(ns frontend.handler
  (:require [frontend.state :as state]
            [frontend.db :as db]
            [frontend.db-schema :as db-schema]
            [frontend.util :as util :refer-macros [profile]]
            [frontend.config :as config]
            [frontend.storage :as storage]
            [clojure.string :as string]
            [promesa.core :as p]
            [cljs-bean.core :as bean]
            [frontend.date :as date]
            [frontend.handler.notification :as notification]
            [frontend.handler.page :as page-handler]
            [frontend.handler.repo :as repo-handler]
            [frontend.handler.file :as file-handler]
            [frontend.handler.ui :as ui-handler]
            [frontend.handler.export :as export-handler]
            [frontend.handler.web.nfs :as nfs]
            [frontend.ui :as ui]
            [goog.object :as gobj]
            [frontend.helper :as helper]
            [frontend.idb :as idb]))

(defn- watch-for-date!
  []
  (js/setInterval (fn []
                    (state/set-today! (date/today))
                    (when-let [repo (state/get-current-repo)]
                      (when (db/cloned? repo)
                        (let [today-page (string/lower-case (date/today))]
                          (when (empty? (db/get-page-blocks-no-cache repo today-page))
                            (repo-handler/create-today-journal-if-not-exists repo))))))
                  1000))

(defn store-schema!
  []
  (storage/set :db-schema db-schema/schema))

(defn schema-changed?
  []
  (when-let [schema (storage/get :db-schema)]
    (not= schema db-schema/schema)))

(defn- get-me-and-repos
  []
  (let [me (and js/window.user (bean/->clj js/window.user))
        logged? (:name me)
        repos (if logged?
                (:repos me)
                [{:url config/local-repo}])]
    {:me me
     :logged? logged?
     :repos repos}))

(declare restore-and-setup!)

(defn clear-stores-and-refresh!
  []
  (p/let [_ (db/clear-local-storage-and-idb!)]
    (let [{:keys [me logged? repos]} (get-me-and-repos)]
      (js/window.location.reload))))

(defn restore-and-setup!
  [me repos logged?]
  (let [interval (atom nil)
        inner-fn (fn []
                   (when (and @interval js/window.pfs)
                     (js/clearInterval @interval)
                     (reset! interval nil)
                     (-> (p/all (db/restore! (assoc me :repos repos)
                                             (fn [repo]
                                               (file-handler/restore-config! repo false)
                                               (ui-handler/add-style-if-exists!))))
                         (p/then
                          (fn []
                            (cond
                              (and (not logged?)
                                   (not (seq (db/get-files config/local-repo)))
                                   ;; Not native local directory
                                   (not (some config/local-db? (map :url repos))))
                              (repo-handler/setup-local-repo-if-not-exists!)

                              :else
                              (state/set-db-restoring! false))

                            (if (schema-changed?)
                              (do
                                (notification/show!
                                 [:p "Database schema changed, your notes will be exported as zip files, your repos will be re-indexed then."]
                                 :warning
                                 false)
                                (let [export-repos (for [repo repos]
                                                     (when-let [url (:url repo)]
                                                       (println "Export repo: " url)
                                                       (export-handler/export-repo-as-zip! url)))]
                                  (-> (p/all export-repos)
                                      (p/then (fn []
                                                (store-schema!)
                                                (js/setTimeout clear-stores-and-refresh! 5000)))
                                      (p/catch (fn [error]
                                                 (log/error :export/zip {:error error
                                                                         :repos repos}))))))
                              (store-schema!))

                            (page-handler/init-commands!)
                            (if (seq (:repos me))
                              ;; FIXME: handle error
                              (helper/request-app-tokens!
                               (fn []
                                 (repo-handler/clone-and-pull-repos me))
                               (fn []
                                 (js/console.error "Failed to request GitHub app tokens."))))

                            (watch-for-date!))))))]
    ;; clear this interval
    (let [interval-id (js/setInterval inner-fn 50)]
      (reset! interval interval-id))))

(defn persist-repo-to-indexeddb!
  ([]
   (persist-repo-to-indexeddb! false))
  ([force?]
   (let [status (state/get-repo-persist-status)]
     (doseq [[repo {:keys [last-stored-at last-modified-at] :as repo-status}] status]
       (when (and (> last-modified-at last-stored-at)
                  (or force?
                      (and (state/get-edit-input-id)
                           (> (- (util/time-ms) last-stored-at) (* 5 60 1000)) ; 5 minutes
)
                      (nil? (state/get-edit-input-id))))
         (p/let [_ (repo-handler/persist-repo! repo)]
           (state/update-repo-last-stored-at! repo)))))))

(defn periodically-persist-repo-to-indexeddb!
  []
  (js/setInterval persist-repo-to-indexeddb! (* 5 1000)))

(defn set-save-before-unload! []
  (.addEventListener js/window "beforeunload"
                     (fn [e]
                       (when (state/repos-need-to-be-stored?)
                         (let [notification-id (atom nil)]
                           (let [id (notification/show!
                                     [:div
                                      [:p "It seems that you have some unsaved changes!"]
                                      (ui/button "Save"
                                                 :on-click (fn [e]
                                                             (persist-repo-to-indexeddb!)
                                                             (notification/show!
                                                              "Saved successfully!"
                                                              :success)
                                                             (and @notification-id (notification/clear! @notification-id))))]
                                     :warning
                                     false)]
                             (reset! notification-id id)))
                         (let [message "\\o/"]
                           (set! (.-returnValue (or e js/window.event)) message)
                           message)))))

(defn- handle-connection-change
  [e]
  (let [online? (= (gobj/get e "type") "online")]
    (state/set-online! online?)))

(defn set-network-watcher!
  []
  (js/window.addEventListener "online" handle-connection-change)
  (js/window.addEventListener "offline" handle-connection-change))

(defn start!
  [render]
  (let [{:keys [me logged? repos]} (get-me-and-repos)]
    (when me (state/set-state! :me me))
    (state/set-db-restoring! true)
    (render)

    (set-network-watcher!)

    (util/indexeddb-check?
     (fn [_error]
       (notification/show! "Sorry, it seems that your browser doesn't support IndexedDB, we recommend to use latest Chrome(Chromium) or Firefox(Non-private mode)." :error false)
       (state/set-indexedb-support! false)))

    ;; (nfs/trigger-check!)
    (p/let [nfs-dbs (idb/get-nfs-dbs)
            nfs-dbs (map (fn [db] {:url db}) nfs-dbs)]
      (let [repos (cond
                    logged?
                    (concat
                     (:repos me)
                     nfs-dbs)

                    (seq nfs-dbs)
                    nfs-dbs

                    :else
                    [{:url config/local-repo}])]
        (restore-and-setup! me repos logged?)))
    (periodically-persist-repo-to-indexeddb!)
    (db/run-batch-txs!))
  (set-save-before-unload!))