#include <SPI.h>
#include <MFRC522.h>
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <EEPROM.h>

#define RST_PIN     5     // SPI Reset Pin (D1  Ausgang)
#define RELAIS_PIN  16    // Relais (D0  Ausgang) [LOW Aktiv] - Auch interne LED nahe USB Port
#define SS_PIN      15    // SPI Slave Select Pin

#define RGBLED_R    2     // Rot (D4  Ausgang) 
#define RGBLED_G    0     // Grün (D3  Ausgang) - Auch interne LED auf dem ESP Modul
#define RGBLED_B    4     // Blau (D2  Ausgang)

#define WiFiPwdLen   25   // Maximale WiFi Passwortlänge
#define STANameLen 20     // Maximale WiFi SSIDlänge
#define ESPHostNameLen 20 // Maximale Anzahl Zeichen ESPHostName

#define LED_BUILTIN 16
#define PIN_WIRE_SDA 4 
#define PIN_WIRE_SCL 5 

ADC_MODE(ADC_TOUT);   // Analogeingang A0 auf extern konfigurieren. ADC_TOUT (for external voltage), ADC_VCC (for system voltage). 
MFRC522 mfrc522(SS_PIN, RST_PIN);   // Instanz des MFRC522 erzeugen
MFRC522::MIFARE_Key key;
ESP8266WebServer server(80);        // Web Server Instanz erzeugen

struct WiFiEEPromData
  {
    char ESPHostName[ESPHostNameLen]; 
    char APSTAName[STANameLen]; // STATION /AP Point Name TO Connect, if definded   
    char WiFiPwd[WiFiPwdLen]; // WiFiPAssword, if definded    
    char ConfigValid[3]; //If Config is Vaild, Tag "TK" is required"
  };

struct PICCardEEPRomData
  {
    char CardVaildUID[4];
    char Reserved[4];
  };

WiFiEEPromData MyWiFiConfig;
PICCardEEPRomData MyEEPROMValidCardUID;

// Global Genutzte Variable
bool Result  = false;
bool LearnNewCard = false;
String temp ="";
unsigned long SessionID;

void setup()  
  { 
  pinMode(RST_PIN,OUTPUT);
  digitalWrite(RST_PIN,HIGH);
  pinMode(RELAIS_PIN,OUTPUT);
  pinMode(RGBLED_R,OUTPUT);
  pinMode(RGBLED_G,OUTPUT);
  pinMode(RGBLED_B,OUTPUT);
  digitalWrite(RELAIS_PIN,HIGH);    // Relais inaktiv
  SetRGBLed(0,0,0,false);            //Led AUS
  Serial.begin(115200);               // Serielle Kommunikation mit dem PC mit 115200 Baud initialisieren
  yield();
  Serial.println("");
  temp = "ATSN:"+ String(ESP.getChipId());
  Serial.println(temp);
  // Serial.print("ADC Value:");Serial.println(analogRead(A0));
  SPI.begin();                      // Initialisiere SPI Kommunikation
  ESP.wdtEnable(WDTO_4S);              // Starte Watchdog
  ESP.wdtFeed(); 
  digitalWrite(RST_PIN,LOW);
  SessionID = millis();
  ESP.wdtFeed();
  Result  = startWiFiClient();
  ESP.wdtFeed();  
  yield();
  EEPROM.begin(512);
  EEPROM.get(100,MyEEPROMValidCardUID);   // Ab Adresse 100 wird die gültige KArte abgelegt
  EEPROM.end();
  InitalizeHTTPServer();
  digitalWrite(RST_PIN,HIGH);
  mfrc522.PCD_Reset();
  mfrc522.PCD_Init();              // Initialisiere MFRC522 Lesemodul
  mfrc522.PCD_AntennaOn();
  yield();
  ESP.wdtFeed();
  SetRGBLed(255,0,255,false);       //Led Farbe Lila Initalisierung abgeschlossen
  }


// ******************* Start Helper/ Optimization Functions ********************************

void SetRGBLed(byte RedValue,byte GreenValue,byte BlueValue,boolean SlowFade)  //Funkion zur Steuerung der RGB Led
{
  digitalWrite(RGBLED_R,LOW);    
  digitalWrite(RGBLED_G,LOW);
  digitalWrite(RGBLED_B,LOW); 
  if (RedValue == 255)   { digitalWrite(RGBLED_R,HIGH); }   
  if (GreenValue == 255) { digitalWrite(RGBLED_G,HIGH); }
  if (BlueValue == 255)  { digitalWrite(RGBLED_B,HIGH); }   
}

