web: also launch a browser at startup; auto-terminate after 2m or on enter

We're now using the wai-handler-launch middleware. This injects a
script in each page that pings the server repeatedly, and terminates
the server if it gets no pings (ie there are no browser tabs
displaying the app) for two minutes. The server can also be easily
terminated at the console by pressing enter, yesod devel style.

hledger-web/Hledger/Web/Main.hs

@@ -17,12 +17,14 @@ import Settings            --  (parseExtra)
 import Application          (makeApplication)
 import Data.Conduit.Network (HostPreference(HostIPv4))
 import Network.Wai.Handler.Warp (runSettings, defaultSettings, settingsPort)
-import Network.Wai.Handler.Launch (run, runUrl, runUrlPort)
+import Network.Wai.Handler.Launch (runUrlPort)
 --
 import Prelude hiding (putStrLn)
+import Control.Concurrent (forkIO)
 import Control.Monad (when)
 import Data.Text (pack)
 import System.Exit (exitSuccess)
+import System.IO (hFlush, stdout)
 import Text.Printf
 
 import Hledger
@@ -54,28 +56,23 @@ withJournalDo' opts cmd = do
 -- | The web command.
 web :: WebOpts -> Journal -> IO ()
 web opts j = do
-  -- unless (debug_ $ cliopts_ opts) $ forkIO (browser baseurl) >> return ()
   d <- getCurrentDay
   let j' = filterJournalTransactions (queryFromOpts d $ reportopts_ $ cliopts_ opts) j
-  server (base_url_ opts) (port_ opts) opts j'
-
--- browser :: String -> IO ()
--- browser baseurl = do
---   threadDelay $ fromIntegral browserstartdelay
---   putStrLn "Attempting to start a web browser"
---   openBrowserOn baseurl >> return ()
-
-server :: String -> Int -> WebOpts -> Journal -> IO ()
-server baseurl port opts j = do
-    _ <- printf "Starting http server on port %d with base url %s\n" port baseurl
-    app <- makeApplication j (AppConfig {
-              appEnv = Development
-            , appPort = port_ opts
-            , appRoot = pack baseurl
-            , appHost = HostIPv4
-            , appExtra = Extra "" Nothing
-            })
-    -- runSettings defaultSettings
-    --     { settingsPort = port_ opts
-    --     } app
-    run app
+      p = port_ opts
+      u = base_url_ opts
+  _ <- printf "Starting http server on port %d with base url %s\n" p u
+  app <- makeApplication j' AppConfig{appEnv = Development
+                                    ,appPort = p
+                                    ,appRoot = pack u
+                                    ,appHost = HostIPv4
+                                    ,appExtra = Extra "" Nothing
+                                    }
+  if False
+   then
+    runSettings defaultSettings{settingsPort=p} app
+   else do
+    putStrLn "Launching web browser" >> hFlush stdout
+    forkIO $ runUrlPort p "" app
+    putStrLn "Press ENTER to quit (or close browser windows for 2 minutes)" >> hFlush stdout
+    getLine >> exitSuccess
+