Use WiFiManager for initial config and reset config with button press

main.ino

@@ -1,25 +1,79 @@
-#define RELAY_PIN 12
-#define LED_PIN 13
+#include <ESP8266WiFi.h>          //https://github.com/esp8266/Arduino
 
+//needed for library
+#include <DNSServer.h>
+#include <ESP8266WebServer.h>
+#include <WiFiManager.h>          //https://github.com/tzapu/WiFiManager
+
+//for LED status
+#include <Ticker.h>
+Ticker ticker;
+
+const byte LED_PIN = 13;
+const byte BUTTON_PIN = 0;
+
+void tick()
+{
+  //toggle state
+  int state = digitalRead(LED_PIN);  // get the current state of LED_PIN pin
+  digitalWrite(LED_PIN, !state);     // set pin to the opposite state
+}
+
+//gets called when WiFiManager enters configuration mode
+void configModeCallback (WiFiManager *myWiFiManager) {
+  Serial.println("Entered config mode");
+  Serial.println(WiFi.softAPIP());
+  //if you used auto generated SSID, print it
+  Serial.println(myWiFiManager->getConfigPortalSSID());
+  //entered config mode, make led toggle faster
+  ticker.attach(0.2, tick);
+}
+
+WiFiManager wifiManager;
 void setup() {
+  // put your setup code here, to run once:
   Serial.begin(115200);
-
-  Serial.println("START");
-
+  
+  //set led pin as output
   pinMode(LED_PIN, OUTPUT);
+  // start ticker with 0.5 because we start in AP mode and try to connect
+  ticker.attach(0.6, tick);
 
-}
+  pinMode(BUTTON_PIN, INPUT);
 
-void loop() {
+  //WiFiManager
+  //Local intialization. Once its business is done, there is no need to keep it around
+  //WiFiManager wifiManager;
+  //reset settings - for testing
+  //wifiManager.resetSettings();
 
-  digitalWrite(LED_PIN, HIGH);
+  //set callback that gets called when connecting to previous WiFi fails, and enters Access Point mode
+  wifiManager.setAPCallback(configModeCallback);
 
-  delay(1000);
+  //fetches ssid and pass and tries to connect
+  //if it does not connect it starts an access point with the specified name
+  //here  "AutoConnectAP"
+  //and goes into a blocking loop awaiting configuration
+  if (!wifiManager.autoConnect()) {
+    Serial.println("failed to connect and hit timeout");
+    //reset and try again, or maybe put it to deep sleep
+    ESP.reset();
+    delay(1000);
+  }
 
+  //if you get here you have connected to the WiFi
+  Serial.println("connected...yeey :)");
+  ticker.detach();
+  //keep LED on
   digitalWrite(LED_PIN, LOW);
-
-  delay(1000);
-
-  Serial.println("LED");
-
+}
+
+bool button_state = 0;
+void loop() {
+  // put your main code here, to run repeatedly:
+  button_state = digitalRead(BUTTON_PIN);
+  if (button_state == 0) {
+    wifiManager.resetSettings();
+    ESP.reset();
+  }
 }