-- This file contains code that is common to modules System.Console.ANSI.Unix,

-- System.Console.ANSI.Windows and System.Console.ANSI.Windows.Emulator, such as

-- type signatures and the definition of functions specific to stdout in terms

-- of the corresponding more general functions, inclduding the related Haddock

-- documentation.

import System.Environment

#if !MIN_VERSION_base(4,8,0)

import Control.Applicative

#endif

import Control.Monad (void)

import Data.Char (isDigit)

import Text.ParserCombinators.ReadP (char, many1, ReadP, satisfy)

hCursorUp, hCursorDown, hCursorForward, hCursorBackward

    :: Handle

    -> Int -- ^ Number of lines or characters to move

    -> IO ()

cursorUp, cursorDown, cursorForward, cursorBackward

    :: Int -- ^ Number of lines or characters to move

    -> IO ()

cursorUp = hCursorUp stdout

cursorDown = hCursorDown stdout

cursorForward = hCursorForward stdout

cursorBackward = hCursorBackward stdout

hCursorDownLine, hCursorUpLine :: Handle

                               -> Int -- ^ Number of lines to move

                               -> IO ()

cursorDownLine, cursorUpLine :: Int -- ^ Number of lines to move

                             -> IO ()

cursorDownLine = hCursorDownLine stdout

cursorUpLine = hCursorUpLine stdout

hSetCursorColumn :: Handle

                 -> Int -- ^ 0-based column to move to

                 -> IO ()

setCursorColumn :: Int -- ^ 0-based column to move to

                -> IO ()

setCursorColumn = hSetCursorColumn stdout

hSetCursorPosition :: Handle

                   -> Int -- ^ 0-based row to move to

                   -> Int -- ^ 0-based column to move to

                   -> IO ()

setCursorPosition :: Int -- ^ 0-based row to move to

                  -> Int -- ^ 0-based column to move to

                  -> IO ()

setCursorPosition = hSetCursorPosition stdout

hSaveCursor, hRestoreCursor, hReportCursorPosition :: Handle -> IO ()

-- | Save the cursor position in memory. The only way to access the saved value

-- is with the 'restoreCursor' command.

saveCursor :: IO ()

-- | Restore the cursor position from memory. There will be no value saved in

-- memory until the first use of the 'saveCursor' command.

restoreCursor :: IO ()

-- | Looking for a way to get the cursors position? See

-- 'getCursorPosition'.

--

-- Emit the cursor position into the console input stream, immediately after

-- being recognised on the output stream, as:

-- @ESC [ \<cursor row> ; \<cursor column> R@

--

-- In isolation of 'getReportedCursorPosition' or 'getCursorPosition', this

-- function may be of limited use on Windows operating systems because of

-- difficulties in obtaining the data emitted into the console input stream.

-- The function 'hGetBufNonBlocking' in module "System.IO" does not work on

-- Windows. This has been attributed to the lack of non-blocking primatives in

-- the operating system (see the GHC bug report #806 at

-- <https://ghc.haskell.org/trac/ghc/ticket/806>).

reportCursorPosition :: IO ()

saveCursor = hSaveCursor stdout

restoreCursor = hRestoreCursor stdout

reportCursorPosition = hReportCursorPosition stdout

hHideCursor, hShowCursor :: Handle

                         -> IO ()

hideCursor, showCursor :: IO ()

hideCursor = hHideCursor stdout

showCursor = hShowCursor stdout

-- | Set the terminal window title

hSetTitle :: Handle

          -> String -- ^ New title

          -> IO ()

-- | Set the terminal window title

setTitle :: String -- ^ New title

         -> IO ()

setTitle = hSetTitle stdout

-- | Use heuristics to determine whether the functions defined in this

-- package will work with a given handle.

--

-- The current implementation checks that the handle is a terminal, and

-- that the @TERM@ environment variable doesn't say @dumb@ (which is what

-- Emacs sets for its own terminal).

hSupportsANSI :: Handle -> IO Bool

-- Borrowed from an HSpec patch by Simon Hengel

-- (https://github.com/hspec/hspec/commit/d932f03317e0e2bd08c85b23903fb8616ae642bd)

hSupportsANSI h = (&&) <$> hIsTerminalDevice h <*> (not <$> isDumb)

  where

    -- cannot use lookupEnv since it only appeared in GHC 7.6

    isDumb = maybe False (== "dumb") . lookup "TERM" <$> getEnvironment

-- | Parses the characters emitted by 'reportCursorPosition' into the console

-- input stream. Returns the cursor row and column as a tuple.

--

-- For example, if the characters emitted by 'reportCursorPosition' are in

-- 'String' @input@ then the parser could be applied like this:

--

-- > let result = readP_to_S cursorPosition input

-- > case result of

-- >     [] -> putStrLn $ "Error: could not parse " ++ show input

-- >     [((row, column), _)] -> putStrLn $ "The cursor was at row " ++ show row

-- >         ++ " and column" ++ show column ++ "."

-- >     (_:_) -> putStrLn $ "Error: parse not unique"

--

cursorPosition :: ReadP (Int, Int)

cursorPosition = do

    void $ char '\ESC'

    void $ char '['

    row <- decimal -- A non-negative whole decimal number

    void $ char ';'

    col <- decimal -- A non-negative whole decimal number

    void $ char 'R'

    return (read row, read col)

  where

    digit = satisfy isDigit

    decimal = many1 digit

-- | Attempts to get the reported cursor position data from the console input

-- stream. The function is intended to be called immediately after

-- 'reportCursorPosition' (or related functions) have caused characters to be

-- emitted into the stream.

--

-- For example, on a Unix-like operating system:

--

-- > hSetBuffering stdin NoBuffering -- set no buffering (the contents of the

-- >                                 -- buffer will be discarded, so this needs

-- >                                 -- to be done before the cursor positon is

-- >                                 -- emitted)

-- > reportCursorPosition

-- > hFlush stdout -- ensure the report cursor position code is sent to the

-- >               -- operating system

-- > input <- getReportedCursorPosition

--

-- On Windows operating systems, the function is not supported on consoles, such

-- as mintty, that are not based on the Win32 console of the Windows API.

-- (Command Prompt and PowerShell are based on the Win32 console.)

getReportedCursorPosition :: IO String

-- | Attempts to get the reported cursor position, combining the functions

-- 'reportCursorPosition', 'getReportedCursorPosition' and 'cursorPosition'.

-- Returns 'Nothing' if any data emitted by 'reportCursorPosition', obtained by

-- 'getReportedCursorPosition', cannot be parsed by 'cursorPosition'.

--

-- On Windows operating systems, the function is not supported on consoles, such

-- as mintty, that are not based on the Win32 console of the Windows API.

-- (Command Prompt and PowerShell are based on the Win32 console.)

getCursorPosition :: IO (Maybe (Int, Int))