hledger/hledger-lib/Hledger/Utils/IO.hs

{- | 
General and hledger-specific input/output-related helpers for
pretty-printing haskell values, error reporting, time, files, command line parsing,
terminals, pager output, ANSI colour/styles, etc.
-}

{-# LANGUAGE LambdaCase          #-}
{-# LANGUAGE PackageImports      #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Hledger.Utils.IO (

  -- * Pretty showing/printing
  pshow,
  pshow',
  pprint,
  pprint',

  -- * Errors
  error',
  usageError,

  -- * Time
  getCurrentLocalTime,
  getCurrentZonedTime,

  -- * Files
  embedFileRelative,
  expandHomePath,
  expandPath,
  expandGlob,
  sortByModTime,
  readFileOrStdinPortably,
  readFileStrictly,
  readFilePortably,
  readHandlePortably,
  -- hereFileRelative,

  -- * Command line parsing
  progArgs,
  getOpt,
  parseYN,
  parseYNA,
  YNA(..),
  -- hasOutputFile,
  -- outputFileOption,

  -- * Terminal size
  getTerminalHeightWidth,
  getTerminalHeight,
  getTerminalWidth,

  -- * Pager output
  setupPager,
  runPager,

  -- * ANSI colour/styles

  -- ** hledger-specific

  colorOption,
  useColorOnStdout,
  useColorOnStderr,
  useColorOnStdoutUnsafe,
  useColorOnStderrUnsafe,
  bold',
  faint',
  black',
  red',
  green',
  yellow',
  blue',
  magenta',
  cyan',
  white',
  brightBlack',
  brightRed',
  brightGreen',
  brightYellow',
  brightBlue',
  brightMagenta',
  brightCyan',
  brightWhite',
  rgb',

  -- ** Generic

  color,
  bgColor,
  colorB,
  bgColorB,
  -- XXX Types used with color/bgColor/colorB/bgColorB,
  -- not re-exported because clashing with UIUtils:
  -- Color(..),
  -- ColorIntensity(..),

  terminalIsLight,
  terminalLightness,
  terminalFgColor,
  terminalBgColor,

  )
where

import           Control.Concurrent (forkIO)
import           Control.Exception (catch, evaluate, throwIO)
import           Control.Monad (when, forM, guard, void)
import           Data.Char (toLower)
import           Data.Colour.RGBSpace (RGB(RGB))
import           Data.Colour.RGBSpace.HSL (lightness)
import           Data.Colour.SRGB (sRGB)
import           Data.FileEmbed (makeRelativeToProject, embedStringFile)
import           Data.Functor ((<&>))
import           Data.List hiding (uncons)
import           Data.Maybe (isJust, catMaybes)
import           Data.Ord (comparing, Down (Down))
import qualified Data.Text as T
import qualified Data.Text.IO as T
import qualified Data.Text.Lazy as TL
import qualified Data.Text.Lazy.Builder as TB
import           Data.Time.Clock (getCurrentTime)
import           Data.Time.LocalTime (LocalTime, ZonedTime, getCurrentTimeZone, utcToLocalTime, utcToZonedTime)
import           Data.Word (Word16)
import           Foreign.C.Error (Errno(..), ePIPE)
import           GHC.IO.Exception (IOException(..), IOErrorType (ResourceVanished))
import           Language.Haskell.TH.Syntax (Q, Exp)
import           Safe (headMay, maximumDef)
import           System.Console.ANSI (Color(..),ColorIntensity(..), ConsoleLayer(..), SGR(..), hSupportsANSIColor, setSGRCode, getLayerColor, ConsoleIntensity (..))
import           System.Console.Terminal.Size (Window (Window), size)
import           System.Directory (getHomeDirectory, getModificationTime, findExecutable)
import           System.Environment (getArgs, lookupEnv, setEnv)
import           System.FilePath (isRelative, (</>))
import "Glob"    System.FilePath.Glob (glob)
import           System.Info (os)
import           System.IO (Handle, IOMode (..), hGetEncoding, hSetEncoding, hSetNewlineMode, openFile, stdin, stdout, stderr, universalNewlineMode, utf8_bom, hIsTerminalDevice, hPutStr, hClose)
import           System.IO.Unsafe (unsafePerformIO)
import           System.Process (CreateProcess(..), StdStream(CreatePipe), shell, waitForProcess, withCreateProcess)
import           Text.Pretty.Simple (CheckColorTty(..), OutputOptions(..), defaultOutputOptionsDarkBg, defaultOutputOptionsNoColor, pShowOpt, pPrintOpt)

import Hledger.Utils.Text (WideBuilder(WideBuilder))



