Handle SQL errors gracefully.

[mailbox-count.git] / src / Main.hs

diff --git a/src/Main.hs b/src/Main.hs
index d153716e3ad575f9368ce2bc779785721986068b..d1d1ea81fa43516bd44b01b294326451b9fbafaf 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,17 +1,23 @@
+{-# LANGUAGE DoAndIfThenElse #-}
+{-# LANGUAGE NoMonomorphismRestriction #-}
 module Main
 where
 
 import Data.Maybe ( fromMaybe )
 import Data.Monoid ( (<>) )
 import Data.String.Utils ( join )
+import Database.HDBC ( SqlError(..), handleSql )
 import Database.HDBC.PostgreSQL ( connectPostgreSQL )
+import Database.HDBC.Sqlite3 ( connectSqlite3 )
 import System.Console.CmdArgs ( def )
-
+import System.Directory ( doesFileExist )
+import System.IO ( hPutStrLn, stderr )
 import CommandLine ( get_args )
 import Configuration ( Configuration(..), merge_optional )
 import qualified OptionalConfiguration as OC ( from_rc )
 import Report ( report )
 
+
 -- | Construct a connection string (postgres-only, for now) from a
 --   'Configuration'. All of these are optional, at least for
 --   Postgres, and so we want to avoid appending e.g. \"host=\" to the
@@ -58,16 +64,22 @@ main = do
   -- log the errors.
   let cfg = (def :: Configuration) `merge_optional` opt_config
 
-  -- Check the optional config for missing required options.
-  --when (isNothing (OC.password opt_config)) $ do
-  --  report_error "No password supplied."
-  --  exitWith (ExitFailure exit_no_password)
+  -- If a database name was specified, and that name exists as a file
+  -- on the system, assume that the user wanted to use SQLite.
+  handleSql show_sql_error $ do
+    r <- case (database cfg) of
+        Nothing -> connectPostgreSQL (connection_string cfg) >>= report cfg
 
-  --when (isNothing (OC.username opt_config)) $ do
-  --  report_error "No username supplied."
-  --exitWith (ExitFailure exit_no_username)
+        Just dbname -> do
+          exists <- doesFileExist dbname
+          if exists
+          then connectSqlite3 dbname >>= report cfg
+          else connectPostgreSQL (connection_string cfg) >>= report cfg
 
-  conn <- connectPostgreSQL (connection_string cfg)
-  r <- report conn (detail cfg)
-  putStrLn r
---  disconnect conn
+    -- The DB connection is implicitly closed when it gets garbage collected.
+    putStrLn r
+
+  where
+    show_sql_error :: SqlError -> IO ()
+    show_sql_error se = hPutStrLn stderr $
+      "SQL Error (" ++ (show $ seNativeError se) ++ "): " ++ (seErrorMsg se)