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

// *** Include the desired Adafruit GFX font header ***
#include <Fonts/FreeSansBold18pt7b.h> 

// --- SSD1306 Display Setup ---
#define SCREEN_WIDTH 128 
#define SCREEN_HEIGHT 64 

// Use the correct I2C address (0x3C or 0x3D)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// --- Rotary Encoder Setup ---
#define ENCODER_CLK 2 
#define ENCODER_DT 3  
#define ENCODER_SW A0 

// --- Rotary Encoder Variables ---
volatile long encoderCount = 0; 
volatile long zeroOffset = 0; 

// --- Physical/Resolution Constants ---
const long PPR = 360000; // 360,000 counts for 0.001 degree resolution
const float DEGREE_PER_COUNT = 360.0 / PPR;

// Set to 2 decimal places. A 3-digit integer + 2 decimals fits best with this font.
const int NUM_DECIMAL_PLACES = 3; 

// --- Interrupt Service Routine (ISR) ---
void readEncoder() {
  if (digitalRead(ENCODER_DT) == HIGH) {
    encoderCount++; 
  } else {
    encoderCount--; 
  }
}

void setup() {
  Serial.begin(115200);

  // --- Encoder Pins Setup ---
  pinMode(ENCODER_CLK, INPUT_PULLUP);
  pinMode(ENCODER_DT, INPUT_PULLUP);
  pinMode(ENCODER_SW, INPUT_PULLUP); 
  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoder, RISING);

  // --- Display Setup ---
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed. Check wiring and address (0x3C or 0x3D)."));
    for(;;); 
  }
  display.display(); 
  delay(1000); 
  display.setTextColor(SSD1306_WHITE); 
  display.clearDisplay();
}

void loop() {
  // --- 1. Read Button and Zero Function ---
  if (digitalRead(ENCODER_SW) == LOW) { 
    zeroOffset = encoderCount; 
    delay(200); 
  }

  // --- 2. Calculate Angle (Floating Point) ---
  long currentCount = encoderCount - zeroOffset;
  float angle = currentCount * DEGREE_PER_COUNT;

  // Apply the modulo 360 wrap
  angle = fmod(angle, 360.0);
  if (angle < 0) {
    angle += 360.0;
  }
  
  // --- 3. Format and Display ---
  display.clearDisplay();
  
  // Set up the output string with 2 decimal places ("XXX.XX")
  char angleString[8]; // Buffer large enough for "360.00" + null terminator
  dtostrf(angle, 6, NUM_DECIMAL_PLACES, angleString); 

  // **Display Angle (Custom GFX Font)**
  display.setTextSize(1); // ALWAYS set size to 1 when using GFX fonts
  display.setFont(&FreeSansBold18pt7b); // Set the custom font
  display.setCursor(0, 30); // Center the font vertically
  display.print(angleString);
  
  // **Display Label (Default System Font)**
  // We switch back to the default font to save space for the label
  display.setFont(NULL); // Switch back to the default 5x7 system font
  display.setTextSize(1);
  display.setCursor(0, 50); // Position the label below
  display.println("DEGREES (XX.XX)");

  display.display(); 

  delay(10); 
}