-- Pretty showing/printing
-- using pretty-simple

-- https://hackage.haskell.org/package/pretty-simple/docs/Text-Pretty-Simple.html#t:OutputOptions

-- | pretty-simple options with colour enabled if allowed.
prettyopts =
  (if useColorOnStderrUnsafe then defaultOutputOptionsDarkBg else defaultOutputOptionsNoColor)
    { outputOptionsIndentAmount = 2
    -- , outputOptionsCompact      = True  -- fills lines, but does not respect page width (https://github.com/cdepillabout/pretty-simple/issues/126)
    -- , outputOptionsPageWidth    = fromMaybe 80 $ unsafePerformIO getTerminalWidth
    }

-- | pretty-simple options with colour disabled.
prettyoptsNoColor =
  defaultOutputOptionsNoColor
    { outputOptionsIndentAmount=2
    }

-- | Pretty show. An easier alias for pretty-simple's pShow.
-- This will probably show in colour if useColorOnStderrUnsafe is true.
pshow :: Show a => a -> String
pshow = TL.unpack . pShowOpt prettyopts

-- | Monochrome version of pshow. This will never show in colour.
pshow' :: Show a => a -> String
pshow' = TL.unpack . pShowOpt prettyoptsNoColor

-- | Pretty print a showable value. An easier alias for pretty-simple's pPrint.
-- This will print in colour if useColorOnStderrUnsafe is true.
pprint :: Show a => a -> IO ()
pprint = pPrintOpt (if useColorOnStderrUnsafe then CheckColorTty else NoCheckColorTty) prettyopts

-- | Monochrome version of pprint. This will never print in colour.
pprint' :: Show a => a -> IO ()
pprint' = pPrintOpt NoCheckColorTty prettyoptsNoColor

-- "Avoid using pshow, pprint, dbg* in the code below to prevent infinite loops." (?)



-- Errors

-- | Simpler alias for errorWithoutStackTrace
error' :: String -> a
error' = errorWithoutStackTrace . ("Error: " <>)

-- | A version of errorWithoutStackTrace that adds a usage hint.
usageError :: String -> a
usageError = error' . (++ " (use -h to see usage)")



-- Time

getCurrentLocalTime :: IO LocalTime
getCurrentLocalTime = do
  t <- getCurrentTime
  tz <- getCurrentTimeZone
  return $ utcToLocalTime tz t

getCurrentZonedTime :: IO ZonedTime
getCurrentZonedTime = do
  t <- getCurrentTime
  tz <- getCurrentTimeZone
  return $ utcToZonedTime tz t



-- Files

-- | Expand a tilde (representing home directory) at the start of a file path.
-- ~username is not supported. Can raise an error.
expandHomePath :: FilePath -> IO FilePath
expandHomePath = \case
    ('~':'/':p)  -> (</> p) <$> getHomeDirectory
    ('~':'\\':p) -> (</> p) <$> getHomeDirectory
    ('~':_)      -> ioError $ userError "~USERNAME in paths is not supported"
    p            -> return p

-- | Given a current directory, convert a possibly relative, possibly tilde-containing
-- file path to an absolute one.
-- ~username is not supported. Leaves "-" unchanged. Can raise an error.
expandPath :: FilePath -> FilePath -> IO FilePath -- general type sig for use in reader parsers
expandPath _ "-" = return "-"
expandPath curdir p = (if isRelative p then (curdir </>) else id) <$> expandHomePath p  -- PARTIAL:

-- | Like expandPath, but treats the expanded path as a glob, and returns
-- zero or more matched absolute file paths, alphabetically sorted.
-- Can raise an error.
expandGlob :: FilePath -> FilePath -> IO [FilePath]
expandGlob curdir p = expandPath curdir p >>= glob <&> sort  -- PARTIAL:

