{-# LANGUAGE CPP #-}
{-|

Standard imports and utilities which are useful everywhere, or needed low
in the module hierarchy. This is the bottom of hledger's module graph.

-}

module Hledger.Data.Utils (
module Data.Char,
module Control.Monad,
module Data.List,
--module Data.Map,
module Data.Maybe,
module Data.Ord,
module Data.Tree,
module Data.Time.Clock,
module Data.Time.Calendar,
module Data.Time.LocalTime,
module Debug.Trace,
module Hledger.Data.Utils,
module Text.Printf,
module Text.RegexPR,
module Test.HUnit,
)
where
import Data.Char
import Codec.Binary.UTF8.String as UTF8 (decodeString, encodeString, isUTF8Encoded)
import Control.Monad
import Data.List
--import qualified Data.Map as Map
import Data.Maybe
import Data.Ord
import Data.Tree
import Data.Time.Clock
import Data.Time.Calendar
import Data.Time.LocalTime
import Debug.Trace
#if __GLASGOW_HASKELL__ <= 610
import Prelude hiding (readFile,putStr,print)
import System.IO.UTF8
#endif
import Test.HUnit
import Text.Printf
import Text.RegexPR
import Text.ParserCombinators.Parsec
import System.Info (os)


-- strings

lowercase = map toLower
uppercase = map toUpper

strip = lstrip . rstrip
lstrip = dropws
rstrip = reverse . dropws . reverse
dropws = dropWhile (`elem` " \t")

elideLeft width s =
    if length s > width then ".." ++ reverse (take (width - 2) $ reverse s) else s

elideRight width s =
    if length s > width then take (width - 2) s ++ ".." else s

underline :: String -> String
underline s = s' ++ replicate (length s) '-' ++ "\n"
    where s'
            | last s == '\n' = s
            | otherwise = s ++ "\n"

unbracket :: String -> String
unbracket s
    | (head s == '[' && last s == ']') || (head s == '(' && last s == ')') = init $ tail s
    | otherwise = s

-- | Join multi-line strings as side-by-side rectangular strings of the same height, top-padded.
concatTopPadded :: [String] -> String
concatTopPadded strs = intercalate "\n" $ map concat $ transpose padded
    where
      lss = map lines strs
      h = maximum $ map length lss
      ypad ls = replicate (difforzero h (length ls)) "" ++ ls
      xpad ls = map (padleft w) ls where w | null ls = 0
                                           | otherwise = maximum $ map length ls
      padded = map (xpad . ypad) lss

-- | Join multi-line strings as side-by-side rectangular strings of the same height, bottom-padded.
concatBottomPadded :: [String] -> String
concatBottomPadded strs = intercalate "\n" $ map concat $ transpose padded
    where
      lss = map lines strs
      h = maximum $ map length lss
      ypad ls = ls ++ replicate (difforzero h (length ls)) ""
      xpad ls = map (padleft w) ls where w | null ls = 0
                                           | otherwise = maximum $ map length ls
      padded = map (xpad . ypad) lss

-- | Compose strings vertically and right-aligned.
vConcatRightAligned :: [String] -> String
vConcatRightAligned ss = intercalate "\n" $ map showfixedwidth ss
    where
      showfixedwidth = printf (printf "%%%ds" width)
      width = maximum $ map length ss

-- | Convert a multi-line string to a rectangular string top-padded to the specified height.
padtop :: Int -> String -> String
padtop h s = intercalate "\n" xpadded
    where
      ls = lines s
      sh = length ls
      sw | null ls = 0
         | otherwise = maximum $ map length ls
      ypadded = replicate (difforzero h sh) "" ++ ls
      xpadded = map (padleft sw) ypadded

-- | Convert a multi-line string to a rectangular string bottom-padded to the specified height.
padbottom :: Int -> String -> String
padbottom h s = intercalate "\n" xpadded
    where
      ls = lines s
      sh = length ls
      sw | null ls = 0
         | otherwise = maximum $ map length ls
      ypadded = ls ++ replicate (difforzero h sh) ""
      xpadded = map (padleft sw) ypadded

-- | Convert a multi-line string to a rectangular string left-padded to the specified width.
padleft :: Int -> String -> String
padleft w "" = concat $ replicate w " "
padleft w s = intercalate "\n" $ map (printf (printf "%%%ds" w)) $ lines s

