(ns sitetools.core
  (:require [clojure.string :as string]
            [goog.events :as evt]
            [goog.history.EventType :as hevt]
            [reagent.core :as r]
            [secretary.core :as secretary :refer-macros [defroute]]
            [reagent.debug :refer-macros [dbg log dev?]]
            [reagent.interop :as i :refer-macros [.' .!]])
  (:import goog.History
           goog.history.Html5History))

(when (exists? js/console)
  (enable-console-print!))

(defn rswap! [a f & args]
  ;; Roughly like swap!, except that recursive swaps are ok
  (let [fs (if-some [arr (.-rswapfs a)]
             arr
             (set! (.-rswapfs a) (array)))]
    (.push fs #(apply f % args))
    (if (< 1 (.-length fs))
      nil
      (let [f' (fn [state]
                 (let [s ((aget fs 0) state)]
                   (.shift fs)
                   (if (-> fs .-length pos?)
                     (recur s)
                     s)))]
        (swap! a f')))))


;;; Configuration

(declare page-content)

(defonce config (r/atom {:page-map {"index.html" [:div "Empty"]}
                         :page-titles {}
                         :body [page-content]
                         :main-content [:div]
                         :pages #{}
                         :site-dir "outsite/public"
                         :css-infiles ["site/public/css/main.css"]
                         :css-file "css/built.css"
                         :js-file "js/main.js"
                         :js-dir "js/out"
                         :main-div "main-content"
                         :default-title ""
                         :allow-html5-history false}))

(defonce page (r/atom "index.html"))
(defonce page-state (r/atom {:has-history false}))

(defonce history nil)

(defn demo-handler [state [id v1 v2 :as event]]
  (case id
    :content (do
               (let [title (if v2
                             (str (:title-prefix @config) v2)
                             (str (:default-title @config)))]
                 (when r/is-client
                   (r/next-tick #(set! js/document.title title)))
                 (assoc state
                        :main-content v1
                        :title title)))
    :set-page (do (secretary/dispatch! v1)
                  (assoc state :page v1))
    :goto-page (do
                 (when r/is-client
                   (.setToken history v1 false)
                   (r/next-tick #(set! js/document.body.scrollTop 0)))
                 (recur state [:set-page v1 v2]))
    state))

(defn dispatch [event]
  (dbg event)
  (rswap! config demo-handler event)
  nil)

(defn reg-page [url]
  (swap! config update-in [:pages] conj url))

(defn init-history []
  (when-not history
    (doto (set! history (History.))
      (evt/listen hevt/NAVIGATE #(dispatch [:set-page (.-token %)]))
      (.setEnabled true))))


;; (defn register-page
;;   ([pageurl comp]
;;    (register-page pageurl comp nil))
;;   ([pageurl comp title]
;;    (assert (string? pageurl)
;;            (str "expected string, not " pageurl))
;;    (assert (vector? comp)
;;            (str "expected vector, not " (pr-str comp)))
;;    (assert (or (nil? title)
;;                (string? title)))
;;    (swap! config update-in [:page-map] assoc pageurl comp)
;;    (swap! config update-in [:page-titles] assoc pageurl title)
;;    pageurl))


;;; Components

(defn link [props child]
  [:a (assoc props
             :on-click #(do (.preventDefault %)
                            (dispatch [:goto-page (:href props)])))
   child])

;; (defn link
;;     [props child]
;;     (let [p (:href props)
;;           f ((:page-map @config) p)]
;;       (assert (vector? f) (str "couldn't resolve page " p))
;;       (assert (string? p))
;;       [:a (assoc props
;;                  :href p
;;                  :on-click (if (:has-history @page-state)
;;                              (fn [e]
;;                                (.preventDefault e)
;;                                (reset! page p)
;;                                (r/next-tick
;;                                 #(set! (.-scrollTop (.-body js/document))
;;                                        0)))
;;                              identity))
;;        child]))

(defn page-content []
  (:main-content @config))



;;; Implementation:

;; (defn get-title []
;;   (get-in @config [:page-titles @page]
;;           (or (get-in @config [:page-titles "index.html"])
;;               "")))

;; (defn default-content []
;;   [:div "Empty"])

;; (add-watch page ::title-watch
;;            (fn [_ _ _ p]
;;              (when r/is-client
;;                (set! (.-title js/document) (get-title)))
;;              ;; First title on a page wins
;;              #_(reset! page-title "")))

;;; History

;; (defn use-html5-history []
;;   (when r/is-client
;;     (let [proto (.' js/window :location.protocol)]
;;       (and (:allow-html5-history @config)
;;            (.isSupported Html5History)
;;            (#{"http:" "https:"} proto)))))

;; (defn create-history [p]
;;   (if (use-html5-history)
;;     (doto (Html5History.)
;;       (.setUseFragment false))
;;     (let [h (History.)]
;;       (when p
;;         (.setToken h p))
;;       h)))

