(ns buchdesmonats.core
  (:gen-class)
  (:require [net.cgrand.enlive-html :as html]
            [clj-http.client :as http-client]
            [clojure.string :as str]
            [clojure.java.io :as io]
            [me.raynes.fs :as fs]))

(def config {:books-url "https://raw.github.com/CTHN/wiki-data/master/pages/projects/buch_des_monats.mkd"
             :target-dir (io/file "public" "book-covers")})

(defn imgurl->bytes [lovelybooks-url]
  (-> (java.net.URL. lovelybooks-url)
      html/html-resource
      (html/select [:div.bookcoverXXL :> :div :> :img])
      first
      (get-in [:attrs :src])
      (#(str "http:" %))
      (http-client/get {:as :byte-array})
      :body))

(defn url->file [lovelybooks-url target-dir]
  (let [[_ author title] (re-find #".\/autor\/([^\/]+)\/(.+)-([0-9]+)-.\/$" lovelybooks-url)]
    (io/file target-dir
             (str/lower-case (str author "_" title ".jpg")))))

(defn scrape-book-urls [github-url]
  (->> (http-client/get github-url)
       :body
       str/split-lines
       (map #(second (re-find #"^\* .*\[.+\]\((.+)\)" %)))
       (remove nil?)))

(defn scrape-book-cover [url target-dir]
  (let [target-file (url->file url target-dir)]
    (with-open [out (io/output-stream target-file)]
      (.write out (imgurl->bytes url)))))

(defn find-missing-covers [books-url target-dir]
  (remove #(fs/exists? (url->file % target-dir))
          (scrape-book-urls books-url)))
  
(defn -main [& args]
  (fs/mkdirs (:target-dir config))
  (doall (pmap #(scrape-book-cover % (:target-dir config))
               (find-missing-covers (:books-url config) (:target-dir config))))
  true)