{-# LANGUAGE ImplicitParams #-}

module Main (main) where
import Data.IORef
import System.IO
import System.IO.Unsafe
import System.Exit
import System.Environment
import Control.Applicative
import qualified Data.ByteString.Lazy.Char8 as L
import qualified Data.IntMap as IM

{-# NOINLINE __POS__ #-}
__POS__ :: IORef Int
__POS__ = unsafePerformIO (newRef 0)

{-# NOINLINE __OBJ__ #-}
__OBJ__ :: IORef Int
__OBJ__ = unsafePerformIO (newRef 0)

{-# NOINLINE __LOC__ #-}
__LOC__ :: IORef (IM.IntMap String)
__LOC__ = unsafePerformIO (newRef IM.empty)

{-# NOINLINE __PAGE__ #-}
__PAGE__ :: IORef [Obj]
__PAGE__ = unsafePerformIO (newRef [])

type M = IO
type Obj = Int

main :: IO ()
main = do
    args <- getArgs

    input <- case args of
        []      -> do
            putStrLn "Usage: line2pdf input.txt > output.pdf"
            putStrLn "  (Form feed (^L) in input denotes a pagebreak.)"
            exitWith ExitSuccess
        (i:_)   -> return i

    hSetBinaryMode stdout True

    pr$ "%PDF-1.2\n" ++ "%\xE2\xE3\xCF\xD3\n"

    (info, root, tPages, resources) <- writeHeader

    pageObjs <- let ?tPages = tPages
                    ?resources = resources in writePages =<< (L.lines <$> L.readFile input)

    markLocation root
    writeObj root $ do
        pr$ "/Type/Catalog" ++ "/Pages "
        pr$ show tPages ++ " 0 R" 

    markLocation tPages
    writeObj tPages $ do
        pr$ "/Type/Pages" ++ "/Count "
        pr$ show (length pageObjs)
         ++ "/MediaBox[0 0 "
         ++ show pageWidth ++ " " ++ show pageHeight
        pr$ "]" ++ "/Kids["
        pr$ concatMap ((++ " 0 R ") . show) pageObjs
        pr$ "]"

    xfer <- currentLocation

    objCount <- incrObj
    pr$ "xref\n" ++ "0 " ++ show objCount ++ "\n"
     ++ "0000000000 65535 f \r"

    writeLocations

    pr$ "trailer\n" ++ "<<" ++ "/Size "
    pr$ show objCount

    pr$ "/Root " ++ show root ++ " 0 R"
    pr$ "/Info " ++ show info ++ " 0 R"
    pr$ ">>\n" ++ "startxref\n"
    pr$ show xfer ++ "\n" ++ "%%EOF\n"

writeObj :: Obj -> M a -> M a
writeObj obj f = do
    pr$ show obj ++ " 0 obj" ++ "<<"
    rv <- f
    pr$ ">>" ++ "endobj\n"
    return rv

writeLocations :: M ()
writeLocations = do
    locs <- IM.elems <$> readRef __LOC__
    pr$ concatMap fmt locs
    where
    fmt x = pad ++ x ++ " 00000 n \r"
        where
        pad = replicate (10-l) '0'
        l = length x 

printObj :: String -> M Obj
printObj str = markObj $ (pr str >>) . return

writeHeader :: M (Obj, Obj, Obj, Obj)
writeHeader = do
    info <- printObj $ "/CreationDate(D:20080707163949+08'00')"
                    ++ "/Producer(line2pdf.hs)"
                    ++ "/Title(Untitled)"
    encoding <- printObj strDefaultEncoding
    everyFont <- (`mapM` ([1..] `zip` baseFonts)) $ \(n, font) -> do
        markObj $ \obj -> do
            pr$ "/Type/Font" ++ "/Subtype/Type1" ++ "/Name/F"
            pr$ show (n :: Int)
            pr$ "/Encoding " ++ show encoding ++ " 0 R"
            pr$ font
            return $ "/F" ++ show n ++ " " ++ show obj ++ " 0 R"
    tradFont <- tradChineseFonts
    root    <- incrObj
    tPages  <- incrObj
    markObj $ \resources -> do
        pr$ "/Font<<" ++ concat everyFont ++ concat tradFont ++ ">>"
            ++ "/ProcSet[/PDF/Text]" ++ "/XObject<<>>"
        return (info, root, tPages, resources)

