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

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

int tankheight = 50; //50cm
int fillheight = 50;  //in cm
int trig = 2;
int echo = 3;

void testdrawstyles(int a) {
  display.clearDisplay();
  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.print(F("Level= "));
  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(WHITE);
  display.print(a);
  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(WHITE);
  display.print(F("%"));
  display.display();
  delay(500);
}

void setup() {
  Serial.begin(9600);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Don't proceed, loop forever
  }

  // Clear the buffer
  display.clearDisplay();

  // Draw a single pixel in white
  display.drawPixel(10, 10, WHITE);
  display.display();
  delay(1000);

}

void loop() {
  long time = 0, height = 0, waterpercent = 0, waterheight = 0;

  // Transmitting pulse
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  // Waiting for pulse
  time = pulseIn(echo, HIGH);
  height = time / (29 * 2); // Calculating distance
  if (height <= 55 && height >= 5) {
    height = height - 5 ;  // offset correction
    // height = 20 - h;  // offset correction
    waterheight = tankheight - height; // water height, 0 - 50 cm
    waterpercent = 2 * waterheight;  // distance in %, 0-100 %
    // Sending to computer
    Serial.print(waterheight);
    Serial.print(" cm\n");
  }
  else {
    if (height >= 0 && height < 5) {
      Serial.println("Tank Full.");
      waterpercent = 100;
      waterheight = 50;
    }
    else {
      Serial.println("No Range");
      // waterpercent =
    }
  }
  delay(1000);
  testdrawstyles(waterpercent);
  // testdrawstyles(water);

}