{-
Bustle.Diagram: shapes for sequence diagrams
Copyright (C) 2008–2009 Collabora Ltd.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-}
module Bustle.Diagram
  ( Diagram

  -- Shapes, and smart constructors therefore
  , Shape(..)
  , memberLabel
  , timestampLabel
  , headers
  , headerHeight

  -- Attributes of shapes
  , Arrowhead(..)
  , Side(..)
  , Colour(..)
  , Rect

  -- Annoying constants that users of this module need.
  , columnWidth
  , timestampAndMemberWidth
  , firstColumnOffset
  , eventHeight

  -- Displaying diagrams
  , diagramDimensions
  , topLeftJustifyDiagram
  , translateDiagram
  , drawDiagram
  , drawRegion
  )
where

import Data.List (unzip4)
import Control.Arrow ((&&&))
import Control.Applicative ((<$>), (<*>))

import Control.Monad.Reader

import Graphics.Rendering.Cairo (Operator(..), Render, arc, curveTo, fill, getCurrentPoint, lineTo, moveTo, newPath, paint, rectangle, restore, save, setDash, setLineWidth, setOperator, setSourceRGB, stroke)
import Graphics.UI.Gtk.Cairo (cairoCreateContext, showLayout)
import Graphics.Rendering.Pango.Layout
import Graphics.Rendering.Pango.Font

import qualified Bustle.Marquee as Marquee
import Bustle.Marquee (Marquee)
import Bustle.Util
import Bustle.Types (ObjectPath, InterfaceName, MemberName)

-- Sorry Mum
import System.IO.Unsafe (unsafePerformIO)

type Point = (Double, Double)
type Rect = (Double, Double, Double, Double)

data Arrowhead = Above | Below
  deriving (Eq, Show, Read, Ord)

above, below :: Arrowhead -> Bool
above Above = True
above Below = False
below = not . above

voffset :: Num a => Arrowhead -> (a -> a -> a)
voffset Above = (-)
voffset Below = (+)

data Side = L | R
  deriving (Eq, Show, Read, Ord)

offset :: Num a => Side -> (a -> a -> a)
offset L = (-)
offset R = (+)

data Colour = Colour Double Double Double
  deriving (Eq, Show, Read, Ord)

data Shape = Header { strs :: [String]
                    , shapex, shapey :: Double
                    }
           | MemberLabel { labelPath :: ObjectPath
                         , labelInterface :: Maybe InterfaceName
                         , labelMember :: MemberName
                         , shapeIsReturn :: Bool
                         , shapex :: Double -- The coordinates of the *centre*
                         , shapey :: Double -- of the label
                         }
           | TimestampLabel { str :: String
                            , shapex :: Double -- The coordinates of the
                            , shapey :: Double -- *centre* of the timestamp
                            }
           | ClientLines { shapexs :: NonEmpty Double -- The x-coordinates of the lines to draw
                         , shapey1, shapey2 :: Double
                         }
           | Rule { shapex1, shapex2, shapey :: Double }
           | Arrow { shapecolour :: Maybe Colour
                   , arrowhead :: Arrowhead
                   , shapex1, shapex2, shapey :: Double
                   }
           | SignalArrow { shapex1, epicentre, shapex2, shapey :: Double }
           | DirectedSignalArrow { epicentre, shapex, shapey :: Double }
           | Arc { topx, topy, bottomx, bottomy :: Double
                 , arcside :: Side
                 , caption :: String
                 }
           | Highlight { highlightRegion :: Rect
                       }
  deriving (Show, Eq)

-- Smart constructors for TimestampLabel and MemberLabel that fill in the
-- hardcoded (spit) x coordinates.
memberLabel :: ObjectPath
            -> Maybe InterfaceName
            -> MemberName
            -> Bool   -- ^ True if this is a return; False if it's a call
            -> Double -- ^ y-coordinate
            -> Shape
memberLabel p i m isReturn y = MemberLabel p i m isReturn memberx y

timestampLabel :: String -> Double -> Shape
timestampLabel s y = TimestampLabel s timestampx y

type Diagram = [Shape]

arcControlPoints :: Shape -> (Point, Point)
arcControlPoints (Arc { topx=x1, topy=y1, bottomx=x2, bottomy=y2, arcside=s }) =
    let (+-) = offset s
        cp1 = (x1 +- 60, y1 + 10)
        cp2 = (x2 +- 60, y2 - 10)
    in (cp1, cp2)
arcControlPoints _ = error "i see you've played arcy-shapey before"

