a2

(* Note: You may introduce new code anywhere in this file. *)
open Yojson.Basic.Util
exception UnknownRoom of string
exception UnknownExit of string

(* TODO: replace [unit] with a type of your own design. *)
type exit = {
  name: string;
  room_id: string
}
type room = {
  id: string;
  description: string;
  exits: exit list;
  }

type t = {
  rooms: Yojson.Basic.t;
  start_room: string
  }


(*[from_json j] is the adventure that j represents. Requires: j is a valid JSON
adventure representation.*)
let from_json json =
  let rooms = json |> member "rooms" in
  let start_room = json |> member "start room" |> to_string in
  {
    rooms = rooms;
    start_room = start_room;
  }

(*[start_room a] is the identifier of the starting room in adventure a.
*)
  let start_room adv = adv.start_room


(*[room_ids a] is a set-like list of all of the room identifiers in adventure a.
*)
let rec room_ids adv =
  let new_lst = to_list adv.rooms in
  let room_lst = [] in
  let rec roomify new_list =
  match new_lst with
    |[] -> []
    |[h] -> (h|>member "id" |> to_string )::room_lst
    |h::t -> (h|>member "id" |> to_string )::(roomify t)
  in
  let lst = roomify new_lst in
  List.sort_uniq compare lst

(*[description a r] is the description of room r in adventure a.
  Raises UnknownRoom r if r is not a room identifier in a.
*)
let description adv room =
  let new_lst = to_list adv.rooms in
  let rec search_describe new_list =
  match new_lst with
  |[] -> raise (UnknownRoom room)
  |h::t -> if (h|>member "id" |> to_string)=room
    then (h|>member "description" |> to_string)
    else search_describe t
  in
  search_describe new_lst

(*[exits a r] is a set-like list of all exit names from room r in adventure a.
Raises UnknownRoom r if r is not a room identifier in a.
*)
let exits adv room =
let new_lst = to_list adv.rooms in
let rec find_exits new_list =
match new_lst with
|[] -> raise (UnknownRoom room)
|h::t -> if (h|>member "id" |> to_string)=room
  then let exits = (h|>member "exits") in
  (exits|>member "name"|> to_string)
  else find_exits t
in
find_exits new_lst

(*[next_room a r e] is the room to which e exits from room r in adventure a.
Raises UnknownRoom r if r is not a room identifier in a.
Raises UnknownExit e if e is not an exit from room r in a.
*)
let next_room adv room ex =
let new_lst = to_list adv.rooms in
let rec find_room new_list =
match new_list with
|[] -> raise (UnknownRoom room)
|h::t -> (if (h|>member "id" |> to_string)=room
  then (h|>member "room id")
  else (find_room t))
in
let room = find_room new_lst in
let exit_lst = (room|> member "exits"|>to_list) in
let rec find_exit exits =
match exits with
  |[] -> raise (UnknownExit ex)
  |h::t -> if (h|>member "name"|>to_string = ex)
    then (h|>member "room id"|>to_string)
    else (find_exit t)
in
(find_exit exit_lst);


  (*[next_rooms a r] is a set-like list of all rooms to which there is an exit from r in
  adventure a. Raises UnknownRoom r if r is not a room identifier in a.*)
let next_rooms adv room =