servlet.clj

(ns socialmetrics.servlet
  (:gen-class :extends javax.servlet.http.HttpServlet)
  (:use compojure.html compojure.http)
  (:import (java.util Properties Date)
           (java.io File FileInputStream OutputStreamWriter
                    BufferedReader InputStreamReader)
           (java.net URL)
           (java.text SimpleDateFormat ParsePosition FieldPosition)
           (org.apache.commons.codec.digest DigestUtils)))

(defmacro load-properties
  "macroexpand/compile time loading of a properties file into a clojure map"
  [filename]
  (let [p (Properties.)
        is (-> filename File. FileInputStream.)]
    (.load p is)
    (into {} p)))

(def facebook (load-properties "facebook.properties"))

(defn call-id
  "many facebook api calls require a call-id and call-ids must be in ascending
  order per session"
  []
  (.getTime (Date.)))

(def now (Date.))

(defn name|str
  "name on Named things and .toString otherwise"
  [x]
  (if (instance? clojure.lang.Named x)
    (name x)
    (.toString x)))

(defn post
  "post stuff to url, clojure.xml/parse output"
  [url stuff]
  (let [con (doto (.openConnection (URL. url))
              (.setDoInput true)
              (.setDoOutput true))]
    (with-open [wrt (-> con .getOutputStream OutputStreamWriter.)]
      (.write wrt stuff))
    (with-open [a (-> con .getInputStream)]
      (clojure.xml/parse a))))


(defn md5 [string]
  (DigestUtils/md5Hex string))

(defn sig
  "facebook api calls require a signature (md5 hash) of the call the api secret"
  [params]
  (md5
  (.concat
    (reduce #(format "%s%s=%s" %1 (name|str (first %2)) (second %2))
            ""
            (sort-by key params))
    (facebook "api.secret"))))

(defn call
  "takes a map representing a facebook api call and makes the call"
  [bag]
  (post "http://api.facebook.com/restserver.php"
  (format "%s&sig=%s"
          (reduce
            #(format "%s%s=%s&" %1 (name|str (first %2)) (second %2))
            ""
            bag)
          (sig bag))))

(defn string->date
  [string]
  (.parse (SimpleDateFormat. "MM/dd/yyyy")
          string
          (ParsePosition. 0)))

(defn date->age [date]
  (let [cy (.getYear now)
        oy (.getYear date)]
    (- cy oy)))

(defn select-birthday_date [foo]
  (-> foo :content
    ((partial filter #(= :birthday_date (:tag %))))
    first
    :content
    first
    ((fn [x]
       (when x (when-let [t (string->date x)] (date->age t)))))))

(defn chart [map-]
  (format "http://chart.apis.google.com/chart?chtt=%s&cht=bvg&chd=t:%s&chs=900x250&chl=%s"
          "Your friends' ages:"
          (reduce #(format "%s,%s" %1 %2) (vals map-))
          (reduce #(format "%s|%s" (or %1 "unknown") (or %2 "unknown")) (keys map-))))

(defn main [request]
  (let [session (-> request :params :fb_sig_session_key) ;facebook passes me a session key
        friends (-> request :params :fb_sig_friends) ; and a list of friends
        foo (call {:api_key (facebook "api.key") ;get the birthday_date profile field from all the friends
                   :method "Users.getInfo"
                   :call_id (call-id)
                   :v "1.0"
                   :uids friends
                   :fields "birthday_date"
                   :session_key session})
        foo (-> foo :content
              ((partial map select-birthday_date))
              ((partial map #(array-map %1 1)))
              ((partial apply (partial merge-with +)))
              ((partial into (sorted-map)))
              chart)]
  (format
    "
    <fb:if-is-app-user>
    <img style=\"width:750px;\" src=\"%s\" />
    <fb:else>
    <fb:redirect url=\"http://www.facebook.com/login.php?v=1.0&api_key=%s&next=%s&canvas=\"/></fb:else>
    </fb:if-is-app-user>
    "
    foo
    (facebook "api.key")
    "http://apps.facebook.com/agegraph/")))

(defroutes socialmetrics
  (ANY "/" main))

(defservice socialmetrics)