-- Copyright: 2010 Dino Morelli
-- License: BSD3 (see LICENSE)
-- Author: Dino Morelli <dino@ui3.info>

{-# LANGUAGE FlexibleContexts #-}

module Cltw.Opts
   ( Options (..)
   , parseOpts, usageText
   )
   where

import Control.Monad.Error
import Data.List
import System.Console.GetOpt


data Options = Options
   { optUser :: String
   , optPassword :: Maybe String
   , optVerbosity :: Int
   , optEchoReqUri :: Bool
   , optAddNoise :: Bool
   }
   deriving Show


defaultOptions :: Options
defaultOptions = Options
   { optUser = ""
   , optPassword = Nothing
   , optVerbosity = 1
   , optEchoReqUri = False
   , optAddNoise = False
   }


options :: [OptDescr (Options -> Options)]
options =
   [ Option ['u'] ["user"]
      (ReqArg
         (\u opts -> opts { optUser = u })
         "USER"
      ) "Username (always required)"
   , Option ['p'] ["password"]
      (ReqArg
         (\u opts -> opts { optPassword = Just u })
         "PASSWORD"
      ) "Password for calls requiring authentication"
   , Option ['v'] ["verbosity"]
      (ReqArg (\v opts -> opts { optVerbosity = read v }) "NUM")
      "Verbosity: 0, 1 (default), 2. Higher is more verbose"
   , Option ['e'] ["echo-request-uri"]
      (NoArg (\opts -> opts { optEchoReqUri = True }))
      "Echo the request URI string sent to Twitter"
   , Option ['a'] ["add-noise"]
      (NoArg (\opts -> opts { optAddNoise = True }))
      "Add a 2-character randomly-generated base-36 'noise' string to end of update. Good for repeating yourself, but please exercise restraint"
   ]


commands :: [String]
commands = ["followers", "friends", "help", "update"]


disambCommand :: (MonadError String m) => String -> m String
disambCommand i = case (filtCmds i) commands of
   [c] -> return c
   []  -> throwError $ "Unknown command: " ++ i
   cs  -> throwError $ "Ambiguous command, could be one of: " ++
      (intercalate " " cs)
   where
      filtCmds = filter . isPrefixOf


parseOpts :: [String] -> IO (Options, String, [String])
parseOpts argv = do
   result <- runErrorT $ do
      (opts, inputCmd, rest) <- case getOpt Permute options argv of
         (o, (i:r), []  ) ->
            return (foldl (flip id) defaultOptions o, i, r)
         (_, []    , []  ) ->
            throwError $ "No command specified\n\n" ++ usageText
         (_, _     , errs) -> throwError $ concat errs

      command <- disambCommand inputCmd

      when ((optUser opts == "") && (command /= "help")) $
         throwError "MUST specify a Twitter account username"

      return (opts, command, rest)

   either error return result


usageText :: String
usageText = (usageInfo header options) ++ "\n" ++ footer
   where
      header = init $ unlines
         [ "Usage: cltw COMMAND [OPTIONS] [COMMAND-SPECIFIC DATA]"
         , "Twitter API command-line utility"
         , ""
         , "Commands:"
         , ""
         , "  followers -u USER"
         , "    Show people following you"
         , ""
         , "  friends -u USER"
         , "    Show people whom you are following"
         , "    Verbosity applies to followers/friends output like this:"
         , "      -v 0 -> <screen name>"
         , "      -v 1 -> <screen name>  <name>  <user ID>"
         , ""
         , "  update -u USER -p PASSWORD STATUS_TEXT"
         , "    Post a status update"
         , ""
         , "  help"
         , "    This help text"
         , ""
         , "Options:"
         ]
      footer = init $ unlines
         [ "This is a tool for performing some Twitter API functions from the command line."
         , ""
         , "What kinds of things can you do?"
         , ""
         , "Keep a list of people you are following:"
         , "  $ cltw fr -u stimpy | sort > some/file"
         , ""
         , "Check to see if somebody specific is following you:"
         , "  $ cltw fo -u stimpy | grep somebodyontwitter"
         , ""
         , "Post an update from a script or cron job:"
         , "  $ cltw update -u stimpy -p spumco \"My message to the world\""
         , ""
         , "Don't get crazy with scripts though, Twitter frowns on spam and so do your followers!"
         , ""
         , "Version 1.1.4  Dino Morelli <dino@ui3.info>"
         ]