// ----------------------------------------------------------------
//
//
//       ESP32 / ESp8266  very basic web server demo - 11Jan21
//
//       shows use of AJAX to show updating info on the web page
//
//
// ----------------------------------------------------------------


//   ---------------------------------------------------------------------------------------------------------

//                                      Wifi Settings

#include <wifiSettings.h>       // delete this line, un-comment the below two lines and enter your wifi details

//const char *SSID = "your_wifi_ssid";

//const char *PWD = "your_wifi_pwd";


//   ---------------------------------------------------------------------------------------------------------



bool serialDebug = 1;          // enable debugging info on serial port
  


// ----------------------------------------------------------------
  

//#include <arduino.h>         // required by platformio?

#if defined ESP32
    // esp32
        byte LEDpin = 2; 
        #include <WiFi.h>
        #include <WebServer.h>
        #include <HTTPClient.h>     
        WebServer server(80);
#elif defined ESP8266
    //Esp8266
        byte LEDpin = D4; 
        #include <ESP8266WiFi.h>  
        #include <ESP8266WebServer.h>  
        #include "ESP8266HTTPClient.h"    
        ESP8266WebServer server(80);  
#else
      #error "This sketch only works with the ESP8266 or ESP32"
#endif


// ----------------------------------------------------------------

  
// this section runs once at startup 

  
void setup() {

  Serial.begin(115200);       // start serial comms at speed 115200
  delay(200);
  Serial.println("\n\nWebserver demo sketch");
  Serial.println("- Reset reason: " + ESP.getResetReason());
  
  // onboard LEDs
    pinMode(LEDpin, OUTPUT);
    digitalWrite(LEDpin, HIGH);   
  
  // Connect to Wifi
    Serial.print("Connecting to ");
    Serial.println(SSID);
    WiFi.begin(SSID, PWD);
    while (WiFi.status() != WL_CONNECTED) {
      Serial.print(".");
      delay(500);
    }
    Serial.print("\nConnected - IP: ");
    Serial.println(WiFi.localIP());

  // set up web server pages to serve
    server.on("/", handleRoot);                   // root web page (i.e. when root page is requested run procedure 'handleroot')
    server.on("/test", handleTest);               // test web page 
    server.on("/button", handleButton);           // demo simple use of buttons
    server.on("/ajax", handleAJAX);               // demo using AJAX to update information on the page (also javascript buttons)
      server.on("/senddata", handleSendData);     // requested by the AJAX web page to request current millis value
      server.on("/setLED", handleLED);            // action when a button is clicked on the AJAX page 
    server.onNotFound(handleNotFound);            // if invalid url is requested

  // start web server
    server.begin();    
    
    // stop the wifi being turned off if not used for a while 
      #if defined ESP32
        WiFi.setSleep(false); 
      #else
        WiFi.setSleepMode(WIFI_NONE_SLEEP); 
      #endif
        
    WiFi.mode(WIFI_STA);                          // turn off access point - options are WIFI_AP, WIFI_STA, WIFI_AP_STA or WIFI_OFF 
        
}  // setup



// ----------------------------------------------------------------


// this section runs repeatedly in a loop


void loop() {

  server.handleClient();                         // service any web page requests 

  //// flash onboard LED
  //digitalWrite(LEDpin, !digitalRead(LEDpin));    // invert onboard LED status 
  //delay(200);                                    // wait 200 milliseconds
  
}  // loop



// ----------------------------------------------------------------
//      -test web page requested     i.e. http://x.x.x.x/
// ----------------------------------------------------------------
// demonstrate sending a plain text reply

void handleRoot(){

  if (serialDebug) Serial.println("Root page requested");

  String message = "root web page";

  server.send(404, "text/plain", message);   // send reply as plain text
  
}  // handleRoot



// ----------------------------------------------------------------
//      -test web page requested     i.e. http://x.x.x.x/test
// ----------------------------------------------------------------
// demonstrate sending html reply

void handleTest(){

  if (serialDebug) Serial.println("Test page requested");

  WiFiClient client = server.client();     // open link with client

  // html header
    client.print("<!DOCTYPE html> <html lang='en'> <head> <title>Web Demo</title> </head> <body>\n");         // basic html header

  // html body
    client.print("<h1>Test Page</h1>\n");

  // end html
    client.print("</body></html>\n");
    delay(3);
    client.stop();
  
