program main
   use iso_fortran_env
   use, intrinsic :: iso_c_binding
   use db
   implicit none

   type(db_type) :: db
   character(len=128):: db_path
   character(len=24):: username
   real(kind=c_double) :: x_pos
   real(kind=c_double) :: y_pos
   integer :: command, rc
   logical :: exist

   inquire (file="debug.log", exist=exist)
   if (exist) then
      open (12, file="debug.log", status="old", position="append", action="write")
   else
      open (12, file="debug.log", status="new", action="write")
   end if

   call getarg(1, db_path)

   inquire (file=db_path(:Len_Trim(db_path)), exist=exist)
   if (.not. exist) then
      stop 1
   end if

  rc = db_open(db, db_path(:Len_Trim(db_path)))
  ! do while not logged out
  server_loop: do

    ! read message from stdin
    read(input_unit, "(i3, 1x, a24, 1x, f8.2, 1x, f8.2)") command, username, x_pos, y_pos

    if (command .eq. 0) then     ! get all logged in users and return their positions to client
      rc = db_count_logged_in_users(db)
      rc = db_get_logged_in_users(db)
    else if (command .eq. 1) then
      rc = db_login_user(db, username)
      rc = db_count_logged_in_users(db)
      rc = db_get_logged_in_users(db)
    else if (command .eq. 3) then ! update new pos to database
      rc = db_move_user(db, username, x_pos, y_pos)
      rc = db_count_logged_in_users(db)
      rc = db_get_logged_in_users(db)
    else ! (2)  if logout update logged_in to database
      rc = db_logout_user(db, username)
      exit server_loop
    end if
  end do server_loop

  rc = db_close(db)
  close(12)

end program main