module Main where

import System.Random (randomRIO)
import Data.IORef
import Data.Char (toUpper)

main :: IO ()
main = do
    putStrLn "*** BAGELS : HASKELL ***"
    running <- newIORef True
    gameOver <- newIORef False
    score <- newIORef 0
    number <- newIORef 0
    guess <- newIORef 0
    attempt <- newIORef 0
    guessed <- newIORef False
    resp <- askToSeeTheRules
    if resp then do
        displayRules
    else
        putStrLn ""
    runningLoop running gameOver score number guess attempt guessed
        
displayRules :: IO ()
displayRules = do    
    putStrLn "I WILL THINK OF A THREE-DIGIT NUMBER. YOU WILL TRY TO"
    putStrLn "GUESS MY NUMBER AND I WILL GIVE YOU CLUES AS FOLLOWS:"
    putStrLn "  PICO   - ONE DIGIT CORRECT BUT IN THE WRONG POSITION"
    putStrLn "  FERMI  - ONE DIGIT CORRECT AND IN THE RIGHT POSITION"
    putStrLn "  BAGELS - NO DIGITS ARE CORRECT"
    putStrLn ""
    putStrLn "YOU GET TWENTY TRIES BEFORE YOU LOSE."
    putStrLn ""

displayGameOver :: IORef Int -> IO ()
displayGameOver number = do
    numberVal <- readIORef number
    putStrLn "OH WELL, THAT WAS TWENTY GUESSES."
    putStrLn $ "MY NUMBER WAS " ++ show numberVal ++ "."

createDigit2 :: Int -> IO Int
createDigit2 digit1 = do
    digit2 <- randomRIO (0, 9)
    if digit2 == digit1
        then createDigit2 digit1
        else return digit2

createDigit3 :: Int -> Int -> IO Int
createDigit3 digit1 digit2 = do
    digit3 <- randomRIO (0, 9)
    if digit3 == digit1 || digit3 == digit2
        then createDigit3 digit1 digit2
        else return digit3

createTheNumber :: IO Int
createTheNumber = do
    digit1 <- randomRIO (1, 9)
    digit2 <- createDigit2 digit1
    digit3 <- createDigit3 digit1 digit2
    let numberVal = (digit1 * 100) + (digit2 * 10) + digit3
    return numberVal

checkGuess :: IORef Int -> IORef Int -> IO Bool
checkGuess guess number = do
    numberVal <- readIORef number
    guessVal <- readIORef guess

    let tmp1 = guessVal `div` 100
    let tmp2 = (guessVal `mod` 100) `div` 10
    let tmp3 = guessVal `mod` 10
    let digit1 = numberVal `div` 100
    let digit2 = (numberVal `mod` 100) `div` 10
    let digit3 = numberVal `mod` 10

    let val1 = if tmp1 == digit1 then 1 else if tmp1 == digit2 || tmp1 == digit3 then 2 else 0
    let val2 = if tmp2 == digit2 then 1 else if tmp2 == digit1 || tmp2 == digit3 then 2 else 0
    let val3 = if tmp3 == digit3 then 1 else if tmp3 == digit1 || tmp3 == digit2 then 2 else 0

    if val1 == 1 && val2 == 1 && val3 == 1 then
        return True
    else do
        if val1 == 0 && val2 == 0 && val3 == 0 then
            putStrLn "BAGELS"
        else do
            putStrLn $ concat [if val1 == 1 then "FERMI " else if val1 == 2 then "PICO " else "",
                           if val2 == 1 then "FERMI " else if val2 == 2 then "PICO " else "",
                           if val3 == 1 then "FERMI" else if val3 == 2 then "PICO" else ""]
        return False   
    
askForGuess :: IORef Int -> IO Int
askForGuess attempt = do
    attemptVal <- readIORef attempt
    putStrLn $ "GUESS #" ++ show attemptVal
    guess <- readLn
    if guess < 0 then do
        putStrLn "PLEASE GUESS A NON-NEGATIVE NUMBER."
        askForGuess attempt
    else if guess < 100 || guess > 999 then do
        putStrLn "PLEASE GUESS A NUMBER BETWEEN 100 AND 999."
        askForGuess attempt
    else do
        return guess
    
runningLoop :: IORef Bool -> IORef Bool -> IORef Int -> IORef Int -> IORef Int -> IORef Int -> IORef Bool -> IO ()
runningLoop running gameOver score number guess attempt guessed = do
    runningVal <- readIORef running
    if runningVal then do
        writeIORef attempt 1
        writeIORef gameOver False
        numberVal <- createTheNumber
        writeIORef number numberVal
        putStrLn "OK, I HAVE A NUMBER IN MIND."        
        gameLoop running gameOver score number guess attempt guessed
    else do
        scoreVal <- readIORef score
        putStrLn $ "A " ++ show scoreVal ++ " POINT BAGLES BUFF!"
        putStrLn "HOPE YOU HAD FUN. BYE!"
        
gameLoop :: IORef Bool -> IORef Bool -> IORef Int -> IORef Int -> IORef Int -> IORef Int -> IORef Bool -> IO ()
gameLoop running gameOver score number guess attempt guessed = do
    gameOverVal <- readIORef gameOver
    if not gameOverVal then do
        guessVal <- askForGuess attempt
        writeIORef guess guessVal
        guessedVal <- checkGuess guess number
        if guessedVal then do
            putStrLn "YOU GOT IT!!!"
            modifyIORef score (\s -> s + 1)
            writeIORef gameOver True  
            gameLoop running gameOver score number guess attempt guessed
        else do
            modifyIORef attempt (\a -> a + 1)
            attemptVal <- readIORef attempt
            if attemptVal > 20 then do
                displayGameOver number
                writeIORef gameOver True  
            else do
                gameLoop running gameOver score number guess attempt guessed
    else do
        putStrLn "*** GAME OVER ***"
        runningVal <- askToPlayAgain
        writeIORef running runningVal
        runningLoop running gameOver score number guess attempt guessed

askQuestion :: String -> IO Bool
askQuestion prompt = do
    putStrLn (prompt ++ "?")
    ans <- getLine
    let answer = map toUpper ans
    if answer == "YES" || answer == "Y" then
        return True
    else if answer == "NO" || answer == "N" then
        return False
    else if answer == "" then do
        putStrLn "PLEASE ANSWER THE QUESTION."
        askQuestion prompt        
    else do
        putStrLn "PLEASE ANSWER \"YES\" OR \"NO\""
        askQuestion prompt        

askToSeeTheRules :: IO Bool
askToSeeTheRules = askQuestion "DO YOU WANT TO SEE THE RULES"

askToPlayAgain :: IO Bool
askToPlayAgain = askQuestion "DO YOU WANT TO PLAY AGAIN"