-- | Given a list of existing file paths, sort them by modification time, most recent first.
sortByModTime :: [FilePath] -> IO [FilePath]
sortByModTime fs = do
  ftimes <- forM fs $ \f -> do {t <- getModificationTime f; return (t,f)}
  return $ map snd $ sortBy (comparing Data.Ord.Down) ftimes

-- | Like readFilePortably, but read all of the file before proceeding.
readFileStrictly :: FilePath -> IO T.Text
readFileStrictly f = readFilePortably f >>= \t -> evaluate (T.length t) >> return t

-- | Read text from a file,
-- converting any \r\n line endings to \n,,
-- using the system locale's text encoding,
-- ignoring any utf8 BOM prefix (as seen in paypal's 2018 CSV, eg) if that encoding is utf8.
readFilePortably :: FilePath -> IO T.Text
readFilePortably f =  openFile f ReadMode >>= readHandlePortably

-- | Like readFilePortably, but read from standard input if the path is "-".
readFileOrStdinPortably :: String -> IO T.Text
readFileOrStdinPortably f = openFileOrStdin f ReadMode >>= readHandlePortably
  where
    openFileOrStdin :: String -> IOMode -> IO Handle
    openFileOrStdin "-" _ = return stdin
    openFileOrStdin f' m   = openFile f' m

readHandlePortably :: Handle -> IO T.Text
readHandlePortably h = do
  hSetNewlineMode h universalNewlineMode
  menc <- hGetEncoding h
  when (fmap show menc == Just "UTF-8") $  -- XXX no Eq instance, rely on Show
    hSetEncoding h utf8_bom
  T.hGetContents h

-- | Like embedFile, but takes a path relative to the package directory.
embedFileRelative :: FilePath -> Q Exp
embedFileRelative f = makeRelativeToProject f >>= embedStringFile

-- -- | Like hereFile, but takes a path relative to the package directory.
-- -- Similar to embedFileRelative ?
-- hereFileRelative :: FilePath -> Q Exp
-- hereFileRelative f = makeRelativeToProject f >>= hereFileExp
--   where
--     QuasiQuoter{quoteExp=hereFileExp} = hereFile



-- Command line parsing

-- | The program's command line arguments.
-- Uses unsafePerformIO; tends to stick in GHCI until reloaded,
-- and may or may not detect args provided by a hledger config file.
{-# NOINLINE progArgs #-}
progArgs :: [String]
progArgs = unsafePerformIO getArgs
-- XX currently this affects:
--  the enabling of orderdates and assertions checks in journalFinalise
--  a few cases involving --color (see useColorOnStdoutUnsafe)
--  --debug

-- | Given one or more long or short option names, read the rightmost value of this option from the command line arguments.
-- If the value is missing raise an error.
-- Concatenated short flags (-a -b written as -ab) are not supported.
getOpt :: [String] -> IO (Maybe String)
getOpt names = do
  rargs <- reverse . splitFlagsAndVals <$> getArgs
  let flags = map toFlag names
  return $
    case break ((`elem` flags)) rargs of
      (_,[])        -> Nothing
      ([],flag:_)   -> error' $ flag <> " requires a value"
      (argsafter,_) -> Just $ last argsafter

-- | Given a list of command line arguments, split any of the form --flag=VAL or -fVAL into two list items.
-- Concatenated short flags (-a -b written as -ab) are not supported.
splitFlagsAndVals :: [String] -> [String]
splitFlagsAndVals = concatMap $
  \case
    a@('-':'-':_) | '=' `elem` a -> let (x,y) = break (=='=') a in [x, drop 1 y]
    a@('-':f:_:_) | not $ f=='-' -> [take 2 a, drop 2 a]
    a -> [a]

-- | Convert a short or long flag name to a flag with leading hyphen(s).
toFlag [c] = ['-',c]
toFlag s   = '-':'-':s

-- | Parse y/yes/always or n/no/never to true or false, or with any other value raise an error.
parseYN :: String -> Bool
parseYN s
  | l `elem` ["y","yes","always"] = True
  | l `elem` ["n","no","never"]   = False
  | otherwise = error' $ "value should be one of " <> (intercalate ", " ["y","yes","n","no"])
  where l = map toLower s

data YNA = Yes | No | Auto deriving (Eq,Show)

