! Copyright (c) 2021 Approximatrix, LLC <support@approximatrix.com>
!
! Permission is hereby granted, free of charge, to any person obtaining a copy
! of this software and associated documentation files (the "Software"), to deal
! in the Software without restriction, including without limitation the rights
! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
! copies of the Software, and to permit persons to whom the Software is
! furnished to do so, subject to the following conditions:
!
! The above copyright notice and this permission notice shall be included in
! all copies or substantial portions of the Software.
!
! The Software shall be used for Good, not Evil.
!
! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
! SOFTWARE.

module logging
implicit none
    
    integer, parameter::LOG_DEBUG  = 8
    integer, parameter::LOG_INFO   = 6
    integer, parameter::LOG_NORMAL = 3
    
    integer, parameter::logunit = 1197
    
    integer::level_threshold

    character(len=:), pointer::logfile
    
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
    
        if(associated(logfile)) then
            deallocate(logfile)
        end if
        logfile => null()
        
    end subroutine shutdown
    
    subroutine write_log(string, level)
    implicit none
    
        character(*), intent(in)::string
        integer, intent(in), optional::level
        
        character(12)::pid_text
        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
        
            write(pid_text, '(I8)') getpid()
        
            ! GNU Extension... :(
            write(logunit, *) fdate()//" ("//trim(adjustl(pid_text))//") :: "//string
            close(logunit)
            
        end if
        
    end subroutine write_log

end module logging