(*
 * implementazione del comando SELECT
 *)

open Mathql;;
open Func;;
open Utility;;

(*
 * valutazione di una stringa
 *)
let stringeval s l =
 match s with
    MQCons s ->
     s
 |  MQFunc (f, rvar) ->
     (
      match f with
         MQName -> func_name (List.assoc rvar l)
     )
 |  MQRVar rvar ->
     List.assoc rvar l
 |  MQSVar svar ->
     List.assoc svar l
 |  MQMConclusion ->
     "MainConclusion"
 |  MQConclusion ->
     "InConclusion"
;;

(*
 *
 *)
let rec is_good l abool =
 match abool with
    MQAnd (b1, b2) ->
     (is_good l b1) && (is_good l b2)
 |  MQOr (b1, b2) ->
     (is_good l b1) || (is_good l b2)
 |  MQNot b1 ->
     not (is_good l b1)
 |  MQTrue ->
     true
 |  MQFalse ->
     false
 |  MQIs (s1, s2) ->
     (stringeval s1 l) = (stringeval s2 l)
;;

(*
 *
 *)
let rec replace avar newval l =
 match l with
    MQAnd (b1, b2) -> MQAnd (replace avar newval b1, replace avar newval b2)
 |  MQOr (b1, b2)  -> MQOr  (replace avar newval b1, replace avar newval b2)
 |  MQNot b1       -> MQNot (replace avar newval b1)
 |  MQIs (s1, s2)  ->
     let ns1 = (
      match s1 with
         MQRVar v when v = avar      -> MQRVar newval
      |  MQFunc (f, v) when v = avar -> MQFunc (f, newval)
      |  _                           -> s1
     )
     and ns2 = (
      match s2 with 
         MQRVar v when v = avar      -> MQRVar newval
      |  MQFunc (f, v) when v = avar -> MQFunc (f, newval)
      |  _                           -> s2
     )
     in
      MQIs (ns1, ns2)
 |  _              -> l (* i casi non compresi sono MQTrue e MQFalse *)
;;

let rec print_booltree b =
 match b with
    MQAnd (b1, b2) ->
     let i = print_booltree b1 in
      let j = print_string " AND " in
       print_booltree b2
 |  MQOr (b1, b2) ->
     let i = print_booltree b1 in
      let j = print_string " OR " in
       print_booltree b2
 |  MQNot b1 ->
     let j = print_string " NOT " in
      print_booltree b1
 |  MQTrue ->
     print_string " TRUE "
 |  MQFalse ->
     print_string " FALSE "
 |  MQIs (s1, s2) ->
     let s1v = match s1 with
        MQCons s ->
         "'" ^ s ^ "'"
     |  MQFunc (f, rvar) ->
        (
          match f with
           MQName -> "NAME " ^ rvar
        )
     |  MQRVar rvar ->
         rvar
     |  MQSVar svar ->
         svar
     |  MQMConclusion ->
         "MainConclusion"
     |  MQConclusion ->
         "InConclusion"
     and s2v = match s2 with
        MQCons s ->
         s
     |  MQFunc (f, rvar) ->
        (
          match f with
           MQName -> "NAME " ^ rvar 
        )
     |  MQRVar rvar ->
         rvar
     |  MQSVar svar ->
         svar 
     |  MQMConclusion ->
         "MainConclusion"
     |  MQConclusion ->
         "InConclusion"
     in
      print_string (s1v ^ " = " ^ s2v)
;;

(*
 * implementazione del comando SELECT
 *)
let select_ex avar alist abool =
 let wrt = replace avar "retVal" abool in
 (*let j = print_booltree wrt in*)
  [List.hd alist]
  @
  List.find_all
   (fun l -> is_good (List.combine (List.hd alist) l) wrt)
   (List.tl alist)
;;