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

#define OLED_RESET -1
Adafruit_SSD1306 display(128, 64, &Wire, OLED_RESET);

#define BTN_INC 0
#define BTN_DEC 4
#define BTN_SET 5
#define BTN_OK 16
#define MOTOR_PWM 13

int rpm = 1000;
unsigned long setTime = 0;
int settingStep = 0;
bool isRunning = false;
unsigned long startTime = 0;



void adjustTime(int step, int delta) {
  unsigned long h = setTime / 3600;
  unsigned long m = (setTime % 3600) / 60;
  unsigned long s = setTime % 60;

  if (step == 1) h = constrain(h + delta, 0, 23);
  if (step == 2) m = constrain(m + delta, 0, 59);
  if (step == 3) s = constrain(s + delta, 0, 59);

  setTime = h * 3600 + m * 60 + s;
}

void updateDisplay() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  display.setCursor(0, 0);
  display.print("RPM: "); display.println(rpm);

  display.setCursor(0, 10);
  display.print("TIME: ");
  int h = setTime / 3600;
  int m = (setTime % 3600) / 60;
  int s = setTime % 60;
  display.printf("%02d:%02d:%02d\n", h, m, s);

  display.setCursor(0, 30);
  display.print("Battery: ");
  float voltage = analogRead(A0) * (3.3 / 1023.0) * (4.2 / 3.3);
  display.print(voltage); display.println("V");

  display.setCursor(0, 45);
  if (isRunning) display.print("Running...");
  else display.print("Ready!");

  display.display();
}

void handleButtons() {
  static bool lastOk = HIGH, lastInc = HIGH, lastDec = HIGH, lastSet = HIGH;
  
  bool nowInc = digitalRead(BTN_INC);
  bool nowDec = digitalRead(BTN_DEC);
  bool nowSet = digitalRead(BTN_SET);
  bool nowOk  = digitalRead(BTN_OK);

  if (lastInc == HIGH && nowInc == LOW) {
    if (settingStep == 0) rpm += 100;
    else adjustTime(settingStep, +1);
  }
  if (lastDec == HIGH && nowDec == LOW) {
    if (settingStep == 0) rpm = max(100, rpm - 100);
    else adjustTime(settingStep, -1);
  }
  if (lastSet == HIGH && nowSet == LOW) {
    settingStep = (settingStep + 1) % 4;
  }
  if (lastOk == HIGH && nowOk == LOW) {
    analogWrite(MOTOR_PWM, map(rpm, 0, 5000, 0, 1023));
    startTime = millis();
    isRunning = true;
  }

  lastInc = nowInc;
  lastDec = nowDec;
  lastSet = nowSet;
  lastOk  = nowOk;
}

void setup() {
  Wire.begin(14, 12);  
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  pinMode(BTN_INC, INPUT_PULLUP);
  pinMode(BTN_DEC, INPUT_PULLUP);
  pinMode(BTN_SET, INPUT_PULLUP);
  pinMode(BTN_OK, INPUT_PULLUP);
  pinMode(MOTOR_PWM, OUTPUT);
  analogWrite(1023);
  analogWrite(1000);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();
}

void loop() {
  handleButtons();
  updateDisplay();

  if (isRunning) {
    if (millis() - startTime >= setTime * 1000) {
      analogWrite(MOTOR_PWM, 0);
      isRunning = false;
    }
  }
}