}  // handleTest



// ----------------------------------------------------------------
//      -button web page requested     i.e. http://x.x.x.x/button
// ----------------------------------------------------------------
// demonstrate simple use of a html buttons without using Javascript

void handleButton(){

  if (serialDebug) Serial.println("Button page requested");
    
  // check if button1 has been pressed
    if (server.hasArg("button1")) {
        Serial.println("Button 1 was pressed");       
    }

  // check if button2 has been pressed
    if (server.hasArg("button2")) {
        Serial.println("Button 2 was pressed");       
    }

    
  // send reply to client
    
  WiFiClient client = server.client();     // open link with client

  // html header
    client.print("<!DOCTYPE html> <html lang='en'> <head> <title>Web Demo</title> </head> <body>\n");         // basic html header
    client.print("<FORM action='/button' method='post'>\n");       // used by the buttons in the html (action = the web page to send it to
    
  // html body
    client.print("<h1>Button demo page</h1>\n");
    if (server.hasArg("button1")) client.print("Button 1 has been pressed!");
    if (server.hasArg("button2")) client.print("Button 2 has been pressed!");
    client.print("<br><br><input style='height: 35px;' name='button1' value='Demo button 1' type='submit'> \n");
    client.print("<br><br><input style='height: 35px;' name='button2' value='Demo button 2' type='submit'> \n");

  // end html
    client.print("</body></html>\n");
    delay(3);
    client.stop();
  
}  // handleButton


// ----------------------------------------------------------------
//      -ajax web page requested     i.e. http://x.x.x.x/ajax
// ----------------------------------------------------------------
// demonstrate use of AJAX to refresh info. on web page
// see:  https://circuits4you.com/2018/02/04/esp8266-ajax-update-part-of-web-page-without-refreshing/
  
void handleAJAX() {

  WiFiClient client = server.client();     // open link with client

  // log page request including clients IP address
    IPAddress cip = client.remoteIP();
    Serial.println("Ajax page requested from: " + String(cip[0]) +"." + String(cip[1]) + "." + String(cip[2]) + "." + String(cip[3]) );
  
  
  //     ---------------------- html ----------------------
  
  client.print (R"=====(
    
    <!DOCTYPE html>
    <html lang='en'>
    <head>
        <title>AJAX Demo</title>
    </head>

    <body>
    <div id='demo'>
        <h1>Update web page using AJAX</h1>
        <button type='button' onclick='sendData(1)'>LED ON</button>
        <button type='button' onclick='sendData(0)'>LED OFF</button><BR>
    </div>
    <div>
        Current Millis : <span id='MillisValue'>0</span><br>
        Received text : <span id='ReceivedText'>NA</span><br>
        LED State is : <span id='LEDState'>NA</span><br>
    </div>
      
  )=====");
  
  //     ------------------- JavaScript -------------------  

  client.print (R"=====(<script>

      function sendData(led) {
        var xhttp = new XMLHttpRequest();
        xhttp.onreadystatechange = function() {
          if (this.readyState == 4 && this.status == 200) {
            document.getElementById('LEDState').innerHTML = this.responseText;
          }
       };
       xhttp.open('GET', 'setLED?LEDstate='+led, true);
       xhttp.send();}
       
       function getData() {
          var xhttp = new XMLHttpRequest();
          xhttp.onreadystatechange = function() {
          if (this.readyState == 4 && this.status == 200) {
            var receivedArr = this.responseText.split(',');
            document.getElementById('MillisValue').innerHTML = receivedArr[0];
            document.getElementById('ReceivedText').innerHTML = receivedArr[1];
          }
       };
       xhttp.open('GET', 'senddata', true);
       xhttp.send();}
       
       setInterval(function() {
          getData();
        }, 2000);
          
  </script>)=====");
  //     --------------------------------------------------    

  // close html page
    client.print("</body></html>\n");        // close HTML
    delay(3);
    client.stop();
  
}   // handleAJAX


// send data to AJAX web page
//   it replies with two items comma separated: the value in millis and some text
void handleSendData() {
   String reply = String(millis());                     // item 1 
   reply += ",";
   reply += "This text sent by handleSendtime()";       // item 2
   server.send(200, "text/plane", reply); //Send millis value only to client ajax request
}