mapX, mapY :: (Double -> Double) -> (Shape -> Shape)
mapX f s = case s of
    Rule {}        -> s { shapex1 = f (shapex1 s)
                        , shapex2 = f (shapex2 s)
                        }
    Arrow {}       -> s { shapex1 = f (shapex1 s)
                        , shapex2 = f (shapex2 s)
                        }
    SignalArrow {} -> s { shapex1 = f (shapex1 s)
                        , epicentre = f (epicentre s)
                        , shapex2 = f (shapex2 s)
                        }
    Arc {}         -> s { topx = f (topx s)
                        , bottomx = f (bottomx s)
                        }
    ClientLines {} -> s { shapexs = mapNonEmpty f (shapexs s) }
    _              -> s { shapex = f (shapex s) }

mapY f s = case s of
    Arc {}        -> s { topy = f (topy s)
                       , bottomy = f (bottomy s)
                       }
    ClientLines {} -> s { shapey1 = f (shapey1 s)
                       , shapey2 = f (shapey2 s)
                       }
    _             -> s { shapey = f (shapey s) }

--
-- Constants
--
eventHeight :: Double
eventHeight = 30

timestampx, timestampWidth :: Double
timestampx = 0 + timestampWidth / 2
timestampWidth = 60

memberx, memberWidth :: Double
memberx = timestampWidth + memberWidth / 2
memberWidth = 340

timestampAndMemberWidth :: Double
timestampAndMemberWidth = timestampWidth + memberWidth

columnWidth :: Double
columnWidth = 90

-- Method return arcs can go outside the first column. Empirically, 20 is
-- enough to stop the arc (or the duration text) overlapping the object path
-- etc.
firstColumnOffset :: Double
firstColumnOffset = 20 + columnWidth / 2

--
-- Calculating bounds of shapes
--
minMax :: Ord a => (a, a) -> (a, a)
minMax = uncurry min &&& uncurry max

xMinMax :: Shape -> (Double, Double)
xMinMax = minMax . (shapex1 &&& shapex2)

fromCentre :: Double -> Double -> Double -> Rect
fromCentre x y width =
    (x - width / 2, y - height / 2,
     x + width / 2, y + height / 2)
  where height = eventHeight

headerHeight :: [String] -> Double
headerHeight = fromIntegral . (10 *) . length

bounds :: Shape -> Rect
bounds s = case s of
  ClientLines {} ->
    let xs = nonEmptyToList (shapexs s)
    in  (minimum xs, shapey1 s, maximum xs, shapey2 s)
  Rule {} -> (shapex1 s, shapey s, shapex2 s, shapey s)
  Arrow {} ->
    let (x1, x2) = xMinMax s
        y1 = shapey s - (if above (arrowhead s) then 5 else 0)
        y2 = shapey s + (if below (arrowhead s) then 5 else 0)
    in (x1, y1, x2, y2)
  SignalArrow {} ->
    let (x1, x2) = xMinMax s
        (y1, y2) = (subtract 5) &&& (+5) $ shapey s
    in (x1, y1, x2, y2)
  DirectedSignalArrow {} ->
    let (x1, x2) = minMax (epicentre s, shapex s)
        (y1, y2) = (subtract 5) &&& (+5) $ shapey s
    in (x1, y1, x2, y2)
  Arc { topx=x1, bottomx=x2, topy=y1, bottomy=y2 } ->
    let ((cx, _), (dx, _)) = arcControlPoints s
       -- FIXME: magic 5 makes the bounding box include the text
    in (min x1 cx, y1, max x2 dx, y2 + 5)
  TimestampLabel { shapex=x, shapey=y } -> fromCentre x y timestampWidth
  MemberLabel { shapex=x, shapey=y } -> fromCentre x y memberWidth
  Header { strs = ss, shapex = x, shapey = y} ->
    let width = columnWidth
        height = headerHeight ss
    in (x - width / 2, y,
        x + width / 2, y + height)
  Highlight r -> r

intersects :: Rect -> Rect -> Bool
intersects (x,y,w,z) (x', y', w', z') =
  not $ or [x > w', w < x', y > z', z < y']

-- Constructs a series of headers of various-sized lists of names,
-- bottom-justified.
headers :: [(Double, [String])]  -- list of (x-coordinate, names)
        -> Double                -- y-coordinate of top of headers
        -> (Double, [Shape])     -- the headers' combined height, and shapes
headers []  _ = (0, [])
headers xss y = (height, shapes)
  where heights = map (headerHeight . snd) xss
        height  = maximum heights
        adjs    = map (height -) heights
        shapes  = zipWith (\(x, ss) adj -> Header ss x (y + adj)) xss adjs