baseFonts :: [String]
baseFonts =
    [ "/BaseFont/Courier"
    , "/BaseFont/Courier-Oblique"
    , "/BaseFont/Courier-Bold"
    , "/BaseFont/Courier-BoldOblique"
    , "/BaseFont/Helvetica"
    , "/BaseFont/Helvetica-Oblique"
    , "/BaseFont/Helvetica-Bold"
    , "/BaseFont/Helvetica-BoldOblique"
    , "/BaseFont/Times-Roman"
    , "/BaseFont/Times-Italic"
    , "/BaseFont/Times-Bold"
    , "/BaseFont/Times-BoldItalic"
    , "/BaseFont/Symbol"
    , "/BaseFont/ZapfDingbats"
    ]
    
pr :: String -> M ()
pr str = do
    putStr str
    modifyRef __POS__ (+ (length str))

currentLocation :: IO Int
currentLocation = readRef __POS__

newRef :: a -> M (IORef a)
newRef = newIORef

readRef :: IORef a -> M a
readRef = readIORef

writeRef :: IORef a -> a -> M ()
writeRef = writeIORef

modifyRef :: IORef a -> (a -> a) -> M ()
modifyRef = modifyIORef

incrObj :: M Obj
incrObj = do
    obj <- succ <$> readRef __OBJ__
    writeRef __OBJ__ obj
    return obj

markObj :: (Obj -> M a) -> M a
markObj f = do
    obj <- incrObj
    markLocation obj
    writeObj obj (f obj)

markLocation :: Obj -> M ()
markLocation obj = do
    loc <- currentLocation
    modifyRef __LOC__ $ IM.insert obj (show loc)

startPage :: (?tPages :: Obj, ?resources :: Obj) => M Int
startPage = do
    markObj $ \obj -> do
        modifyRef __PAGE__ (obj:)
        pr$ "/Type/Page"
        pr$ "/Parent " ++ show ?tPages ++ " 0 R"
        pr$ "/Resources " ++ show ?resources ++ " 0 R"
        pr$ "/Contents " ++ show (succ obj) ++ " 0 R"
        pr$ "/Rotate 0"

    obj <- incrObj
    markLocation obj
    pr$ show obj ++ " 0 obj" ++ "<<"
    pr$ "/Length " ++ show (succ obj) ++ " 0 R"
    pr$ ">>" ++ "stream\n"

    streamPos <- currentLocation
    pr$ "BT\n";
    let fontN = 30 :: Int
        ptSize = 12 :: Int
    pr$ "/F" ++ show fontN ++ " " ++ show ptSize ++ " Tf\n"
    pr$ "1 0 0 1 50 " ++ show (pageHeight - 40) ++ " Tm\n"
    pr$ "12 TL\n"

    return streamPos

endPage :: Int -> M ()
endPage streamStart = do
    pr$ "ET\n"
    streamEnd <- currentLocation
    pr$ "endstream\n"
     ++ "endobj\n"

    obj <- incrObj
    markLocation obj

    pr$ show obj ++ " 0 obj\n"
     ++ show (streamEnd - streamStart) ++ "\n"
     ++ "endobj\n"

writePages :: (?tPages :: Obj, ?resources :: Obj) => [L.ByteString] -> M [Obj]
writePages lns = do
    pos <- newRef =<< startPage

    (`mapM_` lns) $ \ln -> do
        case fromEnum (L.length ln) of
            1 | L.head ln == '\f' -> do
                endPage =<< readRef pos
                writeRef pos =<< startPage
            len -> do
                pr$ "T*("
                L.putStr ln
                modifyRef __POS__ (+ len)
                pr$ ")Tj\n"

