ESP32 RFID Access Control System

/*
 * ESP32 RFID Access Control — Advanced
 * Web admin panel + named users + MQTT events + CSV log export
 *
 * Endpoints:
 *   GET  /          — Admin panel HTML
 *   GET  /api/users — List all users (JSON)
 *   POST /api/enrol — Enrol card: present card within 10s after request
 *   POST /api/revoke?uid=XX:XX — Revoke by UID
 *   GET  /api/log   — Access log (JSON)
 *   GET  /api/log/csv — Download log as CSV
 *
 * Libraries: MFRC522, PubSubClient, WebServer (built-in)
 */
#include <SPI.h>
#include <MFRC522.h>
#include <WiFi.h>
#include <WebServer.h>
#include <PubSubClient.h>
#include <Preferences.h>
#include <time.h>

const char* SSID     = "YOUR_WIFI_SSID";
const char* PASSWORD = "YOUR_WIFI_PASSWORD";
const char* BROKER   = "192.168.1.100";
#define SS_PIN 5
#define RST_PIN 27
#define RELAY_PIN 26
#define LED_GREEN 33
#define LED_RED 32
#define BUZZER 25

MFRC522  rfid(SS_PIN, RST_PIN);
WebServer server(80);
WiFiClient net;
PubSubClient mqtt(net);
Preferences prefs;

struct User { String uid; String name; };
struct LogEntry { String uid; String name; bool granted; String ts; };

#define MAX_USERS 20
#define LOG_SIZE  50
User     users[MAX_USERS];
LogEntry log_[LOG_SIZE];
int      userCount=0, logHead=0;

bool enrolPending=false;
unsigned long enrolDeadline=0;
String enrolName;

String nowStr(){
  struct tm t; char b[20]="";
  if(getLocalTime(&t)) strftime(b,sizeof(b),"%Y-%m-%d %H:%M:%S",&t);
  return String(b);
}
String uidStr(byte* u,byte l){
  String s; for(byte i=0;i<l;i++){if(i)s+=":";s+=String(u[i],HEX);}
  s.toUpperCase(); return s;
}
void loadUsers(){
  userCount=prefs.getInt("count",0);
  for(int i=0;i<userCount;i++){
    users[i].uid  = prefs.getString(("u"+String(i)+"uid").c_str(),"");
    users[i].name = prefs.getString(("u"+String(i)+"nam").c_str(),"User");
  }
}
void saveUsers(){
  prefs.putInt("count",userCount);
  for(int i=0;i<userCount;i++){
    prefs.putString(("u"+String(i)+"uid").c_str(),users[i].uid);
    prefs.putString(("u"+String(i)+"nam").c_str(),users[i].name);
  }
}
void publishEvent(String uid,String name,bool ok){
  if(!mqtt.connected()) return;
  String j="{"uid":""+uid+"","user":""+name+"","granted":"+(ok?"true":"false")+","ts":""+nowStr()+""}";
  mqtt.publish("esp32engine/rfid/events",j.c_str());
}
void addLog(String uid,String name,bool ok){
  log_[logHead%LOG_SIZE]={uid,name,ok,nowStr()};
  logHead++;
  publishEvent(uid,name,ok);
}

// ── Web Handlers ────────────────────────────────────────────────
void handleUsers(){
  String j="[";
  for(int i=0;i<userCount;i++){
    if(i) j+=",";
    j+="{"uid":""+users[i].uid+"","name":""+users[i].name+""}";
  }
  j+="]"; server.send(200,"application/json",j);
}
void handleEnrol(){
  enrolName=server.hasArg("name")?server.arg("name"):"Unknown";
  enrolPending=true; enrolDeadline=millis()+10000;
  server.send(200,"text/plain","Present card within 10 seconds");
}
void handleRevoke(){
  String uid=server.arg("uid");
  for(int i=0;i<userCount;i++){
    if(users[i].uid==uid){
      users[i]=users[--userCount]; saveUsers();
      server.send(200,"text/plain","Revoked"); return;
    }
  }
  server.send(404,"text/plain","Not found");
}
void handleLog(){
  String j="["; int count=min(logHead,LOG_SIZE);
  for(int i=0;i<count;i++){
    auto& e=log_[i]; if(i) j+=",";
    j+="{"uid":""+e.uid+"","user":""+e.name+"","granted":"+(e.granted?"true":"false")+","ts":""+e.ts+""}";
  }
  j+="]"; server.send(200,"application/json",j);
}
void handleLogCSV(){
  String csv="UID,User,Granted,Timestampn";
  for(int i=0;i<min(logHead,LOG_SIZE);i++){
    auto& e=log_[i];
    csv+=e.uid+","+e.name+","+(e.granted?"YES":"NO")+","+e.ts+"n";
  }
  server.sendHeader("Content-Disposition","attachment; filename=access_log.csv");
  server.send(200,"text/csv",csv);
}

void setup(){
  Serial.begin(115200);
  SPI.begin(); rfid.PCD_Init();
  pinMode(RELAY_PIN,OUTPUT); digitalWrite(RELAY_PIN,LOW);
  pinMode(LED_GREEN,OUTPUT); pinMode(LED_RED,OUTPUT); pinMode(BUZZER,OUTPUT);
  prefs.begin("rfid2",false); loadUsers();
  WiFi.begin(SSID,PASSWORD);
  while(WiFi.status()!=WL_CONNECTED) delay(400);
  configTime(0,0,"pool.ntp.org");
  mqtt.setServer(BROKER,1883);
  mqtt.connect("rfid-controller");
  server.on("/api/users",HTTP_GET,handleUsers);
  server.on("/api/enrol",HTTP_POST,handleEnrol);
  server.on("/api/revoke",HTTP_POST,handleRevoke);
  server.on("/api/log",HTTP_GET,handleLog);
  server.on("/api/log/csv",HTTP_GET,handleLogCSV);
  server.begin();
  Serial.printf("Admin panel: http://%s/n",WiFi.localIP().toString().c_str());
}

void loop(){
  server.handleClient();
  if(!mqtt.connected()) mqtt.connect("rfid-controller");
  mqtt.loop();

  if(!rfid.PICC_IsNewCardPresent()||!rfid.PICC_ReadCardSerial()) return;
  String uid=uidStr(rfid.uid.uidByte,rfid.uid.size);

  if(enrolPending && millis()<enrolDeadline){
    if(userCount<MAX_USERS){
      users[userCount++]={uid,enrolName}; saveUsers();
      Serial.printf("Enrolled: %s -> %sn",uid.c_str(),enrolName.c_str());
    }
    enrolPending=false;
    rfid.PICC_HaltA(); rfid.PCD_StopCrypto1(); return;
  }
  enrolPending=false;

  String name="Unknown";
  bool ok=false;
  for(int i=0;i<userCount;i++){
    if(users[i].uid==uid){ ok=true; name=users[i].name; break; }
  }
  addLog(uid,name,ok);
  if(ok){
    digitalWrite(LED_GREEN,HIGH); digitalWrite(RELAY_PIN,HIGH); delay(3000);
    digitalWrite(RELAY_PIN,LOW);  digitalWrite(LED_GREEN,LOW);
  } else {
    for(int i=0;i<3;i++){
      digitalWrite(LED_RED,HIGH);digitalWrite(BUZZER,HIGH);delay(150);
      digitalWrite(LED_RED,LOW); digitalWrite(BUZZER,LOW); delay(100);
    }
  }
  rfid.PICC_HaltA(); rfid.PCD_StopCrypto1();
}