(define-module (org helpers)
  #:autoload (ice-9 match) (list-pictures list-files-by-ext)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-19)		; string/date
  #:export (list-pictures
	    list-files-by-ext
	    date->path 			; do not export later
	    *path-format*))

;; Customize this! (setq! *path-format* ...)
(define *path-format* "~Y/~m/")

;; use lowercase extensions!
(define picture-exts '("png" "jpg"))
(define (join-exts exts)
  (string-join exts "|"))

(define (make-ext-regex exts)
  (string-concatenate `("\\." "(" ,(join-exts exts) ")" "$")) )

(define (list-files-by-ext folder exts)
  (scandir folder
	   (lambda (x) (string-match (make-ext-regex exts)
				     (string-downcase x)))))

(define (list-pictures dir)
  (map (lambda (x) (string-concatenate `(,dir "/" ,x)))
       (list-files-by-ext dir picture-exts)))

(define (date->path date)
  "Create a path structure based on the filename.
Customize this with the variable *path-format*"
  (date->string (current-date) *path-format*))