{-# LANGUAGE FlexibleContexts #-}
{-|

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.Utils (---- provide these frequently used modules - or not, for clearer api:
                          -- module Control.Monad,
                          -- module Data.List,
                          -- module Data.Maybe,
                          -- module Data.Time.Calendar,
                          -- module Data.Time.Clock,
                          -- module Data.Time.LocalTime,
                          -- module Data.Tree,
                          -- module Text.RegexPR,
                          -- module Test.HUnit,
                          -- module Text.Printf,
                          ---- all of this one:
                          module Hledger.Utils,
                          module Hledger.Utils.Debug,
                          module Hledger.Utils.Regex,
                          -- Debug.Trace.trace,
                          -- module Data.PPrint,
                          -- module Hledger.Utils.UTF8IOCompat
                          SystemString,fromSystemString,toSystemString,error',userError',
                          -- the rest need to be done in each module I think
                          )
where
import Control.Monad (liftM)
import Control.Monad.Error (MonadIO)
import Control.Monad.IO.Class (liftIO)
import Data.Char
import Data.List
import qualified Data.Map as M
-- import Data.Maybe
-- import Data.PPrint
import Data.Time.Clock
import Data.Time.LocalTime
import Data.Tree
import System.Directory (getHomeDirectory)
import System.FilePath((</>), isRelative)
import System.IO
import Test.HUnit
import Text.Parsec
import Text.Printf
-- import qualified Data.Map as Map

import Hledger.Utils.Debug
import Hledger.Utils.Regex
-- import Prelude hiding (readFile,writeFile,appendFile,getContents,putStr,putStrLn)
-- import Hledger.Utils.UTF8IOCompat   (readFile,writeFile,appendFile,getContents,putStr,putStrLn)
import Hledger.Utils.UTF8IOCompat (SystemString,fromSystemString,toSystemString,error',userError')

-- strings

lowercase = map toLower
uppercase = map toUpper

-- | Remove leading and trailing whitespace.
strip = lstrip . rstrip

-- | Remove leading whitespace.
lstrip = dropWhile (`elem` " \t") :: String -> String -- XXX isSpace ?

-- | Remove trailing whitespace.
rstrip = reverse . lstrip . reverse

-- | Remove trailing newlines/carriage returns.
chomp = reverse . dropWhile (`elem` "\r\n") . reverse

stripbrackets = dropWhile (`elem` "([") . reverse . dropWhile (`elem` "])") . reverse :: String -> String

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"

-- | Wrap a string in double quotes, and \-prefix any embedded single
-- quotes, if it contains whitespace and is not already single- or
-- double-quoted.
quoteIfSpaced :: String -> String
quoteIfSpaced s | isSingleQuoted s || isDoubleQuoted s = s
                | not $ any (`elem` s) whitespacechars = s
                | otherwise = "'"++escapeSingleQuotes s++"'"

-- | Double-quote this string if it contains whitespace, single quotes
-- or double-quotes, escaping the quotes as needed.
quoteIfNeeded s | any (`elem` s) (quotechars++whitespacechars) = "\"" ++ escapeDoubleQuotes s ++ "\""
                | otherwise = s

-- | Single-quote this string if it contains whitespace or double-quotes.
-- No good for strings containing single quotes.
singleQuoteIfNeeded s | any (`elem` s) whitespacechars = "'"++s++"'"
                      | otherwise = s

quotechars      = "'\""
whitespacechars = " \t\n\r"

escapeDoubleQuotes :: String -> String
escapeDoubleQuotes = regexReplace "\"" "\""

escapeSingleQuotes :: String -> String
escapeSingleQuotes = regexReplace "'" "\'"

escapeQuotes :: String -> String
escapeQuotes = regexReplace "([\"'])" "\\1"

-- | Quote-aware version of words - don't split on spaces which are inside quotes.
-- NB correctly handles "a'b" but not "''a''". Can raise an error if parsing fails.
words' :: String -> [String]
words' "" = []
words' s  = map stripquotes $ fromparse $ parsewith p s
    where
      p = do ss <- (singleQuotedPattern <|> doubleQuotedPattern <|> pattern) `sepBy` many1 spacenonewline
             -- eof
             return ss
      pattern = many (noneOf whitespacechars)
      singleQuotedPattern = between (char '\'') (char '\'') (many $ noneOf "'")
      doubleQuotedPattern = between (char '"') (char '"') (many $ noneOf "\"")

-- | Quote-aware version of unwords - single-quote strings which contain whitespace
unwords' :: [String] -> String
unwords' = unwords . map quoteIfNeeded

-- | Strip one matching pair of single or double quotes on the ends of a string.
stripquotes :: String -> String
stripquotes s = if isSingleQuoted s || isDoubleQuoted s then init $ tail s else s

isSingleQuoted s@(_:_:_) = head s == '\'' && last s == '\''
isSingleQuoted _ = False

isDoubleQuoted s@(_:_:_) = head s == '"' && last s == '"'
isDoubleQuoted _ = False

