(ns blog.precompile
  (:require [me.raynes.fs :as fs]
            [cljs.closure :as cljsc]
            [clojure.java.io :as io])
  (:import [javax.script ScriptEngineManager ScriptException]))

(defn eval-js
  [js]
  (let [engine (.getEngineByName (ScriptEngineManager. ) "nashorn")]
    (.eval engine js)))

(defn precompile-sources
  []
  (let [output-dir "out/lib-precompile"]
    (when (fs/directory? output-dir)
      (fs/delete-dir output-dir))
    (fs/mkdirs output-dir)
    (str
      (cljsc/build
        '[(ns blog.precompiled
            (:require [om.core :as om :include-macros]
                      [om.dom :as dom :include-macros]
                      cljs.reader
                      [blog.page :as b]))

          (defn ^:export precompile
            [app-state-str]
            (dom/render-to-str
              (let [app-state (cljs.reader/read-string app-state-str)]
                (om/build
                  (case (:page-type app-state)
                    :list b/list-page-view
                    :static b/static-page-view
                    :contact-list b/contact-list-page-view
                    :item b/item-page-view
                    :feed b/feed-page-view
                    :home b/home-page-view)
                  app-state))))]
        {:optimizations :advanced
         :elide-asserts true
         :preamble ["patch_react.js" "patch_misc.js" "react/react.min.js"]
         :externs ["react/externs/react.js"]
         :output-dir output-dir
         :output-to "resources/precompiled.js"
         :pretty-print false}))))

(defn precompile-page
  [data]
  (let [output-dir "out/precompile"]
    (when (fs/directory? output-dir)
      (fs/delete-dir output-dir))
    (fs/mkdirs output-dir)
    (when-not (io/resource "precompiled.js")
      (precompile-sources))
    (eval-js
      (str (slurp (io/resource "precompiled.js"))
        "\nblog.precompiled.precompile(" (pr-str (pr-str data)) ");"))))