going somewhere.

src/clj/skirmish/ledger/data_layer.clj

@@ -76,7 +76,8 @@
                                               [?e :skirmish.ledger/sec ?sec]
                                               [?sec :skirmish.security/sec-id ?sec-id]
                                               [?e :skirmish.ledger/owner-public-key ?pk]
-                                       [?tx :db/txInstant ?v]] db account-id)]
+                                              [?tx :db/txInstant ?v]]
+                                     db account-id)]
     {:amount  (when (some? sec-id) (compute-face-value-from-db db amount sec-id date))
      :sec-id sec-id
      :account-public-key pk}))
@@ -86,3 +87,42 @@
 
 (defn create-security [conn sec-id interest-rate]
   (d/transact conn [[:skirmish.ledger/create-security sec-id interest-rate]]))
+
+(defn get-account [db account-id]
+  (d/pull db '[*] [:skirmish.ledger/owner-public-key account-id]))
+
+(defn assoc-accounts [db transaction]
+  (let [from-account (get-account db (:from-account-id transaction))
+        to-account (get-account db (:to-account-id transaction))
+        ret (assoc transaction :from-account from-account)
+        ret (assoc ret :to-account to-account)]
+    ret))
+
+(defn get-new-from-account-value [{amount :amount from-account :from-account} old-change]
+  (if (some? old-change)
+    (assoc old-change 3 (- (get old-change 3) amount))
+    [:db/add
+     (:db/id from-account)
+     :skirmish.ledger/amount
+     (- (:skirmish.ledger/amount from-account) amount)]))
+
+(defn get-new-to-account-value [{amount :amount to-account :to-account} old-change]
+  (if (some? old-change)
+    (assoc old-change 3 (+ (get old-change 3) amount))
+    [:db/add
+     (:db/id to-account)
+     :skirmish.ledger/amount
+     (+ (:skirmish.ledger/amount to-account) amount)]))
+
+(defn compute-transactions [res transaction]
+  (let [res-from-account (get res (:from-account-id transaction))
+        from-account (get-new-from-account-value transaction res-from-account)
+        res (assoc res (:from-account-id transaction) from-account)
+        res-to-account (get res (:to-account-id transaction))
+        to-account (get-new-to-account-value transaction res-to-account)
+        res (assoc res (:to-account-id transaction) to-account)]
+    res))
+
+(defn create-transactions [db transactions]
+  (let [transactions (map #(assoc-accounts db %) transactions)]
+    (into #{} (vals (reduce compute-transactions {} transactions)))))

test/clj/skirmish/ledger/test_core.clj

@@ -226,7 +226,7 @@
                    d+2d #inst"2020-09-07T00:00:00.000-00:00"
                    d+2½d #inst"2020-09-07T12:00:00.000-00:00"
                    d+3d #inst"2020-09-08T00:00:00.000-00:00"
-                   d+3½d #inst"2020-09-08T12:00:00.000-00:00";;
+                   d+3½d #inst"2020-09-08T12:00:00.000-00:00" ;;
                    interest-rates [[10 d] [15 d+1d] [20 d+2d]]]
                (data-layer/split-interest-rates interest-rates d+½d d+3d) => [[10 d+½d d+1d] [15 d+1d d+2d] [20 d+2d d+3d]]
                (data-layer/split-interest-rates interest-rates d+3d d+3½d) => [[20 d+3d d+3½d]]
@@ -259,3 +259,28 @@
 
 ;;    4. transfer sec from one account to the other.
 
+(defn get-account-eids [db & owner-public-keys]
+  (let [q (map #(vector :skirmish.ledger/owner-public-key %) owner-public-keys)
+        ret (d/pull-many db '[:db/id] q)]
+    (map :db/id ret)))
+
+(facts "about transactions"
+       (fact "about transferring an amount from one wallet to another"
+             (let [conn (create-some-securities-and-accounts (create-conn))
+                   transaction {:from-account-id "1-sec-1"
+                                :to-account-id   "2-sec-1"
+                                :amount          50}
+                   db (d/db conn)
+                   [eid1 eid2] (get-account-eids db "1-sec-1" "2-sec-1")
+                   expt #{[:db/add eid1 :skirmish.ledger/amount 50]
+                          [:db/add eid2 :skirmish.ledger/amount 250]}]
+               (data-layer/create-transactions db [transaction]) => expt)) ;expt))
+       (fact "about transferring an amount from one wallet to another"
+             (let [conn (create-some-securities-and-accounts (create-conn))
+                   transaction {:from-account-id "1-sec-1"
+                                :to-account-id   "1-sec-1"
+                                :amount          45}
+                   db (d/db conn)
+                   [eid1] (get-account-eids db "1-sec-1")
+                   expt #{[:db/add eid1 :skirmish.ledger/amount 100]}]
+               (data-layer/create-transactions db [transaction]) => expt)))