Fingerprint Door Security Alerts

#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <EEPROM.h>
#include <SoftwareSerial.h>
#include <Adafruit_Fingerprint.h>
#include <LiquidCrystal_I2C.h>
#include <RTClib.h>

// Original Adafruit 751 sensor; Seeed SIM900 shield in SWSerial mode.
constexpr uint8_t LOCK=5, CAMERA=6, SETUP_KEY=4;
SoftwareSerial fpPort(2,3), gsmPort(7,8);
Adafruit_Fingerprint finger(&fpPort);
LiquidCrystal_I2C lcd(0x27,16,2);
RTC_DS3231 rtc;
bool sensorOK=false, rtcOK=false, removed=true, unlocked=false, recording=false;
uint32_t lockUntil=0, cameraUntil=0, messageUntil=0, pollAt=0;
uint8_t failures=0;
char phone[20]={0}, command[40];
uint8_t commandLen=0;
bool maintenance=false;
const uint8_t MAGIC=0xB7;

void show(const __FlashStringHelper *a,const __FlashStringHelper *b) {
  lcd.clear(); lcd.setCursor(0,0); lcd.print(a); lcd.setCursor(0,1); lcd.print(b);
}
bool due(uint32_t t) { return (int32_t)(millis()-t)>=0; }
void timers() {
  if(unlocked && due(lockUntil)) { digitalWrite(LOCK,LOW); unlocked=false; }
  if(recording && due(cameraUntil)) { digitalWrite(CAMERA,LOW); recording=false; }
}
void idleScreen() {
  if(!sensorOK) show(F("Sensor fault"),F("Door stays locked"));
  else show(F("Place Fingerprint"),F("BioKnob Ready"));
}
void pauseMs(uint32_t ms) {
  uint32_t start=millis();
  while(millis()-start<ms) { timers(); delay(1); }
}
bool validPhone(const char *p) {
  uint8_t n=strlen(p); if(n<9 || n>18 || p[0]!='+') return false;
  for(uint8_t i=1;i<n;i++) if(p[i]<'0'||p[i]>'9') return false;
  return true;
}
// Streaming parser: bounded buffer and explicit modem errors/timeouts.
bool response(const char *token,uint32_t timeout) {
  char buf[100]={0}; uint8_t n=0; uint32_t start=millis();
  while(millis()-start<timeout) {
    timers();
    while(gsmPort.available()) {
      char c=gsmPort.read();
      if(n==sizeof(buf)-1) { memmove(buf,buf+40,n-40); n-=40; }
      buf[n++]=c; buf[n]=0;
      if(strstr(buf,"ERROR")) return false;
      if(strstr(buf,token)) return true;
    }
  }
  return false;
}
void drainModem() { while(gsmPort.available()) gsmPort.read(); }
bool at(const __FlashStringHelper *s,const char *token="OK",uint32_t ms=3000) {
  drainModem(); gsmPort.println(s); return response(token,ms);
}
bool sms() {
  if(!validPhone(phone)) { Serial.println(F("SMS not sent: set administrator number with N+countrycode...")); return false; }
  gsmPort.listen();
  bool ok=false;
  // Retry wake/autobaud only. Never blindly retry a submitted SMS (duplicates).
  for(uint8_t i=0;i<3 && !ok;i++) ok=at(F("AT"));
  if(!ok || !at(F("ATE0")) || !at(F("AT+CPIN?"),"READY") ||
     !at(F("AT+CMGF=1"))) { fpPort.listen(); return false; }
  drainModem(); gsmPort.print(F("AT+CMGS=\"")); gsmPort.print(phone); gsmPort.println('"');
  if(!response(">",5000)) { gsmPort.write(27); fpPort.listen(); return false; }
  gsmPort.print(F("BioKnob: Unauthorized access attempt detected. Three consecutive failed fingerprints. "));
  if(rtcOK && !rtc.lostPower()) {
    DateTime t=rtc.now(); char stamp[22];
    snprintf(stamp,sizeof(stamp),"%04u-%02u-%02u %02u:%02u:%02u",t.year(),t.month(),t.day(),t.hour(),t.minute(),t.second());
    gsmPort.print(stamp);
  } else gsmPort.print(F("RTC time not set."));
  gsmPort.write(26);
  // +CMGS is network submission acknowledgement, not handset delivery proof.