-- | Convert a multi-line string to a rectangular string right-padded to the specified width.
padright :: Int -> String -> String
padright w "" = concat $ replicate w " "
padright w s = intercalate "\n" $ map (printf (printf "%%-%ds" w)) $ lines s

-- | Clip a multi-line string to the specified width and height from the top left.
cliptopleft :: Int -> Int -> String -> String
cliptopleft w h = intercalate "\n" . take h . map (take w) . lines

-- | Clip and pad a multi-line string to fill the specified width and height.
fitto :: Int -> Int -> String -> String
fitto w h s = intercalate "\n" $ take h $ rows ++ repeat blankline
    where
      rows = map (fit w) $ lines s
      fit w = take w . (++ repeat ' ')
      blankline = replicate w ' '

-- encoded platform strings

-- | A platform string is a string value from or for the operating system,
-- such as a file path or command-line argument (or environment variable's
-- name or value ?). On some platforms (such as unix) these are not real
-- unicode strings but have some encoding such as UTF-8. This alias does
-- no type enforcement but aids code clarity.
type PlatformString = String

-- | Convert a possibly encoded platform string to a real unicode string.
-- We decode the UTF-8 encoding recommended for unix systems
-- (cf http://www.dwheeler.com/essays/fixing-unix-linux-filenames.html)
-- and leave anything else unchanged.
fromPlatformString :: PlatformString -> String
fromPlatformString s = if UTF8.isUTF8Encoded s then UTF8.decodeString s else s

-- | Convert a unicode string to a possibly encoded platform string.
-- On unix we encode with the recommended UTF-8
-- (cf http://www.dwheeler.com/essays/fixing-unix-linux-filenames.html)
-- and elsewhere we leave it unchanged.
toPlatformString :: String -> PlatformString
toPlatformString = case os of
                     "unix" -> UTF8.encodeString
                     "linux" -> UTF8.encodeString
                     "darwin" -> UTF8.encodeString
                     _ -> id

-- | A version of error that's better at displaying unicode.
error' :: String -> a
error' = error . toPlatformString

-- | A version of userError that's better at displaying unicode.
userError' :: String -> IOError
userError' = userError . toPlatformString

-- math

difforzero :: (Num a, Ord a) => a -> a -> a
difforzero a b = maximum [(a - b), 0]

-- regexps

containsRegex :: String -> String -> Bool
containsRegex r s = case matchRegexPR ("(?i)"++r) s of
                      Just _ -> True
                      _ -> False


-- lists

splitAtElement :: Eq a => a -> [a] -> [[a]]
splitAtElement e l = 
    case dropWhile (e==) l of
      [] -> []
      l' -> first : splitAtElement e rest
        where
          (first,rest) = break (e==) l'

-- trees

root = rootLabel
subs = subForest
branches = subForest

-- | List just the leaf nodes of a tree
leaves :: Tree a -> [a]
leaves (Node v []) = [v]
leaves (Node _ branches) = concatMap leaves branches

-- | get the sub-tree rooted at the first (left-most, depth-first) occurrence
-- of the specified node value
subtreeat :: Eq a => a -> Tree a -> Maybe (Tree a)
subtreeat v t
    | root t == v = Just t
    | otherwise = subtreeinforest v $ subs t

-- | get the sub-tree for the specified node value in the first tree in
-- forest in which it occurs.
subtreeinforest :: Eq a => a -> [Tree a] -> Maybe (Tree a)
subtreeinforest _ [] = Nothing
subtreeinforest v (t:ts) = case (subtreeat v t) of
                             Just t' -> Just t'
                             Nothing -> subtreeinforest v ts
          
-- | remove all nodes past a certain depth
treeprune :: Int -> Tree a -> Tree a
treeprune 0 t = Node (root t) []
treeprune d t = Node (root t) (map (treeprune $ d-1) $ branches t)

-- | apply f to all tree nodes
treemap :: (a -> b) -> Tree a -> Tree b
treemap f t = Node (f $ root t) (map (treemap f) $ branches t)

-- | remove all subtrees whose nodes do not fulfill predicate
treefilter :: (a -> Bool) -> Tree a -> Tree a
treefilter f t = Node 
                 (root t) 
                 (map (treefilter f) $ filter (treeany f) $ branches t)
    
-- | is predicate true in any node of tree ?
treeany :: (a -> Bool) -> Tree a -> Bool
treeany f t = f (root t) || any (treeany f) (branches t)
    
-- treedrop -- remove the leaves which do fulfill predicate. 
-- treedropall -- do this repeatedly.

