{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
module Sit.Print where

-- pretty-printer generated by the BNF converter

import Sit.Abs
import Data.Char


-- the top-level printing method
printTree :: Print a => a -> String
printTree = render . prt 0

type Doc = [ShowS] -> [ShowS]

doc :: ShowS -> Doc
doc = (:)

render :: Doc -> String
render d = rend 0 (map ($ "") $ d []) "" where
  rend i ss = case ss of
    "["      :ts -> showChar '[' . rend i ts
    "("      :ts -> showChar '(' . rend i ts
    "{"      :ts -> showChar '{' . new (i+1) . rend (i+1) ts
    "}" : ";":ts -> new (i-1) . space "}" . showChar ';' . new (i-1) . rend (i-1) ts
    "}"      :ts -> new (i-1) . showChar '}' . new (i-1) . rend (i-1) ts
    ";"      :ts -> showChar ';' . new i . rend i ts
    t  : ts@(p:_) | closingOrPunctuation p -> showString t . rend i ts
    t        :ts -> space t . rend i ts
    _            -> id
  new i   = showChar '\n' . replicateS (2*i) (showChar ' ') . dropWhile isSpace
  space t = showString t . (\s -> if null s then "" else ' ':s)
  closingOrPunctuation [c] = c `elem` ")],;."
  closingOrPunctuation _   = False

parenth :: Doc -> Doc
parenth ss = doc (showChar '(') . ss . doc (showChar ')')

concatS :: [ShowS] -> ShowS
concatS = foldr (.) id

concatD :: [Doc] -> Doc
concatD = foldr (.) id

replicateS :: Int -> ShowS -> ShowS
replicateS n f = concatS (replicate n f)

-- the printer class does the job
class Print a where
  prt :: Int -> a -> Doc
  prtList :: Int -> [a] -> Doc
  prtList i = concatD . map (prt i)

instance Print a => Print [a] where
  prt = prtList

instance Print Char where
  prt _ s = doc (showChar '\'' . mkEsc '\'' s . showChar '\'')
  prtList _ s = doc (showChar '"' . concatS (map (mkEsc '"') s) . showChar '"')

mkEsc :: Char -> Char -> ShowS
mkEsc q s = case s of
  _ | s == q -> showChar '\\' . showChar s
  '\\'-> showString "\\\\"
  '\n' -> showString "\\n"
  '\t' -> showString "\\t"
  _ -> showChar s

prPrec :: Int -> Int -> Doc -> Doc
prPrec i j = if j<i then parenth else id


instance Print Integer where
  prt _ x = doc (shows x)


instance Print Double where
  prt _ x = doc (shows x)


instance Print Ident where
  prt _ (Ident i) = doc (showString ( i))
  prtList _ [x] = (concatD [prt 0 x])
  prtList _ (x:xs) = (concatD [prt 0 x, prt 0 xs])


instance Print Prg where
  prt i e = case e of
    Prg decls -> prPrec i 0 (concatD [prt 0 decls])

instance Print Decl where
  prt i e = case e of
    Sig id exp -> prPrec i 0 (concatD [prt 0 id, doc (showString ":"), prt 0 exp])
    Def id exp -> prPrec i 0 (concatD [prt 0 id, doc (showString "="), prt 0 exp])
    Open qualid -> prPrec i 0 (concatD [doc (showString "open"), doc (showString "import"), prt 0 qualid])
    Blank -> prPrec i 0 (concatD [])
  prtList _ [x] = (concatD [prt 0 x])
  prtList _ (x:xs) = (concatD [prt 0 x, doc (showString "--;"), prt 0 xs])
instance Print QualId where
  prt i e = case e of
    Sg id -> prPrec i 0 (concatD [prt 0 id])
    Cons qualid id -> prPrec i 0 (concatD [prt 0 qualid, doc (showString "."), prt 0 id])

instance Print IdU where
  prt i e = case e of
    Id id -> prPrec i 0 (concatD [prt 0 id])
    Under -> prPrec i 0 (concatD [doc (showString "_")])
  prtList _ [x] = (concatD [prt 0 x])
  prtList _ (x:xs) = (concatD [prt 0 x, prt 0 xs])
instance Print Bind where
  prt i e = case e of
    BIrrel id -> prPrec i 0 (concatD [doc (showString "."), prt 0 id])
    BRel id -> prPrec i 0 (concatD [doc (showString ".."), prt 0 id])
    BAnn ids exp -> prPrec i 0 (concatD [doc (showString "("), prt 0 ids, doc (showString ":"), prt 0 exp, doc (showString ")")])
  prtList _ [x] = (concatD [prt 0 x])
  prtList _ (x:xs) = (concatD [prt 0 x, prt 0 xs])
instance Print Exp where
  prt i e = case e of
    Var idu -> prPrec i 2 (concatD [prt 0 idu])
    Int n -> prPrec i 2 (concatD [prt 0 n])
    Infty -> prPrec i 2 (concatD [doc (showString "oo")])
    Nat -> prPrec i 2 (concatD [doc (showString "Nat")])
    Set -> prPrec i 2 (concatD [doc (showString "Set")])
    Set1 -> prPrec i 2 (concatD [doc (showString "Set1")])
    Set2 -> prPrec i 2 (concatD [doc (showString "Set2")])
    Zero -> prPrec i 2 (concatD [doc (showString "zero")])
    Suc -> prPrec i 2 (concatD [doc (showString "suc")])
    Fix -> prPrec i 2 (concatD [doc (showString "fix")])
    LZero -> prPrec i 2 (concatD [doc (showString "lzero")])
    LSuc -> prPrec i 2 (concatD [doc (showString "lsuc")])
    Size -> prPrec i 0 (concatD [doc (showString "Size")])
    App exp1 exp2 -> prPrec i 1 (concatD [prt 1 exp1, prt 2 exp2])
    Lam idus exp -> prPrec i 0 (concatD [doc (showString "\\"), prt 0 idus, doc (showString "->"), prt 0 exp])
    Forall binds exp -> prPrec i 0 (concatD [doc (showString "forall"), prt 0 binds, doc (showString "->"), prt 0 exp])
    Pi exp1 exp2 exp3 -> prPrec i 0 (concatD [doc (showString "("), prt 0 exp1, doc (showString ":"), prt 0 exp2, doc (showString ")"), doc (showString "->"), prt 0 exp3])
    Arrow exp1 exp2 -> prPrec i 0 (concatD [prt 1 exp1, doc (showString "->"), prt 0 exp2])
    Case exp1 exp2 exp3 -> prPrec i 0 (concatD [doc (showString "case"), prt 0 exp1, doc (showString "return"), prt 0 exp2, doc (showString "of"), prt 0 exp3])
    Plus exp n -> prPrec i 0 (concatD [prt 1 exp, doc (showString "+"), prt 0 n])
    ELam exp1 idu exp2 -> prPrec i 0 (concatD [doc (showString "\\"), doc (showString "{"), doc (showString "("), doc (showString "zero"), doc (showString "_"), doc (showString ")"), doc (showString "->"), prt 0 exp1, doc (showString ";"), doc (showString "("), doc (showString "suc"), doc (showString "_"), prt 0 idu, doc (showString ")"), doc (showString "->"), prt 0 exp2, doc (showString "}")])