#include <WiFi.h>
#include <WiFiClient.h>
#include <ESP32Servo.h>
#include "ThingSpeak.h"
#include <LiquidCrystal_I2C.h>

// Initialize the LCD with the I2C address and size
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Constants for various timing and pin assignments
#define Second 1000
#define Dry_Echo 18
#define Dry_Trig 19
#define Wet_Echo 4
#define Wet_Trig 23
#define SoilMoisture 33
#define ServoMotor 21

// WiFi credentials and ThingSpeak channel information
const char* WIFI_NAME = "Wokwi-GUEST"; // WiFi SSID
const char* WIFI_PASSWORD = ""; // WiFI Password
const int myChannelNumber = 2520070; // ThingSpeak channel number
const char* myApiKey = "6EZGVRB1XQV3261X"; // ThingSpeak API key
const char* server = "api.thingspeak.com"; // ThingSpeak server address
WiFiClient client;

// Forward declarations of functions used later in the code
float calculate_distance(int Trig, int Echo, char can);
bool is_full(int Trig, int Echo, char can);
float calibrate(int moisture);

// Global variables
char ssid[] = "Wokwi-GUEST";
char pass[] = "";
bool dry_full = 0;
bool wet_full = 0;
int servo_pos = 90;
int max_moisture = 4095;
int min_moisture = 1095;
// Calibration of soil moisture at the start
float threshold = calibrate(4000);
Servo servo;

void setup() {
  // Setup serial communication and WiFi connection
  Serial.begin(115200);
  WiFi.begin(WIFI_NAME, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED){
      delay(1000);
      Serial.println("Wifi not connected");
  }
  Serial.println("Wifi connected !");
  Serial.println("Local IP: " + String(WiFi.localIP()));
  WiFi.mode(WIFI_STA);
  ThingSpeak.begin(client);

  // Initialize the LCD display
  lcd.init();

  lcd.backlight();
  delay(2000); // Wait a bit before clearing the screen
  lcd.clear();

  // Welcome message displayed on the LCD
  lcd.setCursor(0,0);
  lcd.print("Welcome to waste management system");
  delay(2000); // Wait to allow reading the message
  Serial.begin(115200);

  // Setup pin modes for the sensors and servo
  pinMode(Dry_Trig, OUTPUT);
  pinMode(Dry_Echo, INPUT);
  pinMode(Wet_Trig, OUTPUT);
  pinMode(Wet_Echo, INPUT);
  pinMode(SoilMoisture, INPUT);
  servo.attach(ServoMotor, 500, 2400); // Setup the servo motor
}
void loop() {
  Serial.println("______________________");

  // Read and calibrate soil moisture sensor data
  int moisture_value = analogRead(SoilMoisture);
  float moisture = calibrate(moisture_value);
  Serial.print("Moisture : ");
  Serial.print(moisture_value);
  Serial.print(" ----> calibrated : ");
  Serial.print(moisture);
  Serial.println("%");

  // Check if the trash is wet based on the calibrated moisture
  bool wet_trash = moisture > threshold;
  ThingSpeak.setField(3, moisture_value);
  if(wet_trash){
    Serial.print("The trash is wet! (threshold = ");
    Serial.print(threshold);
    Serial.println("%)");
    ThingSpeak.setField(3, 1);
    // Open the gate using the servo
    for (servo_pos = 90; servo_pos >= 0; servo_pos -= 1) {
      servo.write(servo_pos);
      delay(15);
    }
    delay(5 * Second); // Wait before closing the gate
    // Close the gate using the servo
    for (servo_pos = 0; servo_pos <= 90; servo_pos += 1) {
      servo.write(servo_pos);
      delay(15);
    }

    // Send data to ThingSpeak
    int status = ThingSpeak.writeFields(myChannelNumber, myApiKey);
  }
  else{
    ThingSpeak.setField(3, 0);
  }
  delay(2000); // Short delay before updating the LCD
  lcd.clear(); 
  delay(2000); // Wait for LCD to clear
  
  // Check if either trash can is full
  dry_full = is_full(Dry_Trig, Dry_Echo, 'D');
  wet_full = is_full(Wet_Trig, Wet_Echo, 'W');

  // Update the LCD with the status of the trash cans
  if (dry_full && wet_full){
    lcd.setCursor(0, 0);
    lcd.print("Dry can and wet can is full");
    delay(5000);  // Display the message for 5 seconds
  }
  else if (dry_full){
    Serial.println("The dry can is full.");
    lcd.setCursor(0, 0);
    lcd.print("Dry can is full");
    delay(5000); 
  }
  else if (wet_full){
    Serial.println("The wet can is full.");
    lcd.setCursor(0, 0);
    lcd.print("Wet can is full");
    delay(5000); 
  }
  else{
    lcd.setCursor(0, 0);
    lcd.print("Cans are empty");
    delay(5000); 
  }

}

// Function to calculate the distance to the nearest obstacle using ultrasonic sensors
float calculate_distance(int Trig, int Echo, char can){
  // Send out an ultrasonic pulse
  digitalWrite(Trig, LOW);
  delay(2);
  digitalWrite(Trig, HIGH);
  delay(10);
  digitalWrite(Trig, LOW);

  // Measure the time it takes for the echo to return
  int duration = pulseIn(Echo, HIGH);
  float distance = duration * 0.034 /2;
  
  // Log and send the distance data to ThingSpeak
  Serial.print(can);
  if(can=='D'){
    ThingSpeak.setField(1, distance);
  }else{
    ThingSpeak.setField(2, distance);
  }
  Serial.print(" free space : ");
  Serial.print(distance);
  Serial.println(" CM");
  
  return distance;
}

// Function to determine if the can is full based on the distance to the trash
bool is_full(int Trig, int Echo, char can){
  float distance = calculate_distance(Trig, Echo, can);
  return distance < 4; // Return true if the distance is less than 4 cm
}

// Function to calibrate the soil moisture reading
float calibrate(int moisture){
  int x = (max_moisture - min_moisture)/100;
  return (max_moisture - moisture)/x; // Return the calibrated value
}