open Table

let compteur = ref 0

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

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

let mk_node q = {desc = q; id = -1; hash = -1}

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
      | [] -> mk_node Start
      | (a,(test,kind),el) :: r ->
	let qtree = compile_step_list r in
	let res = mk_node ( Binop ( Inter,mk_node( Axis (a,qtree)),mk_node (Tag (test,kind) )) ) in
	List.fold_left (fun acc e ->
	  mk_node (Binop(Inter, acc, compile_expr e))) res el  

  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
      mk_node (Binop (Diff , mk_node (Dom), qtree))

    | Binop (e1,op,e2) -> let qtree1 = compile_expr e1 in
			  let qtree2 = compile_expr e2 in 
			  begin
			    match op with 
			      | Or -> mk_node (Binop (Union , qtree1,qtree2))
			      | And -> mk_node (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 -> mk_node (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 p 

  and compile_step_list_rev p = match p with
    | [] -> mk_node Dom        
    | (a,(test,kind),el) :: r -> 
      let qtree = compile_step_list_rev r in
      let res = mk_node (Binop (Inter , qtree,mk_node (Tag(test,kind)))) in
      let qtree2 = List.fold_left (fun acc e ->
	mk_node (Binop(Inter, acc, compile_expr e))) res el in
      let a_rev = axis_rev a in
      mk_node (Axis (a_rev , qtree2))
						
      
    and axis_rev a =
      let open Xpath.Ast in
	  match a with
	      Self -> Self
	    | Attribute -> Parent
	    | 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 -> mk_node (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 false

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\n"
    (List.length l);
    Format.pp_print_flush Format.std_formatter ();
    print_node_list tree l;
    (*List.iter
      (fun n -> Format.fprintf Format.std_formatter "%i, " (Naive_tree.preorder tree n)) l;*)
    Format.fprintf Format.std_formatter "\n----------------\n";
    Format.pp_print_flush Format.std_formatter ();
  end

let table_query_tree = Hashtbl.create 97 

  
let rec eval_query_tree tree start q =
  let resultat = 
    begin
      try
	Hashtbl.find table_query_tree q
      with Not_found ->	
	let res =
	match q.desc with
	  | Start -> start
	  | Dom ->  all_nodes tree 	    
	  | Tag (t,k) -> element_by_tag tree t k 		     
	  | 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
	let res = List.sort (Table.compare_node tree) res in
	Hashtbl.add table_query_tree q res;
	compteur := !compteur + (List.length res);
	res
    end
  in
  debug tree q resultat;
  resultat