  ok=response("+CMGS:",60000);
  if(ok) ok=response("OK",5000);
  fpPort.listen(); return ok;
}
void alert() {
  digitalWrite(LOCK,LOW); unlocked=false;
  digitalWrite(CAMERA,HIGH); recording=true; cameraUntil=millis()+30000UL;
  show(F("Unauthorized"),F("Attempt Detected"));
  Serial.println(F("Unauthorized Attempt Detected; camera contact held 30 seconds."));
  pauseMs(1000);
  show(F("Sending SMS..."),F("Door locked"));
  bool sent=sms();
  if(sent) show(F("SMS Alert Sent"),F("Network accepted"));
  else show(F("SMS Alert Failed"),F("Check SIM/setup"));
  Serial.println(sent?F("SMS accepted by network; delivery not confirmed."):F("SMS failed/unconfirmed; no automatic duplicate retry."));
  messageUntil=millis()+3000;
}
// Enrollment uses two scans and requires the interior key throughout.
bool capture(uint8_t slot,bool wantFinger) {
  uint32_t start=millis();
  while(millis()-start<20000UL && digitalRead(SETUP_KEY)==LOW) {
    timers(); uint8_t r=finger.getImage();
    if(!wantFinger && r==FINGERPRINT_NOFINGER) return true;
    if(wantFinger && r==FINGERPRINT_OK) return finger.image2Tz(slot)==FINGERPRINT_OK;
    pauseMs(70);
  }
  return false;
}
void enroll(uint16_t id) {
  digitalWrite(LOCK,LOW); unlocked=false; fpPort.listen();
  if(!sensorOK || id<1 || id>162) { Serial.println(F("Use E1 through E162.")); return; }
  show(F("Enroll: place"),F("new finger"));
  if(!capture(1,true)) { Serial.println(F("First scan failed/timeout.")); return; }
  show(F("Remove finger"),F("then scan again"));
  if(!capture(0,false)) return;
  show(F("Scan same finger"),F("a second time"));
  if(!capture(2,true) || digitalRead(SETUP_KEY)!=LOW) return;
  if(finger.createModel()==FINGERPRINT_OK && finger.storeModel(id)==FINGERPRINT_OK)
    Serial.println(F("Fingerprint enrolled in sensor flash."));
  else Serial.println(F("Enrollment failed: scans differ or storage error."));
  removed=false;
}
void execute() {
  if(digitalRead(SETUP_KEY)!=LOW) { Serial.println(F("Setup key is open; command denied.")); return; }
  if(command[0]=='N' && validPhone(command+1)) {
    strncpy(phone,command+1,sizeof(phone));
    for(uint8_t i=0;i<sizeof(phone);i++) EEPROM.update(2+i,phone[i]);
    Serial.println(F("Administrator number saved."));
  } else if(command[0]=='E') enroll(atoi(command+1));
  else if(command[0]=='T' && strlen(command)==15 && rtcOK) {
    bool digits=true; for(uint8_t i=1;i<15;i++) if(!isDigit(command[i])) digits=false;
    if(digits) {
      char b[5]={0}; memcpy(b,command+1,4); uint16_t y=atoi(b);
      uint8_t v[5]; for(uint8_t i=0;i<5;i++) { b[0]=command[5+i*2];b[1]=command[6+i*2];b[2]=0;v[i]=atoi(b); }
      DateTime d(y,v[0],v[1],v[2],v[3],v[4]);
      if(y>=2026 && y<=2099 && d.isValid()) { rtc.adjust(d); Serial.println(F("RTC set. Set camera to SAME time zone separately.")); }
