// ==============================================
// CMPE30274 - Final Activity 3
// PROJECT: ESP32 Interrupts, Timers & Debounce
// TITLE: Pedestrian Traffic Light System
// Group #: 2
// Section: BSCPE LADDERIZED BATCH 2
// MEMBERS:  Ashley Ambas
//   Exequiel John Gicana
//   Jovan Laguitao
//   Aliyah Macy Lara
//   Mark Daryl Sablon
//
// Description:
// This program simulates a pedestrian traffic light system using
// ESP32 hardware interrupt, IRAM_ATTR ISR, volatile flag,
// and millis()-based software debouncing.
// ==============================================

// ===================== PIN DEFINITIONS =====================
#define GREEN_LED      18   // Vehicle green light
#define YELLOW_LED     19   // Vehicle yellow warning light
#define RED_LED        21   // Vehicle red light
#define PED_LED        22   // Pedestrian crossing light
#define BUZZER_PIN     23   // Active buzzer
#define BUTTON_PIN     27   // Push button interrupt pin

// ===================== TIMING CONSTANTS =====================
const unsigned long DEBOUNCE_MS = 200;
const unsigned long YELLOW_TIME = 2000;          // 2 seconds
const unsigned long CROSSING_TIME = 5000;        // 5 seconds
const unsigned long BUZZER_INTERVAL = 300;       // buzzer beep interval
const unsigned long PRINT_INTERVAL = 2000;       // serial print every 2 seconds

// ===================== INTERRUPT VARIABLES =====================
volatile bool buttonInterruptFlag = false;

// Debounce handled in loop()
unsigned long lastValidButtonPress = 0;

// ===================== STATE MACHINE =====================
enum TrafficState {
  NORMAL,
  YELLOW_WARNING,
  PEDESTRIAN_CROSSING,
  RESET_STATE
};

TrafficState currentState = NORMAL;

// ===================== TIMER VARIABLES =====================
unsigned long stateStartTime = 0;
unsigned long lastBuzzerToggle = 0;
unsigned long lastPrintTime = 0;

bool buzzerState = false;

// ===================== ISR FUNCTION =====================
// ISR must be short and safe.
// Do NOT use Serial.print() or delay() inside ISR.
void IRAM_ATTR onButtonPress() {
  buttonInterruptFlag = true;
}

// ===================== STATE NAME HELPER =====================
String getStateName() {
  switch (currentState) {
    case NORMAL:
      return "NORMAL";
    case YELLOW_WARNING:
      return "YELLOW WARNING";
    case PEDESTRIAN_CROSSING:
      return "PEDESTRIAN CROSSING";
    case RESET_STATE:
      return "RESET";
    default:
      return "UNKNOWN";
  }
}

// ===================== OUTPUT CONTROL =====================
void turnOffAllOutputs() {
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(YELLOW_LED, LOW);
  digitalWrite(RED_LED, LOW);
  digitalWrite(PED_LED, LOW);
  digitalWrite(BUZZER_PIN, LOW);
}

// ===================== STATE FUNCTIONS =====================
void setNormalState() {
  turnOffAllOutputs();
  digitalWrite(GREEN_LED, HIGH);

  currentState = NORMAL;
  stateStartTime = millis();

  Serial.println();
  Serial.println("STATE 1: NORMAL OPERATION");
  Serial.println("Vehicle GREEN LED ON");
  Serial.println("Vehicle YELLOW LED OFF");
  Serial.println("Vehicle RED LED OFF");
  Serial.println("Pedestrian LED OFF");
  Serial.println("Buzzer OFF");
  Serial.println("Waiting for pedestrian button press...");
  Serial.println("----------------------------------------");
}

void setYellowWarningState() {
  turnOffAllOutputs();
  digitalWrite(YELLOW_LED, HIGH);

  currentState = YELLOW_WARNING;
  stateStartTime = millis();

  Serial.println();
  Serial.println("STATE 2: YELLOW WARNING");
  Serial.println("Button interrupt detected.");
  Serial.println("Vehicle GREEN LED OFF");
  Serial.println("Vehicle YELLOW LED ON for 2 seconds.");
  Serial.println("----------------------------------------");
}

void setPedestrianCrossingState() {
  turnOffAllOutputs();
  digitalWrite(RED_LED, HIGH);
  digitalWrite(PED_LED, HIGH);

  currentState = PEDESTRIAN_CROSSING;
  stateStartTime = millis();

  lastBuzzerToggle = millis();
  buzzerState = false;
  digitalWrite(BUZZER_PIN, LOW);

