#!/usr/bin/env runghc

import System.FilePath
import System.Environment
import System.Process
import System.Exit
import System.Posix.Process
import System.Directory
import Data.Char (isSpace)

-- Remove trailing whitespace
rstrip = reverse . dropWhile isSpace . reverse

-- Prints a sequence of string pairs to stdout
printEnv = mapM_ $ \(k, v) -> putStrLn $ k ++ ": " ++ v

main = do
    args <- getArgs
    let installArgs = takeWhile ((==) '-' . head) args
    let package:packageArgs =
          if null remainder
            then ["."] else remainder
          where remainder = drop (length installArgs) args
    gOBIN <- getTemporaryDirectory
    -- Take our environment and clobber GOBIN.
    installEnv <- getEnvironment >>= return . (:) ("GOBIN", gOBIN)
    -- Run go install with modified environment.
    (_, _, _, handle) <- createProcess
      (proc "go" $ "install":installArgs++[package])
      { env = Just installEnv }
    code <- waitForProcess handle
    case code of
        ExitSuccess -> return ()
        ExitFailure _ -> exitWith code

    gOEXE <- readProcess "go" ["env", "GOEXE"] "" >>= return . rstrip
    let exeFilePath = joinPath [gOBIN, packageBase <.> gOEXE]
          where packageBase = last . splitDirectories $ package
      in executeFile exeFilePath False packageArgs Nothing