#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>

#define trigPin 9
#define echoPin 10


SoftwareSerial SIM800L(3, 2);
LiquidCrystal_I2C lcd(0x27, 16, 2);

bool changeFlag = 0;
String message;
long duration;
float distanceD;
float WaterPercentage, WaterPercentageOLD;
unsigned long dataMillis = 0;
unsigned long smsMillis = 0;

void setup() {
  lcd.init();
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Hello, world!");
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
  SIM800L.begin(9600);
  delay(5000);
}
void loop() {
  US();
  showData();
}

void US() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distanceD = duration * 0.034 / 2;
  distanceD = constrain(distanceD, 4, 22);
  WaterPercentage = map(distanceD, 4, 22, 100, 1);
  WaterPercentage = constrain(WaterPercentage, 1, 100);
  // 0% 25% 50% 75% 100%
  //0--19
  if (WaterPercentage <= 19) {
    WaterPercentage = 0;
  }

  //20-39
  else if (WaterPercentage <= 39 && WaterPercentage >= 20) {
    WaterPercentage = 25;
  }

  //40-59
  else if (WaterPercentage <= 59 && WaterPercentage >= 40) {
    WaterPercentage = 50;
  }

  //60-85
  else if (WaterPercentage <= 85 && WaterPercentage >= 60) {
    WaterPercentage = 75;
  }

  //86-100
  else if (WaterPercentage >= 86) {
    WaterPercentage = 100;
  }

}

void showData() {
  if (millis() - dataMillis > 1000 && WaterPercentage != WaterPercentageOLD)
  {
    changeFlag = 1;
    dataMillis = millis();
    WaterPercentageOLD = WaterPercentage;
    Serial.print("Distance: ");
    Serial.print(distanceD);
    Serial.print("\t Water Amount:");
    Serial.print(WaterPercentage);
    Serial.println("%");
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Water Level:");
    lcd.setCursor(0, 1);
    lcd.print(WaterPercentage);
    lcd.print("%");
  }
  if (WaterPercentage == WaterPercentageOLD && changeFlag == 1) {
    changeFlag = 0;
    SendMessage();
  }
}


void SendMessage() {
  if (millis() - smsMillis > 30000)
  {
    smsMillis = millis();
    WaterPercentageOLD = WaterPercentage;
    Serial.println ("Sending Message");
    SIM800L.println("AT+CMGF=1");    //Sets the GSM Module in Text Mode
    delay(1000);
    Serial.println ("Set SMS Number");
    SIM800L.println("AT+CMGS=\"+966554522247\"\r"); //Mobile phone number to send message
    delay(1000);
    Serial.println("Set SMS Content");
    message = "Water Level:" + String(WaterPercentage) + "%";
    SIM800L.println(message);// Messsage content
    delay(100);
    Serial.println("Finish");
    SIM800L.println((char)26);// ASCII code of CTRL+Z
    delay(1000);
    Serial.println("Message has been sent");
  }
}