-- | Parse y/yes/always or n/no/never or a/auto to a YNA choice, or with any other value raise an error.
parseYNA :: String -> YNA
parseYNA s
  | l `elem` ["y","yes","always"] = Yes
  | l `elem` ["n","no","never"]   = No
  | l `elem` ["a","auto"]         = Auto
  | otherwise = error' $ "value should be one of " <> (intercalate ", " ["y","yes","n","no","a","auto"])
  where l = map toLower s

-- | Is there a --output-file or -o option in the command line arguments ?
-- Uses getOpt; sticky in GHCI until reloaded, may not always be affected by a hledger config file, etc.
hasOutputFile :: IO Bool
hasOutputFile = do
  mv <- getOpt ["output-file","o"]
  return $
    case mv of
      Nothing  -> False
      Just "-" -> False
      _        -> True

-- -- | Get the -o/--output-file option's value, if any, from the command line arguments.
-- -- Uses getOpt; sticky in GHCI until reloaded, may not always be affected by a hledger config file, etc.
-- outputFileOption :: IO (Maybe String)
-- outputFileOption = getOpt ["output-file","o"]



-- Terminal size

-- | An alternative to ansi-terminal's getTerminalSize, based on
-- the more robust-looking terminal-size package.
-- Tries to get stdout's terminal's current height and width.
getTerminalHeightWidth :: IO (Maybe (Int,Int))
getTerminalHeightWidth = fmap (fmap unwindow) size
  where unwindow (Window h w) = (h,w)

getTerminalHeight :: IO (Maybe Int)
getTerminalHeight = fmap fst <$> getTerminalHeightWidth

getTerminalWidth :: IO (Maybe Int)
getTerminalWidth  = fmap snd <$> getTerminalHeightWidth



-- Pager output
-- somewhat hledger-specific

-- Configure some preferred options for the `less` pager,
-- by modifying the LESS environment variable in this program's environment.
-- If you are using some other pager, this will have no effect.
-- By default, this sets the following options, appending them to LESS's current value:
--
--   --chop-long-lines
--   --hilite-unread
--   --ignore-case
--   --mouse
--   --no-init
--   --quit-at-eof
--   --quit-if-one-screen
--   --RAW-CONTROL-CHARS
--   --shift=8
--   --squeeze-blank-lines
--   --use-backslash
--   --use-color
--
-- You can choose different options by setting the HLEDGER_LESS variable;
-- if set, its value will be used instead of LESS.
-- Or you can force hledger to use your exact LESS settings,
-- by setting HLEDGER_LESS equal to LESS.
--
setupPager :: IO ()
setupPager = do
  let
    -- keep synced with doc above
    deflessopts = unwords [
       "--chop-long-lines"
      ,"--hilite-unread"
      ,"--ignore-case"
      ,"--mouse"
      ,"--no-init"
      ,"--quit-at-eof"
      ,"--quit-if-one-screen"
      ,"--RAW-CONTROL-CHARS"
      ,"--shift=8"
      ,"--squeeze-blank-lines"
      ,"--use-backslash"
      ,"--use-color"
      ]
  mhledgerless <- lookupEnv "HLEDGER_LESS"
  mless        <- lookupEnv "LESS"
  setEnv "LESS" $
    case (mhledgerless, mless) of
      (Just hledgerless, _) -> hledgerless
      (_, Just less)        -> unwords [less, deflessopts]
      _                     -> deflessopts

