(ns de.clojure-buch.lazy-reddit-rss)

(use 'clojure.contrib.lazy-xml)

(defn- match-key-val [m k v]
  (= (m k) v))

(defn- match-start-k [m k]
  (and (match-key-val m :type :start-element)
       (match-key-val m :name k)))

(defn- skip-to-title [s]
  (loop [s s]
    (if (match-start-k (first s) :item)
      s
      (recur (next s)))))

(defn- filter-els [e]
  (or (match-key-val e :type :characters)
      (or (match-start-k e :title)
          (match-start-k e :link))))

(defn- filter-groups [s]
  (and 
   (match-key-val (first s) :name :title)
   (match-key-val (first (nnext s)) :name :link)))

(defn parse-rss [src]
  (map
   (fn [s] [((nth s 1) :str) ((nth s 3) :str)])
   (filter filter-groups
           (partition 4 1
                      (filter filter-els
                              (skip-to-title
                               (parse-seq src)))))))