poc (almost)

.gitignore

@@ -0,0 +1 @@
+node_modules

index.js

@@ -0,0 +1,63 @@
+// var Web3 = require('web3')
+const Events = require('events')
+const events = new Events()
+
+const { Observable, fromEvent, interval, Subject } = require('rxjs');
+const { throttle, map, distinctUntilChanged, filter, average, reduce, count} =  require('rxjs/operators');
+
+var loki = require('lokijs')
+var db = new loki('loki.json')
+var children = db.addCollection('children')
+// var result = children.insert({name: 'foo', legs: 8})
+// console.dir(result)
+// var result2 = children.insert({name: 'bar', legs: 8})
+// console.dir(result2)
+// console.dir(children.get(result2.$loki))
+
+let contractEvents = [
+    { id: 1, from: "0x123", type: "Rating", rating: 3 },
+    { id: 2, from: "0x123", type: "Rating", rating: 1 },
+    { id: 3, from: "0x234", type: "Rating", rating: 5 },
+    { id: 4, from: "0x123", type: "Rating", rating: 4 },
+    { id: 5, from: "0x123", type: "Rating", rating: 2 },
+    { id: 6, from: "0x342", type: "Rating", rating: 2 }
+]
+
+function emitEvents() {
+    let i = 0
+    // emit contract event each 1 second
+    setInterval(() => {
+        if (i >= contractEvents.length) return
+        events.emit("contractEvent", contractEvents[i])
+        i += 1
+    }, 1 * 1000)
+}
+
+function trackEvent(eventName, filterConditions) {
+    let eventKey = eventName + "-from0x123";
+
+    let sub = new Subject();
+
+    for (let previous of children.find({'eventKey': eventKey})) {
+        sub.next(previous)
+    }
+
+    let contractObserver = fromEvent(events, eventName)
+    contractObserver.pipe(filter(filterConditions)).subscribe((e) => {
+        console.dir("------- syncing event");
+        e.eventKey = eventKey
+        console.dir(e);
+        children.insert(e)
+        sub.next(e)
+        // events.emit(eventKey)
+        console.dir("-------");
+    })
+
+    return sub;
+}
+
+trackEvent('contractEvent', ((x) => x.from === "0x123")).pipe(map(x => x.rating)).subscribe((v) => {
+    console.dir("current value is " + v)
+})
+
+emitEvents()

package.json

@@ -2,10 +2,13 @@
   "name": "phoenix",
   "version": "1.0.0",
   "description": "",
-  "main": "test.js",
+  "main": "index.js",
-  "scripts": {
+  "scripts": {},
-    "test": "echo \"Error: no test specified\" && exit 1"
-  },
   "author": "",
-  "license": "ISC"
+  "license": "MIT",
+  "dependencies": {
+    "lokijs": "^1.5.6",
+    "rxjs": "^6.5.2",
+    "web3": "1.0.0-beta.37"
+  }
 }