first commit

web/state/reduceState.js

@@ -0,0 +1,67 @@
+// Redux/vuex inspired reducer, reduces an event into a gekko state.
+// NOTE: this is used by the backend as well as the frontend.
+
+const skipInitialEvents = ['marketUpdate'];
+const skipLatestEvents = ['marketStart', 'stratWarmupCompleted'];
+const trackAllEvents = ['tradeCompleted', 'advice', 'roundtrip'];
+
+const reduce = (state, event) => {
+  const type = event.type;
+  const payload = event.payload;
+
+  state = {
+    ...state,
+    latestUpdate: new Date()
+  }
+
+  if(trackAllEvents.includes(type)) {
+    if(!state.events[type]) {
+      state = {
+        ...state,
+        events: {
+          ...state.events,
+          [type]: [ payload ]
+        }
+      }
+    } else {
+      state = {
+        ...state,
+        events: {
+          ...state.events,
+          [type]: [ ...state.events[type], payload ]
+        }
+      }
+    }
+  }
+
+  if(!state.events.initial[type] && !skipInitialEvents.includes(type)) {
+    state = {
+      ...state,
+      events: {
+        ...state.events,
+        initial: {
+          ...state.events.initial,
+          [type]: payload
+        }
+      }
+    }
+  }
+
+  if(!skipLatestEvents.includes(type)) {
+    state = {
+      ...state,
+      events: {
+        ...state.events,
+        latest: {
+          ...state.events.latest,
+          [type]: payload
+        }
+      }
+    }
+  }
+
+  return state;
+}
+
+// export default reduce;
+module.exports = reduce;