// handle button clicks on AJAX web page
//    it sets the onboard LED status and replies with it's status as plain text
void handleLED() {
    String ledState = "OFF";
    String t_state = server.arg("LEDstate");     //Refer  xhttp.open("GET", "setLED?LEDstate="+led, true);
    Serial.println(t_state);
    if(t_state == "1") {
      digitalWrite(LEDpin,LOW);                   //LED ON
      ledState = "ON";                            //Feedback parameter
    } else {
      digitalWrite(LEDpin,HIGH);                  //LED OFF
      ledState = "OFF";                           //Feedback parameter  
    }
    server.send(200, "text/plane", ledState);     //Send web page
}


// ----------------------------------------------------------------
//                      -invalid web page requested
// ----------------------------------------------------------------
// send this reply to any invalid url requested

void handleNotFound() {

  if (serialDebug) Serial.println("Invalid page requested");

  String tReply;
  
  tReply = "File Not Found\n\n";
  tReply += "URI: ";
  tReply += server.uri();
  tReply += "\nMethod: ";
  tReply += ( server.method() == HTTP_GET ) ? "GET" : "POST";
  tReply += "\nArguments: ";
  tReply += server.args();
  tReply += "\n";

  for ( uint8_t i = 0; i < server.args(); i++ ) {
    tReply += " " + server.argName ( i ) + ": " + server.arg ( i ) + "\n";
  }

  server.send ( 404, "text/plain", tReply );
  tReply = "";      // clear variable
  
}  // handleNotFound



// ----------------------------------------------------------------------------------------------------------------


// Not used in this sketch but provided as an example of how to request an external web page and receive the reply as a string


// ----------------------------------------------------------------
//                        request a web page
// ----------------------------------------------------------------
//     parameters = ip address, page to request, port to use (usually 80), maximum chars to receive, ignore all in reply before this text 
//          e.g.   String reply = requestWebPage("192.168.1.166","/log",80,600,"");

String requestWebPage(String ip, String page, int port, int maxChars, String cuttoffText = ""){

  int maxWaitTime = 3000;                 // max time to wait for reply (ms)

  char received[maxChars + 1];            // temp store for incoming character data
  int received_counter = 0;               // number of characters which have been received

  if (!page.startsWith("/")) page = "/" + page;     // make sure page begins with "/" 

  if (serialDebug) {
    Serial.print("requesting web page: ");
    Serial.print(ip);
    Serial.println(page);
  }
     
    WiFiClient client;

    // Connect to the site 
      if (!client.connect(ip.c_str() , port)) {                                      
        if (serialDebug) Serial.println("Web client connection failed");   
        return "web client connection failed";
      } 
      if (serialDebug) Serial.println("Connected to host - sending request...");
    
    // send request - A basic request looks something like: "GET /index.html HTTP/1.1\r\nHost: 192.168.0.4:8085\r\n\r\n"
      client.print("GET " + page + " HTTP/1.1\r\n" +
                   "Host: " + ip + "\r\n" + 
                   "Connection: close\r\n\r\n");
  
      if (serialDebug) Serial.println("Request sent - waiting for reply...");
  
    // Wait for a response
      uint32_t ttimer = millis();
      while ( !client.available() && (uint32_t)(millis() - ttimer) < maxWaitTime ) {
        delay(10);
      }
      if ( ((uint32_t)(millis() - ttimer) > maxWaitTime ) && serialDebug) Serial.println("-Timed out");

    // read the response
      while ( client.available() && received_counter < maxChars ) {
        delay(4);      
        received[received_counter] = char(client.read());     // read one character
        received_counter+=1;
      }
      received[received_counter] = '\0';     // end of string marker
            
    if (serialDebug) {
      Serial.println("--------received web page-----------");
      Serial.println(received);
      Serial.println("------------------------------------");
      Serial.flush();     // wait for serial data to finish sending
    }
    
    client.stop();    // close connection
    if (serialDebug) Serial.println("Connection closed");

    // if cuttoffText was supplied then only return the text following this 
      if (cuttoffText != "") {
        char* locus = strstr(received,cuttoffText.c_str());    // locus = pointer to the found text
        if (locus) {                                           // if text was found
          if (serialDebug) Serial.println("The text '" + cuttoffText + "' was found in reply");
          return locus;                                        // return the reply text following 'cuttoffText'
        } else if (serialDebug) Serial.println("The text '" + cuttoffText + "' WAS NOT found in reply");
      }
    
  return received;        // return the full reply text
}


// ----------------------------------------------------------------
// end