//------------------------Variable declaration & initialization----------------------------//

// for onboard led //

    #define ledPin 2

// for user input //

    bool canRun1, canCalibrate;

// for PIR sensor //

    #define pirPin 15

    bool isPIRtri;
    unsigned long prevT, pirDy;
	
//---------------------------------Callback functions-------------------------------------//

//---------------------------------------Setup-------------------------------------------//

void setup() {
    Serial.begin(115200);
    Serial.printf("______________________Setup starts_________________________\n");
    pinMode(ledPin , OUTPUT);
    pinMode(pirPin, INPUT);
    Serial.printf("______________________Setup completes_________________________\n");
}

//----------------------------------------Loop--------------------------------------------//

void loop() {
    UserInput();
    PIR();
    if (canRun1 == true){
    }
}

void UserInput(){
    if (Serial.available()) {
        String input_str = Serial.readString();
        input_str.trim(); // remove "/n"
        Serial.printf("You entered: %s\n" , input_str);
        int input_int = input_str.toInt();
        if (input_str != "0" && input_int == 0){
                // input_str.toInt() will return 0 if input_str is not an integer .
            return;
        }
        
        if (canCalibrate == true){
            Calibrate(input_int);
            canCalibrate = false;
            return;
        }
        
        switch (input_int){
            case 0:
                Serial.printf("Stop running\n");
                canRun1 = false;
                ledcWrite(0, 255);
                break;
            case 1:
                Serial.printf("Start running\n");
                canRun1 = true;
                break;
            case 2:
                Serial.printf("Enter your value for calibration:\n");
                canCalibrate = true;
                break;
            default:
                break;
        }
    }
}

    void Calibrate(int num1){
        
    }

//--------------------------------Self-defined functions------------------------------------//

void PIR(){
    if (digitalRead(pirPin) == HIGH && isPIRtri == false){
        Serial.printf("Motion is detected .\n");
        isPIRtri = true; prevT = millis();
        // start counting PIR delayT .
        digitalWrite(ledPin, HIGH);   
    }
    
    if (digitalRead(pirPin) == LOW && isPIRtri == true){
        isPIRtri = false;
        digitalWrite(ledPin, LOW);
        pirDy = millis() - prevT;
        Serial.printf("PIR delay time: %.1lus .\n", pirDy/1000);
    }
}