// *** NOTE ***
// All the relay pins are considered ACTIVE HIGH here !!!
#define SOLENOID_VALVE_1_PIN 4 // Pin for solenoid valve 1
#define SOLENOID_VALVE_2_PIN 5 // Pin for solenoid valve 2
#define SOLENOID_VALVE_3_PIN A4 // Pin for solenoid valve 2
#define SOLENOID_VALVE_4_PIN A5 // Pin for solenoid valve 2
#define WATER_PUMP_PIN 6        // Pin for water pump

// Shift Register Pins 74HC165
#define latchPin 10
#define clockPin 9
#define dataPin 8
#define pulseWidth 10      // pulse width in microseconds
uint16_t buttonState = 0;

// ******************** Shift Register Pins 0 to 15 ********************
// water level indicator TANK 1
#define TANK_1_20_PIN 0   // Pin for tank 1 20% sensor
#define TANK_1_50_PIN 1   // Pin for tank 1 50% sensor
#define TANK_1_100_PIN 2  // Pin for tank 1 100% sensor

// water level indicator TANK 2
#define TANK_2_20_PIN 3   // Pin for tank 2 20% sensor
#define TANK_2_50_PIN 4   // Pin for tank 2 50% sensor
#define TANK_2_100_PIN 5 // Pin for tank 2 100% sensor

// water level indicator TANK 3
#define TANK_3_20_PIN 6   // Pin for tank 3 20% sensor
#define TANK_3_50_PIN 7   // Pin for tank 3 50% sensor
#define TANK_3_100_PIN 8 // Pin for tank 3 100% sensor

// water level indicator TANK 4
#define TANK_4_20_PIN 9   // Pin for tank 4 20% sensor
#define TANK_4_50_PIN 10   // Pin for tank 4 50% sensor
#define TANK_4_100_PIN 11 // Pin for tank 4 100% sensor

// ***************** Shift Register Pins 0 to 15 --end *****************

// Interrupt Pins
#define onIntrPin 2
#define offIntrPin 3

// Tank 1 Water level status
bool tank_1_20 = false;
bool tank_1_50 = false;
bool tank_1_100 = false;

// Tank 2 Water level status
bool tank_2_20 = false;
bool tank_2_50 = false;
bool tank_2_100 = false;

// Tank 3 Water level status
bool tank_3_20 = false;
bool tank_3_50 = false;
bool tank_3_100 = false;

// Tank 4 Water level status
bool tank_4_20 = false;
bool tank_4_50 = false;
bool tank_4_100 = false;

// Solanoid Valve status
bool solenoid_valve_1_on = false;
bool solenoid_valve_2_on = false;
bool solenoid_valve_3_on = false;
bool solenoid_valve_4_on = false;

// Water pump status
bool water_pump_on = false;

// Interrupt Pins
bool led_state = HIGH;
bool Loop_Status = true;


void setup() {
  pinMode(SOLENOID_VALVE_1_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE_2_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE_3_PIN, OUTPUT);
  pinMode(SOLENOID_VALVE_4_PIN, OUTPUT);
  pinMode(WATER_PUMP_PIN, OUTPUT);

  // Shift Register Setup
  pinMode( clockPin, OUTPUT);   // clock signal, idle LOW
  pinMode( latchPin, OUTPUT);   // latch (copy input into registers), idle HIGH
  digitalWrite( latchPin, HIGH);

  // INTERRUPT SETUP
  pinMode(A0, OUTPUT);
  pinMode(onIntrPin, INPUT_PULLUP);
  pinMode(offIntrPin, INPUT_PULLUP);
  digitalWrite(A0, led_state);
  attachInterrupt(digitalPinToInterrupt(onIntrPin), START_ISR, FALLING);
  attachInterrupt(digitalPinToInterrupt(offIntrPin), STOP_ISR, FALLING);
}

void loop() {
  if (Loop_Status) {
    // Check for current water level
    checkWaterLevelStatus();

    // Tank Logic
    tank_1_Logic();
    tank_2_Logic();
    tank_3_Logic();
    tank_4_Logic();

    // Pump Logic
    pumpLogic();

    // Updating pin Status
    updateRelayStatus();
  }
  else {
    solenoid_valve_1_on = false;
    solenoid_valve_2_on = false;
    solenoid_valve_3_on = false;
    solenoid_valve_4_on = false;
    water_pump_on = false;
    updateRelayStatus();
  }

