4 files changed, 31 insertions, 6 deletions

diff --git a/compiler/app/Main.hs b/compiler/app/Main.hs
index 4dd6660..e26055f 100644
--- a/compiler/app/Main.hs
+++ b/compiler/app/Main.hs
@@ -18,8 +18,12 @@
 
 module Main where
 
+import GHC.Generics (Generic)
 import Paths_ldgallery_compiler (version, getDataFileName)
 import Data.Version (showVersion)
+import Data.Int (Int64)
+import Data.Aeson (ToJSON)
+import Data.Time.Clock.System (getSystemTime, systemSeconds)
 import System.FilePath ((</>))
 import System.Console.CmdArgs
 
@@ -27,6 +31,12 @@ import Compiler
 import Files (readDirectory, copyTo)
 
 
+data ViewerConfig = ViewerConfig
+  { galleryRoot :: String
+  , generationTimestamp :: Int64
+  } deriving (Generic, Show, ToJSON)
+
+
 data Options = Options
   { inputDir :: String
   , outputDir :: String
@@ -77,25 +87,27 @@ main :: IO ()
 main =
   do
     opts <- cmdArgs options
-
     buildGallery opts
-
-    if (withViewer opts) then
+    if (withViewer opts) then do
       copyViewer (outputDir opts)
+      writeViewerConfig (outputDir opts </> "config.json")
     else
       return ()
 
   where
+    gallerySubdir :: String
+    gallerySubdir = "gallery/"
+
     buildGallery :: Options -> IO ()
     buildGallery opts =
       compileGallery
         (inputDir opts)
-        (galleryOutputDir "gallery" opts)
+        (galleryOutputDir opts)
         (rebuilAll opts)
         (cleanOutput opts)
 
-    galleryOutputDir :: FilePath -> Options -> FilePath
-    galleryOutputDir gallerySubdir opts =
+    galleryOutputDir :: Options -> FilePath
+    galleryOutputDir opts =
       if withViewer opts then outputBase </> gallerySubdir else outputBase
       where outputBase = outputDir opts
 
@@ -105,3 +117,9 @@ main =
       >>  getDataFileName "viewer"
       >>= readDirectory
       >>= copyTo target
+
+    writeViewerConfig :: FilePath -> IO ()
+    writeViewerConfig fileName =
+      getSystemTime
+      >>= return . ViewerConfig gallerySubdir . systemSeconds
+      >>= writeJSON fileName
diff --git a/compiler/data/viewer/readme.md b/compiler/data/viewer/readme.md
new file mode 100644
index 0000000..5786878
--- /dev/null
+++ b/compiler/data/viewer/readme.md
@@ -0,0 +1,2 @@
+Missing viewer distribution.
+Copy the files in "/viewer/dist/*" here, then rebuild the compiler.
diff --git a/compiler/src/Compiler.hs b/compiler/src/Compiler.hs
index fc40a76..8819ffc 100644
--- a/compiler/src/Compiler.hs
+++ b/compiler/src/Compiler.hs
@@ -18,6 +18,7 @@
 
 module Compiler
   ( compileGallery
+  , writeJSON
   ) where
 
 
diff --git a/viewer/public/config.json b/viewer/public/config.json
new file mode 100644
index 0000000..7023edb
--- /dev/null
+++ b/viewer/public/config.json
@@ -0,0 +1,4 @@
+{
+    "generationTimestamp": 0,
+    "galleryRoot": "gallery/"
+}
\ No newline at end of file