module Chart(barChart) where

import SlideWare

--barChart :: (Num a, Ord a) => (String, String) -> [(String, a)] -> Pict
barChart (xLbl, yLbl) xys =
    let n = fromIntegral (length xys)
	h = clientH / 3
	w = clientW / 2 / n
	my = maximum [ y | (x,y) <- xys ]
	ps = zipWith bar xys (cycle colors)
	p = hbAppend (spacing (2*gapSize) : lbar1 : lbar2 : ps ++ [rbar])
	lbar1 = join (label "__barL1" $ blank 0 h) (t " ")
	lbar2 = label "__barL2" $ join (blank 0 h) (t " ")
	rbar = join (label "__barR" $ blank 0 h) (t " ")
	bar (x, y) c = join (colorize c $ fill $ blank w (y / my * h)) (t x)
	join a b = vcAppend [spacing gapSize, a, b]
	lt2 = findLT ("__barL2") p
	lb1 = findLB ("__barL1") p
	lb2 = findLB ("__barL2") p
	rb = findRB ("__barR") p
	xarr = lineWidth 2 $ arrow (lb1, rb)
	yarr = lineWidth 2 $ arrow (lb2, lt2)
	ch = launderPrefix "__bar" $ ltSuperimpose [p, xarr, yarr]
	yLbl' = yLbl ++ " (max " ++ show my ++ ")"
    in  vlAppend [t yLbl', hbAppend [ch, t xLbl]]

colors = ["red", "yellow", "green", "cyan", "blue", "magenta"]