      else Serial.println(F("Invalid date/time."));
    }
  } else Serial.println(F("Setup: N+countrycodeNumber | E1..E162 | TYYYYMMDDhhmmss"));
  messageUntil=millis()+2000;
}
void usbCommands() {
  while(Serial.available()) {
    char c=Serial.read();
    if(c=='\n' || c=='\r') {
      if(commandLen) { command[commandLen]=0; execute(); commandLen=0; }
    } else if(commandLen<sizeof(command)-1) command[commandLen++]=c;
    else commandLen=0;
  }
}
void setup() {
  digitalWrite(LOCK,LOW); digitalWrite(CAMERA,LOW);
  pinMode(LOCK,OUTPUT);pinMode(CAMERA,OUTPUT);pinMode(SETUP_KEY,INPUT_PULLUP);
  Serial.begin(115200); Wire.begin(); Wire.setWireTimeout(25000,true);
  lcd.init(); lcd.backlight(); show(F("BioKnob starting"),F("Door locked"));
  rtcOK=rtc.begin();
  if(EEPROM.read(0)!=MAGIC) { EEPROM.update(0,MAGIC);EEPROM.update(1,0);EEPROM.update(2,0); }
  failures=min((uint8_t)2,EEPROM.read(1));
  for(uint8_t i=0;i<sizeof(phone);i++) phone[i]=EEPROM.read(2+i);
  phone[sizeof(phone)-1]=0;
  gsmPort.begin(19200); finger.begin(57600);fpPort.listen(); pauseMs(1000);
  sensorOK=finger.verifyPassword();
  Serial.println(F("BioKnob. USB serial 115200, newline. Close interior key for setup."));
  Serial.println(F("N+countrycodeNumber | E1..E162 | TYYYYMMDDhhmmss. Open key to arm."));
  if(!rtcOK || rtc.lostPower()) Serial.println(F("WARNING: RTC unset; set with T command."));
  if(!validPhone(phone)) Serial.println(F("WARNING: SMS recipient not set."));
  idleScreen();
}
void loop() {
  timers(); usbCommands();
  if(messageUntil && due(messageUntil)) { messageUntil=0;idleScreen(); }
  if(digitalRead(SETUP_KEY)==LOW) {
    digitalWrite(LOCK,LOW);unlocked=false;
    if(!maintenance) { show(F("Maintenance mode"),F("USB setup only"));maintenance=true; }
    return;
  }
  if(maintenance) { maintenance=false;messageUntil=0;idleScreen(); }
  if(!sensorOK || unlocked || !due(pollAt)) return;
  pollAt=millis()+120;fpPort.listen();
  uint8_t r=finger.getImage();
  if(r==FINGERPRINT_NOFINGER) { removed=true; return; }
  if(r!=FINGERPRINT_OK || !removed) return;
  removed=false; // require full finger lift before another attempt
  r=finger.image2Tz();
  if(r==FINGERPRINT_OK) r=finger.fingerFastSearch();
  if(r==FINGERPRINT_OK) {
    failures=0;EEPROM.update(1,0);
    digitalWrite(LOCK,HIGH);unlocked=true;lockUntil=millis()+5000;
    show(F("Access Granted"),F("Unlock: 5 sec"));messageUntil=lockUntil;
  } else if(r==FINGERPRINT_NOTFOUND || r==FINGERPRINT_IMAGEMESS || r==FINGERPRINT_FEATUREFAIL || r==FINGERPRINT_INVALIDIMAGE) {
    failures++; EEPROM.update(1,failures);
    show(F("Access Denied"),F("Lift finger")); messageUntil=millis()+2000;
    if(failures>=3) { alert(); failures=0; EEPROM.update(1,0); }
  } else { show(F("Sensor error"),F("Try again"));messageUntil=millis()+2000; }
}