(define CURLOPT-POSTFIELDSIZE 60)
(define CURLOPT-POSTFIELDS 10015)
(define CURLOPT-URL 10002)
(define CURLOPT-HTTPHEADER 10023)
(define CURLOPT-WRITEDATA 10001)
(define CURLOPT-WRITEFUNCTION 20011)
(define CURLOPT-CUSTOMREQUEST 10036)
(define CURLOPT-COOKIE 10022)
(define CURLOPT-COOKIEFILE 10031)
(define CURLOPT-COOKIEJAR 10082)
(define CURLINFO-RESPONSE-CODE 2097154)
(define CURLHE-BADINDEX 1)
(define CURLHE-HEADER 1)
(define CURLINFO-COOKIELIST 4194332)
(define randomized? #f)

(define-c-library libc '("stdlib.h" "stdio.h" "time.h") #f '())
(define-c-procedure c-fopen libc 'fopen 'pointer '(pointer pointer))
(define-c-procedure c-fclose libc 'fclose 'int '(pointer))
(define-c-procedure c-perror libc 'perror 'void '(pointer))

(define-c-library libcurl '("curl/curl.h") "curl" '((additional-versions ("4"))))
(define-c-procedure curl-easy-init libcurl 'curl_easy_init 'pointer '())
(define-c-procedure curl-easy-cleanup libcurl 'curl_easy_cleanup 'void '(pointer))
(define-c-procedure curl-easy-setopt-pointer libcurl 'curl_easy_setopt 'int '(pointer int pointer))
(define-c-procedure curl-easy-setopt-int libcurl 'curl_easy_setopt 'int '(pointer int int))
;(define-c-procedure curl-slist-append libcurl 'curl_slist_append 'pointer '(pointer pointer))
(define-c-procedure curl-easy-strerror libcurl 'curl_easy_strerror 'pointer '(int))
(define-c-procedure curl-easy-perform libcurl 'curl_easy_perform 'int '(pointer))
;(define-c-procedure curl-easy-getinfo libcurl 'curl_easy_getinfo 'int '(pointer int pointer))
;(define-c-procedure curl-easy-nextheader libcurl 'curl_easy_nextheader 'pointer '(pointer int int pointer))


(define (download-file url . download-path)
  (when (not (string? url))
    (error "download-file error: url must be string" url))
  (when (and (not (null? download-path))
             (not (string? (car download-path))))
    (error "download-file error: download-path must be string"
           (car download-path)))
  (let* ((handle (curl-easy-init))
         (to-path (if (null? download-path) "." (car download-path)))
         (to-path-cbv (string->c-bytevector to-path))
         (file-mode-cbv (string->c-bytevector "w"))
         (to-file-cbv (c-fopen to-path-cbv file-mode-cbv))
         (url-cbv (string->c-bytevector url)))
    (when (c-bytevector-null? to-file-cbv)
      (let* ((error-message "download-file error")
             (error-pointer (string->c-bytevector error-message)))
        (c-perror error-pointer)
        (c-bytevector-free file-mode-cbv to-path-cbv o-file-cbv url-cbv error-pointer)
        (error error-message)))
    (curl-easy-setopt-pointer handle CURLOPT-WRITEDATA to-file-cbv)
    (curl-easy-setopt-pointer handle CURLOPT-URL url-cbv)
    (let ((result (curl-easy-perform handle)))
      (when (not (= result 0))
        (let* ((error-cbv (curl-easy-strerror result))
               (error-string (c-bytevector->string error-cbv)))
          (c-bytevector-free error-cbv)
          (error error-string url)))
      (curl-easy-cleanup handle)
      ;(c-bytevector-free file-mode-cbv to-path-cbv to-file-cbv url-cbv)
      )))