module GUI.Timeline.Sparks (
    renderSparkCreation,
    renderSparkConversion,
    renderSparkPool,
  ) where

import GUI.Timeline.Render.Constants

import Events.SparkTree
import qualified Events.SparkStats as SparkStats
import GUI.Types
import GUI.Timeline.CairoDrawing
import GUI.ViewerColours

import Graphics.Rendering.Cairo
import qualified Graphics.Rendering.Cairo as C
import Graphics.UI.Gtk

import GHC.RTS.Events hiding (Event, GCWork, GCIdle)

import Control.Monad

import Text.Printf

-- Rendering sparks. No approximation nor extrapolation is going on here.
-- The sample data, recalculated for a given slice size in sparkProfile,
-- is straightforwardly rendered.

-- TODO; Function sparkProfile, for a given slice size and viewport,
-- is called separately by each render* function, The unused parts of the result
-- won't get computed, but the drilling down the tree and allocating
-- thunks is repeated for each graph, while it could be done just once,
-- for a given zoom level and scroll directive.

renderSparkCreation :: ViewParameters -> Timestamp -> Timestamp -> SparkTree
                       -> Double -> Render ()
renderSparkCreation params !start0 !end0 t !maxSparkValue = do
  let f1 c =        SparkStats.rateDud c
      f2 c = f1 c + SparkStats.rateCreated c
      f3 c = f2 c + SparkStats.rateOverflowed c
  renderSpark params start0 end0 t
    f1 fizzledDudsColour f2 createdConvertedColour f3 overflowedColour
    maxSparkValue

renderSparkConversion :: ViewParameters -> Timestamp -> Timestamp -> SparkTree
                         -> Double -> Render ()
renderSparkConversion params !start0 !end0 t !maxSparkValue = do
  let f1 c =        SparkStats.rateFizzled c
      f2 c = f1 c + SparkStats.rateGCd c
      f3 c = f2 c + SparkStats.rateConverted c
  renderSpark params start0 end0 t
    f1 fizzledDudsColour f2 gcColour f3 createdConvertedColour
    maxSparkValue

renderSparkPool :: ViewParameters -> Timestamp -> Timestamp -> SparkTree
                         -> Double -> Render ()
renderSparkPool params@ViewParameters{..} !start0 !end0 t !maxSparkPool = do
  let slice = round (fromIntegral spark_detail * scaleValue)
      -- round the start time down, and the end time up, to a slice boundary
      start = (start0 `div` slice) * slice
      end   = ((end0 + slice) `div` slice) * slice
      prof  = sparkProfile slice start end t
      f1 c = SparkStats.minPool c
      f2 c = SparkStats.meanPool c
      f3 c = SparkStats.maxPool c
  addSparks outerPercentilesColour maxSparkPool f1 f2 start slice prof
  addSparks outerPercentilesColour maxSparkPool f2 f3 start slice prof
  outlineSparks maxSparkPool f2 start slice prof
  outlineSparks maxSparkPool (const 0) start slice prof
  addScale params maxSparkPool start end

renderSpark :: ViewParameters -> Timestamp -> Timestamp -> SparkTree
               -> (SparkStats.SparkStats -> Double) -> Color
               -> (SparkStats.SparkStats -> Double) -> Color
               -> (SparkStats.SparkStats -> Double) -> Color
               -> Double -> Render ()
renderSpark params@ViewParameters{..} start0 end0 t
            f1 c1 f2 c2 f3 c3 maxSparkValue = do
  let slice = round (fromIntegral spark_detail * scaleValue)
      -- round the start time down, and the end time up, to a slice boundary
      start = (start0 `div` slice) * slice
      end   = ((end0 + slice) `div` slice) * slice
      prof  = sparkProfile slice start end t
      -- Maximum number of sparks per slice for current data.
      maxSliceSpark = fromIntegral slice * maxSparkValue
      -- Maximum spark transition rate in spark/ms.
      maxSlice = maxSparkValue * 1000000
  outlineSparks maxSliceSpark f3 start slice prof
  addSparks c1 maxSliceSpark (const 0) f1 start slice prof
  addSparks c2 maxSliceSpark f1 f2 start slice prof
  addSparks c3 maxSliceSpark f2 f3 start slice prof
  addScale params maxSlice start end

spark_detail :: Int
spark_detail = 4 -- in pixels

off :: Double -> (SparkStats.SparkStats -> Double)
       -> SparkStats.SparkStats
       -> Double
off maxSliceSpark f t = fromIntegral hecSparksHeight * (1 - f t / maxSliceSpark)

dashedLine1 :: Render ()
dashedLine1 = do
  save
  identityMatrix
  setDash [10,10] 0.0
  setLineWidth 1
  stroke
  restore

outlineSparks :: Double
                 -> (SparkStats.SparkStats -> Double)
                 -> Timestamp -> Timestamp
                 -> [SparkStats.SparkStats]
                 -> Render ()
outlineSparks maxSliceSpark f start slice ts = do
  case ts of
    [] -> return ()
    ts -> do
      let dstart = fromIntegral start
          dslice = fromIntegral slice
          points = [dstart-dslice/2, dstart+dslice/2 ..]
          t = zip points (map (off maxSliceSpark f) ts)
      newPath
      moveTo (dstart-dslice/2) (snd $ head t)
      mapM_ (uncurry lineTo) t
      setSourceRGBAhex black 1.0
      save
      identityMatrix
      setLineWidth 1
      stroke
      restore

