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(ns clj-http.examples.progress-download
(:require [clj-http.client :as http]
[clojure.java.io :refer [output-stream]])
(:import (org.apache.commons.io.input CountingInputStream)))
(defn print-progress-bar
"Render a simple progress bar given the progress and total. If the total is zero
the progress will run as indeterminated."
([progress total] (print-progress-bar progress total {}))
([progress total {:keys [bar-width]
:or {bar-width 50}}]
(if (pos? total)
(let [pct (/ progress total)
render-bar (fn []
(let [bars (Math/floor (* pct bar-width))
pad (- bar-width bars)]
(str (clojure.string/join (repeat bars "="))
(clojure.string/join (repeat pad " ")))))]
(print (str "[" (render-bar) "] "
(int (* pct 100)) "% "
progress "/" total)))
(let [render-bar (fn [] (clojure.string/join (repeat bar-width "-")))]
(print (str "[" (render-bar) "] "
progress "/?"))))))
(defn insert-at [v idx val]
"Addes value into a vector at an specific index."
(-> (subvec v 0 idx)
(conj val)
(into (subvec v idx))))
(defn insert-after [v needle val]
"Finds an item into a vector and adds val just after it.
If needle is not found, the input vector will be returned."
(let [index (.indexOf v needle)]
(if (neg? index)
v
(insert-at v (inc index) val))))
(defn wrap-downloaded-bytes-counter
"Middleware that provides an CountingInputStream wrapping the stream output"
[client]
(fn [req]
(let [resp (client req)
counter (CountingInputStream. (:body resp))]
(merge resp {:body counter
:downloaded-bytes-counter counter}))))
(defn download-with-progress [url target]
(http/with-middleware
(-> http/default-middleware
(insert-after http/wrap-redirects wrap-downloaded-bytes-counter)
(conj http/wrap-lower-case-headers))
(let [request (http/get url {:as :stream})
length (Integer. (get-in request [:headers "content-length"] 0))
buffer-size (* 1024 10)]
(println)
(with-open [input (:body request)
output (output-stream target)]
(let [buffer (make-array Byte/TYPE buffer-size)
counter (:downloaded-bytes-counter request)]
(loop []
(let [size (.read input buffer)]
(when (pos? size)
(.write output buffer 0 size)
(print "\r")
(print-progress-bar (.getByteCount counter) length)
(recur))))))
(println))))
;; Example of progress bar output (sample steps)
;;
;; [=== ] 7% 2094930/26572400
;; [============================== ] 60% 16062930/26572400
;; [========================================= ] 83% 22290930/26572400
;; [==================================================] 100% 26572400/26572400
;;
;; In case the content-length is unknown, the bar will be displayed as:
;;
;; [--------------------------------------------------] 4211440/?
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