ESP32 Solenoid Door Lock

#include <Arduino.h>
#include <WiFi.h>
#include <WebServer.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Adafruit_MCP23X17.h>

constexpr int RELAY_1_PIN = 25;
constexpr int RELAY_2_PIN = 32;
constexpr int RELAY_3_PIN = 33;
constexpr int RELAY_4_PIN = 4;
constexpr int BUZZER_PIN = 26;
constexpr int DOOR_1_PIN = 27;
constexpr int QR_RX_PIN = 16;
constexpr int QR_TX_PIN = 17;
constexpr int I2C_SDA_PIN = 21;
constexpr int I2C_SCL_PIN = 22;
constexpr uint8_t MCP_DOOR_2_PIN = 0;
constexpr uint8_t MCP_DOOR_3_PIN = 1;
constexpr uint8_t MCP_DOOR_4_PIN = 2;
constexpr unsigned long UNLOCK_TIME_MS = 3000;

const char *AP_SSID = "Cerraduras-ESP32";
const char *AP_PASSWORD = "Abrir123";
const int relayPins[4] = {RELAY_1_PIN, RELAY_2_PIN, RELAY_3_PIN, RELAY_4_PIN};

WebServer server(80);
LiquidCrystal_I2C lcd(0x27, 16, 2);
Adafruit_MCP23X17 mcp;
HardwareSerial qrSerial(2);
int unlockedDoor = -1;
unsigned long unlockStartedAt = 0;
String lastMessage = "Listo";
String qrBuffer;
String lastLcd1, lastLcd2;

String fit16(String s) { while (s.length() < 16) s += ' '; return s.substring(0, 16); }
void beep(unsigned int ms) { tone(BUZZER_PIN, 2400, ms); }
void setRelay(uint8_t door, bool on) { digitalWrite(relayPins[door], on ? LOW : HIGH); }
bool doorClosed(uint8_t door) {
  if (door == 0) return digitalRead(DOOR_1_PIN) == LOW;
  const uint8_t mcpPins[3] = {MCP_DOOR_2_PIN, MCP_DOOR_3_PIN, MCP_DOOR_4_PIN};
  return mcp.digitalRead(mcpPins[door - 1]) == LOW;
}

void updateLcd(bool force = false) {
  String l1 = "P1:" + String(doorClosed(0) ? "C" : "A") + " P2:" + String(doorClosed(1) ? "C" : "A") + " P3:" + String(doorClosed(2) ? "C" : "A");
  String l2 = "P4:" + String(doorClosed(3) ? "C " : "A ") + lastMessage;
  l1 = fit16(l1); l2 = fit16(l2);
  if (force || l1 != lastLcd1) { lcd.setCursor(0, 0); lcd.print(l1); lastLcd1 = l1; }
  if (force || l2 != lastLcd2) { lcd.setCursor(0, 1); lcd.print(l2); lastLcd2 = l2; }
}

void openDoor(uint8_t door, const String &source) {
  if (unlockedDoor >= 0) setRelay(unlockedDoor, false);
  setRelay(door, true); unlockedDoor = door; unlockStartedAt = millis();
  lastMessage = "Abre P" + String(door + 1); updateLcd(); beep(120);
  Serial.println("Puerta " + String(door + 1) + " abierta por " + source);
}

String page() {
  String html = "<!doctype html><html lang='es'><meta name='viewport' content='width=device-width,initial-scale=1'><style>body{font-family:Arial;text-align:center;background:#f4f6f8;color:#17212b}button{font-size:19px;padding:13px;margin:6px;border:0;border-radius:9px;background:#087f23;color:white}.a{color:#b00020}.c{color:#087f23}</style><h1>Control de cerraduras</h1><p>QR autorizados: PUERTA1, PUERTA2, PUERTA3 y PUERTA4.</p>";
  for (uint8_t d = 0; d < 4; d++) {
    bool closed = doorClosed(d);
    html += "<p>Puerta " + String(d + 1) + ": <b class='" + String(closed ? "c" : "a") + "'>" + String(closed ? "CERRADA" : "ABIERTA O CABLE DESCONECTADO") + "</b><br><form action='/open?door=" + String(d + 1) + "' method='post'><button>Abrir puerta " + String(d + 1) + "</button></form></p>";
  }
  return html + "<p>Red Wi-Fi: <b>Cerraduras-ESP32</b></p></html>";
}

void handleHome() { server.send(200, "text/html; charset=utf-8", page()); }
void handleOpen() {
  int door = server.arg("door").toInt();
  if (door < 1 || door > 4) { server.send(400, "text/plain", "Puerta no valida"); return; }
  openDoor(door - 1, "pagina web"); server.sendHeader("Location", "/"); server.send(303);
}
void processQr(String code) {
  code.trim(); code.toUpperCase();
  for (uint8_t d = 0; d < 4; d++) if (code == "PUERTA" + String(d + 1)) { openDoor(d, "codigo QR"); return; }
  lastMessage = "QR no valido"; updateLcd(); beep(500);
}
void pollQr() {
  while (qrSerial.available()) {
    char c = static_cast<char>(qrSerial.read());
    if (c == '\r' || c == '\n') { if (qrBuffer.length()) { processQr(qrBuffer); qrBuffer = ""; } }
    else if (qrBuffer.length() < 64) qrBuffer += c;
  }
}

void setup() {
  Serial.begin(115200);
  for (uint8_t d = 0; d < 4; d++) { pinMode(relayPins[d], OUTPUT); setRelay(d, false); }
  pinMode(BUZZER_PIN, OUTPUT); pinMode(DOOR_1_PIN, INPUT_PULLUP); noTone(BUZZER_PIN);
  Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
  lcd.init(); lcd.backlight();
  if (mcp.begin_I2C(0x20, &Wire)) {
    mcp.pinMode(MCP_DOOR_2_PIN, INPUT_PULLUP);
    mcp.pinMode(MCP_DOOR_3_PIN, INPUT_PULLUP);
    mcp.pinMode(MCP_DOOR_4_PIN, INPUT_PULLUP);
  } else lastMessage = "Error MCP23017";
  updateLcd(true);
  qrSerial.begin(9600, SERIAL_8N1, QR_RX_PIN, QR_TX_PIN);
  WiFi.mode(WIFI_AP); WiFi.softAP(AP_SSID, AP_PASSWORD);
  server.on("/", HTTP_GET, handleHome); server.on("/open", HTTP_POST, handleOpen); server.begin();
  beep(80); delay(140); beep(80);
}

void loop() {
  server.handleClient(); pollQr();
  if (unlockedDoor >= 0 && millis() - unlockStartedAt >= UNLOCK_TIME_MS) {
    setRelay(unlockedDoor, false); unlockedDoor = -1; lastMessage = "Cerrada"; updateLcd(); beep(180);
  }
  static unsigned long lastDisplayPoll = 0;
  if (millis() - lastDisplayPoll >= 250) { lastDisplayPoll = millis(); updateLcd(); }
}