-- | Render simple trees
module Debug.Trace.Tree.Render.Simple (renderTree) where

import Diagrams.Prelude
import Diagrams.Backend.Cairo (B)
import Graphics.SVGFonts
import Graphics.SVGFonts.ReadFont (PreparedFont)

import Debug.Trace.Tree.Edged (matchAgainst)
import Debug.Trace.Tree.Simple
import Debug.Trace.Tree.Render.Options
import Debug.Trace.Tree.Render.Constants
import qualified Debug.Trace.Tree.Render.Edged as Edged

renderTree :: RenderOptions -> SimpleTree -> Diagram B
renderTree options@RenderOptions{..} =
      Edged.renderTree drawEdgeLabel (drawNode options) renderShowCoords
    . applyOptions options

drawNode :: RenderOptions -> Maybe String -> Diagram B
drawNode RenderOptions{..} node =
      maybeVertical node
    $ makeBox node
  where
    makeBox (Just str) = box str (lookup str renderColours)
    makeBox Nothing    = mempty

    maybeVertical Nothing    = id
    maybeVertical (Just str) = if any (matchAgainst str) renderVertical
                                 then rotateBy (1/4)
                                 else id

drawEdgeLabel :: Maybe String -> Maybe String -> String -> (Diagram B, ArrowOpts Double)
drawEdgeLabel _ Nothing str = (
    stroke (textSVG' (textOpts constEdgeLabelHeight bit) str) # fc black # lw none
  , arrOpts & shaftStyle %~ dashingG [constMissingNodeDash, constMissingNodeDash] 0
            & headTexture .~ solid grey
  )
drawEdgeLabel _ (Just _) str = (
    stroke (textSVG' (textOpts constEdgeLabelHeight bit) str) # fc black # lw none
  , arrOpts
  )

-- NOTE: global sizes are relative to the final vector space of the diagram,
-- and are not affected by scaling. We don't want to use normalized because
-- normalized values depend on the size of the final diagram, and the size of
-- the diagram may very greatly depending on the size of the tree.
-- See Section 2.5, "Measurement units" of the diagrams manual.
arrOpts :: ArrowOpts Double
arrOpts = with & headLength .~ global constArrowHeadLength
               & shaftStyle %~ lw (global constArrowLineWidth) . lc grey

textOpts :: Double -> PreparedFont Double -> TextOpts Double
textOpts h fnt = with {
    textFont   = fnt
  , textHeight = h
  }

box :: String -> Maybe (Colour Double) -> Diagram B
box str mc = mconcat [
      stroke txt # fc black # lw none
    , boundingBoxRect bb # setBg mc # lc black # lw (global 1)
    ]
  where
    txt :: Path V2 Double
    txt = textSVG' (textOpts constNodeLabelHeight lin) str

    bb :: BoundingBox V2 Double
    bb = boundingBoxGrow constNodePadding (boundingBox txt) <> boundingBox minBB

    minBB :: Diagram B
    minBB = square constNodeLabelHeight

    setBg (Just c) = fc c
    setBg Nothing  = id

{-------------------------------------------------------------------------------
  Auxiliary: operations on bounding boxes
-------------------------------------------------------------------------------}

boundingBoxGrow :: Double -> BoundingBox V2 Double -> (BoundingBox V2 Double)
boundingBoxGrow padding bb =
    fromCorners (p2 (x  - padding, y  - padding))
                (p2 (x' + padding, y' + padding))
  where
    (unp2 -> (x, y), unp2 -> (x', y')) = getCorners' bb

boundingBoxRect :: BoundingBox V2 Double -> Diagram B
boundingBoxRect = uncurry rect . boundingBoxSize

boundingBoxSize :: Num a => BoundingBox V2 a -> (a, a)
boundingBoxSize bb = ((x' - x), (y' - y))
  where
    (unp2 -> (x, y), unp2 -> (x', y')) = getCorners' bb

getCorners' :: Num a => BoundingBox V2 a -> (Point V2 a, Point V2 a)
getCorners' bb =
    case getCorners bb of
      Just (ll, ur) -> (ll     , ur    )
      Nothing       -> (origin , origin)