addSparks :: Color
             -> Double
             -> (SparkStats.SparkStats -> Double)
             -> (SparkStats.SparkStats -> Double)
             -> Timestamp -> Timestamp
             -> [SparkStats.SparkStats]
             -> Render ()
addSparks colour maxSliceSpark f0 f1 start slice ts = do
  case ts of
    [] -> return ()
    ts -> do
      -- liftIO $ printf "ts: %s\n" (show (map f1 (ts)))
      -- liftIO $ printf "off: %s\n"
      --   (show (map (off maxSliceSpark f1) (ts) :: [Double]))
      let dstart = fromIntegral start
          dslice = fromIntegral slice
          points = [dstart-dslice/2, dstart+dslice/2 ..]
          t0 = zip points (map (off maxSliceSpark f0) ts)
          t1 = zip points (map (off maxSliceSpark f1) ts)
      newPath
      moveTo (dstart-dslice/2) (snd $ head t1)
      mapM_ (uncurry lineTo) t1
      mapM_ (uncurry lineTo) (reverse t0)
      setSourceRGBAhex colour 1.0
      fill


-- TODO: redesign and refactor the scales code after some feedback and testing.

-- There are ten minor ticks to a major tick and a semi-major tick
-- occurs half way through a major tick (overlapping the corresponding
-- minor tick).
-- The timestamp values are in nanoseconds (1e-9), i.e.,
-- a timestamp value of 1000000000 represents 1s.
-- The x-position on the drawing canvas is in milliseconds (ms) (1e-3).
-- scaleValue is used to divide a timestamp value to yield a pixel value.
addScale :: ViewParameters -> Double -> Timestamp -> Timestamp -> Render ()
addScale ViewParameters{..} maxSpark start end = do
  let dstart = fromIntegral start
      dend = fromIntegral end
      dheight = fromIntegral hecSparksHeight
      -- TODO: this is slightly incorrect, but probably at most 1 pixel off
      maxS = if maxSpark < 100
             then maxSpark  -- too small, accuracy would suffer
             else fromIntegral (2 * (ceiling maxSpark ` div` 2))
      -- TODO: divide maxSpark instead, for nicer round numbers display
      incr = hecSparksHeight `div` 10
      majorTick = 10 * incr

  -- dashed lines across the graphs
  setSourceRGBAhex black 0.3
  save
  forM_ [0 .. 1] $ \h -> do
    let y = fromIntegral (floor (fromIntegral h * fromIntegral majorTick / 2)) - 0.5
    moveTo dstart y
    lineTo dend y
    dashedLine1
  restore

  -- draw scales only if the drawn area includes the very start
  -- TODO: this draws the scale too often, because the drawn area begins
  -- to the left of the 0 mark; will be fixed when scales are moved outside
  -- the scrollable area.
  when (start == 0) $ do

    newPath
    moveTo dstart 0
    lineTo dstart dheight
    setSourceRGBAhex blue 1.0
    save
    identityMatrix
    setLineWidth 1
    stroke
    restore

    selectFontFace "sans serif" FontSlantNormal FontWeightNormal
    setFontSize 12
    setSourceRGBAhex blue 1.0
    save
    scale scaleValue 1.0
    setLineWidth 0.5
    drawTicks maxS start scaleValue 0 incr majorTick hecSparksHeight
    restore

-- TODO: make it more robust when parameters change, e.g., if incr is too small
drawTicks :: Double -> Timestamp -> Double -> Int -> Int -> Int -> Int -> Render ()
drawTicks maxS offset scaleValue pos incr majorTick endPos
  = if pos <= endPos then do
      draw_line (x0, hecSparksHeight - y0) (x1, hecSparksHeight - y1)
      when (pos > 0
            && (atMajorTick || atMidTick || tickWidthInPixels > 30)) $ do
            move_to (offset + 15,
                     fromIntegral hecSparksHeight - pos + 4)
            m <- getMatrix
            identityMatrix
            tExtent <- textExtents tickText
            (fourPixels, _) <- deviceToUserDistance 4 0
            when (textExtentsWidth tExtent + fourPixels < fromIntegral tickWidthInPixels || atMidTick || atMajorTick) $ do
              textPath tickText
              C.fill
            setMatrix m
      drawTicks maxS offset scaleValue (pos+incr) incr majorTick endPos
    else
      return ()
    where
    tickWidthInPixels :: Int
    tickWidthInPixels = truncate ((fromIntegral incr) / scaleValue)
    tickText = showTickText (maxS * fromIntegral pos
                             / fromIntegral hecSparksHeight)
    atMidTick = pos `mod` (majorTick `div` 2) == 0
    atMajorTick = pos `mod` majorTick == 0
    (x0, y0, x1, y1) = if atMajorTick then
                         (offset, pos, offset+13, pos)
                       else
                         if atMidTick then
                           (offset, pos, offset+10, pos)
                         else
                           (offset, pos, offset+6, pos)

showTickText :: Double -> String
showTickText pos
  = deZero (printf "%.2f" pos)

deZero :: String -> String
deZero str
  = if length str >= 4 && take 3 revstr == "00." then
      reverse (drop 3 revstr)
    else
      str
    where
    revstr = reverse str