  Serial.println();
  Serial.println("STATE 3: PEDESTRIAN CROSSING");
  Serial.println("Vehicle RED LED ON");
  Serial.println("Pedestrian LED ON");
  Serial.println("Buzzer beeping for 5 seconds.");
  Serial.println("----------------------------------------");
}

void setResetState() {
  turnOffAllOutputs();

  currentState = RESET_STATE;
  stateStartTime = millis();

  Serial.println();
  Serial.println("STATE 4: RESET");
  Serial.println("Pedestrian LED OFF");
  Serial.println("Buzzer OFF");
  Serial.println("Vehicle RED LED OFF");
  Serial.println("Returning to normal operation.");
  Serial.println("----------------------------------------");
}

// ===================== SETUP =====================
void setup() {
  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(PED_LED, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  // This uses external pull-down resistor in diagram.json.
  // Button gives HIGH signal when pressed.
  pinMode(BUTTON_PIN, INPUT);

  Serial.begin(9600);
  delay(1000);

  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), onButtonPress, RISING);

  Serial.println("========================================");
  Serial.println("CMPE30274 Final Activity 3");
  Serial.println("Group 2 - Pedestrian Traffic Light");
  Serial.println("Interrupt + Timer + Debounce System");
  Serial.println("Serial Monitor Started at 9600 baud");
  Serial.println("========================================");

  setNormalState();
}

// ===================== MAIN LOOP =====================
void loop() {
  unsigned long currentTime = millis();

  // SERIAL MONITOR STATUS PRINT
  if (currentTime - lastPrintTime >= PRINT_INTERVAL) {
    lastPrintTime = currentTime;

    Serial.println("------ STATUS ------");
    Serial.print("Current State: ");
    Serial.println(getStateName());

    Serial.print("Button Reading: ");
    Serial.println(digitalRead(BUTTON_PIN));

    Serial.print("Green LED: ");
    Serial.println(digitalRead(GREEN_LED) ? "ON" : "OFF");

    Serial.print("Yellow LED: ");
    Serial.println(digitalRead(YELLOW_LED) ? "ON" : "OFF");

    Serial.print("Red LED: ");
    Serial.println(digitalRead(RED_LED) ? "ON" : "OFF");

    Serial.print("Pedestrian LED: ");
    Serial.println(digitalRead(PED_LED) ? "ON" : "OFF");

    Serial.print("Buzzer: ");
    Serial.println(digitalRead(BUZZER_PIN) ? "ON" : "OFF");

    Serial.println("--------------------");
    Serial.println();
  }

  // HANDLE INTERRUPT FLAG OUTSIDE ISR
  if (buttonInterruptFlag == true) {
    buttonInterruptFlag = false;

    // millis-based software debounce
    if (currentTime - lastValidButtonPress > DEBOUNCE_MS) {
      lastValidButtonPress = currentTime;

      if (currentState == NORMAL) {
        setYellowWarningState();
      } else {
        Serial.println();
        Serial.println("Button press ignored.");
        Serial.println("Crossing sequence is already running.");
        Serial.println("----------------------------------------");
      }
    }
  }

  // STATE MACHINE LOGIC
  switch (currentState) {
    case NORMAL:
      // Waiting for button press
      break;

    case YELLOW_WARNING:
      if (currentTime - stateStartTime >= YELLOW_TIME) {
        setPedestrianCrossingState();
      }
      break;

    case PEDESTRIAN_CROSSING:
      // Buzzer beep using millis(), no delay()
      if (currentTime - lastBuzzerToggle >= BUZZER_INTERVAL) {
        lastBuzzerToggle = currentTime;
        buzzerState = !buzzerState;
        digitalWrite(BUZZER_PIN, buzzerState);
      }

      if (currentTime - stateStartTime >= CROSSING_TIME) {
        setResetState();
      }
      break;

    case RESET_STATE:
      setNormalState();
      break;
  }
}