    endPage =<< readRef pos
    reverse <$> readRef __PAGE__

strDefaultEncoding :: String
strDefaultEncoding = "/Type/Encoding"
    ++ "/Differences[0 /.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/space/exclam"
    ++ "/quotedbl/numbersign/dollar/percent/ampersand"
    ++ "/quoteright/parenleft/parenright/asterisk/plus/comma"
    ++ "/hyphen/period/slash/zero/one/two/three/four/five"
    ++ "/six/seven/eight/nine/colon/semicolon/less/equal"
    ++ "/greater/question/at/A/B/C/D/E/F/G/H/I/J/K/L"
    ++ "/M/N/O/P/Q/R/S/T/U/V/W/X/Y/Z/bracketleft"
    ++ "/backslash/bracketright/asciicircum/underscore"
    ++ "/quoteleft/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p"
    ++ "/q/r/s/t/u/v/w/x/y/z/braceleft/bar/braceright"
    ++ "/asciitilde/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef"
    ++ "/dotlessi/grave/acute/circumflex/tilde/macron/breve"
    ++ "/dotaccent/dieresis/.notdef/ring/cedilla/.notdef"
    ++ "/hungarumlaut/ogonek/caron/space/exclamdown/cent"
    ++ "/sterling/currency/yen/brokenbar/section/dieresis"
    ++ "/copyright/ordfeminine/guillemotleft/logicalnot/hyphen"
    ++ "/registered/macron/degree/plusminus/twosuperior"
    ++ "/threesuperior/acute/mu/paragraph/periodcentered"
    ++ "/cedilla/onesuperior/ordmasculine/guillemotright"
    ++ "/onequarter/onehalf/threequarters/questiondown/Agrave"
    ++ "/Aacute/Acircumflex/Atilde/Adieresis/Aring/AE"
    ++ "/Ccedilla/Egrave/Eacute/Ecircumflex/Edieresis/Igrave"
    ++ "/Iacute/Icircumflex/Idieresis/Eth/Ntilde/Ograve"
    ++ "/Oacute/Ocircumflex/Otilde/Odieresis/multiply/Oslash"
    ++ "/Ugrave/Uacute/Ucircumflex/Udieresis/Yacute/Thorn"
    ++ "/germandbls/agrave/aacute/acircumflex/atilde/adieresis"
    ++ "/aring/ae/ccedilla/egrave/eacute/ecircumflex"
    ++ "/edieresis/igrave/iacute/icircumflex/idieresis/eth"
    ++ "/ntilde/ograve/oacute/ocircumflex/otilde/odieresis"
    ++ "/divide/oslash/ugrave/uacute/ucircumflex/udieresis"
    ++ "/yacute/thorn/ydieresis]"

pageWidth :: Int
pageWidth = 792

pageHeight :: Int
pageHeight = 612

tradChineseFonts :: M [String]
tradChineseFonts = do
    tradFont <- newRef []
    let addFont o fn = modifyRef tradFont
            (("/F" ++ show (fn :: Int) ++ " " ++ show o ++ " 0 R"):)

        markFont fn suffix = do
            markObj $ \obj -> do
                addFont obj fn
                pr$ "/Type/Font"
                 ++ "/Subtype/Type0"
                 ++ "/Name/F"
                pr$ show fn ++ "/BaseFont/MingLiU"
                pr$ suffix ++ "/Encoding/ETen-B5-H"
                pr$ "/DescendantFonts[" ++ show (succ obj) ++ " 0 R]"
            markObj $ \obj -> do
                pr$ "/Type/Font"
                 ++ "/Subtype/CIDFontType2"
                 ++ "/BaseFont/MingLiU"
                pr$ suffix ++ "/FontDescriptor " ++ show (succ obj) ++ " 0 R"
                 ++ "/CIDSystemInfo<<"
                 ++ "/Registry(Adobe)"
                 ++ "/Ordering(CNS1)"
                 ++ "/Supplement 0"
                 ++ ">>"
                 ++ "/DW 1000"
                 ++ "/W[13500 14000 500]"
            printObj $ "/Type/FontDescriptor"
                    ++ "/FontName/MingLiU"
                    ++ "/FontBBox[0 -199 1000 801]"
                    ++ "/Flags 7"
                    ++ "/CapHeight 0"
                    ++ "/Ascent 800"
                    ++ "/Descent -199"
                    ++ "/StemV 0"
                    ++ "/ItalicAngle 0"
    markFont 30 ""
    markFont 31 ",Italic"
    markFont 32 ",Bold"
    markFont 33 ",BoldItalic"
    readRef tradFont