--
-- Drawing
--

diagramBounds :: Diagram -> ((Double, Double), (Double, Double))
diagramBounds shapes = ((minimum (0:x1s) - padding, minimum (0:y1s) - padding)
                       ,(maximum (0:x2s) + padding, maximum (0:y2s) + padding)
                       )
  where
    (x1s, y1s, x2s, y2s) = unzip4 $ map bounds shapes
    padding              = 6

diagramDimensions :: Diagram -> (Double, Double)
diagramDimensions shapes = (x2 - x1, y2 - y1)
  where
    ((x1, y1), (x2, y2)) = diagramBounds shapes

topLeftJustifyDiagram
    :: Diagram -- ^ the original diagram
    -> ((Double, Double), Diagram) -- ^ the diagram transformed to be in
                                   --   positive space, and the (x, y)-axis
                                   --   shifts necessary to do so
topLeftJustifyDiagram shapes =
    (translation, shapes')
  where
    ((x1, y1), _) = diagramBounds shapes
    translation   = (negate x1, negate y1)
    shapes'       = translateDiagram translation shapes

translateDiagram :: (Double, Double) -> (Diagram -> Diagram)
translateDiagram (x, y) = map (mapX (+ x) . mapY (+ y))

drawDiagramInternal :: (Shape -> Bool) -- ^ A filter for the shapes
                    -> Bool -- ^ True to draw canvas items' bounding boxes
                            --   (for debugging)
                    -> Diagram   -- ^ A diagram to render
                    -> Render ()
drawDiagramInternal f drawBounds shapes = do
    clearCanvas

    forM_ (filter f shapes) $ \x -> do
        when drawBounds (drawBoundingBox x)
        draw x

drawDiagram :: Bool      -- ^ True to draw canvas items' bounding boxes (for
                         --   debugging)
            -> Diagram   -- ^ A diagram to render
            -> Render ()
drawDiagram = drawDiagramInternal (const True)

drawRegion :: Rect -> Bool -> Diagram -> Render ()
drawRegion r = drawDiagramInternal isVisible
    where isVisible = intersects r . bounds

saved :: Render () -> Render ()
saved act = save >> act >> restore

clearCanvas :: Render ()
clearCanvas = saved $ do
    setSourceRGB 1 1 1
    setOperator OperatorSource
    paint

drawBoundingBox :: Shape -> Render ()
drawBoundingBox s = saved $ do
    let (x,y,w,z) = bounds s
    setSourceRGB 0 0 1
    rectangle x y (w - x) (z - y)
    stroke

draw :: Shape -> Render ()
draw s = draw' s
  where draw' = case s of
          Arc {} -> let ((cx, cy), (dx, dy)) = arcControlPoints s
                    in drawArc cx cy dx dy <$>
                          topx <*> topy <*> bottomx <*> bottomy <*> caption
          SignalArrow {} -> drawSignalArrow <$> epicentre
                                            <*> (Just . shapex1)
                                            <*> (Just . shapex2)
                                            <*> shapey
          DirectedSignalArrow { } -> drawDirectedSignalArrow <$> epicentre
                                                             <*> shapex
                                                             <*> shapey
          Arrow {} -> drawArrow <$> shapecolour <*> arrowhead <*> shapex1 <*>
                        shapex2 <*> shapey
          Header {} -> drawHeader <$> strs <*> shapex <*> shapey
          MemberLabel {} -> drawMember <$> labelPath
                                       <*> labelInterface
                                       <*> labelMember
                                       <*> shapeIsReturn
                                       <*> shapex
                                       <*> shapey
          TimestampLabel {} -> drawTimestamp <$> str
                                             <*> shapex
                                             <*> shapey
          ClientLines {} -> drawClientLines <$> shapexs <*> shapey1 <*> shapey2
          Rule {} -> drawRule <$> shapex1
                              <*> shapex2
                              <*> shapey
          Highlight {} -> drawHighlight <$> highlightRegion

halfArrowHead :: Arrowhead -> Bool -> Render ()
halfArrowHead a left = do
    (x,y) <- getCurrentPoint
    let x' = if left then x - 10 else x + 10
    let y' = voffset a y 5
    if left -- work around weird artifacts
      then moveTo x' y' >> lineTo x y
      else lineTo x' y' >> moveTo x y

arrowHead :: Bool -> Render ()
arrowHead left = halfArrowHead Above left >> halfArrowHead Below left

drawArrow :: Maybe Colour -> Arrowhead -> Double -> Double -> Double
          -> Render ()
drawArrow c a from to y = saved $ do
    maybe (return ()) (\(Colour r g b) -> setSourceRGB r g b) c

    moveTo from y
    lineTo to y
    halfArrowHead a (from < to)
    stroke

drawDirectedSignalArrow :: Double -- ^ the signal emission source
                        -> Double -- ^ signal target coordinate
                        -> Double -- ^ vertical coordinate
                        -> Render ()
drawDirectedSignalArrow e x y
    | x < e     = drawSignalArrow e (Just x) Nothing y
    | otherwise = drawSignalArrow e Nothing (Just x) y

