;;
;; logging.scm
;;
;; Universal logging module.
;;
;; ISC License
;;
;; Copyright 2023 Brmlab, z.s.
;; Dominik Pantůček <dominik.pantucek@trustica.cz>
;;
;; Permission to use, copy, modify, and/or distribute this software
;; for any purpose with or without fee is hereby granted, provided
;; that the above copyright notice and this permission notice appear
;; in all copies.
;; 
;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
;;

(declare (unit logging))

(module
 logging
 (
  *log-file*
  
  log-debug
  log-info
  log-warning
  log-error
  )

 (import scheme
	 (chicken base)
	 (chicken format)
	 (chicken time posix)
	 util-string)

 ;; No logging by default
 (define *log-file* (make-parameter #f))

 ;; Opened log file
 (define log-file (make-parameter #f))

 ;; Ensures leading zeroes
 (define (format-number2 n)
   (format "~A~A"
	   (if (< n 10) "0" "")
	   n))

 ;; Current time for logging
 (define (format-current-time)
   (let ((ltime (seconds->local-time)))
     (format "~A-~A-~A ~A:~A:~A"
	     (+ 1900 (vector-ref ltime 5))
	     (format-number2 (add1 (vector-ref ltime 4)))
	     (format-number2 (vector-ref ltime 3))
	     (format-number2 (vector-ref ltime 2))
	     (format-number2 (vector-ref ltime 1))
	     (format-number2 (vector-ref ltime 0)))))

 ;; Handles the actual logging
 (define ((log-line level) fmt . args)
   (when (or (not (*log-file*))
	     (not (log-file)))
     (when (not (log-file))
       (log-file (open-output-file (*log-file*) #:append)))
     (display (format "~A [~A] ~A"
		      (format-current-time)
		      (string-upcase (symbol->string level))
		      (apply format fmt args))
	      (log-file))
     (flush-output (log-file))))

 ;; Specific log procedures
 (define log-debug (log-line 'debug))
 (define log-info (log-line 'info))
 (define log-warning (log-line 'warning))
 (define log-error (log-line 'error))

 )