@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TupleSections #-}
 {-# LANGUAGE RecordWildCards #-}
@@ -8,7 +9,9 @@ module Command.Bundle (command) where
 
 import           Data.Traversable (for)
 import           Data.Aeson (encode)
+import           Data.Aeson.Encode.Pretty (confCompare, defConfig, encodePretty', keyOrder)
 import           Data.Maybe (isNothing)
+import           Data.Text (Text)
 import           Control.Applicative
 import           Control.Monad
 import           Control.Monad.Error.Class
@@ -35,6 +38,7 @@ data Options = Options
   , optionsMainModule  :: Maybe String
   , optionsNamespace   :: String
   , optionsSourceMaps  :: Bool
+  , optionsDebug       :: Bool
   } deriving Show
 
 -- | The main application function.
@@ -59,7 +63,17 @@ app Options{..} = do
 
   currentDir <- liftIO getCurrentDirectory
   let outFile = if optionsSourceMaps then fmap (currentDir </>) optionsOutputFile else Nothing
-  bundleSM input entryIds optionsMainModule optionsNamespace outFile
+  let withRawModules = if optionsDebug then Just bundleDebug else Nothing
+  bundleSM input entryIds optionsMainModule optionsNamespace outFile withRawModules
+
+-- | Print a JSON representation of a list of modules to stderr.
+bundleDebug :: (MonadIO m) => [Module] -> m ()
+bundleDebug = liftIO . hPutStrLn stderr . LBU8.toString . encodePretty' (defConfig { confCompare = keyComparer })
+  where
+  -- | Some key order hints for improved readability.
+  keyComparer :: Text -> Text -> Ordering
+  keyComparer =  keyOrder ["type", "name", "moduleId"]     -- keys to put first
+              <> flip (keyOrder ["dependsOn", "elements"]) -- keys to put last
 
 -- | Command line options parser.
 options :: Parser Options
@@ -69,6 +83,7 @@ options = Options <$> some inputFile
                   <*> optional mainModule
                   <*> namespace
                   <*> sourceMaps
+                  <*> debug
   where
   inputFile :: Parser FilePath
   inputFile = Opts.strArgument $
@@ -105,6 +120,11 @@ options = Options <$> some inputFile
        Opts.long "source-maps"
     <> Opts.help "Whether to generate source maps for the bundle (requires --output)."
 
+  debug :: Parser Bool
+  debug = Opts.switch $
+       Opts.long "debug"
+    <> Opts.help "Whether to emit a JSON representation of all parsed modules to stderr."
+
 -- | Make it go.
 command :: Opts.Parser (IO ())
 command = run <$> (Opts.helper <*> options) where
 
@@ -39,6 +39,7 @@ extra-source-files:
 dependencies:
   - aeson >=1.0 && <1.5
   - aeson-better-errors >=0.8
+  - aeson-pretty
   - ansi-terminal >=0.7.1 && <0.9
   - array
   - base >=4.11 && <4.13
 
@@ -14,6 +14,7 @@ module Language.PureScript.Bundle
   , ErrorMessage(..)
   , printErrorMessage
   , getExportedIdentifiers
+  , Module
   ) where
 
 import Prelude.Compat
@@ -23,6 +24,7 @@ import Control.Monad
 import Control.Monad.Error.Class
 import Control.Arrow ((&&&))
 
+import Data.Aeson ((.=))
 import Data.Array ((!))
 import Data.Char (chr, digitToInt)
 import Data.Foldable (fold)
@@ -31,11 +33,14 @@ import Data.Graph
 import Data.List (stripPrefix)
 import Data.Maybe (catMaybes, fromMaybe, mapMaybe)
 import Data.Version (showVersion)
+import qualified Data.Aeson as A
 import qualified Data.Map as M
 import qualified Data.Set as S
+import qualified Data.Text.Lazy as T
 
 import Language.JavaScript.Parser
 import Language.JavaScript.Parser.AST
+import Language.JavaScript.Process.Minify
 
 import qualified Paths_purescript as Paths
 
@@ -69,6 +74,12 @@ showModuleType Foreign = "Foreign"
 -- | A module is identified by its module name and its type.
 data ModuleIdentifier = ModuleIdentifier String ModuleType deriving (Show, Eq, Ord)
 
+instance A.ToJSON ModuleIdentifier where
+  toJSON (ModuleIdentifier name mt) =
+    A.object [ "name" .= name
+             , "type" .= show mt
+             ]
+
 moduleName :: ModuleIdentifier -> String
 moduleName (ModuleIdentifier name _) = name
 
@@ -110,9 +121,71 @@ data ModuleElement
   | Skip JSStatement
   deriving (Show)
 
