From fe5bd004272e5bdf6a0a909f92d7fd47e00d60e9 Mon Sep 17 00:00:00 2001
From: Nicholas Kariniemi <nicholas.kariniemi@gmail.com>
Date: Tue, 16 Sep 2014 23:27:10 +0300
Subject: [PATCH] Refactor - wip

---
 src/clj/grub/state.clj            | 28 ++++++++++++++++
 src/test/grub/test/unit/state.clj | 56 +++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 src/test/grub/test/unit/state.clj

diff --git a/src/clj/grub/state.clj b/src/clj/grub/state.clj
index 3b19142..df433dc 100644
--- a/src/clj/grub/state.clj
+++ b/src/clj/grub/state.clj
@@ -5,6 +5,33 @@
             [clojure.core.async :as a :refer [<! >! chan go]]
             [hasch.core :as hasch]))
 
+(def initial-state {:hash (hasch/uuid cs/empty-state)
+                    :state cs/empty-state})
+(def states (atom [initial-state]))
+
+(defn get-history-state [states hash]
+  (:state (first (filter #(= (:hash %) hash) states))))
+
+(defn add-history-state [current new-state]
+  (let [{:keys [state hash]} (first current)
+        new-hash (hasch/uuid new-state)]
+    (if (= hash new-hash)
+      current
+      (conj current {:hash hash :state state}))))
+
+(defn receive-diff [states diff shadow-hash]
+  (let [state (:state (first states))
+        shadow (get-history-state states shadow-hash)]
+    (if shadow
+      {:new-state (diff/patch-state state diff)
+       :new-shadow (diff/patch-state shadow diff)
+       :full-sync? false}
+      {:new-state state
+       :new-shadow state
+       :full-sync? true})))
+
+
+
 (def state (atom cs/empty-state))
 (def to-db (atom nil))
 (def to-all (chan))
@@ -26,6 +53,7 @@
   {:grubs (util/map-by-key :id grubs)
    :recipes (util/map-by-key :id recipes)})
 
+
 (defn sync-new-client! [to from]
   (let [client-id (java.util.UUID/randomUUID)
         client-state (atom cs/empty-state)
diff --git a/src/test/grub/test/unit/state.clj b/src/test/grub/test/unit/state.clj
new file mode 100644
index 0000000..c30a04d
--- /dev/null
+++ b/src/test/grub/test/unit/state.clj
@@ -0,0 +1,56 @@
+(ns grub.test.unit.state
+  (:require [grub.state :as s]
+            [grub.common-state :as cs]
+            [clojure.test :refer :all]
+            [hasch.core :as hasch]))
+
+(deftest apply-diff-normally
+  ;; Apply changes and return ACK for in sync client/server
+  (let [state {:grubs {"1" {:text "2 apples" :completed false}}
+               :recipes {}}
+        hash (hasch/uuid state)
+        states [{:hash hash :state state}]
+        diff {:grubs {:updated {"1" {:completed true}} :deleted #{}}}
+        shadow-hash hash
+        {:keys [new-state new-shadow full-sync?]} (s/receive-diff states diff shadow-hash)]
+    (do 
+      (is (= {:grubs {"1" {:text "2 apples" :completed true}}
+              :recipes {}}
+             new-state))
+      (is (= {:grubs {"1" {:text "2 apples" :completed true}}
+              :recipes {}}
+             new-shadow))
+      (is (not full-sync?)))))
+
+(deftest server-state-changed
+  ;; Send differences back if server state changed
+  (let [state {:grubs {"1" {:text "3 apples" :completed false}} :recipes {}}
+        prev {:grubs {"1" {:text "2 apples" :completed false}} :recipes {}}
+        states [{:hash (hasch/uuid state) :state state}
+                {:hash (hasch/uuid prev) :state prev}]
+        diff {:grubs {:updated {"1" {:completed true}} :deleted #{}}}
+        shadow-hash (hasch/uuid prev)
+        {:keys [new-state new-shadow full-sync?]} (s/receive-diff states diff shadow-hash)]
+    (do 
+      (is (= {:grubs {"1" {:text "3 apples" :completed true}}
+              :recipes {}}
+             new-state))
+      (is (= {:grubs {"1" {:text "2 apples" :completed true}}
+              :recipes {}}
+             new-shadow))
+      (is (not full-sync?)))))
+
+(deftest full-sync-if-client-too-far-out-of-sync
+  ;; Shadow hash not in history means client has fallen too far
+  ;; out of sync. Send a full sync
+  (let [state {:grubs {"1" {:text "2 apples" :completed false}} :recipes {}}
+        prev {:grubs {"1" {:text "2 apples" :completed false}} :recipes {}}
+        states [{:hash (hasch/uuid state) :state state}
+                {:hash (hasch/uuid prev) :state prev}]
+        shadow-hash (hasch/uuid {:grubs {} :recipes {}})
+        diff {:grubs {:updated {"1" {:completed true}} :deleted #{}}}
+        {:keys [new-state new-shadow full-sync?]} (s/receive-diff states diff shadow-hash)]
+    (do 
+      (is (= state new-state))
+      (is (= state new-shadow))
+      (is full-sync?))))