{-# LANGUAGE CPP #-}
{-|
hledger-web - a hledger add-on providing rudimentary pie chart generation.
Copyright (c) 2007-2010 Simon Michael <simon@joyful.com>
Released under GPL version 3 or later.
-}

module Hledger.Chart.Main
where
import Graphics.Rendering.Chart
import Data.Colour
import Data.Colour.Names
import Data.Colour.RGBSpace
import Data.Colour.RGBSpace.HSL (hsl)
import Data.Colour.SRGB.Linear (rgb)
import Data.List
import Safe (readDef)
import System.Console.GetOpt
import System.Exit (exitFailure)
#if __GLASGOW_HASKELL__ <= 610
import Prelude hiding (putStr, putStrLn)
import System.IO.UTF8 (putStr, putStrLn)
#endif

import Hledger.Cli.Options
import Hledger.Cli.Utils (withJournalDo)
import Hledger.Cli.Version (progversionstr, binaryfilename)
import Hledger.Data


progname_chart = progname_cli ++ "-chart"

defchartoutput   = "hledger.png"
defchartitems    = 10
defchartsize     = "600x400"

options_chart :: [OptDescr Opt]
options_chart = [
  Option "o" ["output"] (ReqArg ChartOutput "FILE")       ("output filename (default: "++defchartoutput++")")
 ,Option ""  ["items"]  (ReqArg ChartItems "N")           ("number of accounts to show (default: "++show defchartitems++")")
 ,Option ""  ["size"]   (ReqArg ChartSize "WIDTHxHEIGHT") ("image size (default: "++defchartsize++")")
 ]

usage_preamble_chart =
  "Usage: hledger-chart [OPTIONS] [PATTERNS]\n" ++
  "\n" ++
  "Reads your ~/.journal file, or another specified by $LEDGER or -f, and\n" ++
  "generates simple pie chart images.\n" ++
  "\n"

usage_options_chart = usageInfo "hledger-chart options:" options_chart ++ "\n"

usage_chart = concat [
             usage_preamble_chart
            ,usage_options_chart
            ,usage_options_cli
            ,usage_postscript_cli
            ]

main :: IO ()
main = do
  (opts, args) <- parseArgumentsWith $ options_cli++options_chart
  run opts args
    where
      run opts args
       | Help `elem` opts             = putStr usage_chart
       | Version `elem` opts          = putStrLn $ progversionstr progname_chart
       | BinaryFilename `elem` opts   = putStrLn $ binaryfilename progname_chart
       | otherwise                    = withJournalDo opts args "chart" chart

-- | Generate an image with the pie chart and write it to a file
chart :: [Opt] -> [String] -> Journal -> IO ()
chart opts args j = do
  t <- getCurrentLocalTime
  if null $ jtxns j
   then putStrLn "This journal has no transactions, can't make a chart." >> exitFailure
   else do
     let chart = genPie opts (optsToFilterSpec opts args t) j
     renderableToPNGFile (toRenderable chart) w h filename
     return ()
      where
        filename = getOption opts ChartOutput defchartoutput
        (w,h) = parseSize $ getOption opts ChartSize defchartsize

-- | Extract string option value from a list of options or use the default
getOption :: [Opt] -> (String->Opt) -> String -> String
getOption opts opt def = 
    case reverse $ optValuesForConstructor opt opts of
        [] -> def
        x:_ -> x

-- | Parse image size from a command-line option
parseSize :: String -> (Int,Int)
parseSize str = (read w, read h)
    where
    x = fromMaybe (error' "Size should be in WIDTHxHEIGHT format") $ findIndex (=='x') str
    (w,_:h) = splitAt x str

-- | Generate pie chart
genPie :: [Opt] -> FilterSpec -> Journal -> PieLayout
genPie opts filterspec j = defaultPieLayout { pie_background_ = solidFillStyle $ opaque $ white
                                            , pie_plot_ = pie_chart }
    where
      pie_chart = defaultPieChart { pie_data_ = map (uncurry accountPieItem) chartitems'
                                  , pie_start_angle_ = (-90)
                                  , pie_colors_ = mkColours hue
                                  , pie_label_style_ = defaultFontStyle{font_size_=12}
                                  }
      chartitems' = debug "chart" $ top num samesignitems
      (samesignitems, sign) = sameSignNonZero rawitems
      rawitems = debug "raw" $ flatten $ balances $
                 ledgerAccountTree (fromMaybe 99999 $ depthFromOpts opts) $ journalToLedger filterspec j
      top n t = topn ++ [other]
          where
            (topn,rest) = splitAt n $ reverse $ sortBy (comparing snd) t
            other = ("other", sum $ map snd rest)
      num = readDef (fromIntegral defchartitems) (getOption opts ChartItems (show defchartitems))
      hue = if sign > 0 then red else green where (red, green) = (0, 110)
      debug s = if Debug `elem` opts then ltrace s else id

-- | Select the nonzero items with same sign as the first, and make
-- them positive. Also return a 1 or -1 corresponding to the original sign.
sameSignNonZero :: [(AccountName, Double)] -> ([(AccountName, Double)], Int)
sameSignNonZero is | null nzs = ([], 1)
                   | otherwise = (map pos $ filter (test.snd) nzs, sign)
                   where
                     nzs = filter ((/=0).snd) is
                     pos (a,b) = (a, abs b)
                     sign = if snd (head nzs) >= 0 then 1 else (-1)
                     test = if sign > 0 then (>0) else (<0)

-- | Convert all quantities of MixedAccount to a single commodity
amountValue :: MixedAmount -> Double
amountValue = quantity . convertMixedAmountToSimilarCommodity unknown

-- | Generate a tree of account names together with their balances.
--   The balance of account is decremented by the balance of its subaccounts
--   which are drawn on the chart.
balances :: Tree Account -> Tree (AccountName, Double)
balances (Node rootAcc subAccs) = Node newroot newsubs
    where
      newroot = (aname rootAcc,
                 amountValue $
                 abalance rootAcc - (sum . map (abalance . root)) subAccs)
      newsubs = map balances subAccs

-- | Build a single pie chart item
accountPieItem :: AccountName -> Double -> PieItem
accountPieItem accname balance = PieItem accname offset balance where offset = 0

-- | Generate an infinite color list suitable for charts.
mkColours :: Double -> [AlphaColour Double]
mkColours hue = cycle $ [opaque $ rgbToColour $ hsl h s l | (h,s,l) <- liftM3 (,,)
                         [hue] [0.7] [0.1,0.2..0.7] ]

rgbToColour :: (Fractional a) => RGB a -> Colour a
rgbToColour (RGB r g b) = rgb r g b