#include <FastLED.h>
#include <TM1637Display.h>

#define LED_PIN 6
#define NUM_LEDS 8
CRGB leds[NUM_LEDS];

#define SENSOR_PIN 2
#define BUTTON_PIN 3
#define LDR_PIN 4

#define DIGIT_CLK 7
#define DIGIT_DIO 8
TM1637Display display(DIGIT_CLK, DIGIT_DIO);

volatile unsigned long time_old = 0;
volatile unsigned long time_new = 0;
volatile unsigned long rpm = 0;

volatile unsigned long starting_time = 0;
volatile unsigned long current_time = 0;
volatile unsigned long time_delay = 1000; // time to filter out spikes and noise
volatile unsigned long zero_time = 2000000; // time to zero out display when no pulse detected

unsigned long update_interval = 50000;  // Update interval in microseconds
unsigned long last_update_time = 0;

int rpm_1 = 100;
int rpm_2 = 200;
int rpm_3 = 300;
int rpm_4 = 400;
int rpm_5 = 500;
int rpm_6 = 600;
int rpm_7 = 700;
int rpm_8 = 800;

int flashing_speed = 200; // bigger value, slower speed

void setup() {
  pinMode(SENSOR_PIN, INPUT);
  pinMode(BUTTON_PIN, INPUT);
  pinMode(LDR_PIN, INPUT);
  attachInterrupt(digitalPinToInterrupt(SENSOR_PIN), rpm_isr, RISING);
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(255);
  display.setBrightness(7);
}

void loop() {

  //uncomment following line for testing flashing lighs
  //rpm = 850; 

  unsigned long current_time = micros();
  if (current_time - last_update_time >= update_interval) 
  {
    last_update_time = current_time;
    if (digitalRead(LDR_PIN))
    {
      FastLED.setBrightness(100);
    }
    else
    {
      FastLED.setBrightness(255);
    }
    update_leds();
    update_display();
  }
  if(current_time - starting_time > zero_time)
  {
    rpm = 0;
  }
  if(digitalRead(BUTTON_PIN))
  {
    rpm_1 = 100;
    rpm_2 = 200;
    rpm_3 = 300;
    rpm_4 = 400;
    rpm_5 = 500;
    rpm_6 = 600;
    rpm_7 = 700;
    rpm_8 = 800;
  }
  else
  {
    rpm_1 = 50;
    rpm_2 = 100;
    rpm_3 = 150;
    rpm_4 = 200;
    rpm_5 = 250;
    rpm_6 = 300;
    rpm_7 = 350;
    rpm_8 = 400;
  }
  if(rpm>=850)
  {
    delay(flashing_speed);
    for(int a=0; a<8; a++)
    {
      leds[a] = CRGB::Black;
    }
    FastLED.show();
    delay(flashing_speed);
  }
}

void update_leds() {
  if (rpm >= rpm_1) {
    leds[0] = CRGB::Green;
  } else {
    leds[0] = CRGB::Black;
  }

  if (rpm >= rpm_2) {
    leds[1] = CRGB::Green;
  } else {
    leds[1] = CRGB::Black;
  }

  if (rpm >= rpm_3) {
    leds[2] = CRGB::Green;
  } else {
    leds[2] = CRGB::Black;
  }

  if (rpm >= rpm_4) {
    leds[3] = CRGB::Green;
  } else {
    leds[3] = CRGB::Black;
  }

  if (rpm >= rpm_5) {
    leds[4] = CRGB::Yellow;
  } else {
    leds[4] = CRGB::Black;
  }

  if (rpm >= rpm_6) {
    leds[5] = CRGB::Yellow;
  } else {
    leds[5] = CRGB::Black;
  }

  if (rpm >= rpm_7) {
    leds[6] = CRGB::Yellow;
  } else {
    leds[6] = CRGB::Black;
  }

  if (rpm >= rpm_8) {
    leds[7] = CRGB::Red;
  } else {
    leds[7] = CRGB::Black;
  }

  FastLED.show();
}

void update_display() {
  display.showNumberDec(rpm, false, 4, 0);
}

void rpm_isr() 
{
  starting_time = micros();
  while(digitalRead(SENSOR_PIN)==HIGH);
  current_time = micros();
  if(current_time - starting_time >= time_delay)
  {
    time_new = micros();
    rpm = 60000000 / (time_new - time_old);
    time_old = time_new;
  } 
}