------------------------------------------------------------------------------
-- Example for HTML programming in Curry:
--
-- A recursive form for a number guessing game
-- which also counts the number of guesses
------------------------------------------------------------------------------

import Global

import HTML.Base
import HTML.Session

--- The data stored in the session is the number of guesses.
trials :: Global (SessionStore Int)
trials = global emptySessionStore (Persistent (inSessionDataDir "trials"))

guessForm :: HtmlFormDef Int
guessForm = formDef (getSessionData trials 1) guessFormHtml

guessFormHtml :: Int -> [HtmlExp]
guessFormHtml t =
  [htxt "Guess a number: ", textField nref "", button "Check" guessHandler]
 where
  nref free

  guessHandler env = do
    let nr = read (env nref)
    if nr==42
      then do
        removeSessionData trials
        return $ headerPage ("Correct! " ++ show t ++ " guesses!") []
      else do
        putSessionData trials (t+1)
        return $ headerPage ("Too " ++ if nr<42 then "small!" else "large!")
           [formElem guessForm]

-- main HTML page containing the form
main :: IO HtmlPage
main = withSessionCookieInfo $
  headerPage "Number Guessing Game" [ formElem guessForm ]

-- Install the CGI script in user homepage by:
-- > cypm exec curry2cgi -o ~/public_html/cgi-bin/guess.cgi Guess