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 (padright 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 ' '

-- tuples

first3  (x,_,_) = x
second3 (_,x,_) = x
third3  (_,_,x) = x

first4  (x,_,_,_) = x
second4 (_,x,_,_) = x
third4  (_,_,x,_) = x
fourth4 (_,_,_,x) = x

first5  (x,_,_,_,_) = x
second5 (_,x,_,_,_) = x
third5  (_,_,x,_,_) = x
fourth5 (_,_,_,x,_) = x
fifth5  (_,_,_,_,x) = x

-- math

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

-- lists

splitAtElement :: Eq a => a -> [a] -> [[a]]
splitAtElement x l =
  case l of
    []          -> []
    e:es | e==x -> split es
    es          -> split es
  where
    split es = let (first,rest) = break (x==) es
               in first : splitAtElement x rest

-- trees

-- standard tree helpers

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 (regexMatches "[^ \\|]") . lines . drawTree . treemap show

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


-- | An efficient-to-build tree suggested by Cale Gibbard, probably
-- better than accountNameTreeFrom.
newtype FastTree a = T (M.Map a (FastTree a))
  deriving (Show, Eq, Ord)

emptyTree = T M.empty

mergeTrees :: (Ord a) => FastTree a -> FastTree a -> FastTree a
mergeTrees (T m) (T m') = T (M.unionWith mergeTrees m m')

treeFromPath :: [a] -> FastTree a
treeFromPath []     = T M.empty
treeFromPath (x:xs) = T (M.singleton x (treeFromPath xs))

treeFromPaths :: (Ord a) => [[a]] -> FastTree a
treeFromPaths = foldl' mergeTrees emptyTree . map treeFromPath


-- parsing

-- | Backtracking choice, use this when alternatives share a prefix.
-- Consumes no input if all choices fail.
choice' :: Stream s m t => [ParsecT s u m a] -> ParsecT s u m a
choice' = choice . map Text.Parsec.try

parsewith :: Parsec [Char] () a -> String -> Either ParseError a
parsewith p = runParser p () ""

parseWithCtx :: Stream s m t => u -> ParsecT s u m a -> s -> m (Either ParseError a)
parseWithCtx ctx p = runParserT p ctx ""

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

parseerror :: ParseError -> a
parseerror e = error' $ showParseError e

showParseError :: ParseError -> String
showParseError e = "parse error at " ++ show e

showDateParseError :: ParseError -> String
showDateParseError e = printf "date parse error (%s)" (intercalate ", " $ tail $ lines $ show e)

nonspace :: (Stream [Char] m Char) => ParsecT [Char] st m Char
nonspace = satisfy (not . isSpace)

spacenonewline :: (Stream [Char] m Char) => ParsecT [Char] st m Char
spacenonewline = satisfy (`elem` " \v\f\t")

restofline :: (Stream [Char] m Char) => ParsecT [Char] st m String
restofline = anyChar `manyTill` newline

eolof :: (Stream [Char] m Char) => ParsecT [Char] st m ()
eolof = (newline >> return ()) <|> eof

-- time

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

-- testing

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

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

-- | Filter TestLists in a Test, recursively, preserving the structure.
filterTests :: (Test -> Bool) -> Test -> Test
filterTests p (TestLabel l ts) = TestLabel l (filterTests p ts)
filterTests p (TestList ts) = TestList $ filter (any p . flattenTests) $ map (filterTests p) ts
filterTests _ 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 successful, printing the parse error on failure.
assertParseFailure :: (Either ParseError a) -> Assertion
assertParseFailure parse = either (const $ return ()) (const $ assertFailure "parse should not have succeeded") 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

-- | Apply a function the specified number of times. Possibly uses O(n) stack ?
applyN :: Int -> (a -> a) -> a -> a
applyN n f = (!! n) . iterate f

-- | Convert a possibly relative, possibly tilde-containing file path to an absolute one,
-- given the current directory. ~username is not supported. Leave "-" unchanged.
expandPath :: MonadIO m => FilePath -> FilePath -> m FilePath -- general type sig for use in reader parsers
expandPath _ "-" = return "-"
expandPath curdir p = (if isRelative p then (curdir </>) else id) `liftM` expandPath' p
  where
    expandPath' ('~':'/':p)  = liftIO $ (</> p) `fmap` getHomeDirectory
    expandPath' ('~':'\\':p) = liftIO $ (</> p) `fmap` getHomeDirectory
    expandPath' ('~':_)      = error' "~USERNAME in paths is not supported"
    expandPath' p            = return p

firstJust ms = case dropWhile (==Nothing) ms of
    [] -> Nothing
    (md:_) -> md

-- | Read a file in universal newline mode, handling whatever newline convention it may contain.
readFile' :: FilePath -> IO String
readFile' name =  do
  h <- openFile name ReadMode
  hSetNewlineMode h universalNewlineMode
  hGetContents h