Clojure web scraper: Scrape Nasa Apod and download the image

core.clj

;;Scrape Nasa Apod webpage and download the image.
;; This is a quick project to familiarize myself with Clojure and Enlive
(ns apod-scraper.core
  (:require [net.cgrand.enlive-html :as html])
  (:require [clojure.string :as str])
  (:gen-class))

(def apod-base-url "https://apod.nasa.gov/apod/")

(def apod-url (apply str [apod-base-url "astropix.html"]))

(def apod-content
  "Get website content from Nasa Astronomy image of the day.
  Returns: list of html content as hash-maps"
  (html/html-resource (java.net.URL. apod-url)))

;; Example hash-mapped Image Element from Nasa Site:
;; {:tag :img, :attrs {:src image/2301/KembleCascade_Lease_960.jpg, 
;;                     :alt The featured image shows a line of bright stars..., 
;;                     :style max-width:100%}, 
;;  :content nil}

;; On the  apod website, this is the first img tag on the page:
(def img-link (apply str [apod-base-url (:src (:attrs (first (html/select apod-content [:img]))))]))

;;Copy uri to file - From Stack Overflow: 
;;https://stackoverflow.com/questions/15628682/in-clojure-how-do-you-download-an-image-from-the-web-and-save-it-to-your-file-s
(defn copy-uri-to-file [uri file]
  "Downloads a file from a uri and saves to local file."
  (with-open [in (clojure.java.io/input-stream uri)
              out (clojure.java.io/output-stream file)]
    (clojure.java.io/copy in out)))

(defn -main []
  "Download and save the image, using the file name split from the img link.."
  (copy-uri-to-file img-link (last (str/split img-link #"/")))
  (println "Downloaded: " img-link))

project.clj

(defproject apod-scraper "0.0.1"
  :description "Scrape Nasa Apod webpage and download the image. This is a quick project to familiarize myself with Clojure and Enlive"
  :dependencies [[org.clojure/clojure "1.11.1"]
                 [enlive "1.1.6"]]
  :main apod-scraper.core)