module logging
implicit none
    
    integer, parameter::logunit = 1197
    
    integer::level_threshold

    character(len=:), pointer::logfile
    !integer::logunit
    
contains

    subroutine initialize(filename, logging_threshold)
    implicit none
    
        character(*), intent(in)::filename
        integer, intent(in)::logging_threshold
        
        allocate(character(len=len_trim(filename)) :: logfile)
        logfile = filename
        level_threshold = logging_threshold
        
    end subroutine initialize
    
    subroutine shutdown()
    implicit none
    
        deallocate(logfile)
        logfile => null()
        
    end subroutine shutdown
    
    subroutine write_log(string, level)
    implicit none
    
        character(*), intent(in)::string
        integer, intent(in), optional::level
        
        integer::ierr
        
        if(present(level)) then
            if(level > level_threshold) then 
                return
            end if
        end if
        
        open(unit=logunit, file=logfile, action="write", &
             status="unknown", position="append", iostat=ierr)
        
        ! Silently move on if we failed to open the file
        if(ierr == 0) then
        
            ! GNU Extension... :(
            write(logunit, *) fdate()//" :: "//string
            call close(logunit)
            
        end if
        
    end subroutine write_log

end module logging