;;
;; brmsaptool.scm
;;
;; 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.
;;
(import (chicken condition)
	(chicken file)
	(chicken pathname)
	(chicken file posix)
	(chicken io)
	(chicken string)

	(chicken process-context))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Static default configuration

(define *members-directory* (make-parameter "members"))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Testing

(define-syntax with-handler
  (syntax-rules ()
    ((_ handler body ...)
     (call-with-current-continuation
      (lambda (k)
	(with-exception-handler
	 (lambda (x) (k (handler x)))
	 (lambda () body ...)))))))

(define-syntax unit-test
  (syntax-rules ()
    ((_ name condition)
     (if (with-handler (lambda (x) #f)
		       (lambda () condition))
	 (display ".")
	 (error 'unit-test name)))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Dictionary

;; Returns an empty dictionary represented as empty list.
(define (make-dict)
  '())

;; Checks whether given dictionary d contains the key k.
(define (dict-has-key? d k)
  (if (assq k d) #t #f))

;; Retrieves the value for key k from dictionary d. If third argument
;; is provided it is used as default value in case the key does not
;; exist. If only two arguments are given and the key does not exist,
;; raises an error.
(define (dict-ref d k . r)
  (let ((p (assq k d)))
    (if p
	(cdr p)
	(if (null? r)
	    (error 'dict-ref "Key does not exist" k)
	    (car r)))))

;; Returns a new dictionary based on d with key k removed. If it
;; doesn't contain the key, an error is raised.
(define (dict-remove d k)
  (let loop ((s d)
	     (r '())
	     (e #t))
    (if (null? s)
	(if e
	    (error 'dict-remove "Key does not exist" k)
	    r)
	(if (eq? (caar s) k)
	    (loop (cdr s) r #f)
	    (loop (cdr s) (cons (car s) r) e)))))

;; Adds a new value v under the key k to the dictionary d possibly
;; overwriting any value which has been stored under the key
;; before. Returns the updated dictionary.
(define (dict-set d k v)
  (let ((dr (let loop ((s d)
		       (r '()))
	      (if (null? s)
		  r
		  (if (eq? (caar s) k)
		      (loop (cdr s) r)
		      (loop (cdr s) (cons (car s) r)))))))
    (cons (cons k v)
	  dr)))

;; Returns the list of keys stored in given dictionary.
(define (dict-keys d)
  (map car d))

(define (dict-tests!)
  (display "[test] dict ")
  (unit-test 'make-dict (null? (make-dict)))
  (unit-test 'dict-ref-nonexistent (with-handler (lambda (x) #t) (dict-ref (make-dict) 'nonexistent) #f))
  (unit-test 'dict-ref-default (dict-ref (make-dict) 'nonexistent #t))
  (unit-test 'dict-set-nonexistent (equal? (dict-set (make-dict) 'nonexistent 1) '((nonexistent . 1))))
  (unit-test 'dict-set-existent (equal? (dict-set (dict-set (make-dict) 'existent 1) 'existent 2) '((existent . 2))))
  (unit-test 'dict-remove-nonexistent (with-handler (lambda (x) #t) (dict-remove (make-dict) 'nonexistent) #f))
  (unit-test 'dict-remove-existing (null? (dict-remove (dict-set (make-dict) 'existing 1) 'existing)))
  (unit-test 'dict-keys (equal? (dict-keys (dict-set (make-dict) 'existing 1)) '(existing)))
  (print " ok."))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Months support

;; Returns true if this is a valid month representation - a list with
;; two integer elements within the allowed range.
(define (month-valid? m)
  (and (list? m)
       (car m)
       (cdr m)
       (cadr m)
       (nil? (cddr m))
       (integer? (car m))
       (integer? (cadr m))
       (>= (car m 1000))
       (<= (car m 9999))
       (>= (cadr m 1))
       (<= (cadr m 12))))

;; Converts string in a format YYYY-MM to valid month. Returns #f if
;; the conversion fails.
(define (string->month s)
  (let ((l (string-split s "-")))
    (if (or (not l)
	    (nil? l)
	    (nil? (cdr l))
	    (not (nil? (cddr l))))
	#f
	(let ((y (string->number (car l)))
	      (m (string->number (cadr l))))
	  (if (and y m)
	      (let ((M (list y m)))
		(if (valid-month? M)
		    M
		    #f))
	      #f)))))

;; Formats (valid) month as YYYY-MM string
(define (month->string M)
  (if (month-valid? M)
      (let ((y (car s))
	    (m (cadr s)))
	(sprintf "~A-~A~A"
		 y
		 (if (< m 10) " " "")
		 m))
      (error 'string->month "Invalid month" M)))

