(ns mailhead.parser
  (:require [clojure.string :as st]
            [clj-time.core :as time]
            [clj-time.coerce :as timec])
  (:use [clojure.contrib.java-utils :only [as-properties]]
        [clojure.java.io :only [input-stream file]])
  (:import 
   (javax.mail Session)
   (javax.mail.internet MimeMessage)
   (javax.mail.internet InternetHeaders)))

(def session
  (Session/getDefaultInstance 
   (as-properties [["mail.store.protocol" "imaps"]])))

(defn all-headers [message]
  (enumeration-seq (:allHeaders (bean message))))

(defn received-headers [all-headers]
  (map #(.getValue %) (filter (fn [header] (= "Received" (.getName header))) all-headers)))

(defn parse-received-headers [received-header]
  (let [datetime (str/trim (last (st/split received-header #";")))
        ;; Hacky hacky, but no time to make this proper ...
        cleaned-date (st/trim (st/replace datetime #"(\(.*\)|  )" " "))]
    {:sender (nth (re-find #"\s*from ([^ ]+)" received-header) 1)
     :receiver (nth (re-find #"\s*by ([^ ]+)" received-header) 1)
     :time (timec/from-string cleaned-date)}))

(defn extract-relevant-stuff [mime-message]
  (->> mime-message
       all-headers
       received-headers
       (map parse-received-headers)))

(defn parse-from-string [email-string]
  (let [email-stream (java.io.ByteArrayInputStream. (.getBytes email-string))]
    (extract-relevant-stuff (MimeMessage. session email-stream))))

(defn parse-from-file [filename]
  (extract-relevant-stuff (MimeMessage. session (input-stream filename))))