From d0ed01433d39e7bedd7f96a6defcde480e58b178 Mon Sep 17 00:00:00 2001
From: Shawn A <spam@rumental.com>
Date: Sat, 24 Feb 2018 08:40:01 -0600
Subject: [PATCH] add wifiscan preloading with cache

This uses core scan object and assumes its lifetime, I am not sure what the scope is or how long it lives, will have to convert to local copy if its being lost, caching for 60s after startweb portal and 10s after root load, refresh bypasses cache
---
 WiFiManager.cpp | 29 +++++++++++++++++++++++++----
 WiFiManager.h   |  7 ++++++-
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/WiFiManager.cpp b/WiFiManager.cpp
index f6a6b88..d720a42 100644
--- a/WiFiManager.cpp
+++ b/WiFiManager.cpp
@@ -372,6 +372,8 @@ void WiFiManager::setupConfigPortal() {
   
   server->begin(); // Web server start
   DEBUG_WM(F("HTTP server started"));
+
+  WiFi_scanNetworks(); // preload wifiscan 
 }
 
 boolean WiFiManager::startConfigPortal() {
@@ -696,7 +698,8 @@ void WiFiManager::handleRoot() {
 
   server->sendHeader(FPSTR(HTTP_HEAD_CL), String(page.length()));
   server->send(200, FPSTR(HTTP_HEAD_CT), page);
-  // server->close(); // testing reliability fix for content length mismatches during mutiple flood hits
+  // server->close(); // testing reliability fix for content length mismatches during mutiple flood hits  WiFi_scanNetworks(); // preload wifiscan 
+  WiFi_scanNetworks(10000); // preload wifiscan throttled
 }
 
 /**
@@ -707,6 +710,7 @@ void WiFiManager::handleWifi(boolean scan) {
   handleRequest();
   String page = getHTTPHead(FPSTR(S_titlewifi)); // @token titlewifi
   if (scan) {
+    if(server->hasArg(F("refresh"))) WiFi_scanNetworks(true); // preload wifiscan, force
     page += getScanItemOut();
   }
   String pitem = "";
@@ -775,11 +779,28 @@ String WiFiManager::getMenuOut(){
   return page;
 }
 
-String WiFiManager::getScanItemOut(){
+bool WiFiManager::WiFi_scanNetworks(){
+  return WiFi_scanNetworks(false);
+}
+bool WiFiManager::WiFi_scanNetworks(int cachetime){
+    return WiFi_scanNetworks(millis()-_lastscan > cachetime);
+}
+bool WiFiManager::WiFi_scanNetworks(bool force){
+    DEBUG_WM(_numNetworks,(millis()-_lastscan ));
+    if(force || _numNetworks == 0 || (millis()-_lastscan > 60000)){
+      _numNetworks = WiFi.scanNetworks();
+      _lastscan = millis();
+      DEBUG_WM(F("Scan done"));
+      return true;
+    } else DEBUG_WM("Scan is cached");
+    return false;
+}
+
+String WiFiManager::WiFiManager::getScanItemOut(){
     String page;
 
-    int n = WiFi.scanNetworks();
-    DEBUG_WM(F("Scan done"));
+    int n = _numNetworks;
+    WiFi_scanNetworks();
     if (n == 0) {
       DEBUG_WM(F("No networks found"));
       page += FPSTR(S_nonetworks); // @token nonetworks
diff --git a/WiFiManager.h b/WiFiManager.h
index 438f004..4571c52 100644
--- a/WiFiManager.h
+++ b/WiFiManager.h
@@ -245,7 +245,9 @@ class WiFiManager
     WiFiMode_t    _usermode               = WIFI_OFF;
     String        _wifissidprefix         = FPSTR(S_ssidpre); // auto apname prefix prefix+chipid
     uint8_t       _lastconxresult         = WL_IDLE_STATUS;
-    
+    int           _numNetworks            = 0;
+    unsigned long _lastscan               = 0; // ms
+
     #ifdef ESP32
     static uint8_t _lastconxresulttmp; // tmp var for esp32 callback
     #endif
@@ -312,6 +314,9 @@ class WiFiManager
     bool          WiFi_hasAutoConnect();
     void          WiFi_autoReconnect();
     String        WiFi_SSID();
+    bool          WiFi_scanNetworks();
+    bool          WiFi_scanNetworks(bool force);
+    bool          WiFi_scanNetworks(int cachetime);
 
     #ifdef ESP32
     static void   WiFiEvent(WiFiEvent_t event, system_event_info_t info);