open Table



let all_nodes tree = let root = Naive_tree.root tree in
		     eval_axis tree [root] (Descendant true)

let element_by_tag tree tagset = let dom = all_nodes tree in
			      List.filter (fun c -> QNameSet.mem (Naive_tree.tag tree c) tagset ) dom

let rec compile_single_path p =
  let open Xpath.Ast in
      match p with
	| Absolute p | Relative p -> compile_step_list (List.rev p)
      
and compile_step_list p = 
    match p with
      | [] -> Start
      | (a,(test,_),el) :: r ->
	let qtree = compile_step_list r in
	let res = Binop ( Inter,Axis (a,qtree), Tag (test) ) in
	List.fold_left (fun acc e ->
	  Binop(Inter, acc, compile_expr e)) res el  (*avant j'ai utilise une function compile_expr_list ,c'est pas genial*)

  and compile_expr  (e : Xpath.Ast.expr )  = match e with
    | Fun_call (f, [ e0 ]) when (QName.to_string f) = "not" ->
      let qtree = compile_expr e0 in
      Binop (Diff , Dom, qtree)

    | Binop (e1,op,e2) -> let qtree1 = compile_expr e1 in
			  let qtree2 = compile_expr e2 in 
			  begin
			    match op with 
			      | Or -> Binop (Union , qtree1,qtree2)
			      | And -> Binop (Inter ,qtree1,qtree2)
			      | _ -> failwith "Unknown operator"
			  end
    | Path p -> compile_path_rev p
    | _ -> failwith "Unknown expression"
      
  and compile_path_rev p = 
    match p with
      | [] -> assert false
      | [p] -> compile_single_path_rev p  
      | p::r -> List.fold_left (fun acc p -> Binop (Union , acc, compile_single_path_rev p) ) (compile_single_path_rev p) r
	
  and compile_single_path_rev p = 
    match p with
      | Absolute p | Relative p -> compile_step_list_rev (List.rev p)

  and compile_step_list_rev p = match p with
    | [] -> Dom         (*assert false*) (*on fait rien , mais comment signifer ???*)
    | (a,(test,_),el) :: r -> 
      let qtree = compile_step_list_rev r in
      let res = Binop (Inter , qtree, Tag(test)) in
      let qtree2 = List.fold_left (fun acc e ->
	Binop(Inter, acc, compile_expr e)) res el in
      let a_rev = axis_rev a in
      Axis (a_rev , qtree2)
						
      
    and axis_rev a =
      let open Xpath.Ast in
	  match a with
	      Self -> Self
	    | Attribute -> assert false
	    | Child -> Parent
	    | Descendant b -> 
	      if not b then (Ancestor false)
	      else (Ancestor true)    (* true = descendant-or-self, false = descendant *)
	    | FollowingSibling -> PrecedingSibling
	    | Parent -> Child
	    | Ancestor b -> 
	      if not b then (Descendant false) 
	      else (Descendant true)  (* true = ancestor-or-self, false = ancestor *)
	    | PrecedingSibling -> FollowingSibling
	    | Preceding -> Following
	    | Following -> Preceding
	    
	    
let compile_xpath p = match p with
  | [] -> assert false
  | [p] -> compile_single_path p
  | p::r -> List.fold_left (fun acc p -> Binop (Union , acc, compile_single_path p) ) (compile_single_path p) r

let comp_node t n1 n2 = (Naive_tree.preorder t n1) < (Naive_tree.preorder t n2)


let rec union_list t l1 l2 =
  match l1,l2 with
    | [],l2 -> l2
    | l1, [] -> l1
    | h1::ll1, h2::ll2 -> if (comp_node t h2 h1) then h2 :: (union_list t l1 ll2)
      else if (comp_node t h1 h2) then h1::(union_list t ll1 l2)
      else h1 ::(union_list t ll1 ll2)

let rec inter_list t l1 l2 =
  match l1,l2 with
    | [],l2 -> []
    | l1, [] -> []
    | h1::ll1, h2::ll2 -> if (comp_node t h1 h2) then inter_list t ll1 l2
      else if (comp_node t h2 h1) then inter_list t l1 ll2
      else h1 :: (inter_list t ll1 ll2)

let rec diff_list t l1 l2 =
  match l1,l2 with
    | [],l2 -> []
    | l1, [] -> l1
    | h1::ll1, h2::ll2 -> if (comp_node t h1 h2) then h1::(diff_list t ll1 l2)
      else if (comp_node t h2 h1)  then h2 :: (diff_list t l1 ll2)
      else diff_list t ll1 ll2


let do_debug = ref true

let debug tree q l =
  if !do_debug then begin
    Format.fprintf Format.std_formatter "Evaluation de: ";
    print_query_tree Format.std_formatter q;
    Format.fprintf Format.std_formatter "\nResultat: %i"
    (List.length l);
    Format.pp_print_flush Format.std_formatter ();
    print_node_list tree l;
    Format.fprintf Format.std_formatter "\n----------------\n";
    Format.pp_print_flush Format.std_formatter ();
  end


let rec eval_query_tree tree start q =
  let resultat = 
    match q with
      | Start ->  start
      | Dom -> all_nodes tree
      | Tag t -> element_by_tag tree t
      | Axis (a,q1) -> let ls = eval_query_tree tree start q1 in
		       eval_axis tree ls a
      | Binop (op,q1,q2)-> begin
	let ls1 = eval_query_tree tree start q1 in
	let ls2 = eval_query_tree tree start q2 in
	match op with	  
	  | Union -> union_list tree ls1 ls2	    
	  | Inter -> inter_list tree ls1 ls2
	  | Diff -> diff_list tree ls1 ls2
      end
  in
  debug tree q resultat;
  resultat