PDF generation improvements.

* `Text.Pandoc.PDF` exports `makePDF` instead of `tex2pdf`.
  (API change.)
* `makePDF` walks the pandoc AST and checks for the existence of
  images in the local directory.  If they are not found, it attempts
  to find them, either in the directory containing the first source
  file, or at an absolute URL, or at a URL relative to the base URL
  of the first command line argument.
* Closes #917.

3 files changed, 56 insertions, 9 deletions

diff --git a/pandoc.hs b/pandoc.hs
index 18124da3a..79bade221 100644
--- a/pandoc.hs
+++ b/pandoc.hs
@@ -31,7 +31,7 @@ writers.
 -}
 module Main where
 import Text.Pandoc
-import Text.Pandoc.PDF (tex2pdf)
+import Text.Pandoc.PDF (makePDF)
 import Text.Pandoc.Readers.LaTeX (handleIncludes)
 import Text.Pandoc.Shared ( tabFilter, readDataFileUTF8, safeRead,
                             headerShift, normalize, err, warn )
@@ -1113,7 +1113,7 @@ main = do
     Right (IOByteStringWriter f) -> f writerOptions doc0 >>= writeBinary
     Right (PureStringWriter f)
       | pdfOutput -> do
-              res <- tex2pdf latexEngine $ f writerOptions doc0
+              res <- makePDF latexEngine f writerOptions doc0
               case res of
                    Right pdf -> writeBinary pdf
                    Left err' -> err 43 $ UTF8.toStringLazy err'
diff --git a/src/Text/Pandoc/MIME.hs b/src/Text/Pandoc/MIME.hs
index eb54bd48d..d9cb94a33 100644
--- a/src/Text/Pandoc/MIME.hs
+++ b/src/Text/Pandoc/MIME.hs
@@ -27,7 +27,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 Mime type lookup for ODT writer.
 -}
-module Text.Pandoc.MIME ( getMimeType )
+module Text.Pandoc.MIME ( getMimeType, extensionFromMimeType )
 where
 import System.FilePath
 import Data.Char ( toLower )
@@ -37,7 +37,14 @@ import qualified Data.Map as M
 getMimeType :: FilePath -> Maybe String
 getMimeType "layout-cache" = Just "application/binary"  -- in ODT
 getMimeType f = M.lookup (map toLower $ drop 1 $ takeExtension f) mimeTypes
-  where mimeTypes = M.fromList -- List borrowed from happstack-server.
+  where mimeTypes = M.fromList mimeTypesList
+
+extensionFromMimeType :: String -> Maybe String
+extensionFromMimeType mimetype = M.lookup mimetype reverseMimeTypes
+  where reverseMimeTypes = M.fromList $ map (\(k,v) -> (v,k)) mimeTypesList
+
+mimeTypesList :: [(String, String)]
+mimeTypesList = -- List borrowed from happstack-server.
            [("gz","application/x-gzip")
            ,("cabal","application/x-cabal")
            ,("%","application/x-trash")
diff --git a/src/Text/Pandoc/PDF.hs b/src/Text/Pandoc/PDF.hs
index b36f2a0af..49b455285 100644
--- a/src/Text/Pandoc/PDF.hs
+++ b/src/Text/Pandoc/PDF.hs
@@ -28,12 +28,13 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
 Conversion of LaTeX documents to PDF.
 -}
-module Text.Pandoc.PDF ( tex2pdf ) where
+module Text.Pandoc.PDF ( makePDF ) where
 
 import System.IO.Temp
 import Data.ByteString.Lazy (ByteString)
 import qualified Data.ByteString.Lazy as B
 import qualified Data.ByteString.Lazy.Char8 as BC
+import qualified Data.ByteString as BS
 import System.Exit (ExitCode (..))
 import System.FilePath
 import System.Directory
@@ -42,9 +43,15 @@ import System.Environment
 import Control.Exception (evaluate)
 import System.IO (hClose)
 import Control.Concurrent (putMVar, takeMVar, newEmptyMVar, forkIO)
-import Text.Pandoc.UTF8 as UTF8
 import Control.Monad (unless)
 import Data.List (isInfixOf)
+import qualified Data.ByteString.Base64 as B64
+import qualified Text.Pandoc.UTF8 as UTF8
+import Text.Pandoc.Definition
+import Text.Pandoc.Generic (bottomUpM)
+import Text.Pandoc.Shared (fetchItem, warn)
+import Text.Pandoc.Options (WriterOptions(..))
+import Text.Pandoc.MIME (extensionFromMimeType)
 
 withTempDir :: String -> (FilePath -> IO a) -> IO a
 withTempDir =
@@ -54,12 +61,45 @@ withTempDir =
   withSystemTempDirectory
 #endif
 
-tex2pdf :: String       -- ^ tex program (pdflatex, lualatex, xelatex)
-        -> String       -- ^ latex source
+makePDF :: String              -- ^ pdf creator (pdflatex, lualatex, xelatex)
+        -> (WriterOptions -> Pandoc -> String)  -- ^ writer
+        -> WriterOptions       -- ^ options
+        -> Pandoc              -- ^ document
         -> IO (Either ByteString ByteString)
-tex2pdf program source = withTempDir "tex2pdf." $ \tmpdir ->
+makePDF program writer opts doc = withTempDir "tex2pdf." $ \tmpdir -> do
+  doc' <- handleImages (writerSourceDirectory opts) tmpdir doc
+  let source = writer opts doc'
   tex2pdf' tmpdir program source
 
+handleImages :: String        -- ^ source directory/base URL
+             -> FilePath      -- ^ temp dir to store images
+             -> Pandoc        -- ^ document
+             -> IO Pandoc
+handleImages baseURL tmpdir = bottomUpM (handleImage' baseURL tmpdir)
+
+handleImage' :: String
+             -> FilePath
+             -> Inline
+             -> IO Inline
+handleImage' baseURL tmpdir (Image ils (src,tit)) = do
+    exists <- doesFileExist src
+    if exists
+       then return $ Image ils (src,tit)
+       else do
+         res <- fetchItem baseURL src
+         case res of
+              Right (contents, Just mime) -> do
+                let ext = maybe (takeExtension src) id $
+                          extensionFromMimeType mime
+                let basename = UTF8.toString $ B64.encode $ UTF8.fromString src
+                let fname = tmpdir </> basename <.> ext
+                BS.writeFile fname contents
+                return $ Image ils (fname,tit)
+              _ -> do
+                warn $ "Could not find image `" ++ src ++ "', skipping..."
+                return $ Image ils (src,tit)
+handleImage' _ _ x = return x
+
 tex2pdf' :: FilePath                        -- ^ temp directory for output
          -> String                          -- ^ tex program
          -> String                          -- ^ tex source