add routes to pause/start/cancel transfers

This commit includes a paydown on technical debt incurred two years ago,
when I didn't know that it was bad to make custom Read and Show instances
for types. As the routes need Read and Show for Transfer, which includes a
Key, and deriving my own Read instance of key was not practical,
I had to finally clean that up.

So the compact Key read and show functions are now file2key and key2file,
and Read and Show are now derived instances.

Changed all code that used the old instances, compiler checked.
(There were a few places, particularly in Command.Unused, and the test
suite where the Show instance continue to be used for legitimate
comparisons; ie show key_x == show key_y (though really in a bloom filter))

Assistant/WebApp/DashBoard.hs

@@ -42,13 +42,18 @@ transfersDisplay warnNoScript = do
 	queued <- liftIO $ getTransferQueue $ transferQueue webapp
 	let ident = "transfers"
 	autoUpdate ident NotifierTransfersR (10 :: Int) (10 :: Int)
-	let transfers = current ++ queued
+	let transfers = current ++ queued ++ dummy
 	if null transfers
 		then ifM (lift $ showIntro <$> getWebAppState)
 			( introDisplay ident
 			, $(widgetFile "dashboard/transfers")
 			)
 		else $(widgetFile "dashboard/transfers")
+	where
+		dummy = [(t, i), (t, i)]
+		t = Transfer Download (UUID "00000000-0000-0000-0000-000000000001") k
+		k = Types.Key.Key "foo" "bar" Nothing Nothing
+		i = TransferInfo Nothing Nothing Nothing Nothing Nothing Nothing
 
 {- Called by client to get a display of currently in process transfers.
  -
@@ -98,7 +103,10 @@ postFileBrowserR = void openFileBrowser
 {- Used by non-javascript browsers, where clicking on the link actually
  - opens this page, so we redirect back to the referrer. -}
 getFileBrowserR :: Handler ()
-getFileBrowserR = whenM openFileBrowser $ do
+getFileBrowserR = whenM openFileBrowser $ redirectBack
+
+redirectBack :: Handler ()
+redirectBack = do
 	clearUltDest
 	setUltDestReferer
 	redirectUltDest HomeR
@@ -130,3 +138,27 @@ openFileBrowser = do
 #else
 		cmd = "xdg-open"
 #endif
+
+{- Transfer controls. The GET is done in noscript mode and redirects back
+ - to the referring page. The POST is called by javascript. -}
+getPauseTransferR :: Transfer -> Handler ()
+getPauseTransferR t = pauseTransfer t >> redirectBack
+postPauseTransferR :: Transfer -> Handler ()
+postPauseTransferR t = pauseTransfer t
+getStartTransferR :: Transfer -> Handler ()
+getStartTransferR t = startTransfer t >> redirectBack
+postStartTransferR :: Transfer -> Handler ()
+postStartTransferR t = startTransfer t
+getCancelTransferR :: Transfer -> Handler ()
+getCancelTransferR t = cancelTransfer t >> redirectBack
+postCancelTransferR :: Transfer -> Handler ()
+postCancelTransferR t = cancelTransfer t
+
+pauseTransfer :: Transfer -> Handler ()
+pauseTransfer t = liftIO $ putStrLn "pause"
+
+startTransfer :: Transfer -> Handler ()
+startTransfer t = liftIO $ putStrLn "start"
+
+cancelTransfer :: Transfer -> Handler ()
+cancelTransfer t = liftIO $ putStrLn "cancel"