-- | Deals with three.js meshes.

module MolDraw.DrawMol.Mesh
( Mesh
, MeshOptions
, Color
, Material
, meshes
) where


import Prelude
import Data.Array (fromFoldable)
import MolDraw.GeometryAtom as GA
import MolDraw.BondSegment as BondSegment
import MolDraw.GeometryData as GD
import MolDraw.Position (Position)
import MolDraw.Utils.ElementSizes (size)
import MolDraw.Utils.ElementColors (color)


type Color = Int

-- | Represents three.js materials.
data Material = Material


-- | Holds user-provided options for customizing the drawn mesh.
-- |
-- | * `atomSize`: Takes a `GeometryAtom` and returns the size it
-- | should be drawn with.
-- | * `atomColor`: Takes a `GeometryAtom` and returns the color
-- | it should be drawn with.
-- | * `atomScale`: A scaling factor applied to the sizes of all atoms.
-- | * `atomWidthSegments`: The number of width segments used to
-- | draw each atom. More segments make the the atoms look rounder,
-- | but are more expensive to draw.
-- | * `atomHeightSegments`: The number of height segments used to draw
-- | each atom. More segments make the atoms look rounder, but are
-- | more expensive to draw.
-- | `bondRadialSegments`: The number of radial segments used to draw
-- | bonds.
-- | `bondHeightSegments`: The number of height segments used to draw
-- | bonds.
-- | `material`: Takes a color, and returns the material used for
-- | drawing atoms and bonds.
type MeshOptions =
    { atomSize           :: GA.GeometryAtom -> Number
    , atomColor          :: GA.GeometryAtom -> Color
    , atomScale          :: Number
    , atomWidthSegments  :: Int
    , atomHeightSegments :: Int
    , bondRadialSegments :: Int
    , bondHeightSegments :: Int
    , material           :: Color -> Material
    }



-- | Holds data needed to create a three.js mesh.
type MeshData =
    { atoms              :: Array GA.GeometryAtom
    , atomSize           :: GA.GeometryAtom -> Number
    , atomColor          :: GA.GeometryAtom -> Color
    , atomScale          :: Number
    , atomWidthSegments  :: Int
    , atomHeightSegments :: Int
    , bondSegments       :: Array BondSegment.BondSegment
    , bondRadialSegments :: Int
    , bondHeightSegments :: Int
    , material           :: Color -> Material
    }



meshData :: MeshOptions -> GD.GeometryData -> MeshData
meshData
    (
        { atomSize
        , atomColor
        , atomScale
        , atomWidthSegments
        , atomHeightSegments
        , bondRadialSegments
        , bondHeightSegments
        , material
        }
    )
    geometryData =
        { atoms: fromFoldable $ GD.atoms geometryData
        , bondSegments: fromFoldable $ GD.bondSegments geometryData
        , atomSize: atomSize
        , atomColor: atomColor
        , atomScale: atomScale
        , atomWidthSegments
        , atomHeightSegments
        , bondRadialSegments
        , bondHeightSegments
        , material
        }



-- | Represents a three.js mesh.
data Mesh = Mesh



-- | Holds functions useful to the JavaScript implementation.
type Helpers =
    { atomPosition        :: GA.GeometryAtom         -> Position
    , defaultAtomSize     :: GA.GeometryAtom         -> Number
    , defaultAtomColor    :: GA.GeometryAtom         -> Color
    , bondSegmentPosition :: BondSegment.BondSegment -> Position
    , bondSegmentAtom     :: BondSegment.BondSegment -> GA.GeometryAtom
    , bondSegmentWidth    :: BondSegment.BondSegment -> Number
    , bondSegmentLength   :: BondSegment.BondSegment -> Number
    , bondSegmentGapSize  :: BondSegment.BondSegment -> Number
    }


foreign import meshesImpl :: Helpers -> MeshData -> Array Mesh


helpers :: Helpers
helpers =
    { atomPosition              : GA.position
    , defaultAtomSize           : size  <<< GA.chemicalSymbol
    , defaultAtomColor          : color <<< GA.chemicalSymbol
    , bondSegmentPosition       : BondSegment.position
    , bondSegmentAtom           : BondSegment.atom
    , bondSegmentWidth          : BondSegment.width
    , bondSegmentLength         : BondSegment.length
    , bondSegmentGapSize        : BondSegment.gapSize
    }


-- | Create the meshes which compose a molecule.
meshes :: MeshOptions -> GD.GeometryData -> Array Mesh
meshes meshOptions geometryData
    = meshesImpl helpers $ meshData meshOptions geometryData