{-|
Some QuickCheck utility functions.
-}
module B9.QCUtil where

import           Control.Monad
import           Test.QuickCheck

arbitraryEnv :: Arbitrary a => Gen [(String, a)]
arbitraryEnv = listOf ((,) <$> listOf1 (choose ('a', 'z')) <*> arbitrary)

halfSize :: Gen a -> Gen a
halfSize g = sized (flip resize g . flip div 2)

smaller :: Gen a -> Gen a
smaller g = sized (flip resize g . max 0 . flip (-) 1)

arbitraryFilePath :: Gen FilePath
arbitraryFilePath = do
    path <- join <$> listOf
        (elements
            [ "/"
            , "../"
            , "./"
            , "etc/"
            , "opt/"
            , "user/"
            , "var/"
            , "tmp/"
            , "doc/"
            , "share/"
            , "conf.d/"
            ]
        )
    prefix    <- elements ["foo_", "", "alt_", "ssh-", ""]
    body      <- elements ["www", "passwd", "cert", "opnsfe", "runtime"]
    extension <- elements [".txt", ".png", ".ps", ".erl", ""]
    return (path ++ prefix ++ body ++ extension)

arbitraryLetter :: Gen Char
arbitraryLetter = oneof [arbitraryLetterUpper, arbitraryLetterLower]

arbitraryLetterUpper :: Gen Char
arbitraryLetterUpper = elements ['A' .. 'Z']

arbitraryLetterLower :: Gen Char
arbitraryLetterLower = elements ['a' .. 'z']

arbitraryDigit :: Gen Char
arbitraryDigit = elements ['0' .. '9']