ESP IP Button

/* This program is a mash up of the example given in Rui Santos'
 * Home Automation course, some code I found at
 * https://tttapa.github.io/ESP8266/Chap10%20-%20Simple%20Web%20Server.html
 * (Be sure to read the whole beginner's guide https://tttapa.github.io) for
 * tons of good info! EXCELLENT!) and I used some html code found on the web,
 * that I cannot seem to find again. The latter taught me to put the web
 * pagebutton into a string  * variable, and send it as a string...good idea!
 *
 * Rui's code allowed toggling pins on an ESP8266 from a web page
 * served from the ESP, as did Pieter's little GitHub Page from the link above,
 * but the pages did not include a pin status on the control webpage after it
 * updated. With a bit of tweaking, I now have this feature running on an
 * ESP8266-07, and I am quite thrilled! :) It simply controls the
 * built in LED on the board, (the first step to controlling the WORLD!),
 * and the page notifies you of the current state of the LED (on/off).
 *
 * Thanks to those that made this possible!!
 *
 * Please feel free to use this code as you wish.
 */

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WiFiMulti.h>
#include <ESP8266mDNS.h>
#include <ESP8266WebServer.h>


String form =                                             // String form to sent to the client-browser
  "<p>"
  "<center>"
  "<h1>ESP8266 Pin D2 LED Controller</h1>"
  "<form action=\"/LED\" method=\"POST\"><input type=\"submit\" value=\"Toggle LED\"></form>" //display a form button"
  "</center>";

ESP8266WiFiMulti wifiMulti;     // Create an instance of the ESP8266WiFiMulti class, called 'wifiMulti'

ESP8266WebServer server(80);    // Create a webserver object that listens for HTTP request on port 80
String ledStatus;
const int led = 2;

void handleRoot();              // function prototypes for HTTP handlers
void handleLED();
void handleNotFound();

void setup(void){
  Serial.begin(115200);         // Start the Serial communication to send messages to the computer
  delay(10);
  Serial.println('\n');
  Serial.println("ESP IP Button");
  Serial.println();

  pinMode(led, OUTPUT);

  wifiMulti.addAP("SSID", "PASSWORD");   // add Wi-Fi networks you want to connect to
  wifiMulti.addAP("SSID", "PASSWORD");
  wifiMulti.addAP("SSID", "PASSWORD");

  Serial.println("Connecting ...");
  int i = 0;
  while (wifiMulti.run() != WL_CONNECTED) { // Wait for the Wi-Fi to connect: scan for Wi-Fi networks, and connect to the strongest of the networks above
    delay(250);
    Serial.print('.');
  }
  Serial.println('\n');
  Serial.print("Connected to ");
  Serial.println(WiFi.SSID());              // Tell us what network we're connected to
  Serial.print("IP address:\t");
  Serial.println(WiFi.localIP());           // Send the IP address of the ESP8266 to the computer

  if (MDNS.begin("esp8266")) {              // Start the mDNS responder for esp8266.local
    Serial.println("mDNS responder started");
  } else {
    Serial.println("Error setting up MDNS responder!");
  }

  server.on("/", HTTP_GET, handleRoot);     // Call the 'handleRoot' function when a client requests URI "/"
  server.on("/LED", HTTP_POST, handleLED);  // Call the 'handleLED' function when a POST request is made to URI "/LED"
  server.onNotFound(handleNotFound);        // When a client requests an unknown URI (i.e. something other than "/"), call function "handleNotFound"

  server.begin();                           // Actually start the server
  Serial.println("HTTP server started");
}

void loop(void){
  server.handleClient();                    // Listen for HTTP requests from clients
}

void handleRoot() {                         // When URI / is requested, send a web page with a button to toggle the LED
  bool ledState = digitalRead(led);  //state storage
   if (ledState == false){
       ledStatus= "<center><p> LED is ON </p></center>";
   }
   else{
       ledStatus= "<center><p> LED is OFF </p></center>";
   }
   Serial.println(!ledState);

  server.send(200, "text/html", form+ledStatus); //display a form button
}

void handleLED() {                          // If a POST request is made to URI /LED
  digitalWrite(led,!digitalRead(led));      // Change the state of the LED
  server.sendHeader("Location","/");        // Add a header to respond with a new location for the browser to go to the home page again
  server.send(303);                         // Send it back to the browser with an HTTP status 303 (See Other) to redirect
}

void handleNotFound(){
  server.send(404, "text/plain", "404: Not found"); // Send HTTP status 404 (Not Found) when there's no handler for the URI in the request
}