-- | Display the given text on the terminal, trying to use a pager ($PAGER, less, or more)
-- when appropriate, otherwise printing to standard output. Uses maybePagerFor.
--
-- hledger's output may contain ANSI style/color codes
-- (if the terminal supports them and they are not disabled by --color=no or NO_COLOR),
-- so the pager should be configured to handle these.
-- setupPager tries to configure that automatically when using the `less` pager.
--
runPager :: String -> IO ()
runPager s = do
  mpager <- maybePagerFor s
  case mpager of
    Nothing -> putStr s
    Just pager -> do
      withCreateProcess (shell pager){std_in=CreatePipe} $
        \mhin _ _ p -> do
          -- Pipe in the text on stdin.
          case mhin of
            Nothing  -> return ()  -- shouldn't happen
            Just hin -> void $ forkIO $   -- Write from another thread to avoid deadlock ? Maybe unneeded, but just in case.
              (hPutStr hin s >> hClose hin)  -- Be sure to close the pipe so the pager knows we're done.
                -- If the pager quits early, we'll receive an EPIPE error; hide that.
                `catch` \(e::IOException) -> case e of
                  IOError{ioe_type=ResourceVanished, ioe_errno=Just ioe, ioe_handle=Just hdl} | Errno ioe==ePIPE, hdl==hin
                    -> return ()
                  _ -> throwIO e
          void $ waitForProcess p

-- | Should a pager be used for displaying the given text on stdout, and if so, which one ?
-- Uses a pager if findPager finds one and none of the following conditions are true:
-- We're running in a native MS Windows environment like cmd or powershell.
-- Or the --pager=n|no option is in effect.
-- Or the -o/--output-file option is in effect.
-- Or INSIDE_EMACS is set, to something other than "vterm".
-- Or the terminal's current height and width can't be detected.
-- Or the output text is less wide and less tall than the terminal.
maybePagerFor :: String -> IO (Maybe String)
maybePagerFor output = do
  let
    ls = lines output
    oh = length ls
    ow = maximumDef 0 $ map length ls
    windows = os == "mingw32"
  pagerno    <- maybe False (not.parseYN) <$> getOpt ["pager"]
  outputfile <- hasOutputFile
  emacsterm  <- lookupEnv "INSIDE_EMACS" <&> (`notElem` [Nothing, Just "vterm"])
  mhw        <- getTerminalHeightWidth
  mpager     <- findPager
  return $ do
    guard $ not $ windows || pagerno || outputfile || emacsterm
    (th,tw) <- mhw
    guard $ oh > th || ow > tw
    mpager

-- | Try to find a pager executable robustly, safely handling various error conditions
-- like an unset PATH var or the specified pager not being found as an executable.
-- The pager can be specified by a path or program name in the PAGER environment variable.
-- If that is unset or has a problem, "less" is tried, then "more".
-- If successful, the pager's path or program name is returned.
findPager :: IO (Maybe String)  -- XXX probably a ByteString in fact ?
findPager = do
  mpagervar <- lookupEnv "PAGER"
  let pagers = [p | Just p <- [mpagervar]] <> ["less", "more"]
  headMay . catMaybes <$> mapM findExecutable pagers



-- ANSI colour/styles
-- Some of these use unsafePerformIO to read info.

-- hledger-specific:

-- | Get the value of the rightmost --color or --colour option from the program's command line arguments.
colorOption :: IO YNA
colorOption = maybe Auto parseYNA <$> getOpt ["color","colour"]

-- | Should ANSI color and styles be used with this output handle ?
-- Considers colorOption, the NO_COLOR environment variable, and hSupportsANSIColor.
useColorOnHandle :: Handle -> IO Bool
useColorOnHandle h = do
  no_color       <- isJust <$> lookupEnv "NO_COLOR"
  supports_color <- hSupportsANSIColor h
  yna            <- colorOption
  return $ yna==Yes || (yna==Auto && not no_color && supports_color)

-- | Should ANSI color and styles be used for standard output ?
-- Considers useColorOnHandle stdout and hasOutputFile.
useColorOnStdout :: IO Bool
useColorOnStdout = do
  nooutputfile <- not <$> hasOutputFile
  usecolor <- useColorOnHandle stdout
  return $ nooutputfile && usecolor

-- | Should ANSI color and styles be used for standard error output ?
-- Considers useColorOnHandle stderr; is not affected by an --output-file option.
useColorOnStderr :: IO Bool
useColorOnStderr = useColorOnHandle stderr

-- | Like useColorOnStdout, but using unsafePerformIO. Useful eg for low-level debug code.
-- Sticky in GHCI until reloaded, may not always be affected by --color in a hledger config file, etc.
useColorOnStdoutUnsafe :: Bool
useColorOnStdoutUnsafe = unsafePerformIO useColorOnStdout

