Bus.hs

module Bus where

import Data.List (find, intercalate)

data BuildStatus = AllGreen
                 | Borken
                 deriving (Eq, Show)

data Brogrammer = Johnny
                | Arthur
                | Bryan
                | Nand
                | RJ
                deriving (Eq, Show)

data Team = Rails
          | Mobile
          | Go
          | Backend
          deriving (Show)

data Bus = Bus 
  { team :: Team          -- ^ the Team this Bus belongs to.
  , bros :: [Brogrammer]  -- ^ the Brogrammers on board.
  }
  deriving (Show)

mkString = intercalate " "

-- Setup the BookShout! buses.
railsBus   = Bus Rails   [Johnny, Bryan]
mobileBus  = Bus Mobile  [Arthur]
goBus      = Bus Go      [Nand]
backendBus = Bus Backend [RJ]

-- |Given a Bus, finds who broke the build. Always returns RJ.
whoBrokeTheBuild :: Bus -> Brogrammer
whoBrokeTheBuild = maybe RJ id . find (==RJ) . bros

-- |Determines Jenkins happiness level for the given Bus.
isJenkinsSad :: Bus -> Bool
-- arthur writes flawless code
isJenkinsSad (Bus Mobile _) = False
-- everything else is always borken
isJenkinsSad _              = True

-- |Checks whether or not Jenkins is sad and returns the approriate build status.
buildStatus :: Bus -> BuildStatus
buildStatus bus = if (isJenkinsSad bus) then Borken
                  else AllGreen

-- |Generates a displayable String based on the build status of the given Bus.
throwUnderBus :: Bus -> String
throwUnderBus bus = mkString $ case buildStatus bus of
    Borken ->
      [ "Who broke it?"
      , innocent
      , guilty
      , "did."
      ]
    AllGreen -> 
      [ "If it were broken, who would've done it?"
      , innocent
      , guilty
      , "would."
      ]
  where 
    guilty = show $ whoBrokeTheBuild bus
    innocent = mkString $ map ((++".") . ("Not "++) . show) $ filter (/=RJ) (bros bus)

main = do
  performCheck "Let's check on the Rails build." railsBus
  performCheck "Now how about the mobile build?" mobileBus
  performCheck "What about Go?" goBus
  performCheck "Finally, the backend." backendBus
  where
    status bus = mkString
      [ show $ team bus
      , "build is"
      , show $ buildStatus bus
      ]
    performCheck msg bus = putStrLn msg 
      >> putStrLn (status bus) 
      >> putStrLn (throwUnderBus bus)

{-

Running this program produces the following output:

Let's check on the Rails build.
Rails build is Borken
Who broke it? Not Johnny. Not Bryan. RJ did.
Now how about the mobile build?
Mobile build is AllGreen
If it were broken, who would've done it? Not Arthur. RJ would.
What about Go?
Go build is Borken
Who broke it? Not Nand. RJ did.
Finally, the backend.
Backend build is Borken
Who broke it?  RJ did.

 -}

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