/**
 * @file main.cpp
 * @brief Ember Mug 3 Prototype Firmware
 * @details This firmware manages temperature control and water level detection for the Ember Mug 3 prototype. 
 * Developed using ESP32 with OneWire, DallasTemperature, and HC-SR04 sensors.
 * 
 * @author Leonardo Patrocinio Escalante
 * @version 1.0
 * @date 2024-11-26
 */

#include <Wire.h>
#include <WiFi.h>
#include <OneWire.h>
#include <DallasTemperature.h>

// --- Pin Definitions ---
#define TEMP_SENSOR_PIN 4
#define BUTTON_PLUS_PIN 16
#define BUTTON_MINUS_PIN 17
#define PROXIMITY_SENSOR_TRIGGER_PIN 25
#define PROXIMITY_SENSOR_ECHO_PIN 26
#define RELAY_PIN 27
#define LED_BAR_PIN 32
#define LED_STATUS_PIN 33

// --- Constants ---
const float TEMP_MIN = 45.0;  // Minimum allowable temperature
const float TEMP_MAX = 63.5;  // Maximum allowable temperature
const float TEMP_STEP = 0.5;  // Temperature adjustment step
const float PROXIMITY_THRESHOLD = 18.0; // Threshold distance in cm

// --- Global Variables ---
float idealTemperature = 50.0; // Default ideal temperature
float currentTemperature = 0.0; // Current temperature measured
bool relayState = false; // Relay status (heater control)
bool ledStatus = false;  // Status LED
bool proximityDetected = false; // Proximity detection flag

// --- Sensor Setup ---
OneWire oneWire(TEMP_SENSOR_PIN);
DallasTemperature tempSensor(&oneWire);

/**
 * @brief Initializes all components and prints a welcome message.
 */
void setup() {
  Serial.begin(115200); // Set up serial communication
  while (!Serial) {
    // Wait for Serial to initialize
  }
  
  Serial.println("Welcome to Ember Mug 3 Prototype!");
  Serial.println("Developer: Leonardo Patrocinio Escalante");

  // Initialize pins
  pinMode(BUTTON_PLUS_PIN, INPUT_PULLUP);
  pinMode(BUTTON_MINUS_PIN, INPUT_PULLUP);
  pinMode(PROXIMITY_SENSOR_TRIGGER_PIN, OUTPUT);
  pinMode(PROXIMITY_SENSOR_ECHO_PIN, INPUT);
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(LED_BAR_PIN, OUTPUT);
  pinMode(LED_STATUS_PIN, OUTPUT);

  // Initialize sensors
  tempSensor.begin();
}

/**
 * @brief Main program loop to manage temperature, proximity, and device status.
 */
void loop() {
  handleTemperature(); // Manage temperature control
  handleProximity();   // Monitor proximity detection
  updateDeviceStatus(); // Output current status to serial monitor
  delay(5000); // Update status every 5 seconds
}

/**
 * @brief Handles temperature monitoring and heater control.
 */
void handleTemperature() {
  tempSensor.requestTemperatures();
  currentTemperature = tempSensor.getTempCByIndex(0);

  if (currentTemperature < idealTemperature) {
    digitalWrite(RELAY_PIN, HIGH); // Turn on heater
    relayState = true;
    ledStatus = false;
  } else if (currentTemperature > idealTemperature) {
    digitalWrite(RELAY_PIN, LOW); // Turn off heater
    relayState = false;
    ledStatus = false;
  } else {
    relayState = false;
    ledStatus = true; // Indicate ideal temperature reached
  }
  digitalWrite(LED_STATUS_PIN, ledStatus);
}

/**
 * @brief Monitors proximity using the HC-SR04 ultrasonic sensor.
 */
void handleProximity() {
  digitalWrite(PROXIMITY_SENSOR_TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(PROXIMITY_SENSOR_TRIGGER_PIN, LOW);

  long duration = pulseIn(PROXIMITY_SENSOR_ECHO_PIN, HIGH);
  float distance = (duration / 2) * 0.0343;

  if (distance >= PROXIMITY_THRESHOLD) {
    proximityDetected = false; // Stand-by mode
    digitalWrite(RELAY_PIN, LOW);
  } else {
    proximityDetected = true; // Active mode
  }
}

/**
 * @brief Updates the device's operational status and outputs it to the serial monitor.
 */
void updateDeviceStatus() {
  String macAddress = WiFi.macAddress();
  String mode = proximityDetected ? "ACTIVE" : "STAND_BY";

  Serial.print("{");
  Serial.print("\"deviceMacAddress\": \"" + macAddress + "\", ");
  Serial.print("\"operationMode\": \"" + mode + "\", ");
  Serial.print("\"idealTemperature\": " + String(idealTemperature) + ", ");
  Serial.print("\"currentTemperature\": " + String(currentTemperature) + ", ");
  Serial.print("\"waterLevelDistance\": " + String(proximityDetected ? "In Range" : "Out of Range") + ", ");
  Serial.print("\"createdAt\": \"" + String(millis()) + "\"");
  Serial.println("}");
}