// ******************* Stop Helper/ Optimization Functions *********************************

// ******************* Start Functions Webserver *******************************************

//Cookie Basisroutinen basieren auf GIT Auszug:
//https://github.com/esp8266/ESPWebServer/blob/master/examples/SimpleAuthentification/SimpleAuthentification.ino
bool is_authentified()
{ 
   if (server.hasHeader("Cookie")){ 
     // Cookie gefunden
     temp = server.header("Cookie"); 
     //Serial.println(temp);
     String SessionStr = String(ESP.getChipId()) + "=" + String(SessionID);
     if (temp.indexOf(SessionStr) != -1) { 
       // Web Authentification erfolgreich
       temp = "";
       return true; 
     } 
   }    
   // Web Authentification fehlgeschlagen
   temp = "";
   SessionID = millis();
   return false; 
} 

void handleLogin(){
  String msg;
  //String cookie = server.header("Cookie");
  //Serial.println(cookie);
  if (server.hasArg("DISCONNECT")){
    //Disconnection Benutzers;
    server.sendHeader("Location","/login");
    server.sendHeader("Cache-Control","no-cache");
    SessionID = millis();
    temp = String(ESP.getChipId()) + "= NA ; HttpOnly ; SameSite=Strict";
    server.sendHeader("Set-Cookie",temp);
    temp = "";
    server.send(301);
    return;
  }
  if (server.hasArg("USERNAME") && server.hasArg("PASSWORD")){
    temp = String(ESP.getChipId());
    if (server.arg("USERNAME") == "admin" &&  server.arg("PASSWORD") == temp ){
      server.sendHeader("Location","/");
      server.sendHeader("Cache-Control","no-cache");
      SessionID = millis();
      temp = String(ESP.getChipId()) + "=" + String(SessionID) + "; HttpOnly ; SameSite=Strict";
      server.sendHeader("Set-Cookie",temp);
      temp = "";
      server.send(301);
      return;
    }
  msg = "<script>alert('Falscher Benutzername oder falsches Passwort !');</script>";
  }
   CSS_Header_Template();
   temp = "<head><title>Login</title></head><body><DIV ALIGN=CENTER>";
   server.sendContent(temp);
   temp = "<h2>Anmeldung an Kartenleser RC522</h2><body><br><br><table border=0 bgcolor=black><tr><th><DIV ALIGN=RIGHT>";
   server.sendContent(temp);
   temp = "<form action='/login' method='post'>Benutzername: <input type=text Name='USERNAME' Size=17 required><br>";
   server.sendContent(temp);
   temp = "Passwort: <input type=password Name='PASSWORD' Size=17 required><br><br><br><button type='submit' ";
   server.sendContent(temp);
   temp = "name='Login_Button' value='1' style='height: 30px; width: 100px' >Login</button><br></th></tr></form></DIV></table>";
   server.sendContent(temp);
   temp = "<br><SMALL>Damit die Anmeldung funktioniert, sind Cookies für diese Webseite zu erlauben.</SMALL>";  
   server.sendContent(temp);
   temp = msg + "</DIV></body></HTML>";
   server.sendContent(temp);
   temp = "";
}

void handleNotFound() 
  {
  SessionID = millis();
  temp = "Seite nicht gefunden.\n\n";
  temp += "URI: ";
  temp += server.uri();
  temp += "\nMethod: ";
  temp += (server.method() == HTTP_GET)?"GET":"POST";
  temp += "\nArguments: ";
  temp += server.args();
  temp += "\n";
  for (uint8_t i=0; i<server.args(); i++){
    temp += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", temp);
  temp = "";
  }


void handleNewPICC()
{
  if (!is_authentified())
    {
    server.sendHeader("Location","/login");
    server.sendHeader("Cache-Control","no-cache");
    server.send(301);
    return;
    }
  CSS_Header_Template();
  temp = "<head><title>Kartenleser RC522</title></head><body>";
  server.sendContent(temp);
  HtmlNavStructure();
  temp = "<script>alert('Bitte JETZT Karte vor den Leser halten!');</script>";   
  server.sendContent(temp);
  SetRGBLed(255,255,0,false);       //Led Farbe Gelb Programmierungsmodus
  LearnNewCard = true;    
  temp = "</body></html>";
  server.sendContent(temp);
  server.client().stop();
  temp = "";
}