  // delay(10000);
}

void pumpLogic() {
  // Water pump logic
  if ((solenoid_valve_1_on || solenoid_valve_2_on || solenoid_valve_3_on || solenoid_valve_4_on) && !water_pump_on) {
    // Turn on water pump if any solenoid valve is on and pump is not already on
    water_pump_on = true;
  } else if (!(solenoid_valve_1_on || solenoid_valve_2_on || solenoid_valve_3_on || solenoid_valve_4_on) && water_pump_on) {
    // Turn off water pump if no solenoid valve is on and pump is already on
    water_pump_on = false;
  }
}

void tank_1_Logic() {
  // Tank 1 logic
  if (!tank_1_100) { // Tank is not full
    if (!tank_1_50) {
      if (!solenoid_valve_1_on && !tank_1_20) {
        // Turn on solenoid valve 1 if tank 1 is 20% or below
        solenoid_valve_1_on = true;
      }
    }
  } else if (solenoid_valve_1_on && tank_1_100) {
    // Turn off solenoid valve 1 if tank 1 is 100%
    solenoid_valve_1_on = false;
  }
}

void tank_2_Logic() {
  // Tank 2 logic
  if (!tank_2_100) { // Tank is not full
    if (!tank_2_50) {
      if (!solenoid_valve_2_on && !tank_2_20) {
        // Turn on solenoid valve 2 if tank 2 is 20% or below
        solenoid_valve_2_on = true;
      }
    }
  } else if (solenoid_valve_2_on && tank_2_100) {
    // Turn off solenoid valve 2 if tank 2 is 100%
    solenoid_valve_2_on = false;
  }
}

void tank_3_Logic() {
  // Tank 3 logic
  if (!tank_3_100) { // Tank is not full
    if (!tank_3_50) {
      if (!solenoid_valve_3_on && !tank_3_20) {
        // Turn on solenoid valve 3 if tank 3 is 20% or below
        solenoid_valve_3_on = true;
      }
    }
  } else if (solenoid_valve_3_on && tank_3_100) {
    // Turn off solenoid valve 3 if tank 3 is 100%
    solenoid_valve_3_on = false;
  }
}

void tank_4_Logic() {
  // Tank 4 logic
  if (!tank_4_100) { // Tank is not full
    if (!tank_4_50) {
      if (!solenoid_valve_4_on && !tank_4_20) {
        // Turn on solenoid valve 4 if tank 4 is 20% or below
        solenoid_valve_4_on = true;
      }
    }
  } else if (solenoid_valve_4_on && tank_4_100) {
    // Turn off solenoid valve 4 if tank 4 is 100%
    solenoid_valve_4_on = false;
  }
}

void checkWaterLevelStatus() {
  read_state();
  // Since all water level indicator pins are pilled up
  // Hence their values are inverted !!!

  // Read tank 1 sensors
  tank_1_20 = bitRead( buttonState, TANK_1_20_PIN);
  tank_1_50 = bitRead( buttonState, TANK_1_50_PIN);
  tank_1_100 = bitRead( buttonState, TANK_1_100_PIN);

  // Read tank 2 sensors
  tank_2_20 = bitRead( buttonState, TANK_2_20_PIN);
  tank_2_50 = bitRead( buttonState, TANK_2_50_PIN);
  tank_2_100 = bitRead( buttonState, TANK_2_100_PIN);

  // Read tank 3 sensors
  tank_3_20 = bitRead( buttonState, TANK_3_20_PIN);
  tank_3_50 = bitRead( buttonState, TANK_3_50_PIN);
  tank_3_100 = bitRead( buttonState, TANK_3_100_PIN);

  // Read tank 4 sensors
  tank_4_20 = bitRead( buttonState, TANK_4_20_PIN);
  tank_4_50 = bitRead( buttonState, TANK_4_50_PIN);
  tank_4_100 = bitRead( buttonState, TANK_4_100_PIN);
}

// It is set up for ACTIVE HIGH devices
void updateRelayStatus() {
  // USE `` ! `` WHEN USING "' ACTIVE LOW '" DEVICES
  digitalWrite(SOLENOID_VALVE_1_PIN, solenoid_valve_1_on);
  digitalWrite(SOLENOID_VALVE_2_PIN, solenoid_valve_2_on);
  digitalWrite(SOLENOID_VALVE_3_PIN, solenoid_valve_3_on);
  digitalWrite(SOLENOID_VALVE_4_PIN, solenoid_valve_4_on);
  digitalWrite(WATER_PUMP_PIN, water_pump_on);
}


// ************************* Shift Register Func. *************************

void read_state(){
  // Give a pulse to the parallel load latch of all 74HC165
  buttonState = 0;

  digitalWrite( latchPin, LOW);    
  delayMicroseconds( pulseWidth);
  digitalWrite( latchPin, HIGH);

  for( int i=8; i>=0; i-=8)
  {
    buttonState |= ((uint16_t) ReadOne165()) << i;
  }
}

byte ReadOne165()
{

  byte ret = 0x00;

  // The first one that is read is the highest bit (input D7 of the 74HC165).
  for( int i=7; i>=0; i--)
  {
    if( digitalRead( dataPin) == HIGH)
      bitSet( ret, i);

    digitalWrite( clockPin, HIGH);
    delayMicroseconds( pulseWidth);
    digitalWrite( clockPin, LOW);
  }

  return( ret);
}

// ********************** Shift Register Func. --end ***********************







// INTERRUPT FUNCTIONS :- ISRs  (INTERRUPT SERVICE ROUTINE)s

void STOP_ISR() {
  Loop_Status = false;

  led_state = LOW;
  digitalWrite(A0, led_state);
}

void START_ISR() {
  Loop_Status = true;

  led_state = HIGH;
  digitalWrite(A0, led_state);
}