-- | Like useColorOnStdoutUnsafe, but for stderr.
useColorOnStderrUnsafe :: Bool
useColorOnStderrUnsafe = unsafePerformIO useColorOnStderr

-- | Detect whether ANSI should be used on stdout using useColorOnStdoutUnsafe,
-- and if so prepend and append the given SGR codes to a string.
-- Currently used in a few places (the commands list, the demo command, the recentassertions error message);
-- see useColorOnStdoutUnsafe's limitations.
ansiWrapUnsafe :: SGRString -> SGRString -> String -> String
ansiWrapUnsafe pre post s = if useColorOnStdoutUnsafe then pre<>s<>post else s

type SGRString = String

sgrbold          = setSGRCode [SetConsoleIntensity BoldIntensity]
sgrfaint         = setSGRCode [SetConsoleIntensity FaintIntensity]
sgrnormal        = setSGRCode [SetConsoleIntensity NormalIntensity]
sgrresetfg       = setSGRCode [SetDefaultColor Foreground]
sgrblack         = setSGRCode [SetColor Foreground Dull Black]
sgrred           = setSGRCode [SetColor Foreground Dull Red]
sgrgreen         = setSGRCode [SetColor Foreground Dull Green]
sgryellow        = setSGRCode [SetColor Foreground Dull Yellow]
sgrblue          = setSGRCode [SetColor Foreground Dull Blue]
sgrmagenta       = setSGRCode [SetColor Foreground Dull Magenta]
sgrcyan          = setSGRCode [SetColor Foreground Dull Cyan]
sgrwhite         = setSGRCode [SetColor Foreground Dull White]
sgrbrightblack   = setSGRCode [SetColor Foreground Vivid Black]
sgrbrightred     = setSGRCode [SetColor Foreground Vivid Red]
sgrbrightgreen   = setSGRCode [SetColor Foreground Vivid Green]
sgrbrightyellow  = setSGRCode [SetColor Foreground Vivid Yellow]
sgrbrightblue    = setSGRCode [SetColor Foreground Vivid Blue]
sgrbrightmagenta = setSGRCode [SetColor Foreground Vivid Magenta]
sgrbrightcyan    = setSGRCode [SetColor Foreground Vivid Cyan]
sgrbrightwhite   = setSGRCode [SetColor Foreground Vivid White]
sgrrgb r g b     = setSGRCode [SetRGBColor Foreground $ sRGB r g b]

-- | Set various ANSI styles/colours in a string, only if useColorOnStdoutUnsafe says we should.
bold' :: String -> String
bold'  = ansiWrapUnsafe sgrbold sgrnormal

faint' :: String -> String
faint'  = ansiWrapUnsafe sgrfaint sgrnormal

black' :: String -> String
black'  = ansiWrapUnsafe sgrblack sgrresetfg

red' :: String -> String
red'  = ansiWrapUnsafe sgrred sgrresetfg

green' :: String -> String
green'  = ansiWrapUnsafe sgrgreen sgrresetfg

yellow' :: String -> String
yellow'  = ansiWrapUnsafe sgryellow sgrresetfg

blue' :: String -> String
blue'  = ansiWrapUnsafe sgrblue sgrresetfg

magenta' :: String -> String
magenta'  = ansiWrapUnsafe sgrmagenta sgrresetfg

cyan' :: String -> String
cyan'  = ansiWrapUnsafe sgrcyan sgrresetfg

white' :: String -> String
white'  = ansiWrapUnsafe sgrwhite sgrresetfg

brightBlack' :: String -> String
brightBlack'  = ansiWrapUnsafe sgrbrightblack sgrresetfg

brightRed' :: String -> String
brightRed'  = ansiWrapUnsafe sgrbrightred sgrresetfg

brightGreen' :: String -> String
brightGreen'  = ansiWrapUnsafe sgrbrightgreen sgrresetfg

brightYellow' :: String -> String
brightYellow'  = ansiWrapUnsafe sgrbrightyellow sgrresetfg

brightBlue' :: String -> String
brightBlue'  = ansiWrapUnsafe sgrbrightblue sgrresetfg

brightMagenta' :: String -> String
brightMagenta'  = ansiWrapUnsafe sgrbrightmagenta sgrresetfg

brightCyan' :: String -> String
brightCyan'  = ansiWrapUnsafe sgrbrightcyan sgrresetfg

brightWhite' :: String -> String
brightWhite'  = ansiWrapUnsafe sgrbrightwhite sgrresetfg

rgb' :: Float -> Float -> Float -> String -> String
rgb' r g b  = ansiWrapUnsafe (sgrrgb r g b) sgrresetfg