drawSignalArrow :: Double -- ^ the signal emission source
                -> Maybe Double -- ^ left-pointing arrow coordinate
                -> Maybe Double -- ^ right-pointing arrow coordinate
                -> Double -- ^ vertical coordinate
                -> Render ()
drawSignalArrow e mleft mright y = do
    newPath
    arc e y 5 0 (2 * pi)
    stroke

    maybeM mleft $ \left -> do
        moveTo left y
        arrowHead False
        lineTo (e - 5) y
        stroke

    maybeM mright $ \right -> do
        moveTo (e + 5) y
        lineTo right y
        arrowHead True
        stroke

drawArc :: Double -> Double -> Double -> Double
        -> Double -> Double -> Double -> Double
        -> String
        -> Render ()
drawArc cx cy dx dy x1 y1 x2 y2 cap = saved $ do
    setSourceRGB 0.4 0.7 0.4
    setDash [3, 3] 0

    moveTo x1 y1
    curveTo cx cy dx dy x2 y2
    stroke

    setSourceRGB 0 0 0
    l <- mkLayout (Marquee.escape cap) EllipsizeNone AlignLeft
    (PangoRectangle _ _ textWidth _, _) <- liftIO $ layoutGetExtents l
    let tx = min x2 dx + abs (x2 - dx) / 2
    moveTo (if x1 > cx then tx - textWidth else tx) (y2 - 5)
    showLayout l

font :: FontDescription
font = unsafePerformIO $ do
    fd <- fontDescriptionNew
    fontDescriptionSetSize fd 7
    fontDescriptionSetFamily fd "Sans"
    return fd
{-# NOINLINE font #-}

mkLayout :: (MonadIO m)
         => Marquee -> EllipsizeMode -> LayoutAlignment
         -> m PangoLayout
mkLayout s e a = liftIO $ do
    ctx <- cairoCreateContext Nothing
    layout <- layoutEmpty ctx
    -- layoutSetMarkup returns the un-marked-up text. We don't care about it,
    -- but recent versions of Pango give it the type
    --    GlibString string => ... -> IO string
    -- which we need to disambiguate between Text and String. Old versions were
    --    .. -> IO String
    -- so go with that.
    layoutSetMarkup layout (Marquee.toPangoMarkup s) :: IO String
    layoutSetFontDescription layout (Just font)
    layoutSetEllipsize layout e
    layoutSetAlignment layout a
    return layout

withWidth :: MonadIO m => m PangoLayout -> Double -> m PangoLayout
withWidth m w = do
    l <- m
    liftIO $ layoutSetWidth l (Just w)
    return l

drawHeader :: [String] -> Double -> Double -> Render ()
drawHeader names x y = forM_ (zip [0..] names) $ \(i, name) -> do
    l <- mkLayout (Marquee.escape name) EllipsizeEnd AlignCenter `withWidth` columnWidth
    moveTo (x - (columnWidth / 2)) (y + i * h)
    showLayout l
  where h = 10

drawMember :: ObjectPath
           -> Maybe InterfaceName
           -> MemberName
           -> Bool
           -> Double
           -> Double
           -> Render ()
drawMember p i m isReturn x y = do
    drawOne path (y - 10)
    drawOne fullMethod y
  where
    drawOne markup y' = do
      l <- mkLayout markup EllipsizeStart AlignLeft `withWidth` memberWidth
      moveTo (x - memberWidth / 2) y'
      showLayout l

    path = (if isReturn then id else Marquee.b) $ Marquee.escape p
    fullMethod =
        (if isReturn then Marquee.i else id) $ Marquee.formatMember i m

drawTimestamp :: String -> Double -> Double -> Render ()
drawTimestamp ts x y = do
    moveTo (x - timestampWidth / 2) (y - 10)
    showLayout =<< mkLayout (Marquee.escape ts) EllipsizeNone AlignLeft `withWidth` timestampWidth

drawClientLines :: NonEmpty Double -> Double -> Double -> Render ()
drawClientLines xs y1 y2 = saved $ do
    setSourceRGB 0.7 0.7 0.7
    forM_ (nonEmptyToList xs) $ \x -> do
        moveTo x y1
        lineTo x y2
        stroke

drawRule :: Double -> Double -> Double -> Render ()
drawRule x1 x2 y = saved $ do
    setSourceRGB 0.9 0.9 0.9
    setLineWidth 0.5

    moveTo x1 y
    lineTo x2 y
    stroke

drawHighlight :: Rect -> Render ()
drawHighlight (x1, y1, x2, y2) = saved $ do
    setSourceRGB 0.8 0.9 1.0
    rectangle x1 y1 (x2 - x1) (y2 - y1)
    fill

-- vim: sw=2 sts=2