate (char ',') . map expr2C $ params)

expr2C (BinOp op expr1 expr2) = (expr2C expr1) <+> op2C op <+> (expr2C expr2)

{-    | FunCall Identifier [Expression]

    | PrefixOp String Expression

    | BinOp String Expression Expression

    -}            

expr2C _ = empty

op2C = text

maybeVoid "" = "void"

maybeVoid a = a