-- Generic:

-- | Wrap a string in ANSI codes to set and reset foreground colour.
-- ColorIntensity is @Dull@ or @Vivid@ (ie normal and bold).
-- Color is one of @Black@, @Red@, @Green@, @Yellow@, @Blue@, @Magenta@, @Cyan@, @White@.
-- Eg: @color Dull Red "text"@.
color :: ColorIntensity -> Color -> String -> String
color int col s = setSGRCode [SetColor Foreground int col] ++ s ++ setSGRCode []

-- | Wrap a string in ANSI codes to set and reset background colour.
bgColor :: ColorIntensity -> Color -> String -> String
bgColor int col s = setSGRCode [SetColor Background int col] ++ s ++ setSGRCode []

-- | Wrap a WideBuilder in ANSI codes to set and reset foreground colour.
colorB :: ColorIntensity -> Color -> WideBuilder -> WideBuilder
colorB int col (WideBuilder s w) =
    WideBuilder (TB.fromString (setSGRCode [SetColor Foreground int col]) <> s <> TB.fromString (setSGRCode [])) w

-- | Wrap a WideBuilder in ANSI codes to set and reset background colour.
bgColorB :: ColorIntensity -> Color -> WideBuilder -> WideBuilder
bgColorB int col (WideBuilder s w) =
    WideBuilder (TB.fromString (setSGRCode [SetColor Background int col]) <> s <> TB.fromString (setSGRCode [])) w


-- | Detect whether the terminal currently has a light background colour,
-- if possible, using unsafePerformIO.
-- If the terminal is transparent, its apparent light/darkness may be different.
terminalIsLight :: Maybe Bool
terminalIsLight = (> 0.5) <$> terminalLightness

-- | Detect the terminal's current background lightness (0..1), if possible, using unsafePerformIO.
-- If the terminal is transparent, its apparent lightness may be different.
terminalLightness :: Maybe Float
terminalLightness = lightness <$> terminalColor Background

-- | Detect the terminal's current background colour, if possible, using unsafePerformIO.
terminalBgColor :: Maybe (RGB Float)
terminalBgColor = terminalColor Background

-- | Detect the terminal's current foreground colour, if possible, using unsafePerformIO.
terminalFgColor :: Maybe (RGB Float)
terminalFgColor = terminalColor Foreground

-- | Detect the terminal's current foreground or background colour, if possible, using unsafePerformIO.
{-# NOINLINE terminalColor #-}
terminalColor :: ConsoleLayer -> Maybe (RGB Float)
terminalColor = unsafePerformIO . getLayerColor'

-- A version of ansi-terminal's getLayerColor that is less likely to leak escape sequences to output,
-- and that returns a RGB of Floats (0..1) that is more compatible with the colour package.
-- This does nothing in a non-interactive context (eg when piping stdout to another command),
-- inside emacs (emacs shell buffers show the escape sequence for some reason),
-- or in a non-colour-supporting terminal.
getLayerColor' :: ConsoleLayer -> IO (Maybe (RGB Float))
getLayerColor' l = do
  inemacs       <- not.null <$> lookupEnv "INSIDE_EMACS"
  interactive   <- hIsTerminalDevice stdout
  supportscolor <- hSupportsANSIColor stdout
  if inemacs || not interactive || not supportscolor then return Nothing
  else fmap fractionalRGB <$> getLayerColor l
  where
    fractionalRGB :: (Fractional a) => RGB Word16 -> RGB a
    fractionalRGB (RGB r g b) = RGB (fromIntegral r / 65535) (fromIntegral g / 65535) (fromIntegral b / 65535)  -- chatgpt