-- | show a compact ascii representation of a tree
showtree :: Show a => Tree a -> String
showtree = unlines . filter (containsRegex "[^ \\|]") . lines . drawTree . treemap show

-- | show a compact ascii representation of a forest
showforest :: Show a => Forest a -> String
showforest = concatMap showtree

-- debugging

-- | trace (print on stdout at runtime) a showable expression
-- (for easily tracing in the middle of a complex expression)
strace :: Show a => a -> a
strace a = trace (show a) a

-- | labelled trace - like strace, with a label prepended
ltrace :: Show a => String -> a -> a
ltrace l a = trace (l ++ ": " ++ show a) a

-- | monadic trace - like strace, but works as a standalone line in a monad
mtrace :: (Monad m, Show a) => a -> m a
mtrace a = strace a `seq` return a

-- | trace an expression using a custom show function
tracewith f e = trace (f e) e

-- parsing

choice' :: [GenParser tok st a] -> GenParser tok st a
choice' = choice . map Text.ParserCombinators.Parsec.try

parsewith :: Parser a -> String -> Either ParseError a
parsewith p = parse p ""

parseWithCtx :: b -> GenParser Char b a -> String -> Either ParseError a
parseWithCtx ctx p = runParser p ctx ""

fromparse :: Either ParseError a -> a
fromparse = either parseerror id

parseerror e = error' $ showParseError e

showParseError e = "parse error at " ++ show e

showDateParseError e = printf "date parse error (%s)" (intercalate ", " $ tail $ lines $ show e)

nonspace :: GenParser Char st Char
nonspace = satisfy (not . isSpace)

spacenonewline :: GenParser Char st Char
spacenonewline = satisfy (`elem` " \v\f\t")

restofline :: GenParser Char st String
restofline = anyChar `manyTill` newline

-- time

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

-- testing

-- | Get a Test's label, or the empty string.
tname :: Test -> String
tname (TestLabel n _) = n
tname _ = ""

-- | Flatten a Test containing TestLists into a list of single tests.
tflatten :: Test -> [Test]
tflatten (TestLabel _ t@(TestList _)) = tflatten t
tflatten (TestList ts) = concatMap tflatten ts
tflatten t = [t]

-- | Filter TestLists in a Test, recursively, preserving the structure.
tfilter :: (Test -> Bool) -> Test -> Test
tfilter p (TestLabel l ts) = TestLabel l (tfilter p ts)
tfilter p (TestList ts) = TestList $ filter (any p . tflatten) $ map (tfilter p) ts
tfilter _ t = t

-- | Simple way to assert something is some expected value, with no label.
is :: (Eq a, Show a) => a -> a -> Assertion
a `is` e = assertEqual "" e a

-- | Assert a parse result is successful, printing the parse error on failure.
assertParse :: (Either ParseError a) -> Assertion
assertParse parse = either (assertFailure.show) (const (return ())) parse

-- | Assert a parse result is some expected value, printing the parse error on failure.
assertParseEqual :: (Show a, Eq a) => (Either ParseError a) -> a -> Assertion
assertParseEqual parse expected = either (assertFailure.show) (`is` expected) parse

printParseError :: (Show a) => a -> IO ()
printParseError e = do putStr "parse error at "; print e


-- misc

isLeft :: Either a b -> Bool
isLeft (Left _) = True
isLeft _        = False

isRight :: Either a b -> Bool
isRight = not . isLeft

-- -- | Expand ~ in a file path (does not handle ~name).
-- tildeExpand :: FilePath -> IO FilePath
-- tildeExpand ('~':[])     = getHomeDirectory
-- tildeExpand ('~':'/':xs) = getHomeDirectory >>= return . (++ ('/':xs))
-- --handle ~name, requires -fvia-C or ghc 6.8:
-- --import System.Posix.User
-- -- tildeExpand ('~':xs)     =  do let (user, path) = span (/= '/') xs
-- --                                pw <- getUserEntryForName user
-- --                                return (homeDirectory pw ++ path)
-- tildeExpand xs           =  return xs