#include <Wire.h> 
#include <Adafruit_BMP085.h> 
#include <Adafruit_GFX.h> 
#include <Adafruit_SSD1306.h>

// --- REQUIRED FONT INCLUDE ---
// This is the file that contains the smooth font data.
#include <Fonts/FreeSansBold9pt7b.h> 
// -----------------------------

// --- I2C OLED Display Definitions ---
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, 0x3C);

// --- Sensor Object Initialization ---
Adafruit_BMP085 bmp;

// --- Pin Definitions ---
const int POT_PIN = A0;      
const int BUZZER_PIN = 8;    
const int LED_GREEN = 9;     
const int LED_YELLOW = 10;   
const int LED_RED = 11;      

// --- Global Variables & Constants ---
const float MAX_UPPER_RANGE = 1095.0; 
const int ALERT_TONE = 1000;

float setpointPressure = 1000.0;
float pressureBand = 10.0;       

// --- FUNCTION PROTOTYPES ---
void updateOLED(float currentP, float lowerL, float upperL, int status);
void updateAlerts(float currentP, float lowerL, float upperL);

// =========================================================
// SETUP FUNCTION
// =========================================================
void setup() {
  Serial.begin(9600);
  
  // --- Initialize Outputs ---
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
  pinMode(LED_RED, OUTPUT);

  noTone(BUZZER_PIN); 
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_YELLOW, LOW);
  digitalWrite(LED_RED, LOW);

  // --- Initialize BMP180 ---
  if (!bmp.begin()) {
    Serial.println("Could not find BMP180 sensor!");
    digitalWrite(LED_RED, HIGH);
    while (1);
  }
  
  Serial.print("Baseline Pressure Set: ");
  Serial.print(setpointPressure);
  Serial.println(" hPa");

  // --- Initialize OLED ---
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println("SSD1306 allocation failed");
    while (true); 
  }
  display.display();
  delay(1000); 
  display.clearDisplay();
}

// =========================================================
// LOOP FUNCTION (Main Logic)
// =========================================================
void loop() {
  float currentPressure = bmp.readPressure() / 100.0F; 

  int rawBand = analogRead(POT_PIN);
  pressureBand = map(rawBand, 0, 1023, 5, 50); 
  
  float lowerLimit = setpointPressure - pressureBand;
  float potUpperLimit = setpointPressure + pressureBand; 
  float upperLimit = min(potUpperLimit, MAX_UPPER_RANGE);
  
  int status;
  if (currentPressure >= upperLimit) {
    status = 2; // High Alert (Red LED)
  } else if (currentPressure <= lowerLimit) {
    status = 1; // Low Alert (Yellow LED)
  } else {
    status = 0; // Normal (Green LED)
  }
  
  updateAlerts(currentPressure, lowerLimit, upperLimit);
  updateOLED(currentPressure, lowerLimit, upperLimit, status);
  
  delay(1000); 
}

// =========================================================
// CUSTOM FUNCTIONS
// =========================================================

/**
 * @brief Drives the physical outputs (LEDs and Passive Buzzer) based on status
 */
void updateAlerts(float currentP, float lowerL, float upperL) {
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(LED_YELLOW, LOW);
  digitalWrite(LED_RED, LOW);
  noTone(BUZZER_PIN); 
  
  if (currentP >= upperL) {
    digitalWrite(LED_RED, HIGH);
    tone(BUZZER_PIN, ALERT_TONE);
  } 
  else if (currentP <= lowerL) {
    digitalWrite(LED_YELLOW, HIGH);
    tone(BUZZER_PIN, ALERT_TONE);
  }
  else {
    digitalWrite(LED_GREEN, HIGH);
  }
}

/**
 * @brief Updates the OLED display with current pressure and limits
 * Uses a custom GFX font for the main pressure reading.
 */
void updateOLED(float currentP, float lowerL, float upperL, int status) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  // --- 1. Current Pressure (Smooth Font) ---
  // Sets the custom font for the large reading
  display.setFont(&FreeSansBold9pt7b);
  display.setTextSize(1); 
  display.setCursor(0, 15); // Adjust Y-position to account for font height
  display.print("P: ");
  display.print((int)currentP); 
  display.print(" hPa");

  // --- 2. Status Indicator (Switch back to standard font) ---
  display.setFont(); // Clears the custom font setting
  display.setTextSize(1);
  display.setCursor(0, 25); 
  display.print("Status: ");
  
  if (status == 2) {
    display.print("HIGH ALERT");
  } else if (status == 1) {
    display.print("LOW ALERT");  
  } else {
    display.print("NORMAL");
  }
  
  // --- 3. Limit Settings (Standard Font) ---
  display.setTextSize(1);
  display.setCursor(0, 40);
  display.print("UPPER: ");
  display.print((int)upperL);
  display.print(" hPa");
  
  display.setCursor(0, 55);
  display.print("LOWER: ");
  display.print((int)lowerL);
  display.print(" hPa");
  
  display.display();
}