(ns isahn.core
  (:require
   [config.core :refer [env]]
   [clojure.java.io :as io]
   [clj-http.client :as client]
   [cheshire.core :as json])
  (:gen-class))

;; VARIABLES

;; URL send for Telegram
(def url_telegram_send (str "https://api.telegram.org/" (:bot_token env) "/sendMessage"))
;;  URLs from API Hacker News
(def url_all_stories "https://hacker-news.firebaseio.com/v0/topstories.json")
;;  Min score
(def min_score (:min_score env))
;;  Now unixtime
(def now (quot (System/currentTimeMillis) 1000))
;;  24h in unixtime
(def unixtime24h 86400)
;;  Now - 24h
(def min_time (- now unixtime24h))
;;  Path file save history
(def path_history "isahn_history.json")
(def history (if (.exists (io/file path_history)) (json/parse-string (slurp (io/file path_history)) true) (str "")))
(def history_ids (map :id history))

;; FUNCTIONS

(defn one_story
  " Get url from item "
  [id]
  (str "https://hacker-news.firebaseio.com/v0/item/" id ".json"))

(defn get_all_stories
  "Get all stories"
  [url_all_stories]
  ;; Get all ids stories
  (let [;; Get all API urls stories
        ids_stories  (json/parse-string (:body (client/get url_all_stories {:accept :json})))
        ;; Get all data stories
        urls_stories (map one_story ids_stories)]
    (map #(json/parse-string (:body (client/get % {:accept :json}))) urls_stories)))

(defn lazy_contains? [col key]
  (some #{key} col))

(defn add_history
  "Add to file history news_stories"
  [news_stories]
  (let [history_news_ids (concat history_ids (map #(get-in % ["id"]) news_stories))
        history_all      (map #(assoc {} :id %) (vec history_news_ids))]
    (with-open [w (clojure.java.io/writer path_history :append false)]
      (.write w (json/generate-string history_all)))))

(defn filter_stories
  "Filter stories by last 24h, remove histories and lower score"
  [stories]
  ;; Filter created less 24h
  (let [stories_24h               (filter #(> (get-in % ["time"]) min_time) stories)
        ;; Filter history
        stories_without_histories (filter #(not (lazy_contains? history_ids (get-in % ["id"]))) stories_24h)]

    ;; Filter with score min_score
    (filter #(> (get-in % ["score"]) min_score) stories_without_histories)))

(defn send_stories_telegram
  "Send stories by Telegram Channel"
  [stories]
  (doseq [story stories] (client/post url_telegram_send {:body         (json/generate-string {:chat_id              (:chat env)
                                                                                              :text                 (str (get-in story ["title"]) ": " (get-in story ["url"]))
                                                                                              :disable_notification true})
                                                         :content-type :json
                                                         :accept       :json})))

(defn check_stories
  "Check news stories and send message to Telegram"
  []
  (let [stories_top (filter_stories (get_all_stories url_all_stories))]
    (add_history stories_top)
    (send_stories_telegram stories_top)))

(defn -main
  "Main execution"
  []
  (check_stories))