#lang scheme/base

(require (only-in (planet synx/util:1/pipe-between) pipe-between)
         (only-in (planet synx/util:1/gui-system) copy-file)
         (prefix-in temp: (planet synx/util:1/temp)))

(define (incremental dump base name)
  (define base-file (build-path base name))
  (if (not (file-exists? base-file))
      (begin
        (dump base-file)
        (copy-file base-file name))
      (temp:with-file
       (λ (holder)
         (define delta (string-append name ".xdelta"))
         (dump holder)
         (pipe-between
          ("xdelta" "delta" (path->string base-file) (path->string holder) delta))
         (when (> (file-size delta) (file-size base-file))
           (delete-file delta)
           (dump base-file)
           (copy-file base-file name))))))
(provide incremental)