{- git-annex command line parsing
 -
 - Copyright 2010 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module CmdLine (
	dispatch,
	parseCmd,
	usage,
) where

import System.Console.GetOpt
import Control.Monad (when)
import Control.Monad.State (liftIO)

import qualified Annex
import qualified GitRepo as Git
import Types
import Command
import BackendList
import Core
import Upgrade
import Options

{- Runs the passed command line. -}
dispatch :: Git.Repo -> [String] -> [Command] -> [Option] -> String -> IO ()
dispatch gitrepo args cmds options header = do
	state <- Annex.new gitrepo allBackends
	(actions, state') <- Annex.run state $ parseCmd args header cmds options
	tryRun state' $ [startup, upgrade] ++ actions

{- Parses command line, stores configure flags, and returns a 
 - list of actions to be run in the Annex monad. -}
parseCmd :: [String] -> String -> [Command] -> [Option] -> Annex [Annex Bool]
parseCmd argv header cmds options = do
	(flags, params) <- liftIO $ getopt
	when (null params) $ error $ "missing command" ++ usagemsg
	case lookupCmd (head params) of
		[] -> error $ "unknown command" ++ usagemsg
		[command] -> do
			_ <- sequence flags
			prepCmd command (drop 1 params)
		_ -> error "internal error: multiple matching commands"
	where
		getopt = case getOpt Permute options argv of
			(flags, params, []) ->
				return (flags, params)
			(_, _, errs) ->
				ioError (userError (concat errs ++ usagemsg))
		lookupCmd cmd = filter (\c -> cmd  == cmdname c) cmds
		usagemsg = "\n\n" ++ usage header cmds options

{- Usage message with lists of commands and options. -}
usage :: String -> [Command] -> [Option] -> String
usage header cmds options =
	usageInfo (header ++ "\n\nOptions:") options ++
		"\nCommands:\n" ++ cmddescs
	where
		cmddescs = unlines $ map (indent . showcmd) cmds
		showcmd c =
			cmdname c ++
			pad (longest cmdname + 1) (cmdname c) ++
			cmdparams c ++
			pad (longest cmdparams + 2) (cmdparams c) ++
			cmddesc c
		indent l = "  " ++ l
		pad n s = replicate (n - length s) ' '
		longest f = foldl max 0 $ map (length . f) cmds