+instance A.ToJSON ModuleElement where
+  toJSON = \case
+    (Require _ name (Right target)) ->
+      A.object [ "type"   .= A.String "Require"
+               , "name"   .= name
+               , "target" .= target
+               ]
+    (Require _ name (Left targetPath)) ->
+      A.object [ "type"       .= A.String "Require"
+               , "name"       .= name
+               , "targetPath" .= targetPath
+               ]
+    (Member _ public name _ dependsOn) ->
+      A.object [ "type"       .= A.String "Member"
+               , "name"       .= name
+               , "visibility" .= A.String (if public then "Public" else "Internal")
+               , "dependsOn"  .= map keyToJSON dependsOn
+               ]
+    (ExportsList exports) ->
+      A.object [ "type"    .= A.String "ExportsList"
+               , "exports" .= map exportToJSON exports
+               ]
+    (Other stmt) ->
+      A.object [ "type" .= A.String "Other"
+               , "js"   .= getFragment stmt
+               ]
+    (Skip stmt) ->
+      A.object [ "type" .= A.String "Skip"
+               , "js"   .= getFragment stmt
+               ]
+
+    where
+
+    keyToJSON (mid, member) =
+      A.object [ "module" .= mid
+               , "member" .= member
+               ]
+
+    exportToJSON (RegularExport sourceName, name, _, dependsOn) =
+      A.object [ "type"       .= A.String "RegularExport"
+               , "name"       .= name
+               , "sourceName" .= sourceName
+               , "dependsOn"  .= map keyToJSON dependsOn
+               ]
+    exportToJSON (ForeignReexport, name, _, dependsOn) =
+      A.object [ "type"      .= A.String "ForeignReexport"
+               , "name"      .= name
+               , "dependsOn" .= map keyToJSON dependsOn
+               ]
+
+    getFragment = ellipsize . renderToText . minifyJS . flip JSAstStatement JSNoAnnot
+      where
+      ellipsize text = if T.compareLength text 20 == GT then T.take 19 text `T.snoc` ellipsis else text
+      ellipsis = '\x2026'
+
 -- | A module is just a list of elements of the types listed above.
 data Module = Module ModuleIdentifier (Maybe FilePath) [ModuleElement] deriving (Show)
 
+instance A.ToJSON Module where
+  toJSON (Module moduleId filePath elements) =
+    A.object [ "moduleId" .= moduleId
+             , "filePath" .= filePath
+             , "elements" .= elements
+             ]
+
 -- | Prepare an error message for consumption by humans.
 printErrorMessage :: ErrorMessage -> [String]
 printErrorMessage (UnsupportedModulePath s) =
@@ -730,8 +803,9 @@ bundleSM :: (MonadError ErrorMessage m)
        -> Maybe String -- ^ An optional main module.
        -> String -- ^ The namespace (e.g. PS).
        -> Maybe FilePath -- ^ The output file name (if there is one - in which case generate source map)
+       -> Maybe ([Module] -> m ()) -- ^ Optionally report the parsed modules prior to DCE -- used by "bundle --debug"
        -> m (Maybe SourceMapping, String)
-bundleSM inputStrs entryPoints mainModule namespace outFilename = do
+bundleSM inputStrs entryPoints mainModule namespace outFilename reportRawModules = do
   let mid (a,_,_) = a
   forM_ mainModule $ \mname ->
     when (mname `notElem` map (moduleName . mid) inputStrs) (throwError (MissingMainModule mname))
@@ -745,6 +819,8 @@ bundleSM inputStrs entryPoints mainModule namespace outFilename = do
 
   modules <- traverse (fmap withDeps . (\(a,fn,c) -> toModule mids a fn c)) input
 
+  forM_ reportRawModules ($ modules)
+
   let compiled = compile modules entryPoints
       sorted   = sortModules (filter (not . isModuleEmpty) compiled)
 
@@ -759,4 +835,4 @@ bundle :: (MonadError ErrorMessage m)
        -> Maybe String -- ^ An optional main module.
        -> String -- ^ The namespace (e.g. PS).
        -> m String
-bundle inputStrs entryPoints mainModule namespace = snd <$> bundleSM (map (\(a,b) -> (a,Nothing,b)) inputStrs) entryPoints mainModule namespace Nothing
+bundle inputStrs entryPoints mainModule namespace = snd <$> bundleSM (map (\(a,b) -> (a,Nothing,b)) inputStrs) entryPoints mainModule namespace Nothing Nothing
@@ -12,3 +12,6 @@ nix:
   - nodejs
   - nodePackages.npm
   - nodePackages.bower
+flags:
+  aeson-pretty:
+    lib-only: true
@@ -74,7 +74,7 @@ assertBundles supportModules supportExterns supportForeigns inputFiles outputFil
             js <- liftIO $ readUTF8File filename
             mid <- guessModuleIdentifier filename
             length js `seq` return (mid, Just filename, js) 
-          bundleSM input entryModule (Just $ "Main") "PS" (Just entryPoint)
+          bundleSM input entryModule (Just $ "Main") "PS" (Just entryPoint) Nothing
         case bundled of
             Right (_, js) -> do
               writeUTF8File entryPoint js