; my first clojure program -- pings a subnet looking for existing hosts
; usage (you'll need a clj repl script):
; clj pingdom.clj 192.168.2
; clj pingdom.clj --used 10.0.0
;
(ns pingdom
  (:use [clojure.contrib.shell-out :only (sh)])
  (:use [clojure.contrib.str-utils :only (re-split str-join)])
  (:use [clojure.contrib.string :only (replace-first-re)]))

(def *default-subnet* "192.168.1")
(def *ping-cmd* {:mac "ping -c 1 -W 5 -s 1 ",
                 :nix "ping -c 1 -w 5 -s 1 "})

(defn platform []
  (let [os-name (System/getProperty "os.name")]
    (cond
      (.startsWith os-name "Mac") :mac
      (or (.startsWith os-name "Linux") (re-find #"nix" os-name)) :nix
      :else :other)))

(defn ping [ip]
  (let [cmd ((platform) *ping-cmd*)
        args (re-split #"\s+" (str cmd ip))]
    (apply sh args)))

(defn host-exists? [ip]
  (let [ping-results (ping ip)]
    (not (re-find #"100(\.0)?% packet loss" ping-results))))

(defn ping-ips [subnet]
  (let [subnet-with-dot (replace-first-re #"\.?$" "." subnet)
        ips (map #(str subnet-with-dot %) (range 1 255))
        futures (map #(future {:ip %, :exists (host-exists? %)}) ips)]
    (map deref (doall futures))))

(defn available-ips [subnet]
  (map :ip (remove :exists (ping-ips subnet))))

(defn used-ips [subnet]
  (map :ip (filter :exists (ping-ips subnet))))

(defn get-subnet-from-args [args default]
  (or
    (first (filter #(re-find #"^\d" %) args))
    default))

(defn get-options-from-args [args]
  (filter #(re-find #"^\-" %) args))

(defn options-include? [options & args]
  (some #((set options) %) options))

(let [args *command-line-args*
      subnet (get-subnet-from-args args *default-subnet*)
      options (get-options-from-args args)]
  (if (options-include? options "-u" "--used")
    (println (str "Used IPs:\n"
               (str-join "\n" (used-ips subnet))))
    (println (str "Available IPs\n"
               (str-join "\n" (available-ips subnet))))))

(shutdown-agents)