import Control.Monad
import Data.List
import System.Directory
import System.Environment
import System.Exit
import System.IO
import System.IO.Temp
import System.Process
import Text.PDF.Info
import Text.Printf

texBegin = "\
	\\\documentclass{article}\
	\\\usepackage[paperwidth=4.25in,paperheight=11in]{geometry}\
	\\\usepackage{pdfpages}\
	\\\begin{document}\
	\"
includeTemplate = "\
	\\\includepdf[pages=%d,noautoscale,offset=2.125in 0]{%s}\
	\\\includepdf[pages=%d,noautoscale,offset=-2.125in 0]{%s}\
	\"
texEnd = "\\end{document}"
usageTemplate = "\
	\USAGE: %s infile.pdf [infile.pdf ...]\n\
	\\n\
	\Each filename given on the command line is treated as a standard US-letter\n\
	\(8.25\" x 11\") sized, two-column PDF, and a new PDF file is produced. If the\n\
	\input file name has the form <file>.pdf, then the new file will be named\n\
	\<file>-split.pdf. Otherwise, the output file name will be identical to the\n\
	\input file name, but with -split.pdf appended. Input filenames must not\n\
	\contain whitespace (not even properly-escaped whitespace!).\n\
	\\n\
	\Also, don't name your input files -h or --help. Come on.\n\
	\"
fixTheHighlighting = "--"

splitPages name n = withTempFile "." "pdfsplit.tex" $ \tmp h -> do
	hPutStr h texBegin
	forM_ [1..n] $ \i -> hPrintf h includeTemplate i name i name
	hPutStr h texEnd
	hFlush h
	readProcess "pdflatex" [tmp] ""
	renameFile (base "tex" tmp ++ ".pdf") (base "pdf" name ++ "-split.pdf")
	forM_ [".aux", ".log"] (removeFile . (base "tex" tmp ++))

base ext s
	| ('.':ext) `isSuffixOf` s = zipWith const s (drop (1 + length ext) s)
	| otherwise = s

problem s = printf (printf "Error processing file <%%s>: %s\n" s)
process name = do
	info <- pdfInfo name
	case (info, words name) of
		(Left error, _) -> problem "%s" name (show error) >> return 1
		(_, _:_:_) -> problem "filenames must not contain whitespace" name >> return 1
		(Right PDFInfo { pdfInfoPages = Nothing }, _) -> problem "can't divine the page count" name >> return 1
		(Right PDFInfo { pdfInfoPages = Just n }, _) -> splitPages name n >> return 0

usage = getProgName >>= printf usageTemplate >> exitWith ExitSuccess

main = do
	names <- getArgs
	when (names `elem` [[], ["--help"], ["-h"]]) usage
	successes <- mapM process names
	case sum successes of
		0 -> exitWith ExitSuccess
		n -> exitWith (ExitFailure n)