void handleRoot(){
  if (!is_authentified()){
    server.sendHeader("Location","/login");
    server.sendHeader("Cache-Control","no-cache");
    server.send(301);
    return;
    }
  // HTML Content
  CSS_Header_Template();
  temp = "<head><title>Kartenleser RC522</title></head><body>";
  server.sendContent(temp);
  HtmlNavStructure();
  temp = "<div ALIGN=CENTER><br><br><br><br><BIG>Willkommen auf der Smartkartenleser RC522 Webseite.</BIG><br>";
  server.sendContent(temp);
  temp = "Resetgrund: " + String(ESP.getResetReason()) + "<br>";
  server.sendContent(temp);
  temp = "Freier Heapspeicher: " + String(ESP.getFreeHeap()) + " Bytes<br>";
  server.sendContent(temp);
  temp = "Int. Flash: " + String(ESP.getFlashChipRealSize()) + " Bytes<br>";
  server.sendContent(temp);
  Result = mfrc522.PCD_PerformSelfTest(); 
  mfrc522.PCD_Init();                       // Initialisiere MFRC522 Lesemodul
  mfrc522.PCD_AntennaOn(); 
  if (Result) {temp = "RC522 PCD-Status: OK<br>"; } else {temp = "RC522 PCD-Status: Fehler!<br>"; } 
  server.sendContent(temp);
  temp = "CPU ID: " + String(ESP.getChipId()) + " @ " + String(ESP.getCpuFreqMHz()) + " MHz<br>"; 
  server.sendContent(temp);
  temp = "<br>Sie sind erfolgreich angemeldet !<br><br><form action='/login' method='get'>";
  server.sendContent(temp);
  temp = "<button type='submit' name='DISCONNECT' value='YES' style='height: 30px; width: 200px' >Logout</button>";
  server.sendContent(temp);
  temp = "</form></div></body></html>";
  server.sendContent(temp);
  if (server.hasArg("Reboot") )  // Reboot System 
    {
    ESP.wdtFeed();        
    ESP.wdtDisable();
    temp = "<script>alert('Das System startet JETZT neu.');</script>";   
    server.sendContent(temp);
    server.client().stop();
    temp = "";
    delay(1000); 
    ESP.reset();
    delay(4000); 
    }  
  server.client().stop();
  temp = "";
}

void CSS_Header_Template() // Formatvorlage für alle internen ESP Webseiten. https://wiki.selfhtml.org/wiki/CSS
  {
   server.setContentLength(CONTENT_LENGTH_UNKNOWN);
   temp = "<!DOCTYPE HTML PUBLIC '-/-//W3C//DTD HTML 4.01 Transitional//EN'><html lang='de'><meta charset='UTF-8'>";
   server.send (200, "text/html", temp);
   temp = "<style type='text/css'>*{margin: 0;padding: 0;}body{background:black;color:darkorchid;font-size: 16px;";
   server.sendContent(temp);
   temp = "font-family: sans-serif,arial;}.nav{width: 1300px;height: 30px;margin: 0 auto;border-radius: 5px;}";
   server.sendContent(temp);
   temp = "ul li{list-style: none;width: 200px;line-height: 60px;position: relative;background: darkorchid;";
   server.sendContent(temp);
   temp = "box-shadow: 0px 2px 5px 0px grey;text-align: center;float: left;background-color: #010000;}ul li ul{";
   server.sendContent(temp);
   temp = "position: absolute;}.nav > ul > li:nth-of-type(1){border-radius: 5px 0px 0px 5px;}.nav > ul > li:nth-of-type(5)";
   server.sendContent(temp);
   temp = "{border-radius: 0px 5px 5px 0px;}ul li a{color: rgb(182, 18, 18);width: 200px;height: 58px;display: inline-block;";
   server.sendContent(temp);
   temp = "text-decoration: none;}ul li a:hover{font-weight: bold;border-bottom: 2px solid #fff;}ul li ul{display: none;}";
   server.sendContent(temp);
   temp = ".nav ul li:hover ul{display: block;}.fa{margin-right: 5px;}.container{width: 1000px;height: 200px;";
   server.sendContent(temp);
   temp = "margin: 0 auto;padding:20px 20px;}@media screen and (max-width: 480px){header{width: 100%;}";
   server.sendContent(temp);
   temp = ".nav{display: none;width: 100%;height: auto;}ul li{width: 100%;float: none;}ul li a{width: 100%;";
   server.sendContent(temp);
   temp = "display: block;}ul li ul{position: static;}ul li ul li a{background: #222;}.fa-list.modify{display: block;}";
   server.sendContent(temp);
   temp = ".container{width: 100%;height: auto;}body{overflow-x:hidden;}}</style>";
   server.sendContent(temp);
   temp = "";
  }