;; Returns true if both arguments are a valid month and are equal
(define (month=? m n)
  (and (valid-month? m)
       (valid-month? n)
       (equal? m n)))

;; Returns true if the first argument is a month in the past of the
;; second argument month
(define (month<? m n)
  (and (month-valid? m)
       (month-valid? n)
       (or (< (car m) (car n))
	   (and (= (car m) (car n))
		(< (cadr m) (cadr n))))))

(define (month-diff m n)
  ; Exclusive
  1)

(define (month-tests!)
  (display "[test] month ")
  (unit-test 'month-valid? (month-valid? '(2023 5)))
  (unit-test 'month-valid?-bad-year (not (month-valid? '(999 8))))
  (unit-test 'month-valid?-bad-month (not (month-valid? '(2023 -5))))
  (unit-test 'string->month (equal? (string->month "2023-01" '(2023 1))))
  (unit-test 'string->month-bad-month (not (string->month "2023-13")))
  (unit-test 'string->month-nonumber-year (not (string->month "YYYY-01")))
  (unit-test 'string->month-nonumber-month (not (string->month "2023-MMM")))
  (unit-test 'month->string (equal? (month->string '(2023 1)) "2023-01"))
  (unit-test 'month->string-bad-year (with-handler (lambda (x) #t) (month->string '(999 12)) #f))
  (unit-test 'month->string-bad-month (with-handler (lambda (x) #t) (month->string '(2023 13)) #f))
  (unit-test 'month<? (month<? '(2023 5) '(2023 6)))
  (unit-test 'month<?-cross-year (month<? '(2022 12) '(2023 1)))
  (unit-test 'month<?-equal (not (month<? '(2023 1) '(2023 1))))
  (unit-test 'month<?-greater (not (month<? '(2023 1) '(2023 2))))
  (unit-test 'month-equal? (month-equal? '(2023 4) '(2023 4)))
  (unit-test 'month-equal? (not (month-equal? '(2023 4) '(2023 5))))
  ;; Difference - exclusive end
  (print " ok."))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Members database


;; Loads all symlinks from (*members-directory*) returning a list of
;; pairs (name . destination)
(define (load-members-raw-index)
  (let loop ((fns (directory (*members-directory*)))
	     (rs '()))
    (if (null? fns)
	rs
	(let* ((fn (car fns))
	       (ffn (make-pathname (*members-directory*) fn))
	       (sl (if (symbolic-link? ffn) (read-symbolic-link ffn) #f)))
	  (loop (cdr fns)
		(if sl
		    (cons (cons fn sl) rs)
		    rs))))))

;; Converts the raw members index to a list of dictionaries with keys
;; 'id, 'name and 'file. File names are without directory element.
(define (expand-members-raw-index ri)
  (let loop ((ri ri)
	     (ds '()))
    (if (null? ri)
	ds
	(let* ((mp (car ri))
	       (lnk (car mp))
	       (dfn (cdr mp))
	       (lnkn (string->number lnk))
	       (dfnn (string->number dfn))
	       (id (or dfnn lnkn))
	       (name (if lnkn dfn lnk)))
	  (loop (cdr ri)
		(cons (list (cons 'id id)
			    (cons 'name name)
			    (cons 'file dfn))
		      ds))))))

;; Parses given key-value line. Key is up to first space, value is the
;; rest of the line. If the line doesn't contain anything, returns #f.
(define (parse-member-line l)
  ;;(print 'pm)
  ;;(print l)
  (let ((sp (string-split l " ")))
    (and sp
	 (not (null? sp))
	 (list (string->symbol (car sp))
	       (string-intersperse (cdr sp))))))
	   
;; TODO: student and suspend special handling - should create list of
;; (start date) (stop date) which will be later sorted by date and
;; computation performed
(define (parse-member-lines ls)
  (let loop ((ls ls)
	     (r (make-dict)))
    ;;(print '---)
    ;;(print r)
    (if (null? ls)
	r
	(let ((p (parse-member-line (car ls))))
	  ;;(print p)
	  (loop (cdr ls)
		(if p
		    (apply dict-set r p)
		    r))))))

;; Loads lines from given file in (*members-directory*) and parses
;; them.
(define (load-member-file fn)
  (let* ((ffn (make-pathname (*members-directory*) fn))
	 (f (open-input-file ffn))
	 (ls (read-lines f)))
    (parse-member-lines ls)))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Run everything

;; Print banner
(print "brmsaptool 0.1 (c) 2023 Brmlab, z.s.")
(newline)

;; Run tests
(print "Running self-tests:")
(dict-tests!)
(month-tests!)
(print "All self-tests ok!")
(newline)

;; Perform requested action
;(print (expand-members-raw-index (load-members-raw-index)))

(print (load-member-file "joe"))