(*Declaring area*)

type id = ID of int
type email = Email of string
type password = Password of string
type active = Active of bool

module User = struct
  type t = id * email * password * active
  let compare = fun (id1 , _, _, _) -> fun (id2, _, _, _) -> compare id1 id2
end

module UserDB = Set.Make(User);;

let db = UserDB.empty

let addUser email password db =
  let checkEmail email = String.contains email '@' in
  let checkPassword password = String.length password >= 6 in
  match (checkEmail email, checkPassword password) with
  | (true, true) -> UserDB.add (ID (List.length (UserDB.elements db)), Email email, Password password, Active true) db
  | (false, false) -> print_string "Invalid email and password\n"; db
  | (false, _) -> print_string "Invalid email\n"; db
  | (_, false) -> print_string "Invalid password\n"; db

let login thisEmail thisPassword db =
  match UserDB.find_first_opt(fun (_, thatEmail, thatPassword, _) -> Password thisPassword = thatPassword && Email thisEmail = thatEmail) db with
  | Some (_, _, _, active) as user -> if active = Active true
                                      then (print_string "The user was found\n"; Some user)
                                      else (print_string "The users account is deactivated\n"; None)
  | None -> print_string "Incorrect username or password\n"; None;;

let deactivateAccount email db = UserDB.fold(fun ((thatId, thatEmail, thatPassword, _) as user) db -> if Email email = thatEmail
                                                                                                      then UserDB.add (thatId, thatEmail, thatPassword, Active false) db
                                                                                                      else UserDB.add user db) db UserDB.empty

(*Usage area*)

let db = addUser "email1@lsd.com" "upt123" db
let db = addUser "email2@lsd.com" "upt123" db
let db = addUser "email2@lsd.com" "upt123" db
let db = addUser "email.com" "upt123" db;;
let db = addUser "email@lsd.com" "upt" db;;
let db = addUser "emaillsd.com" "upt" db;;

login "test" "parola" db;;
login "email1@lsd.com" "parola" db;;
login "emai@test.ro" "upt2" db;;
login "email1@lsd.com" "upt2" db;;
login "email1@lsd.com" "upt123" db;;
login "email2@lsd.com" "upt123" db;;

let db = deactivateAccount "email2@lsd.com" db;;

login "email2@lsd.com" "upt123" db;;
login "email1@lsd.com" "upt123" db;;