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

// === OLED Setup ===
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// === Speaker Pin ===
#define SPEAKER_PIN 13

// === Matrix Setup ===
const uint8_t rowPins[5] = {A0, A1, A2, A3, A4}; // Octaves
const uint8_t colPins[8] = {2, 3, 4, 5, 6, 7, 8, 9}; // Notes

// Note names for MIDI
const char* noteNames[] = {
  "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"
};

// Convert MIDI note to frequency
float midiToFreq(int midiNote) {
  return 440.0 * pow(2.0, (midiNote - 69) / 12.0);
}

void setup() {
  // Row (octave) outputs
  for (uint8_t i = 0; i < 5; i++) {
    pinMode(rowPins[i], OUTPUT);
    digitalWrite(rowPins[i], HIGH); // Inactive
  }

  // Column (note) inputs with pullups
  for (uint8_t j = 0; j < 8; j++) {
    pinMode(colPins[j], INPUT_PULLUP);
  }

  pinMode(SPEAKER_PIN, OUTPUT);

  // OLED init
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    while (true); // OLED failed
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
}

void showNote(int row, int col, int midiNote) {
  int noteIndex = midiNote % 12;
  int octave = (midiNote / 12) - 1;

  display.clearDisplay();
  display.setCursor(0, 0);
  display.print("Note: ");
  display.print(noteNames[noteIndex]);
  display.println(octave);

  display.print("MIDI: ");
  display.println(midiNote);

  display.print("Row: ");
  display.println(row + 1);
  display.print("Col: ");
  display.println(col + 1);
  display.display();
}

void loop() {
  bool keyPressed = false;

  for (uint8_t row = 0; row < 5; row++) {
    digitalWrite(rowPins[row], LOW); // Enable row

    for (uint8_t col = 0; col < 8; col++) {
      if (digitalRead(colPins[col]) == LOW) {
        int baseNote = 60; // Middle C
        int midiNote = baseNote + col + (row * 12);
        float freq = midiToFreq(midiNote);
        tone(SPEAKER_PIN, freq);
        showNote(row, col, midiNote);
        keyPressed = true;
        delay(100); // debounce and sustain
        break; // only one note at a time
      }
    }

    digitalWrite(rowPins[row], HIGH); // Disable row
    if (keyPressed) break;
  }

  if (!keyPressed) {
    noTone(SPEAKER_PIN);
    display.clearDisplay();
    display.setCursor(0, 0);
    display.println("No key pressed");
    display.display();
  }

  delay(50);
}