void HtmlNavStructure()
  {
  temp = "<div class='menu'><nav class='nav'><ul>";
  server.sendContent(temp);
  temp = "<li><a href='#'>System</a>";
  server.sendContent(temp);
  temp = "<ul><li><a href='/'>Information</a></li>";
  server.sendContent(temp);
  temp = "<li><a href='/?Reboot=YES'>Neustart</a></li>";
  server.sendContent(temp);
  temp = "</ul>";
  server.sendContent(temp);
  temp = "</li><li><a href='#'>PICC</a>";
  server.sendContent(temp);
  temp = "<ul><li><a href='/newPICC'>Karte registrieren</a></li></ul>";
  server.sendContent(temp);
  temp = "</li>";
  server.sendContent(temp);
  temp = "</ul></nav></div>";
  server.sendContent(temp);
  temp = "";
  }
  
  
void InitalizeHTTPServer() 
  {
  bool initok = false;
  const char * headerkeys[] = {"User-Agent","Cookie"} ; //Header zum Tracken
  size_t headerkeyssize = sizeof(headerkeys)/sizeof(char*); //Header zum Tracken
  server.on("/", handleRoot);
  server.on("/login", handleLogin);
  server.on("/newPICC", handleNewPICC);
  server.onNotFound ( handleNotFound );
  server.collectHeaders(headerkeys, headerkeyssize );// Server anweisen, diese zu Tracken 
  server.begin(); // Web server start
  }
      
// ******************* End Functions Webserver *********************************************

// ******************* Start Functions WiFi Management *************************************
// Funktion von https://www.az-delivery.de/blogs/azdelivery-blog-fur-arduino-und-raspberry-pi/wps-mit-dem-esp8266?ls=de
bool startWPS() {
  bool wpsSuccess = WiFi.beginWPSConfig();
  if(wpsSuccess) {
      // Muss nicht immer erfolgreich heißen! Nach einem Timeout ist die SSID leer
      String newSSID = WiFi.SSID();
       if(newSSID.length() > 0) {
        // Nur wenn eine SSID gefunden wurde waren wir erfolgreich 
        yield(); 
        Serial.println("ATWPS:OK");
        saveCredentials(); // Save Credentials to EEPROM       
      } else {
        Serial.println("ATWPS:NOK");
      }
  }
  return wpsSuccess; 
}

bool startWiFiClient() {
  bool WiFiClientStarted = false;
  size_t A0_ADCValue = 0;
  byte i = 0;
  byte connRes = 0;
  Serial.setDebugOutput(false);  // Zu Debugzwecken aktivieren. 
  WiFi.hostname("CrdRdr41667");
  WiFi.softAPdisconnect(true);
  WiFi.disconnect();
  WiFi.mode(WIFI_STA);
  if(loadCredentials()) 
    {
     WiFi.begin(MyWiFiConfig.APSTAName, MyWiFiConfig.WiFiPwd);
     while (( connRes != 3 ) and( connRes != 4 ) and (i != 30))  //if connRes == 0  "IDLE_STATUS - change Statius"
      { 
      i++;
      // Serial.print("."); // Connect vorgang auf der seriellen Schnittstelle beobachten
      ESP.wdtFeed();
      delay(500);
      yield();
      connRes  = WiFi.waitForConnectResult();
      }
     if (connRes == 4 ) { // if password is incorrect
      Serial.println("ATWIFI:PWDERR");      
      WiFi.disconnect();
      }
     if (connRes == 6 ) { //  module is not configured in station mode
      Serial.println("ATWIFI:STAERR");
      WiFi.disconnect();
      } 
    }
  if(WiFi.status() == WL_CONNECTED) 
    {
    ESP.wdtFeed(); 
    Serial.print("ATIP:");
    Serial.println(WiFi.localIP());
    WiFi.setAutoReconnect(true); // Set whether module will attempt to reconnect to an access point in case it is disconnected.
    // Setup MDNS responder
    if (!MDNS.begin("CrdRdr41667")) 
      {
      Serial.println("ATMDNS:NOK");
      } else { MDNS.addService("http", "tcp", 80); }   
    WiFiClientStarted = true;
    } else 
    {
    A0_ADCValue = analogRead(A0);
    //Wir waren nicht erfolgreich, daher starten wir WPS, wenn WPS Taster an A0 während des Resets gedrückt ist
    if (A0_ADCValue > 499)
      {
        if(startWPS()) 
          {
            ESP.wdtFeed(); 
            delay(500);
            WiFi.disconnect();
            WiFi.mode(WIFI_STA);
            WiFi.begin(WiFi.SSID().c_str(), WiFi.psk().c_str());
            ESP.wdtFeed(); 
            WiFiClientStarted = true;
          } else
          {
            WiFiClientStarted = false;
            WiFi.disconnect();
          }
      } else
      {
        WiFi.disconnect();
      } 
  } 
  return WiFiClientStarted; 
}
// ******************* END Functions WiFi Management *************************************

