module XParsec

#if INTERACTIVE
  #r "System.Xml.Linq.dll"
#endif

  open System
  open System.Xml.Linq
  open System.Collections.Generic

  type X  = XElement
  type XS = XElement IEnumerator

  type 'a Reply      = S of 'a | F
  type 'a Reply with
    static member inline FromBool  b = if b then S () else F
    static member inline Negate    r = match r with F -> S () | S _ -> F
    static member inline Map    f  r = match r with F -> F    | S x -> S <| f x
    static member inline Put    x  r = match r with F -> F    | S _ -> S x
    static member inline Choose f  r = match r with F -> F    | S x -> match f x with Some v -> S v | None -> F

  type 'a Parser = XS -> 'a Reply

  let inline pzero     (_ : XS) = S <| Unchecked.defaultof<_>
  let inline preturn x (_ : XS) = S x

  module Operators =

    let inline (-!-)  a b = (a : string).Contains b |> not
    let inline (-?-)  a b = (a : string).Contains b
    let inline (~~) s = s |> String.IsNullOrWhiteSpace
    let inline (!>) x = ( ^a : (static member op_Implicit : ^b -> ^a) x )

    let inline (@)  (x : XElement) n   = let a = x.Attribute(!> n) in if a <> null then a.Value else String.Empty
    let inline (@<) (x : XElement) n v = x.SetAttributeValue(!> n, v)
    let inline (@~) x a   = ~~(x @ a)
    let inline (@?) x a v =   (x @ a) -?- v
    let inline (@!) x a v =   (x @ a) -!- v

  module Primitives =

    open Operators

    let inline (!)    (p : _ Parser)   e = e |> p |> Reply<_>.Negate
    let inline (|?>)  (p : _ Parser) f e = e |> p |> Reply<_>.Choose f
    let inline (|>>)  (p : _ Parser) f e = e |> p |> Reply<_>.Map f
    let inline (>>.)  (p : _ Parser) (q : _ Parser) e = match p e with F -> F | S _ -> q e
    let inline (.>>)  (p : _ Parser) (q : _ Parser) e = match p e with F -> F | S p -> q e |> Reply<_>.Put p
    let inline (.>>.) (p : _ Parser) (q : _ Parser) e = match p e with F -> F | S p -> q e |> Reply<_>.Map (fun q -> (p,q))
    let inline (.<<.) (p : _ Parser) (q : _ Parser) e = match p e with F -> F | S p -> q e |> Reply<_>.Map (fun q -> (q,p))

    let inline current (e : XS) = e.Current |> S
    let inline one     (e : XS) = e.MoveNext() |> ignore; e |> current

    let inline (!@)  a   (e : XS) = let x = e.Current.Attribute(!> a) in if x <> null then S x.Value else F
    let inline (!@+) a   (e : XS) = (e.Current @~ a |> not) |> Reply<_>.FromBool
    let inline (@~?) a v (e : XS) = (e.Current @? a <| v)   |> Reply<_>.FromBool
    let inline (@~!) a v (e : XS) = (e.Current @! a <| v)   |> Reply<_>.FromBool

  module Test =

    open Operators
    open Primitives

(*
<block bbox="63.2999 584.626 250.351 651.456">
  <line bbox="63.2999 584.626 246.826 595.656">
    <span bbox="63.2999 584.626 152.105 595.656" font="TimesNewRoman,Bold" size="9.96" s="Sahra Wagenknecht " />
    <span bbox="152.16 584.626 246.826 595.656" font="TimesNewRoman" size="9.96" s="(DIE LINKE)  . . . . . . ." />
  </line>
  <line bbox="63.2999 600.362 250.351 613.34">
    <span bbox="63.2999 601.546 139.327 612.576" font="TimesNewRoman,Bold" size="9.96" s="Siegfried Kauder " />
    <span bbox="139.38 601.546 247.762 612.576" font="TimesNewRoman" size="9.96" s="(Villingen-Schwenningen) " />
    <span bbox="247.861 600.362 250.351 613.34" font="Symbol" size="9.96" s=" " />
  </line>
  <line bbox="74.6404 612.526 246.911 623.556">
    <span bbox="74.6404 612.526 246.911 623.556" font="TimesNewRoman" size="9.96" s="(CDU/CSU) . . . . . . . . . . . . . . . . . . . . . . . ." />
  </line>
  <line bbox="63.2999 628.202 191.909 641.18">
    <span bbox="63.2999 629.386 126.374 640.416" font="TimesNewRoman,Bold" size="9.96" s="Jürgen Trittin " />
    <span bbox="126.419 629.386 189.433 640.416" font="TimesNewRoman" size="9.96" s="(BšNDNIS 90/" />
    <span bbox="189.419 628.202 191.909 641.18" font="Symbol" size="9.96" s=" " />
  </line>
  <line bbox="74.6394 640.426 246.813 651.456">
    <span bbox="74.6394 640.426 246.813 651.456" font="TimesNewRoman" size="9.96" s="DIE GRÜNEN)  . . . . . . . . . . . . . . . . . . . . ." />
  </line>
</block>
*)

    let x = "<span bbox=\"63.2999 584.626 152.105 595.656\" font=\"TimesNewRoman,Bold\" size=\"9.96\" s=\"Sahra Wagenknecht \" />"   |> XElement.Parse
    let y = "<span bbox=\"152.16 584.626 246.826 595.656\" font=\"TimesNewRoman\" size=\"9.96\" s=\"(DIE LINKE)  . . . . . . .\" />" |> XElement.Parse

    let o x  = ([|x|] |> Array.toSeq).GetEnumerator()
    let e xs = (xs |> List.toSeq).GetEnumerator()

    let inline sbbox s    = (s:string).Split [| ' ' |] |> Seq.map float |> Seq.toList
    let inline l x   = x |> sbbox |> List.head

//  1 = < font=?'Bold' bbox=F'l ..' s      >                       ;      < ~s >*
//  2 = < font=!'Bold' bbox=F'l ..' s=?'(' > | [ 1.l < 2.l ]       ;      < ~s >*
//  3 = < font=!'Bold' bbox=F'l ..' s=?')' > | [ 1.l < 3.l ]    

    let ss : _ Parser = one .>>. ("font" @~? "Bold" >>. !@+ "s"                         >>. !@ "bbox" |>> l)
    let so : _ Parser = one .>>. ("font" @~! "Bold" >>.     "s" @~? "("                 >>. !@ "bbox" |>> l)
    let sc : _ Parser = one .>>. ("font" @~! "Bold" >>.                     "s" @~? ")" >>. !@ "bbox" |>> l)
//  let ss : _ Parser = one .>>. ("font" @~? "Bold" >>. !@+ "s"                         >>. !@ "bbox" |>> l)
    let oc : _ Parser = one .>>. ("font" @~! "Bold" >>.     "s" @~? "(" >>. "s" @~? ")" >>. !@ "bbox" |>> l)

    let inline (|?>) (p : _ Parser) f e = e |> p |> Reply<_>.Choose f

    let si : _ Parser = ss .>>. oc |?> fun ((c1,l1),(c2,l2)) -> if l1 < l2 then Some (c1,c2) else None

  open Operators
  open Primitives
  open Test