@@ -43,6 +43,7 @@

 (def default-db

   {:name "DMR"

    :cmdline {:current ""

+             :selected-history nil

              :history []}

    :spells spells

    :equipment equipment

@@ -40,6 +40,44 @@

  (fn [_ [_ x]]

      {:window/scroll-to x}))

+(defn- cycle-history [cs direction]

+  (let [history (-> cs :history)

+        current (-> cs :current)

+        orig (some-> cs :selected-history :orig)

+        idx (some-> cs :selected-history :index)

+        history-end (- (count history) 1)

+        historical-input #(-> history (get %) :input)

+        next (case direction :backward dec :forward inc)

+        at-first? (= idx history-end)

+        at-last?  (= idx 0)

+        going-forward? (= direction :forward)

+        going-backward? (= direction :backward)

+        not-cycling? (-> cs :selected-history nil?)]

+    (cond

+      (empty? history)                   {:current current :selected-history nil}

+      (and at-first? going-forward?)     {:current orig :selected-history nil}

+      (and at-last? going-backward?)     {} ; do nothing

+      (and not-cycling? going-forward?)  {} ; do nothing

+      (and not-cycling? going-backward?) {:current (historical-input history-end)

+                                          :selected-history {:orig current

+                                                             :index history-end}}

+      :else                              {:current (historical-input (next idx))

+                                          :selected-history {:orig orig

+                                                             :index (next idx)}})))

+

+(re-frame/reg-event-db

+ ::prompt-keypress

+ (re-frame/path :cmdline)

+ (fn [cmd [_ event]]

+   (let [direction (case (.-key event)

+                     "ArrowUp"   :backward

+                     "ArrowDown" :forward

+                     nil)]

+     (if direction

+       (do (.preventDefault event)

+           (merge cmd (cycle-history cmd direction)))

+       cmd))))

+

 (re-frame/reg-event-fx

  ::submit-cmd

  (fn [cofx [_ prompt]]

@@ -51,9 +89,12 @@

      ; don't always have to prefix with a conditional

      (cond-> db

       true (update-in [:cmdline :current] (constantly nil))

+      true (update-in [:cmdline :selected-history] (constantly nil))

       (not-empty? cmdline)

       (as-> db

         (let [output (execute db cmdline)]

             (update-in db [:cmdline :history] conj

                 {:input cmdline :output output}))))

-     :fx [[:dispatch [::scroll-to prompt]]]})))

+     ; dispatch-later to ensure that the DOM has already been updated,

+     ; so that scrollMaxY has been changed appropriately.

+     :fx [[:dispatch-later {:ms 10 :dispatch [::scroll-to prompt]}]]})))

@@ -12,12 +12,14 @@

   (let [cmdline (re-frame/subscribe [::subs/cmdline])

         update-cmdline #(re-frame/dispatch-sync

                          [::events/update-cmdline (-> % .-target .-value)])

+        key-pressed #(re-frame/dispatch-sync [::events/prompt-keypress %])

         submit-cmd #(do (.preventDefault %)

                         (re-frame/dispatch [::events/submit-cmd (-> % .-target)]))]

     [:form {:class (styles/prompt-style)

             :on-submit submit-cmd}

      [:input {:value @cmdline

               :on-change update-cmdline

+              :on-keyDown key-pressed

               :type "text"}]]))

 (defn title []