Implemented history writer

Client/streamhub/App.cpp

@@ -503,6 +503,8 @@ void App::handleJSON(const std::string& json) {
     else if (type == "stats")            { onStats(json); }
     else if (type == "triggerState")     { onTriggerState(json); }
     else if (type == "zoom")             { onZoom(json); }
+    else if (type == "historyZoom")      { onHistoryZoom(json); }
+    else if (type == "historyInfo")      { onHistoryInfo(json); }
     else if (type == "maxPointsUpdated") { onMaxPointsUpdated(json); }
     /* pong: ignore */
 }
@@ -705,4 +707,40 @@ void App::onMaxPointsUpdated(const std::string& json) {
     }
 }
 
+/* ---- History ------------------------------------------------------------ */
+
+void App::onHistoryZoom(const std::string& json) {
+    ZoomResponse resp;
+    if (!ParseZoom(json, resp)) { return; }
+
+    /* Route the reply to the plot that requested it (via histZoomCache_) */
+    for (int i = 0; i < kMaxPlotSlots; i++) {
+        auto& hc = histZoomCache_[i];
+        if (hc.pending && hc.reqId == resp.reqId) {
+            hc.signals = std::move(resp.signals);
+            hc.t0      = hc.reqT0;
+            hc.t1      = hc.reqT1;
+            hc.valid   = true;
+            hc.pending = false;
+            return;
+        }
+    }
+}
+
+void App::onHistoryInfo(const std::string& json) {
+    ParseHistoryInfo(json, historyInfo_);
+}
+
+void App::requestHistoryZoom(int plotIdx, double t0, double t1,
+                              const std::string& signalsCsv) {
+    if (plotIdx < 0 || plotIdx >= kMaxPlotSlots) { return; }
+    if (!ws_.isConnected() || signalsCsv.empty()) { return; }
+    auto& hc = histZoomCache_[plotIdx];
+    hc.reqId   = nextZoomReqId_++;
+    hc.reqT0   = t0;
+    hc.reqT1   = t1;
+    hc.pending = true;
+    ws_.sendText(BuildHistoryZoom(hc.reqId, t0, t1, 2400, signalsCsv));
+}
+
 } /* namespace StreamHubClient */