;; (defn token-base []
;;   (if (use-html5-history)
;;     (:base-path @config)))

;; (defn setup-history [p]
;;   (when (nil? history)
;;     (set! history (create-history p))
;;     (swap! page-state assoc :has-history (some? history))
;;     (when-let [h history]
;;       (evt/listen h hevt/NAVIGATE
;;                   (fn [e]
;;                     (let [t (.-token e)
;;                           tb (token-base)]
;;                       (reset! page (if (and tb (== 0 (.indexOf t tb)))
;;                                      (subs t (count tb))
;;                                      t)))
;;                     (r/flush)))
;;       (add-watch page ::history
;;                  (fn [_ _ oldp newp]
;;                    (when-not (= oldp newp)
;;                      (.setToken h (str (token-base) newp)))))
;;       (.setEnabled h true))))

;; (defn base-path [loc p]
;;   ;; Find base-path for html5 history
;;   (let [split #".[^/]*"
;;         depth (->> (case p "" "." p) (re-seq split) count)
;;         base (->> loc (re-seq split) (drop-last depth) (apply str))]
;;     (string/replace (str base "/") #"^/" "")))

;; (defn set-start-page [p]
;;   (when (and (not (:base-path @config))
;;              (use-html5-history))
;;     (swap! config assoc :base-path
;;            (base-path (.' js/window -location.pathname) p)))
;;   (reset! page p))

(defn prefix [href]
  (let [depth (-> #"/" (re-seq @page) count)]
    (str (->> "../" (repeat depth) (apply str)) href)))


;;; Static site generation

(defn body []
  (let [b (:body @config)]
    (assert (vector? b) (str "body is not a vector: " b))
    b))

(defn danger [t s]
  [t {:dangerouslySetInnerHTML {:__html s}}])

(defn html-template [{:keys [title body timestamp page-conf
                             opt-none req]}]
  (let [c @config
        main (str (:js-file c) timestamp)
        css-file (:css-file c)
        opt-none (:opt-none c)]
    (r/render-to-static-markup
     [:html
      [:head
       [:meta {:charset "utf-8"}]
       [:meta {:name 'viewport
               :content "width=device-width, initial-scale=1.0"}]
       [:base {:href (prefix "")}]
       [:link {:href (str css-file timestamp) :rel 'stylesheet}]
       [:title title]]
      [:body
       [:div {:id (:main-div @config)}
        (danger :div body)]
       (danger :script (str "var pageConfig = " (-> page-conf
                                                    clj->js
                                                    js/JSON.stringify)))
       [:script {:src main :type "text/javascript"}]]])))

(defn gen-page [page-name timestamp]
  (reset! page page-name)
  (let [b (r/render-component-to-string (body))]
    (str "<!doctype html>"
         (html-template {:title (:title @config) ;;(get-title)
                         :body b
                         :page-conf {:allow-html5-history true
                                     :page-name page-name}
                         :timestamp timestamp}))))

(defn mkdirs [f]
  (let [fs (js/require "fs")
        path (js/require "path")
        items (as-> f _
                (.' path dirname _)
                (.' path normalize _)
                (string/split _ #"/"))
        parts (reductions #(str %1 "/" %2) items)]
    (doseq [d parts]
      (when-not (.' fs existsSync d)
        (.' fs mkdirSync d)))))

(defn write-file [f content]
  (let [fs (js/require "fs")]
    (mkdirs f)
    (.' fs writeFileSync f content)))

(defn read-file [f]
  (let [fs (js/require "fs")]
    (.' fs readFileSync f)))

(defn path-join [& paths]
  (let [path (js/require "path")]
    (apply (.' path :join) paths)))

(defn read-css []
  (clojure.string/join "\n"
                       (map read-file (:css-infiles @config))))

(defn write-resources [dir]
  (write-file (path-join dir (:css-file @config))
              (read-css)))


;;; Main entry points

(defn ^:export genpages [opts]
  (log "Generating site")
  (swap! config merge (js->clj opts :keywordize-keys true))
  (let [dir (:site-dir @config)
        timestamp (str "?" (.' js/Date now))]
    (doseq [f (keys (:page-map @config))]
      (write-file (path-join dir f)
                  (gen-page f timestamp)))
    (write-resources dir))
  (log "Wrote site"))

(defn start! [site-config]
  (swap! config merge site-config)
  (when r/is-client
    (let [conf (when (exists? js/pageConfig)
                 (js->clj js/pageConfig :keywordize-keys true))
          page-name (:page-name conf)]
      (swap! config merge conf)
      (when (nil? history)
        ;; (when page-name
        ;;   (set-start-page page-name))
        (init-history)
        ;; (setup-history page-name)
        ;; (set! (.-title js/document) (get-title))
        )
      (r/render-component (body)
                          (.' js/document getElementById
                              (:main-div @config))))))