module Pas2C where

import PascalParser
import Text.PrettyPrint.HughesPJ
import Data.Maybe
import Data.Char
import Text.Parsec.String


pas2C :: String -> IO String
pas2C fileName = do
    ptree <- parseFromFile pascalUnit fileName
    case ptree of
         (Left a) -> return (show a)
         (Right a) -> (return . render . pascal2C) a

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) returnType Nothing) = 
    type2C returnType <+> text (name ++ "();")
tvar2C (FunctionDeclaration (Identifier name) returnType (Just phrase)) = 
    type2C returnType <+> text (name ++ "()") 
    $$
    phrase2C phrase
tvar2C (TypeDeclaration (Identifier i) t) = text "type" <+> text i <+> type2C t <> text ";"
tvar2C (VarDeclaration isConst (ids, t) mInitExpr) = 
    if isConst then text "const" else empty
    <+>
    type2C t
    <+>
    (hsep . punctuate (char ',') . map (\(Identifier i) -> text i) $ ids)
    <+>
    initExpr mInitExpr
    <>
    text ";"
    where
    initExpr Nothing = empty
    initExpr (Just e) = text "=" <+> initExpr2C e

initExpr2C :: InitExpression -> Doc    
initExpr2C _ = text "<<expression>>"

type2C :: TypeDecl -> Doc
type2C UnknownType = text "void"
type2C String = text "string"
type2C (SimpleType (Identifier i)) = text i
type2C (PointerTo t) = type2C t <> text "*"
type2C (RecordType tvs) = text "{" $+$ (nest 4 . vcat . map tvar2C $ tvs) $+$ text "}"
type2C (RangeType r) = text "<<range type>>"
type2C (Sequence ids) = text "<<sequence type>>"
type2C (ArrayDecl r t) = text "<<array type>>"


phrase2C :: Phrase -> Doc
phrase2C (Phrases p) = text "{" $+$ (nest 4 . vcat . map phrase2C $ p) $+$ text "}"
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) $+$ (phrase2C . wrapPhrase) phrase1 $+$ elsePart
    where
    elsePart | isNothing mphrase2 = empty
             | otherwise = text "else" $$ (phrase2C . wrapPhrase) (fromJust mphrase2)
phrase2C (Assignment ref expr) = ref2C ref <> text " = " <> expr2C expr <> semi
phrase2C (WhileCycle expr phrase) = text "while" <> parens (expr2C expr) $$ (phrase2C $ wrapPhrase 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;")
phrase2C (WithBlock ref p) = text "namespace" <> parens (ref2C ref) $$ (phrase2C $ wrapPhrase p)
phrase2C (ForCycle (Identifier i) e1 e2 p) = 
    text "for" <> (parens . hsep . punctuate (char ';') $ [text i <+> text "=" <+> expr2C e1, text i <+> text "<=" <+> expr2C e2, text "++" <> text i])
    $$
    phrase2C (wrapPhrase p)
phrase2C (RepeatCycle e p) = text "do" <+> phrase2C (Phrases p) <+> text "while" <> parens (text "!" <> parens (expr2C e))


wrapPhrase p@(Phrases _) = p
wrapPhrase p = Phrases [p]


expr2C :: Expression -> Doc
expr2C (Expression s) = text s
expr2C (BinOp op expr1 expr2) = parens $ (expr2C expr1) <+> op2C op <+> (expr2C expr2)
expr2C (NumberLiteral s) = text s
expr2C (HexNumber s) = text "0x" <> (text . map toLower $ s)
expr2C (StringLiteral s) = doubleQuotes $ text s 
expr2C (Reference ref) = ref2C ref
expr2C (PrefixOp op expr) = op2C op <+> expr2C expr
    {-
    | PostfixOp String Expression
    | CharCode String
    -}            
expr2C _ = empty


ref2C :: Reference -> Doc
ref2C (ArrayElement exprs ref) = ref2C ref <> (brackets . hcat) (punctuate comma $ map expr2C exprs)
ref2C (SimpleReference (Identifier name)) = text name
ref2C (RecordField (Dereference ref1) ref2) = ref2C ref1 <> text "->" <> ref2C ref2
ref2C (RecordField ref1 ref2) = ref2C ref1 <> text "." <> ref2C ref2
ref2C (Dereference ref) = parens $ text "*" <> ref2C ref
ref2C (FunCall params ref) = ref2C ref <> parens (hsep . punctuate (char ',') . map expr2C $ params)
ref2C (Address ref) = text "&" <> ref2C ref


op2C "or" = text "|"
op2C "and" = text "&"
op2C "not" = text "!"
op2C "xor" = text "^"
op2C "div" = text "/"
op2C "mod" = text "%"
op2C "shl" = text "<<"
op2C "shr" = text ">>"
op2C "<>" = text "!="
op2C "=" = text "=="
op2C a = text a

maybeVoid "" = "void"
maybeVoid a = a