(** Common  module for ensuring that the function is evaluated only once *)

module type REPRESENTABLE = sig
  type t

  (** Represent the path *)
  val repr
    : t -> (module Path.Repr.M with type t = Path.Point.t and type repr = 's) -> 's -> 's
end

(* Canva representation *)

module FillCanvaRepr = FillPrinter.Make(CanvaPrinter)
module DuctusCanvaRepr = DuctusPrinter.Make(CanvaPrinter)
module LineCanvaRepr = LinePrinter.Make(CanvaPrinter)
module WireCanvaRepr = WireFramePrinter.Make(CanvaPrinter)

(* SVG representation *)

module FillSVGRepr = FillPrinter.Make(Svg)
module DuctusSVGRepr = DuctusPrinter.Make(Svg)
module WireSVGRepr = WireFramePrinter.Make(Svg)


type printer =
  [ `Fill
  | `Line
  | `Ductus ]

(** Draw a path to a canva *)
let to_canva
  : (module REPRESENTABLE with type t = 's)  -> 's -> Brr_canvas.C2d.t -> printer -> unit
  = fun (type s) (module R:REPRESENTABLE with type t = s) path ctx -> function
    | `Fill ->
      R.repr
        path
        (module FillCanvaRepr)
        (FillCanvaRepr.create_path (fun p -> Brr_canvas.C2d.fill ctx p; p))
      |> FillCanvaRepr.get
      |> Brr_canvas.C2d.stroke ctx
    | `Line ->
      R.repr
        path
        (module LineCanvaRepr)
        (LineCanvaRepr.create_path (fun p -> Brr_canvas.C2d.fill ctx p; p))
      |> LineCanvaRepr.get
      |> Brr_canvas.C2d.stroke ctx
    | `Ductus ->
      R.repr
        path
        (module DuctusCanvaRepr)
        (DuctusCanvaRepr.create_path (fun p -> Brr_canvas.C2d.fill ctx p; p))
      |> DuctusCanvaRepr.get
      |> Brr_canvas.C2d.stroke ctx


(** Draw a path and represent it as SVG *)
let to_svg
  : (module REPRESENTABLE with type t = 's) -> color:Jstr.t -> 's -> printer -> Brr.El.t
  = fun (type s) (module R:REPRESENTABLE with type t = s) ~color path -> function
    | `Fill ->

      (* In order to deal with over crossing path, I cut the path in as
         many segment as there is curve, and fill them all. Then, all of theme
         are grouped inside a single element *)
      let paths = ref [] in
      let _ = R.repr
          path
          (module FillSVGRepr)
          (FillSVGRepr.create_path
             (fun p ->
                let repr = Svg.path
                    ~at:Brr.At.[ v (Jstr.v "d") p ]
                    [] in

                paths := repr::!paths;
                Jstr.empty)) in

      Brr.El.v (Jstr.v "g")
        ~at:Brr.At.[
            v (Jstr.v "fill")  color
          ; v (Jstr.v "stroke") color]
        !paths

    | `Ductus ->
      let svg_path = R.repr
          path
          (module DuctusSVGRepr)
          (DuctusSVGRepr.create_path (fun _ -> ()))
                     |> DuctusSVGRepr.get in
      Svg.path
        ~at:Brr.At.[
            v (Jstr.v "fill")  color
          ; v (Jstr.v "stroke") color
          ; v (Jstr.v "d") svg_path ]
        []
    | `Line ->
      raise Not_found