#lang racket/base

(require racket/sequence
         racket/generator
         racket/string
         racket/path
         file/glob)

(provide make-file-walker
         )


(define (make-file-walker base-path glob-pattern callback)
  (let* ((gen (sequence->generator
               (sequence-filter
                (λ (p)
                  (let ((basename (file-name-from-path p)))
                    (glob-match? glob-pattern basename)))
                (in-directory base-path))))
         (str-base-path* (format "~a" (normalize-path base-path)))
         (delim (if (eq? (system-path-convention-type) 'windows) "\\" "/"))
         (str-base-path (if (string-suffix? str-base-path* delim)
                            str-base-path*
                            (string-append str-base-path* delim)))
         (base-path-len (string-length str-base-path))
         (result #f)
         )
    (λ ()
      (let ((path (gen)))
        (if (void? path)
            result
            (let* ((str-path (path->string path))
                   (ext* (path-get-extension path))
                   (ext (substring
                         (if (eq? ext* #f)
                             "."
                             (bytes->string/utf-8 ext*)) 1))
                   (path-part (substring str-path base-path-len))
                   (str-n-path (string-replace path-part "\\" "/"))
                   (info (if (directory-exists? path)
                             (list 'dir str-n-path ext)
                             (list 'file str-n-path ext
                                   (file-size path)
                                   (file-or-directory-modify-seconds path))
                             ))
                   )
              (set! result (callback (eq? (car info) 'dir)
                                     base-path
                                     path
                                     path-part ext info))
              'more))))
    )
  )