// ******************* Start Functions Store WiFi Credentials to EEPROM ******************
bool loadCredentials() 
{
 bool RetValue;
 EEPROM.begin(512);
 EEPROM.get(0,MyWiFiConfig);
 EEPROM.end();
 if (String(MyWiFiConfig.ConfigValid) == "TK") 
  {
    RetValue = true;
  } else
  {
    RetValue = false; // WLAN Settings nicht gefunden.
  }
  ESP.wdtFeed(); 
  return RetValue; 
}

void saveCredentials() // Speichere WLAN credentials auf EEPROM 
{
  size_t i;
  for (i = 0 ; i < sizeof(MyWiFiConfig) ; i++) // Loeschen der alten Konfiguration
     {
      EEPROM.write(i, 0); 
     }
  for (i = 0 ; i < STANameLen  ; i++) // Loeschen der alten Konfiguration
     {
      MyWiFiConfig.WiFiPwd[i] = 0; 
     }
  for (i = 0 ; i < WiFiPwdLen ; i++) // Loeschen der alten Konfiguration
     {
      MyWiFiConfig.APSTAName[i] = 0; 
     }   
  temp = WiFi.SSID().c_str();
  i = temp.length();
  temp.toCharArray(MyWiFiConfig.APSTAName,i+1); 
  temp = WiFi.psk().c_str();
  i = temp.length();
  temp.toCharArray(MyWiFiConfig.WiFiPwd,i+1);
  temp = "";   
  strncpy(MyWiFiConfig.ConfigValid , "TK", sizeof(MyWiFiConfig.ConfigValid) ); 
  EEPROM.begin(512);
  EEPROM.put(0, MyWiFiConfig);
  EEPROM.commit();
  EEPROM.end();
  ESP.wdtFeed(); 
}
// ******************* END Functions StoreCredentialsto EEPROM ***************************
 
void loop()  // Hauptschleife
{
  // Nur wenn eine Karte gefunden wird und gelesen werden konnte, wird der Inhalt von IF ausgeführt
  if (mfrc522.PICC_IsNewCardPresent() && mfrc522.PICC_ReadCardSerial() )   // PICC = proximity integrated circuit card = kontaktlose Chipkarte
  {
    Serial.print("PICC UID:");
    for (byte i = 0; i < mfrc522.uid.size; i++) 
    {
      // Abstand zwischen HEX-Zahlen und führende Null bei Byte < 16
      Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
      Serial.print(mfrc522.uid.uidByte[i], HEX);
    } 
  bool IsValid = true;
  if (LearnNewCard)
  {
   for (byte i = 0; i < sizeof(MyEEPROMValidCardUID.CardVaildUID); i++) 
    {
     MyEEPROMValidCardUID.CardVaildUID[i] = mfrc522.uid.uidByte[i];
     EEPROM.begin(512);
     EEPROM.put(100,MyEEPROMValidCardUID);
     EEPROM.commit();
     EEPROM.end();
     LearnNewCard = false;
    } 
   IsValid = true;    
  } else
  {  
  for (byte i = 0; i < sizeof(MyEEPROMValidCardUID.CardVaildUID); i++) 
    {
    if (mfrc522.uid.uidByte[i] != MyEEPROMValidCardUID.CardVaildUID[i]) { IsValid = false; }    
    }
  }  
  if (IsValid)
   {
      bool PinState= digitalRead(RELAIS_PIN);
      PinState = !PinState;
      digitalWrite(RELAIS_PIN, PinState);
      SetRGBLed(0,255,0,false);        //Led Grün
      Serial.print("  gültig.");
      delay(2000);      
      SetRGBLed(0,0,255,false);        //Led Farbe Blau Leser ist in Grundzustand
   } else
   {      
      SetRGBLed(255,0,0,false) ;      //Led Rot - Letzte Karte war ungültig
      Serial.print(" ungültig.");
      delay(2000);   
   } 
    Serial.println(); 
   // mfrc522.PICC_HaltA();  // Versetzt die gelesene Karte in einen Ruhemodus, um nach anderen Karten suchen zu können.
    delay(100);
  }
  server.handleClient(); // Webserveranfragen bearbeiten
  yield();               // interne ESP8266 Funktionen aufrufen
  ESP.wdtFeed();         // Watchdog zurückstellen. 
  delay(20);
}